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Forum: Pentax SLR Lens Discussion 09-08-2016, 12:50 AM  
F Series Porn
Posted By LennyBloke
Replies: 34
Views: 4,022
For Autofocus they are excellent - rapid, almost violent when focus locking, but accurate. If you're a Wildlife photographer then the F series aren't the best, the AF is pretty noisy and would probably scare off a Bear ;)
Manual Focus is a bit strange - the MF ring is pretty narrow on most F's and very "free" - it's easy to knock something back out of focus if you're not careful.

The overall feel of the F series is pretty solid - I like the rubberized feel of the barrel cover and the feeling of metal beneath. In terms of looks, they tend to split opinion - as some have said in this thread I think they look great but I know many think they look cheap. There are a few F's that look a little different (the 10-17 and 100-300?), but I don't have much experience with them.

I use most of them fairly regularly simply because I enjoy them - every now and then I have a trip that I take a selection of "F only" lenses...
F in Stratford | Flickr
The biggest limitation is that 28mm is the widest prime (although the K1 would solve that problem for me ) and I do like to go a little wider some of the time.

The 2 zooms get very little use now (since buying a DA*60-250 I rarely use any other long zoom), nor does the F50/1.7 (just because the F50/1.4 is my first choice) - but the F*300 is my clear winner at that length.

Overall they are a pleasure to View and to Use :) :) :)
Forum: Pentax SLR Lens Discussion 07-18-2016, 09:03 PM  
My DA Limiteds on the K1
Posted By Paul the Sunman
Replies: 27
Views: 4,976
For anyone trawling this old thread for information on the how DA Limiteds perform on FF, I have done some more controlled testing (shooting the brick front of my house). My results are basically consistent with what was stated earlier in this thread.

DA 40
With or without hood, there is not much vignetting. However, wide open (f/2.8) the corners are extremely muddy, and not really useable unless they are already a long way out of focus. This gradually improves with stopping down, is still very apparent at f/4, but good by f/8. It continues to improve beyond f/8. I recommend shooting the DA40 in FF mode, but cropping as required. Even at f/2.8, the "good" area is much bigger than APS-C.

DA 70
The DA 70 Limited is sharper in the corners than the DA 40 at all apertures, though they are noticeably darker at f/2.4. The vignetting is rectified in LR by clicking on "Enable Profile Corrections". Comparing with a "proper" FF zoom at 70mm (the D FA 28-105), the DA 70 Limited is much sharper at frame centre, but less sharp in the corners at all apertures. Results are the same with and without hood. Even on APS-C, the DA 70 is not noted for it's "across the frame sharpness"; it is essentially a portrait lens. This is certainly the case on FF as well, where though it remains very useable.
Forum: Pentax SLR Lens Discussion 07-03-2016, 09:50 AM  
My DA Limiteds on the K1
Posted By micromacro
Replies: 27
Views: 4,976
It's custom crop, yes, for maximum preservation. In my opinion, shooting in crop mode with DA 15 is easy way to adjust the image in LR, and the area is almost the same, but I don't need to deal with tonal editing. I'm going to search my images, if I have two similar in crop mode and FF, I will post them to show.

Here. The first one is crop mode.
The second one is FF mode, basically from the same distance.

I love DA15ltd, but it almost hurts :) to see how much frame is missing one way or another.
Forum: Pentax SLR Lens Discussion 07-03-2016, 12:35 AM  
My DA Limiteds on the K1
Posted By Paul the Sunman
Replies: 27
Views: 4,976
I have finally had a chance to try out my beloved SMC DA Limiteds (15, 40, and 70) on the K1. Although they are all officially crop lenses, the latter two at least have shown signs of being able to migrate to FF. So here are my findings, with representative images.
  • DA 70 Limited definitely FF compatible (1/160, f/8, ISO100)


  • DA 40 Limited little vignetting but a bit muddy in the extreme corners (fine on the edges); useable-to-good (1/40, f/11, ISO100)


  • DA 15 Limited forget it (1/30, f/4, ISO1250)



The DA70 and DA40 were with hoods; the DA15 without. Using the hood on the DA15 vignettes much more.
Forum: Pentax SLR Lens Discussion 05-29-2016, 09:05 AM  
Head to Head comparison between FA 31ltd and Sigma 30mm f/1.4
Posted By kp0c
Replies: 7
Views: 2,227
I had the 31mm for a little while and now have the much cheaper (older withough HSM) Sigma 30mm 1.4.
First, the Sigma is APSC only, maybe it matters to you, maybe not. The 31mm is of course a FF compatible lens.
I haven't use the 31mm enough to give you a faire comparaison, so I won't do that. I'll however comment on sharpness and share some other random thoughts.
The Sigma is as sharp wide open as any f/1.4 lens I've seen. I will say however that I only use the lens wide open at relatively close range, for portraiture and similar application, so well within 8 meters. Beyond that, it's probably fine as well. Not that I would shoot at infinity and wide open. The center focus point is dead accurate on my K-5ii (I may have calibrated the lens, but that's something I do with all of my lenses anyway). I never noticed any problem with off center point either, but I mostly use center point. The focussing is about as fast a other screw drive lenses in that focal range, maybe a little slower than the DA 35mm 2.4, but nothing to complain about on my side.
As mentioned before, I use the Sigma for portraiture, low light indoor photojournalism and other indoor assignments. I never use this lens hoping to get edge to edge sharpness, so I wouldn't even be able to tell you how it fairs in that regard. Some people say corners and edge are terribles, I've never notice it, but my edges and corners are usually oof anyway.
About rendering, I absolutely love the shallow depth of field this lens provide and I haven't notice any problem in the bokeh either. I don't think it has a lot of character, meaning it seems "normal" most of time. To better explain, I'll try to compare with other lenses. The DA* 55mm 1.4 in comparaison sometimes offer Bokeh that will make you look twice and go "wait, what just happened?" because the Bokeh is either very nervous, or looks strange in some way. It's not a bad thing, but it happens. My 50mm f1.7 will also offer some strange, but lovely, Bokeh as well sometimes. It seems to me the Sigma is more constant in that regards, in the context I use it in anyway. I honestly think it doesn't offer anything crazy, but that it does offer very nice images for a good price and I'm perfectly happy with it. I will say however that I'm never tempted to use it outside in good light condition as I just don't think it would make the image pop as a limited like the 31mm would. But for indoor low light stuff, I think it rocks really good.

The FA 31mm offers a rendering that is more complex to me. I was looking at some shots I took wide open with it and couldn't help but look twice at most of the images. Most of them were snapshots of my kids doing their things, or picture in a book store, etc. I don't know if it was the colours, the contrast, or simply the presence of subtle chromatics aberrations in the transition from in focus to the out of focus zone that made the image special but truth be told, even after selling the lens, I could tell it produced some "special" images for me. Also, when I had it, I was more compelled to use outdoor - I think the coating made for better images of the outdoor colours.

I don't know what you would use the lens for (do tell us if you have an idea, it may help people offer you comparison), but I can recommend the Sigma for anything low light as I believe it offers good sharpness at 1.4 and pleasant bokeh, without being a complicated lens in my view, like some other lenses are. (For instance, I find hard to like the DA 70mm 2.4, but it sometimes just offer me that very nice picture that convince me to keep it, even if I own the 50-135mm that covers the 70mm focal length and is about as fast of a lens (although much bigger, of course!).
Forum: Pentax SLR Lens Discussion 05-27-2016, 11:18 AM  
Diglloyd reviews DA 35, DFA 50 and DFA 100 Macro lenses on the K-1
Posted By MadMathMind
Replies: 19
Views: 4,337
I'm starting to question the value of professional reviews. They do tell things like "they are" but "like they are" tends to focus on really small details and performance and trying to get 40MP of image out of a 36MP camera. So much emphasis on resolution...so much emphasis on resolution and MTF charts. Most of the discussions you see around the web break down to pixel counting. And what happens at maximum aperture because so many people subscribe to the "It's a 1.8 lens so it should be shot there or it's a waste. And all portraiture must be done below f/2.8." I guess that is what 'the people' want to read?

I'd really like to think professional photographers are above MP counting and pixel peeping arguments but I guess not because if they weren't, these articles wouldn't be written. Or is that the point? They're not written for them and instead written for the guy who shoots with a 5D Mark III simply because it costs more and is therefore must be necessary. I learned Canon made a 50mm f/1.0 lens for $6000k+...but why? I can't imagine anything anyone would need this for....or heck, even want it. But I'm sidetracking.

Let me start over. Who are reviews written for these days? The stuff that's in them can't be for professionals; anyone who needs all that resolution should be shooting MF. So instead, we have products designed for....people with too much money on their hands? People who are not succeeding in the 'business' and think better lenses and more pixels will get them there? That could just be the forum audience. That would make sense. Certain reviewers become popular because they focus on a certain quality of the product that the people who are likely to read these reviews care about.

It's not the say that the bloggers have driven the megapixels war. Somewhere, people wanted this as the screen sizes increased because viewing an image at 30% makes it look better than at 75% and that can greatly hide your lack of skill. I find it interesting that there's still so much emphasis on MP at all, as the hype over the 5DR/s shows us. Aside from the few magazines and other print media, 'normal people' just want to put their pictures on Instagram and Facebook. Heck, over 50% of my Flickr viewership comes from phones. Resolution is becoming less important because the screens are shrinking. The pixel counts on them are going up but at some point, they're too small to see the difference. Once you get 10 good MP, that probably does it for the way most people consume images.
Forum: Pentax SLR Lens Discussion 05-12-2016, 07:03 PM  
DA* 55mm vs DA* 50-135mm AF speed
Posted By kp0c
Replies: 9
Views: 1,207
Alright, testing with only one body is rather difficult, but I still did a quick and dirty test that hopefully will help you assess the situation, at least a little bit.
Camera : Pentax K-5ii
Focus mode : single center point
Light level : fairly dim, all indoor lightings, settings for proper exposure were about iso 2000-3200, f/2.8 at 1/125th of a second
Target : the side of a grey shoe box with big letters, about 4 meters away

Approximate results:
Times are in seconds. So, in this case, 0,51 means 51/100th of a second. I think it makes sense, I just used my editor (Final Cut) timeline to approximate the time.




*It failed to acquire focus, I had to repress the shutter, then it acquired focus. I repeated several time and it was just a lone incident.

video :
I'm sorry for the video. I tried to do something quickly that would allow for an "easy" visual comparison, but I quickly realized it would take me a lot of time to make it right, so I ended up doing something that I find pointless, but some of you may benefit from it, so I post it anyway. However, I figure you could just ask me for the original videos and you could then sync them yourself and maybe time them on a more precise fashion.
















Youtu.be





Finally :
While I had the camera set up, I figured I would test some other lenses that might be of interest for portrait work, or for general AF speed concerns.
Therefore, I have similar videos for the following lenses, all taken minutes from each other in the same light condition, at the same approximate distance of 4m :
Pentax DA*55mm f1.4
Pentax DA* 50-135mm f2.8
Pentax DA* 60-250mm f4
Pentax DA ltd 70mm f2.4
Pentax F 50mm f1.7

If you would like access to any of the videos to make your own comparison, just pm me, I'll send you a link for download.

I have not calculated the time for the other lenses, but I plan to do it eventually. The F 50mm 1.7 seems quite fast.
Forum: Pentax SLR Lens Discussion 04-14-2016, 12:32 AM  
Disappointed by the 20-40mm Limited
Posted By DSims
Replies: 36
Views: 4,129
Outis, don't feel bad - it's really not a special lens. The fact that it's now discounted almost 50% may be a clue (although lenses like the 100 WR Macro are an exception to this idea). If we could see 5-10 years into the future at the comparative used prices of this lens we'd get a clearer idea of how good it is - I'm thinking around $300 (or maybe less) for this one. But of course you can simply judge with your own eyes right now.


You have 3 great Ltd primes - 15, 31, and 77 - all of which I've owned. This isn't in their league.


Those who have this lens and like it, just ignore me and keep on loving it - no harm done and you can continue to be happy. But I've never seen anything special out of this lens. I'd much rather have my FA20-35/4 back, if I needed such a lens. For that matter, I also prefer my F24-50/4.


No, I haven't owned this lens, but after owning 20 or 30 of the best Pentax lenses (I lost count) and diligently studying others' photos before purchasing them, I gained a pretty good understanding of what a lens would give me - even before it ever arrived. This is not a lens I would purchase.

So don't feel guilty Outis. I don't think you're missing anything here.
Forum: Pentax SLR Lens Discussion 11-04-2014, 04:56 PM  
Square Bokeh modification to Helios 44-2 (Tutorial)
Posted By stubyles
Replies: 18
Views: 15,204
Ok, so I've been modifying the ubiquitous Helios 44-2 to give it an aperture that produces square bokeh.
This is not a cardboard cutout in front of the lens but an alteration to the aperture blades.
Below is the whole process with lots of pictures.

A word of warning before we start:
This procedure is not a complex idea, it's simple, But it requires a high level of technical skill. It is very tricky and there is a high probability that most people who are not used to taking fiddly things apart and altering them will screw-up their lens. That being said, these are not expensive lenses so a replacement will not break the bank.

I would not advise starting with your best Helios (if you have more than 1), if your 1 and only helios 44-2 is in great condition then you might want to buy another one for your first attempt.

By the way, this will only work with the Helios 44-2 which has 8 blades anchored at each end.
There may be other lenses where this is possible but I haven't found any yet.

I will not be held in any way responsible if you screw up your lens, you have been warned.

If you don't feel comfortable taking on this task you may find one of these lenses (and maybe some other interesting lenses) for sale on my ebay account here:
superchameleon | eBay


First off we need to release the focusing mechanism from the optical assembly. This just unscrews. Hold the lens by the base and unscrew the optical assembly using the preset aperture rings (if it's never been taken apart it might need a sharp turn to start it, it's a normal thread - anti-clockwise to release)



Put the focussing assembly to one side.



Unscrew the rear lens assembly and put it to one side (being careful not to scratch the glass elements).


Now take note of the amount of thread protruding from beneath the aperture ring (where the screwdriver tip is pointing), you'll need to get this right when re-assembling the lens (taking a photo of this part will be useful).



Now remove the aperture ring limiting screw with a flat screwdriver.



Then carefully remove the aperture actuating screw (this is screwed into a plastic ring so be gentle).



Unscrew the aperture ring (normal thread), holding the preset ring.




Clean off the grease from the threads and locate the grub-screw which holds the aperture assembly in place, unscrew this grub-screw (be careful it's very small and easy to break).



Now you can unscrew the aperture assembly from the front optics.



Note the position of the screw-hole in the plastic aperture ring through the cutout in the side of the aperture assembly.



Carefully release the spring-clip and remove it from inside the aperture assembly.




Carefully lift out the plastic aperture ring.



Now you can see the aperture blades, note the orientation of the blades (another photo here would be advisable).



Tip the blades out onto a suitable surface, you may have to use a small screwdriver blade to gently push the anchor pins through from the other side.



Gently wipe any oil from the blades with a soft absorbant cloth.



Now the modification:
I've used a five pence piece (approximately 18mm diameter) clamped onto the blade, equidistant from each end and covering approximately 2.5mm of the blade width at the middle. Do not cover too much of the blade or you will weaken it too much.



Now with a scalpel cut round the coin making sure to keep the blade against the coins edge. It will take several scores to cut the blade, start gently and increase the pressure with each score until the free (exposed) part of the blade comes away by itself. you must not bend the blade.




Using the flat scalpel edge angled down and flat against the blade, smooth the edge of the blade, trying not to apply to much force which will curl the blade up. The flatter you keep the blade here, the easier it will be to re-assemble the blades.



This is what the part under the coin should look like.
Repeat this procedure with 3 other blades.
You should end up with 4 modified blades and 4 untouched blades.



Now re-assemble the blades in the aperture assembly, alternating between modified and untouched blades (this may take several tries, remove small children and other sensitive souls from the room). Make sure the blades are oriented the correct way.



Next place the plastic aperture ring back over the blades, note the orientation of the screw-hole compared to the cutout in the aperture housing. You may need to carefully re-position the blade pins with a small screwdriver into the slots in the plastic ring.



Replace the spring clip, positioning the gap opposite to the cutout in the aperture housing, make sure it is properly seated in the groove in the housing (you should be able to rotate the clip easily).



Now if you carefully rotate the plastic ring the aperture should open and close easily. If you've got it right you should be feeling very smug right now.



Screw the aperture assembly back onto the front optic assembly.



Replace the grub-screw



Screw the aperture ring back on refering to the picture you took of the protruding thread.



Replace the aperture actuating screw being careful not to over tighten it (you're screwing it into the plastic ring).




Replace the aperture ring limiting screw making sure it finishes flush.



Screw the rear optical assembly back in, tighten gently with lens spanner if you have one.



Screw the optical assembly back into the focusing assembly fairly tightly.


Et Voila! you now have a Helios 44-2 that will produce lovely square bokeh.

Enjoy.

If you haven't managed this mod successfully or if you don't feel comfortable taking on this task you may find one of these lenses (and maybe some other interesting lenses) for sale on my ebay account here:
superchameleon | eBay
Forum: Pentax SLR Lens Discussion 02-10-2016, 11:57 AM  
Another FA 77 question
Posted By a5m
Replies: 28
Views: 2,293
If you buy a new one it'll be an Assembled in Vietnam (AIV) copy, and it was probably manufactured fairly recently - I'd guess within the last year or two. Pentax doesn't make lenses in Japan anymore.

As far as the differences go, people will generally tell you there are no differences. Some people just prefer a MIJ copy because of the perceived notion that things made in Japan are of higher quality. I mostly agree, but I read somewhere that the very early 77 Limiteds had a different design of something relating to the focus mechanism, and it was faulty in one way or another so they updated and revised it. IMO you're probably better off buying a new one, or if you prefer MIJ, a relatively new used copy.

BTW this is a topic that has come up several times so people generally don't respond to it very positively. If you had gone through all the topics on the AIV vs MIJ discussions you probably wouldn't have started this thread.
Forum: Pentax SLR Lens Discussion 02-02-2016, 04:31 AM  
Practical shutter speed limits?
Posted By amoringello
Replies: 11
Views: 1,063
The physical shutter mechanism on a Pentax DSLR has a limit of about 1/180 second.
The extra "speed" comes from the reduced space between the "first curtain" and "second curtain" to create a light-limiting effect of 1/8000 shutter speed.
This cannot capture very fast moving objects in the same manner as an actual shutter sped of 1/8000. i.e. you may get smearing, tearing or bending of objects as they move through the frame.

Better to capture with relatively long shutter speed, low to no ambient light and a very quick flash duration.
Forum: Pentax SLR Lens Discussion 01-29-2016, 01:18 PM  
I got a new PRIME lens......
Posted By JML69
Replies: 17
Views: 1,962
Installed in my right eyeball after Cataract surgery this week and WOW I can't believe I waited this long to have it done. :D It's like going from a kit lens (not that there is anything wrong with them) to a DA* lens. Now I have to re-learn how to use the camera with my right eye until March when they are installing the left eyeball.

If anyone is on the Fence about this procedure, don't be, it is unreal how quick and painless it is for the results you will get.

Now I am going to go make an Adult Beverage and take some crappy bird pictures.....:o
Forum: Pentax SLR Lens Discussion 01-27-2016, 04:34 PM  
And down the Limited rabbit hole I go....
Posted By robthebloke
Replies: 24
Views: 2,049
The DA21 is a great little lens. It's not a macro, but the minimum focus distance means it quite often feels like it. It's not a portrait lens, but it can do a very good impression of one. Stopped down to F8, and it becomes a very sharp landscape lens. At minimum focus distance, field curvature can cause minor problems in the corners (the DA15 is worse in this respect); the SMC version can suffer from busy bokeh in some cases; and at f3.2 it does need a dash more ISO in low light than I'd like. None of those minor gripes should put you off though. I've owned it for almost 5 years now, and whilst it may not be a 'perfect' lens, it is extremely capable, and extremely versatile. Of all the FA and DA limiteds (I own all of them) it's by far the most versatile, and possibly my favourite of the lot (Once I get my hands on an FF pentax, I suspect the FA31 may reclaim that title though....)
Forum: Pentax SLR Lens Discussion 01-26-2016, 09:13 AM  
DA 15/4 vs Samyang 16/2 - advice wanted
Posted By northcoastgreg
Replies: 30
Views: 4,591
While I don't own the Samyang 16mm, I do own a couple of other Samyang derived lenses (the 10mm and the 7.5mm fisheye). Generally speaking, what the Samyang lenses provide is fast apertures and very good edge to edge sharpness. They also are fairly well corrected for coma, and therefore make good astrophotography lenses. The DA 15, on the other hand, suffers from fairly wide field curvature, reduced resolution toward the edges, and fairly significant coma. Plus it's f4. While you could probably get fairly decent astrophotography images out of the lens (if you used OGPS1 and cropped out the offending edges), it's obviously not the best tool for that particular job. Where the DA 15 excels is in the aesthetics of the image: color, contrast, rendering. It's a true art lens (as opposed to the Sigma "Art" lenses, which are, in reality, high performance, rather than "art" lenses). With its superb flare control, it captures more color data (and enhances that which it captures) than any of the Samyang derived lenses. The consequence are images that look great and perform very well when it comes to the aesthetics of the image (although you may be sacrificing a bit on the edge and corner resolution). In comparison, the colors that come out of my Samyang 10mm seem flat and uninspired; nor can all manner of PP tricks (e.g., cranking up the saturation) make up for the difference.

If you're planning on getting a lens primarily to do astrophotography, get the Samyang 16mm. If you're primarily going to use the lens for non-astro photography, get the DA 15.

Also, keep in mind: even if you choose to get the DA 15, that doesn't mean you can't get one of the Samyang lenses (either the 16mm, the 14mm, or the 10mm) for astrophotography further on down the line, when your budget allows for it. The 14mm is cheaper than the 16mm and is FF, while the 10mm would provide a complimentary FOV to the DA 15.
Forum: Pentax SLR Lens Discussion 01-26-2016, 08:58 AM  
DA 15/4 vs Samyang 16/2 - advice wanted
Posted By csa
Replies: 30
Views: 4,591
Is this really fair to the seller? I can see returning a defective lens, but taking one on vacation to use for free, then sticking the seller by returning it because you now have no need for it?:(
Forum: Pentax SLR Lens Discussion 01-19-2016, 01:16 PM  
Need Wide Lens Recommendation
Posted By Nicolas06
Replies: 96
Views: 7,475
Nah, you really need an UWA to get anything done.

Impossible to get any architecture shoot with a tele


F135

IMGP5076 by Nicolas, sur Flickr

FA77

IMGP2359 by Nicolas, sur Flickr

And landscapes? An UWA or nothing. Also remember you always need to have lot of detail in the shadows. That's a D810 or nothing

F135

French riviera sunset - in explore - by Nicolas, sur Flickr

FA77

IMGP4974 by Nicolas, sur Flickr


For a walkaround in the city the same, WA and UWA rules

FA77
I
MGP5424 by Nicolas, sur Flickr

FA77

IMGP5439 by Nicolas, sur Flickr

And of course, never portrait orientation for a landscape. That's nonsense. Ah and yes, never contra light , it ruin any shoot.
DA15 this time.

IMGP9623-HDR by Nicolas, sur Flickr
Forum: Pentax SLR Lens Discussion 01-18-2016, 02:15 AM  
Need Wide Lens Recommendation
Posted By Digitalis
Replies: 96
Views: 7,475
You can get shots with the sigma 8-16mm that few other lenses could pull off. If you want to go really wide, there isn't anything that is really like the 8-16mm.

While it is true that super wide angle lenses are specialized, and typically see less use than normal focal range zoom lenses: they are a lot of fun to work with.


PentaxK5IIs - Sigma 8-16mm f/4.5-5.6 EX DC @ 8mm 1/320th f/16 ISO160


Pentax K5IIs - Sigma 8-16mm f/4.5-5.6 @ 12mm ISO80 1/30th f/11

Though I will warn you - it is possible you might have to go through a few copies of the 8-16mm to find a good one. I went though four which were all de-centered, my fifth and final copy which was sent to me from Sigma Japan is superb. The DA15mm f/4 seems to have lower sample variation in this regard.
Forum: Pentax SLR Lens Discussion 01-17-2016, 05:00 AM  
Need Wide Lens Recommendation
Posted By Nicolas06
Replies: 96
Views: 7,475
Basically I have the 10-17 (surprise present from my father for Christmas) and the DA15 ithat I used for 1.5 year. I also have the 21 and I have mostly primes like you.

For WA, depending of subject I use the 21 or 15, in a sense you might want to cover both focal length as 21 is quite moderate still natural look and 15mm is already an UWA with some extreme perspectives.

What I like about the 15 is that it is very small and light and it has almost infinite flare resistance and outstanding constrast. It is already quite large field of view and for landscape a pano is quite easy to do with Microsoft ICE 2 (much better than the one) and free. The DA15 is in a sense narrow enough to still be usable in many situations and small enough you can have it always with you in case of need. That not the case to me of the zooms even the 10-17 that while small is already bigger. For somebody that shoot wide only on the occasion I find the compromize quite good.

The DA15 is very sharp closed down on center but tend to be soft on corners due to field curvature. That if you focus on center, the border might not be in focus and a bit blury. It depend of the sample but many are affected. For my current one the right top border show it a bit more than the other borders and basically if the scene on border is less distant than the center focus distance then it will be in focus, but if it is more distant it will be out of focus. You might get a perfect sample, but it is not that common.

Still the picture taken with it are great and the center performance mean you quite crop it to get a wide field of view like to match 21-22mm... Done it quite a few time, no issue. But I would not crop more than that don't expect to get a nice 25mm picture that would be asking too much of it.

I still didn't process the 10-17 pictures but let say they are very special. The lense look like very contrasty and sharp on center and a bit soft on border, but that was to be expected. On selected subject I guess it shine, got a few shoot, but still it is not a a do all lense.

To me the DA21 is the best WA lens we have overall as a compromize, even smaller than the 15, you can fully forget it. Great colors, picture quality, nice field of view that is not extreme at all, it fit many subjects, but when you want really wide, it will be more limitating than the DA15. You can do a pano sure, but you'd have to do that in many more case and that could be annoying. So I can see a benefit to have only a used 15 in the pocket to have really some wide alternative. The 31 can anyway do already a good third of the shoot the DA21 would do while the DA15 would do another third quite easily.

PS: On WA, it is important to get the perspective right for buildings and alike and/or to correct them in post. I typically do that.

A few DA15 examples, you can always click to go to flickr and download the full high rez pictures:

Wide open at f/4 (an error), 1/1000:

IMGP9434 by Nicolas, sur Flickr


IMGP0120 by Nicolas, sur Flickr


Sevilla - Metropol parasol by Nicolas, sur Flickr

Croped to 18-19mm, iso 400, f/5.6

Sevilla - Metropol parasol by Nicolas, sur Flickr

A pano sticked with Microsoft ICE 2 (free) from arround 10 pics. We are not far from a 180 view horizontally.

IMGP9652_stitch by Nicolas, sur Flickr

A high iso shot, blur and vigneting added in post on borders:
DA15, iso 2500, f/4, 1/10s

IMGP2820 by Nicolas, sur Flickr
Forum: Pentax SLR Lens Discussion 01-16-2016, 07:38 PM  
Need Wide Lens Recommendation
Posted By Scorpio71GR
Replies: 96
Views: 7,475
I have been debating this myself for awhile now. I have the 16-50 which is an excellent lens but on ASP-C 16mm sometimes just is not wide enough. I also have the 10-17 which actually was my first DA lens. The 10-17 is an interesting lens. It can be very fishy at times and other times not fishy at all. From 14-17mm it is nearly rectangular if you position the lens just right. I am not sure how well in camera corrections can handle the distortion though. I correct the distortions in post. The nice thing about the 10-17 is that stopped down it is very sharp and it is so small you can take it anytime. I also have the 21 limited which is just a fine piece of glass. I wanted a 15 limited but got the 21 on really good buy. If I need to go wider I can stitch the shots and it works fine. I had a Sigma10-20 4-5.6 on loan and really liked it. The size is not too large and it takes the same 77mm filters my 16-50 takes. I did find some distortion at 10mm in the corners but nothing I could not handle in post. I never had a 12-24 but to me 12mm is really not wide to call it an UWA. There is a huge difference between 12mm and 10mm. Of course with the 12-20 you get that Pentax pixie dust. I have never seen a 12-24 go for less than $400 though.

Since I have been watching lenses this is what I have observed.
10-17, small, easy to fit in the camera bag, 14-17mm is not really fishy, 10-12mm distortion can not be fully corrected, nice IQ when stopped down, $300 new.
12-24, larger lens, heavy, covers more at the longer end for OP seems not so important since he sold his 16-50, excellent IQ, used usually goes for around $450-550.
Sigma 10-20 4-5.6, size is not too large, takes 77mm filters, nice IQ when stopped down, 10-11mm can have some corner distortion easy to fix in post, IQ quality can very copy to copy make sure you get a good copy, $250- $350 used.
Sigma 10-20 3.5 essentially the same as the 4-5.6 in terms of IQ, larger and heavier, takes 82mm filters, HSM focusing, better focusing in low light especially at 20mm f3.5, rarely see one used, $450 new
Da 15 small easy to take with you, it is a limited nothing more needs to be said use it and fall in love with it, smc version gives better starbursts, smc used usually right around $270-$300.
Tamaron 10-24 Widest focal range if UWA zooms, IQ is good when stopped down, can suffer corner sharpness, used around $350 when you can find one.

I have been debating what lens to buy for awhile now. For me it comes down to two, the DA 15 or the Sigma 10-20. Both have their advantages. The Sigma 10-20 3.5 at $450 new is quite tempting since you get a 4 year USA warranty with it too.

21 limited smc on the K3

Blue Bridge.jpg by Michael, on Flickr
21 limited smc Two shot pano

Great Egret Landing-4.jpg by Michael, on Flickr
10-17 17mm K50

Moon Over The Blue Bridge-2015-1.jpg by Michael, on Flickr
10-17 15mm K3

Blue Bridge In Purple.jpg by Michael, on Flickr
Yes it is a fisheye and sometimes that is fun too, 10mm K3

Fredrick Meijer Gardens-2015-1.jpg by Michael, on Flickr
Forum: Pentax SLR Lens Discussion 12-29-2015, 09:49 PM  
Poll: Are you 50mm or 35mm fella?
Posted By Scintilla
Replies: 20
Views: 1,795
You know, I actually had to get out my kit lens to answer this question. Just looking around my computer room, it turned out that the 24mm setting seemed to agree best with how I naturally saw things, so I guess my answer would be "35mm". That also means I have an excuse to keep cursing Pentax's lack of affordable primes between 21 and 35... :p

However, though I know this isn't what the poll was asking, I think that closer to 40-45mm feels more natural sometimes, because it means that what my left eye sees through the viewfinder is close to the same size as when I take the camera away.
And if we're talking about how natural I perceive the final results to be, I'd probably be okay with anything in the 30-50mm range. The 21 strikes me as clearly wide angle, the 28 is just barely trying too hard to get more into the frame, but on the long end sometimes even the 50 doesn't jump out at me as looking compressed.

But honestly, I'd never really thought about it before. I just know what lenses I like: if the result grabs me in some way, I don't particularly care how close to my naked eye the FoV comes. Of all the normal-ish-on-APS-C lenses I have, most of them I didn't get for their particular focal lengths:
  • I got the A 50/1.7 because it was cheap

  • I got the M 28/3.5 because it was cheap and the A 50/1.7 wasn't wide enough for landscape

  • I got the Rokinon 35/1.4 because I discovered the A 50/1.7 was too tight for most indoor uses

  • I got the FA 43 Ltd mainly to see what all the fuss was about (and now it's pretty much completely supplanted my A 50/1.7)

  • Same with the CZ Distagon 28/2.8 and CZ Planar 50/1.7 -- and I had no particular preference at the time between the 28 and 35 Distagons; the 28 was just what I managed to get first on Ebay

Forum: Pentax K-3 05-31-2015, 02:59 AM  
Implementing automatic artifact removal from PS shot in dcraw
Posted By tomtor
Replies: 12
Views: 2,084
I finished an initial version:

http://www.v7f.eu/public/pentax/dcrawps.c

Example usage:

dcraw -T -4 IMGP0121.DNG

IMGP0121.DNG was posted with other files in this thread:

https://www.pentaxforums.com/forums/172-pentax-k-3/296122-k3ii-pixel-shift-first-test-5.html

By default it wil detect artifacts by unexpected changes in the green channel.
Artifacts are repaired by the bayer interpolation on the first image.

-G sets the threshold, by default 10%. -G 1000 will disable, -G 20 sets the threshold to 20

By specifying -v it will highlight the spot in purple. This can also be usefull if you want to repair manually.

The example file has a moving tick :lol:

-- edit --
And a compiled windows version:

http://www.v7f.eu/public/pentax/dcrawps32.exe
Forum: Pentax SLR Lens Discussion 03-17-2015, 10:58 PM  
prime, prime, everywhere a prime...
Posted By alamo5000
Replies: 11,613
Views: 589,272
My opinions on that are as follows:

If you are shooting low light then yes there is a noticeable difference. That said, don't be shy to experiment kicking up the ISO a few notches.

As for focal length, on a crop camera I tend to like the 28mm to 35mm focal length better but it depends on the shot. There is no one perfect lens. That's why most of us have a 'collection' rather than 'a' lens.

There is a lot to be said for old manual glass. I love my auto focus but manual glass has benefits too. It will definitely get you out of point and shoot mode if you use a manual lens.

To me the three most important parts of a photograph are subject matter, lighting, and composition. Each one can have volumes written about them. Gear comes way down on the list.

As a learning tool though let's take lighting for example.You're going to have to screw up a lot to start to learn. But which lens you choose on a particular day can help you learn. Try doing things like shooting at different times of the day. Try shooting in different weather not just bright sunshiny perfect days. It will eventually become an exercise in observation. If you really look around you will see interesting shadows and little nooks and crannies where an interesting shot could be made. You will see that if you shoot at high noon you get one thing, if you come back at 6pm you get another, and if you run out 2 minutes before a down pour you will get yet another... all of the same subject.

If you use it right the manual lens will force you into observation mode. You might only take 5 shots, but if those 5 are well thought out it's better than 100 random clicks.

An auto focus lens allows you to react faster but it also allows you to learn about how your gear sees the world and how it reacts. You will eventually be able to say that under X type of light I will get Y type of result.

The third part of this is to experiment with shutter speeds and apertures at different lighting conditions. Try to create different effects. Try to darken the background or lighten the background or try for even lighting. Use a variation of combinations of different shutter speeds and apertures to get different effects. This can much more easily be done with an AF lens because you are only worried about how the controls effect the results and you can quickly change on the fly and it gives you almost instant feedback.

I think using a variety of manual/auto lenses helps IF you let it help you.
Forum: Pentax SLR Lens Discussion 03-17-2015, 07:28 PM  
prime, prime, everywhere a prime...
Posted By UncleVanya
Replies: 11,613
Views: 589,272
Curious what your background is in photography? Are you an ex-film geek like me or new to the whole thing?
Also what is your budget?

In the meantime let's see about these questions.

1) 35 vs. 50. The answer as indicated by others is accurate; this is a big difference. If you have the kit lens you can show this to yourself by taking a day to shoot nothing but 35mm or 50mm and then another day with the opposite requirements. The fact is that 50mm was the "Normal" lens on old film 35mm or current "Full Frame" digital cameras but on APSC which is the size sensor you have on the K50, the "normal" lens is a 35mm. The 50mm is more of a short telephoto and portrait lens (just at the low end of that range) However with room to move back this is less of an issue - indoors it is a problem, outdoors not so much.

2) AF vs. Manual. You will get many answers but MY answer is get the AF lenses for now. The ability to manually focus on the K50 is so so, through the use of Live View you can do focus peaking and you can use focus confirmation via the viewfinder but these are a poor substitute for split prism focusing screens like we used on manual film bodies.

3) Religion vs. Science. A lot of cult like info exists and few people take the time to be careful to directly compare old primes vs. today's lenses. There are many fantastic lenses of all ages - and some of the things that drive the acceptance of a lens vary from person to person. As an example, many older lenses exhibit significant purple fringing. Modern lenses are designed with this in mind and often (but not always) perform better in this respect. This is just one of many factors.

Now back to the start; a prime to fulfill these functions on APSC here is what I think of for each:
Portrait - typically between 50-135mm and large fast opening f/2.8 or better
Walk about - typically between 20-50mm (or larger range) and medium fast opening f/2.8 preferred but not required
Landscape - typically between 10-20mm and speed is not important since most shots will be f/8 or slower.

The point is these are three completely different optimizations. The specific focal range and f/stop can vary and there are plenty who would have different opinions, the point of my listing them is to give some guidance not to set anything in stone.

In terms of price I don't think you really set your budget out but let's talk about options.

A)DA 50 f/1.8, F/FA 50 f/1.7 - Long but usable for walk-about, fast enough for that and just long enough to use for portraits. F is the sturdiest, DA is the cheapest and most modern optimizations. All of these almost the same.

B) DA 35 f/2.4, DA 40 f/2.8 (Limited or XS version) - fits the walkabout category, fast enough, not too tight for "normal" perspectives. Doesn't provide that classic rangefinder street photography angle of view that the DA 21 or an FA 24 would provide. These lenses also fit the walk around but are more expensive.

C) Nothing particularly cheap in the landscape class that stands out. The DA 15 is fantastic but not cheap.

There is no single lens PRIME option that fits all of these but a two lens kit can come close. The DA 21 f/3.2 and the DA 50 f/1.8 (or F/FA 50 f/1.7) is probably the closest you can get. The 21 is a bit narrow for some landscapes but great as a walkabout and the 50 is a bit short for portraits but not bad. The fact that you can turn your camera vertical and use the 21 or the 50 to make a stitched panorama means the lack of the ultrawide landscape lens isn't really a huge loss. Where this fails is indoors where the distance minimum for the framing you want may not be there with the 50 and the 21 may seem too slow but don't be afraid to push ISO a bit.

The other way to go would be to get a high quality zoom like the 16-50 f/2.8 which fills all these roles and more.
Forum: Pentax SLR Lens Discussion 03-17-2015, 04:55 PM  
prime, prime, everywhere a prime...
Posted By Na Horuk
Replies: 11,613
Views: 589,272
Yes.

Yes, there is a noticeable difference between f1.8 and f2.4. But keep in mind that 35mm is wider, so you can get away with a longer shutter speed before motion blur will be noticeable, so this is not such a big low light advantage as it might seem. But f1.8 at 50mm will render a much shallower DoF and bigger bokeh blur. Big difference for portraits with shallow DoF for subject isolation, for example. Not to say that shallow DoF is something to be valued, but it is a tool that can be useful.

Different lenses might render images differently. Old lenses tend to have the classic "film" look. Some old lenses are very good even by modern standards, others are funky or have a pleasing effect despite their shortcomings. Sometimes they are so cheap that you can ignore their flaws. It comes down to what you need as a photographer. If you always rely on AF, don't buy a manual lens. If you don't want to spend time to learn about M mode, don't buy a manual lens.

Btw, there are many threads about DA 35mm f2.4 vs. DA 40mm XS vs. DA 50mm f1.8. Usually the DA 35mm gets most votes for "first prime to buy" because it has a more comfortable field of view and can be used for most everyday stuff. DA 50mm is preferred if you want artsy shallow DoF photos, portraiture, things like that. I would not recommend the DA 35mm for portraiture, at least not of just a person's face, due to distortion - faces start to look round.
DA 40mm XS has slightly higher build quality than the other two and is generally a nice lens, quite sharp, very contrasty. Basically you get the DA 40mm ltd for a much lower cost, with a couple missing features.

I'd say buy DA 35mm f2.4 and older A 50mm f1.7. A series are not fully manual, but don't have AF.
Forum: Pentax K-5 04-30-2011, 04:52 AM  
Best screen ever for manual focus : Canon ee-S!!!
Posted By dlacouture
Replies: 769
Views: 169,376
Hello all!

Well, I've been using old lenses for quite a time now, on the MZ-7, MZ-6, K10, K20, K7, Kx, and now K5...

I've stumbled on the infamous stop-down metering problem plaguing the K10/20, and still visible on the K7/5...

I've tried several split screens, but I quickly found that my keepers rate was the same with the stock screen, so I ditched them, as they are useless anyway when you recompose the shot and severely mess the metering... And their blank parts were limited to f/2, in the best cases...

I then took a leap of faith and ordered the Pentax ME-60 blank screen, hoping that it was optimized for fast lenses, but, alas, it has the same f/2 limit than the stock screens... But to my surprise, I found the utterly blank viewfinder really pleasing and it helped me much in composition, as there is no disturbing element (as the focus brackets)...

Then, after a little research, I've found out that the Canon ee-S screens were optimized for fast lenses, and were supposedly able to accurately show DoF right down to f/1.7... So I immediately bought one and took out my saw... I already made a DIY split from a MZ-M screen, so I was not adverse to a little plastic dust...

I ended with a nearly mint focus screen (got a little scratch on it, visible only at about f/8 :mad: ).

OK, time for the tests...

DoF rendering:
I took out my f/1.4 lenses (Pentax FA50 and Samyang 85) and played a little with the DoF Preview, and hallelujah, I can now see a difference between f/1.4 and f/2 (try it with the stock screen)!!! Even f/1.7 produce a slight darkening of the viewfinder, so the eeS screen actually work right down to f/1.4!

Focusing:
With now an accurate DoF, seeing what is actually in focus at f/1.4 became really easy! But there was a severe back-focus, so I had to remove the metal shim and replace it by two thin strips of post-it...
Now, focus is eerily accurate, with both lenses! Even a split screen could not give me such a precision...
I'll order the proper metallic shim now that I have the exact thickness needed...

Metering:
OK, here I was worried...
So, I put the FA50 out of its A position, and took a series going from f/1.4 to f/22 in 1 stop increments... Here is what I got (repeated several times): 3000, 2000, 1000, 500, 250, 125, 60, 30, 15...
Yep, you've read it right : a near-perfect linearity on the whole range, with only a slight +0.5 overexposure at f/1.4...

With the 85mm now... 800, 500, 320, 160, 80, 40, 20, 10, 5... Really good, too, with a little +0.5 overexposure at f/1.4 and f/2...

I simply never had a screen so accurate before!!! For reference, the K5 stock screen has nearly 1Ev of leeway around the proper value...
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