|
Forum: Pentax SLR Lens Discussion
09-29-2015, 11:43 AM
|
| |
I shoot RAW and only that. I used Photivo to convert. I have changed that to Darktable now.
Regards,
Chris
|
|
Forum: Pentax SLR Lens Discussion
09-29-2015, 11:32 AM
|
| |
Dude, calm down! There was not offence intended here!
I merely meant to say that I disagree with your observation. I do not disagree with your post, your experience or your person for that matter. :) People disagreeing on things and discussing how that could be is a contructive method to learn things. That's part of the fun of a forum. It has nothing to do with disrespect. If you have had good experiences with this lens I do not doubt you are telling the truth. If I am telling the truth too with my not so good experiences with the lens (I tried two of them), then we can at least speculate that there is a certain spread in quality.
So, again, no disrespect intended, this was supposed to be a lively and interesting discussion. If we expected everyone to agree with us, we'd be on feminist frequency. :D
|
|
Forum: Pentax SLR Lens Discussion
09-29-2015, 09:51 AM
|
| |
I disagree on this point.
After a dancing tournament I shot a couple of group stills of the teams at maybe 22mm focal length (don't know the exact value but it definately was not 16mm). On these shots, the people on the sides (both left and right) looked significantly chubbier (like they gained 10-15kg) than those in the middle. Since there were lots of girls amoung the dancers, this was not very flattering and I had to put in a lot of work to undo the mess. So the distortion is not only visible when shooting architecture - IMHO.
Best,
Chris
|
|
Forum: Pentax SLR Lens Discussion
09-29-2015, 08:14 AM
|
| |
This is a good choice! I own it myself and for me it has way outperformed its price. It isn't the fastest to focus on my K3 but then again, the K3 isn't a top performer in this regard anyway. The focus speed is acceptable - I use it a lot for dance sport shots and I also used this recently on a friend's wedding. It is very sharp for a zoom and even open really good. IMHO the sweet spot is f/4. This is a definate recommendation from me!
Unfortunately, this lens does not exist. At the longer end of the zoom range it only has f/4.
I have not actually used this lens but only held it in my hands. It does not hold up to the 17-50mm noted above. While this is not a bad lens (going by reviews and samples) at a good price, I think the 17-50 is a much better choice.
Rightfully so! I borrowed this lens from a shop for a small fee to test it before I buy it. While this lens feels and looks superb, it is optically outperformed by the Sigma. While the sharpness is ok, this lens distorts far more than the Sigma. The AF is a little quieter, but I felt it to be slower (I took it to a dancing tournament like I did the Sigma). I was pretty underwhelmed all-in-all, especially considering that the pricetag is nearly three times as high as the Sigma's.
Another lens you might want to consider (with caution) is Sigma's 18-35mm f/1.8 DC Art. This lens really rocks on Canon and Nikon but somehow seems to be problematic on Pentax - or so I have heard and read. You might want to check the lens out before you take it into consideration.
Note that all the lenses mentioned in this thread (including the two you listed which I have not commented because I have no knowledge about them) are all APS-C only. If you do buy the Pentax full format next year, you will not be able to use any of these lenses on it - at least not without major vignetting! If you buy an FA lens however, you can use it on your new camera too.
Best regards,
Chris
|
|
Forum: Pentax DSLR Discussion
03-12-2015, 09:55 AM
|
| |
Actually, I don't know if my K-3 actually does this everything-auto-thing. I don't even know what colour the square has. I have never used it. :cool:
I just remember seeing pics on the web that had these crazy settings and I assumed they were done by some auto mode because the people who would have been dumb enough to actually use these settings would not know how to set them. :p I just read my camera's manual and decided that auto ISO is evil.
Regards,
Chris
|
|
Forum: Pentax DSLR Discussion
03-12-2015, 09:18 AM
|
| |
I remember the K-x fondly although I have never had one of my own. I borrowed one from a friend a couple of times and after I got my K-3 I was there thinking "Bloody hell this thing is big and heavy!" although the K-3 is actually of quite modest size.
I never did any side by side shots with the K-x and the K-3 but I do have the impression that the K-3 has far better image quality. I only shoot RAW. The K-x to me often seemed like an OLED in comparison with an LCD. The colours were very flashy, attractive but "even better than the real thing". They were pleasing to the eye but didn't quite copy the reality which is a camera's main purpose.
There is one thing in this discussion that is really important to me:
I hate auto ISO! To me it is one of the most useless functions of modern cameras - especially if aperture and shutter speed are also in auto mode. The first thing I do with any SLR is restrict the auto ISO to some sane value (like 400 or 800), should I for some reason turn it on by accident. After that, I never use any mode that fiddles with the ISO value. The ISO is a value I check/set before every shoot and I may change it during a shoot, but only by hand. If all three values are set to auto it just happens too often that the exposure is correct but the values are just plain stupid. An extrem example could be 1s/1000, f/22 ISO 12800. If I have glass that goes up to f/1.8 or even 1.4, I don't need to stop that lens down to values that turn every picture into a blur - unless I want that effect, but then it is my choice, not my camera's - and use ISOs that make my pics grainy like rice pudding. :D
Just my two cents... :cool:
Best regards,
Chris
|
|
Forum: Troubleshooting and Beginner Help
10-15-2014, 03:44 AM
|
| |
Hey everyone!
Last Friday I shot an FA 100mm f/2.8 macro at eBay for 300 EUR. The price seemed pretty good, especially since the seller claimed the lens is in near mint condition. This was to be my first macro lense ever. :) The little guy arrived yesterday, wonderfully packaged and appart from one really minor scratch on the bottom (probably caused by a grain of sand on the surface the lens was set upon at some time), I can see nothing that suggests the lens isn't new! :cool:
The only thing I find irritating is that I can't figure out what the clamp is supposed to do - or if it does anything at all for that matter. The wheel itself feels pretty loose (it's easy to turn), but it locks into place at each end when you turn it. I can't really say that the focus ring feels any tighter because of this.
Am I entirely missing the point here or does this mean there is a problem with my lense?
Best regards
Pix
|
|
Forum: Post Your Photos!
10-14-2014, 06:39 AM
|
| |
Ok, I get it, I have to lose the "dude". :p
|
|
Forum: Post Your Photos!
10-14-2014, 05:46 AM
|
| |
Dude, you have some gorgeous photos there! You have my admiration!
|
|
Forum: Photographic Technique
10-14-2014, 05:40 AM
|
| |
Sorry - my bad!
Just fixed it. :cool:
Pix
|
|
Forum: Post Your Photos!
10-13-2014, 01:21 AM
|
| |
The other half my friend, is blowin' in the wind... :cool:
Really cool photo, dude! Pretty good DoF and all. I could never get the little buggers to hold still long enough. :p
Regards,
Pix
|
|
Forum: Troubleshooting and Beginner Help
10-11-2014, 11:59 AM
|
| |
Although I am not in the discussion yet, I am gonna give you my two cents anyway... :p
I made my choice at the end of Febuary when the K-3 was much more expensive than it is now. My main reason was the AF. While I am truly not a fan of the K-3's AF, it is still a noticeable improvement over the K-5 II and with the firmware upgrades out there, the K-3 is now in an area that I would consider "workable". Now I can get a reasonable amount of good shots when I go to a dancing tournament.
But even when shooting portraits, I think a good AF is often highly underrated! I tend to talk to my models, get them to laugh or do funny things naturally. Sure I can tell them to do poses and I am not above doing that. Looking back I'd say that many of the best shots I have made were not strictly posed, but quite spontaneous. If your AF doesn't work correctly in those situations, you lose. Remember that portraits are often shot relatively open, so the DoF is pretty narrow.
Now (with current firmware) I'd trust my K-3 not to let me down. In case you are wondering, I am no professional. But while it is not so absolutely vital for me making money that I get exactly that money shot, I don't want to miss the moment when the person I am shooting has a really cute smile on his or her face. And when I shoot photos of children, I can't really make them stand still. :)
Ok, I am going a little overboard here. What I am basicly trying to say is: AF does matter and the K-3's is better.
I have only shot with a K-5 II on a couple of occasions (I don't own one myself), but in those cases I was not thrilled by the AF and quite a few reviews on the subject seems to think the same: AF still isn't Pentax's strongest side, but the K-3 is a good step in the right direction.
Apart from the AF, the K-3 has higher resolution (although this isn't important to you) and quite a bit more responsive (at least that's what I felt). Both are built very well (apart from the battery grip) and have great image quality.
Oh, there is one thing I forgot: The gun metal version of the K-3 looks really sexy! :cool:
Regards,
Pix
---------- Post added 10-11-14 at 09:03 PM ----------
As I was saying. :cool:
The amount of focus points however is really a non-issue (IMHO). There are more points but they are not spread out more which I find very disappointing. Especially with portraits I'd like more points to the side because moving the camera after focus with 85mm and f/2 is usually a bad idea.
Regards,
Pix
|
|
Forum: Photographic Technique
10-11-2014, 09:29 AM
|
| |
Hello Albert!
Your question cannot be answered quite like this. While someone did give the equations that give a rough indication of the DoF, this is not an exact science and probably was a little more mathematical than you had hoped for. :p
Important for the DoF is not only the aperture but also: focal length, distance to the object in focus and the size of the sensor. If you are using a Pentax DSLR, the sensor size doesn't vary terribly. :D
You already know that stopping down will increase the DoF. These are rules too:
- longer focal length => shorter DoF
- longer distance to the object in focus => longer DoF
- smaller sensor => longer DoF
To pick up your example (however in metric, lenses are in mm, not in inches)..
- 28mm focal length, f/2.8, Pentax DSLR, 3m distance to object in focus: DoF ~1.35m (~2.5m near and ~3.8m far)
- 28mm focal length, f/8, Pentax DSLR, 3m distance to object in focus: DoF ~5.75m (~1.9m near and ~7.6m far)
- 100mm focal length, f/2.8, Pentax DSLR, 3m distance to object in focus: DoF <10cm (~296cm near and ~305cm far)
- 28mm focal length, f/8, Pentax DSLR, 3m distance to object in focus: DoF ~27cm (~287cm near and ~314cm far)
- 100mm focal length, f/8, Pentax DSLR, 50cm distance to object in focus: DoF ~6mm
As you can see, the focal length and the distance to the object have a much bigger impact on the DoF than the stopping down. Note that these numbers are not absolute numbers! I like the term "acceptable sharpness" Na Horuk used. The only object actually in focus is 3m away in my first examples. Everything else is out of focus, although that relatively hard to spot within the limits shown.
Regards,
Pix
|
|
Forum: Pentax SLR Lens Discussion
04-08-2014, 12:02 PM
|
| |
I am sorry for being so blunt, but do you actually know what you are talking about?
I am not an expert at this calculation, but if I am not completely missing something...
aperture: f/4
focal length: 26mm
distance to subjects: ~4m (probably more)
APS-C sensor size
That results in a DOF of about 4.5m. That means, the near limit should be about 1.2m in front of the point of focus. If we assume, the point of focus is the face of the girl in the middle, the girl on the very right would have to be more than 1.5m in front of the focal plain (probably more like 1.8m) for this kind of blurring. The tiles on the floor are 1m by 1m. I have not measured this, but I would say the focal plain is at most 30cm further to the back on the right side - and with that well within the DOF. Please also remember that the girls on the right are further away from the camera than those in the middle and this would reduce the distance to the focal plain a little.
No offence, but I think that shot was a miss. :)
Regards,
Chris
---------- Post added 04-08-14 at 09:05 PM ----------
Hey everyone!
As requested, I set up my camera on a tripod after work today and took a few test shots. Actually hitting the 26mm focal length (to get the same results as to the end of the tournament) wasn't too easy, but I did it. :cool: This is the result:
http://media.advico.de/photo/misc/boring_wall.jpg
I can still see an ugly blur on the right. :(
Regards,
Chris
|
|
Forum: Pentax SLR Lens Discussion
04-08-2014, 05:26 AM
|
| |
This is one of these cases where I'd say "Never ask an expert any simple questions." :) Although there is not a single answer in this thread that I would completely disagree with, most are very technical and very specific. Considering that the OP is probably a beginner, the information given here might overwhelm him or her slightly if not put into context. Just for this I'd like to add a few things.
The Holy Grail of landscape photography is DOF!
This is true as a general rule to which there are always exceptions. Probably more than 80% of the landscapes you see on postcards or the like are shot with the goal of everything being in focus. If you like these pictures, then most probably you will be shooting with a wider angle.
Before you buy a new lens, buy a tripod!
Don't be stingy when doing this and don't be surprized if you have to spend more than 200 USD on the tripod and head each! A cheap tripod will shake around in a light breeze as much as you after taking a dip in an ice cold mountain lake. Remember that when shooting landscapes you will often be stopping down and as a result have longer exposure times. Always buy a tripod with a detachable head! You can find a good demo of the different types of heads and tripods
You Tube
|
src="https://www.youtube.com/embed/CW_mb2yNm9Y?controls=1" allowfullscreen>
|
Do not go with a monopod! When shooting landscapes, you will often compose your photo and then sit around waiting for better light. A monopod is no good for this. A remote for your camera will cost you about 25 USD and is well worth it.
A little knowledge goes a long way.
If you like photos where everything is in focus and you have a good tripod, the one thing that will really improve you pictures next is something that will cost you nothing (in terms of money). If you use your camera's AF, the setting will most likely be at infinity. Don't use that. When you read up on DOF, you will understand this better. Let's assume the calculated DOF is 3m, then the thing you focussed on isn't in the middle of that field, but the field begins 1m in front of that object and ends 2m behind it. It's easy to see that having two thirds of the area in focus beyond infinity (while objects in the foreground are out of focus) is pretty pointless. If you are not too good at calculations "on foot", you can download apps that will tell you what the best focus point is for your combination of focal length and aperture.
Check your white balance.
Most cameras are set to auto white balance. This is a bad choice for landscapes. In auto mode the camera tends to compensate if a picture seems to have "too much" of a colour. A lush and green mountain side can suddenly look really muted and drab. If you are shooting in sunlight, use the sunlight mode! Note that a sunset is sunlight too. It looks red in nature and so should it on your photo. This is the setting which will be the best choice most of the time. There are exceptions like really cloudy or overcast skies, or if you are shooting in a valley under a blue sky but the sun behind the mountains (so no direct sunlight). Especially in the second case the light is noticeabely bluer than direct sunlight.
Don't expect too much from your kit lens.
The 18-55mm kit lens is ok for starters. Use it by all means, but don't be disappointed if your photos aren't as good as you hoped. Even stopped down its sharpness isn't exactly breathtaking. Additionally, it distorts at the wider end. Use it to practice composition and focus. Use it to find out what focal length you prefer. But if the photo somehow looks boring and you are sure it's not the composition or the lighting, it might well be the lens. It will help you to take photos and you might even get some really great shots with it. But you might miss sharpness and details when using it.
Think about a new lens.
Several people have told you to get a prime because primes are better. This may be true if your only criterion is sharpness at a wide open aperture. Since you will most likely not be shooting like this, you might want to think about other criteria too. A good zoom lens has just about the same image quality at f/8 or above as a prime. What is true is that primes are usually smaller and less costly. I have and use primes too, mainly for portraits. In that setting, walking a bit for a better composition is usually not a big deal, because the distance I have to cover is relatively small (not more than 3 or 4m in most cases). When shooting landscapes the distances can be much bigger. If this movement involves crossing a river, it can be annoying. Should you be standing on the edge of a cliff, you're out of luck. :p You can never get all the flexibility you might want. 18-200mm zooms just don't cut it in terms of picture quality.
An idea for a lens - just so I don't only answer questions the OP didn't ask. :D
The Sigma 18-35mm f/1.8 EX HSM (and a few more letters) offers only a small zoom range but has stunning image quality that in many cases is equal to a prime - even if the aperture is wide open! Stopped down, I am pretty sure you won't see any difference to a prime. It gives you that little bit of flexibility in terms of focal length that might make the difference to getting the shot or not. The price isn't exactly chicken feed, but it's actually quite good considering what you get for your money. Be warned though, this lens is pretty big and pretty heavy.
Get yourself a polarizer!
You may notice that this comes in last. Others think you should get the polarizer for your kit lense. I don't. I have never owned your kit lens, but the last time I saw and touched one of these, the front element turned with the focus. When moving the focus ring manually, it was way to easy to turn. In my personal opinion, there is little point to attaching a polorizer to that lens - especially since a good one will cost as much as the entire lens! When you do get yourself a polarizer, don't be stingy either! I have been quite happy with the two I have from b+w. If you don't want to spend quite that much, you could use a Hoya or something in that range, but please do not go below that, or you will be wasting the money you do spend.
I hope this little intro helped you out a bit!
Regards,
Chris
|
|
Forum: Pentax SLR Lens Discussion
04-08-2014, 01:20 AM
|
| |
Bonjour!
I have my doubts about the ambient light ghosting, for three reasons:
1. It's only ever on the right side of the frame, never on the left and never in the middle. I shot 425 photos that Saturday, so I think there is enough material for a statistic evaluation. :)
2. I habbitually test out what settings I would need to be able to shoot without a flash. On this day I was at about f/2.8, 1s/50, ISO400. The shot was made with 1s/180 and f/4. The ghosting is just too bright for the ambient light IMHO and also far to wide considering the exposure time.
3. I never encountered this with the kit lens (18-135mm) and I've used that several times already for this kind of shoot.
The lens is still at my place. I had one of these 12 hour workdays yesterday - the kind we all love so very much. :p It was far too late to bring the lens anywhere by the time I got home. And since it was dark, I couldn't shoot any test photos either. What I could do was look at the lense very carefully under a light. I saw no signs of smudges, fingerprints or anything else on both the front or the rear element.
I will try to leave the office before 6 today and thus maybe still have some daylight when I come home, and if it's not raining, I'll take some photos of houses and walls. :cool:
Regards,
Chris
|
|
Forum: Pentax SLR Lens Discussion
04-07-2014, 01:04 PM
|
| |
Hey everyone!
Thanks for your thoughts!
Just to make it clear: I was holding the camera in my hand (no tripod anywhere to be seen), but this was a pretty wide angle and the shutter speed was at 1s/180. There should not be any visible movement due to an unsteady hand.
I found a photo that shows the effect even better:
http://media.advico.de/photo/misc/blurrrrr.jpg
Note the dude in the middle. You can see the cord on his blazer. But the guy on the far right seems to be getting ahead of himself (get a load of his chin!). If there is any blurring due to camera shake, it should be in the other direction.
Regards,
Chris
|
|
Forum: Pentax SLR Lens Discussion
04-06-2014, 03:37 PM
|
| |
Hi everyone!
I went to a formation dancing tournament yesterday with the said lens that I borrowed from my dealer. It's a pretty pricey lens and I wasn't sure if the focal lengths would be ok for what I wanted to shoot. I was especially worried about the long end of the zoom range because the subjects I wanted to shoot are sometimes 10 to 15m away from me (and I am not allowed any closer). I never suspected I'd have a problem with the image quality!
After the tournament I took a group photo. Noone was moving around, the girls were actually sitting down. This is the photo I am talking about:
http://media.advico.de/photo/misc/hilden_group_2.jpg
It has full resolution, no copping was done and no post-processing in terms of sharpness. I did lift the colours up a bit. The EXIF info is still there, so you can see it was shot with a K-3, f/4, 1s/180, 26mm focal length (absolute). I used a Metz 58 AF-2 in P-TTL mode with a small mobile softbox over the flash. The flash was set to the widest possible angle - normal when it is stuck into a softbox. :) The camera focussed onto one of the girls in the middle of the photo.
Take a look at the row of girls. They are sharp in the middle. I know that most zoom lenses aren't that great at the edges (which is why I stopped down to f/4) but what this lens offers especially on the right side is absolutely hideous! :eek: Really weird is the difference between left and right. The left side seems a bit on the soft side (which I find a bit less than thrilling considering the price of the lens) but the right side is really gruesome. Not only this photo has this effect, not all, but many. The reason I wanted to try out this lens was because I found the softness of my kit lens (18-135mm) around the corners annoying. However, I can't remember a single photo shot with my kit lens being anywhere near as bad as this.
Am I too dumb to operate a camera? Is the lens broken? Or is this a problem with the shake reduction?
Kind regards,
Chris
|
|
Forum: Troubleshooting and Beginner Help
04-02-2014, 04:05 PM
|
| |
Hi Bob and thanks for your input!
You pretty much expressed many of my thoughts to. I loved (and still love) my father's Spotmatic dearly. I shot some great portraits and landscapes with it and I still enjoy many of the work methods and tools that to me seem quite normal - among them my Lunasix F.
For a long time I could not afford a new camera, so I had to use what I could borrow. That is where the old rebel came in to play. Last year I got a new job and I could afford a new camera. So I went out to research what was on the market. At the time, the dancing wasn't really part of the equation, because I had given that up years ago - including shooting photos of dancers. I narrowed the choice down to: Nikon D7100 and D800, Canon 70D and 7D and the K-3. The D800 was soon out of consideration because it's just too pricey. The 7D is a good camera but it has been around for quite a while and is missing several new features like WiFi. The D7100 and 70D don't have the magnesium alloy (IIRC the D7100 in part, the 70D not at all). Additionally, the K-3 has a 100% viewfinder, shake reduction in the body, weather sealing (although that was not a major consideration) and a bunch of other features.
I watched lots of reviews on youtube and read even more - not only of the K-3, but also of the Canons and Nikons. The K-3 looked good in all reviews. The AF was sometimes criticized, but more along the lines of it not being as good as the D4's AF. By what we are looking at here, you'd expect the reviews to call the K-3's AF seriously flawed and not just "not quite on par with Canon and Nikon". I expected the AF to be slower than Canon's or Nikon's but the difference only to be noticeable in direct comparison. I did not expect to run into problems during a dancing shoot.
After having used the K-3 for several weeks now, there are only four things I could complain about:
- AF
- The shutter button feels cheesey and wobbley-
- I keep pushing the shutter button on the battery grip accidentally with my lower hand.
- The battery grip is a little cheesey (no magnesium, only plastic) and only takes one battery. The other battery must be inserted into the camera's main slot which means the battery grip has to be removed to get at it,
Apart from those (of which only one is a real issue) I am really happy with the camera and I want to keep it!
Cheers
Chris
|
|
Forum: Troubleshooting and Beginner Help
04-02-2014, 09:44 AM
|
| |
My slight irritation by your response had nothing to do with the fact that is was short. :) What I find frustrating in this discussion is the fact that things I write are being ignored. Imagine an argument like this:
him: The chair is green.
her: I disagree! The table is blue.
This argument is not going to be settled any time soon. :)
I do not doubt for a second that you guys are really trying to help me out here and I hope you believe that I really believe, I want to learn something. But for that to work we have to be talking about the same things. I have stated several times that neither the 50mm Sigma prime nor the 85mm Sigma prime is any faster (at focussing) than the kit lens (DA 18-135mm) - and yes I did try all of them. :p If you suggest the 85mm SIgma when I write about slow AF, then one of us is missing something. :o I will go into the focal length issue a little further down.
Somthing similar applies to a post after yours concerning microcorrections and screwdrive focus. The poster says this combination makes the microcorrections very obvious while SDM or HSM tend to "hide" them. I currently have no Pentax screwdrive lenses and all of my SDM (HSM) lenses show very noticeable microcorrections.
Basicly, it's fine if you disagree with me, but then please disagree with me! :D
Another detail, that might be unclear:
Photography is a hobby of mine. This means, I watch my budget and although I probably could spend more money on my stuff, the money is a very important factor to me. I also tend to buy less lenses and try to get good ones. I actually bought the two Sigma lenses for portraits, not for action. I do not make any money with my photos, I take photos because I enjoy doing so and it relaxes me. Unless I suddenly turn rich, I will probably never buy a second body.
I've taken a look at the link an there are some nice shots. However, these are not the kind of shots I am going for. I used to dance as a sport too, so I know what is important to dancers. I like the "portraits" you short, but with very few exceptions, I always try to get the whole body in the shot, because I want to capture more of the dancing while your photos seem to go more for the personality. This is not a bad thing, just a different emphesis. Here are some examples of shots I made last time...
 
Note: These photos actually were sharp when I submitted them.
Now you can hopefully see why I can't work with 85mm. For that to work, I'd need a distance of at least 5m to the subject for a full-body shot - something I just can't do most of the time. I would never have gotten that line of dancers with 85mm. Additionally, because I work with a flash, the distance shouldn't be that big either.
I get that the kit lens isn't ideal - not by a long shot. But if the focal length of a lens just doesn't let me catch the subject I wish, then talking about its other qualities is pointless. I have used a full-format Canon before with the 24-105mm f/4 L IS. I would like something similar for my Pentax. That would mean something like 16-70mm, if the long end goes a little further, good. I know there are 17-70mm lenses, but these are not DA* (for Pentax) or EX /for Sigma).
I rarely use AF-C, because it too often misses (for my taste). I know most of the routines, so I usually know when I want to take the shot.
As I have said, the focus motor is not the issue here. I have seen reviews of the 16-50mm where people say the motor is slow. This is not my problem. The speed of the contrast AF I could work with, no worries.
Cheers!
Chris
|
|
Forum: Troubleshooting and Beginner Help
03-31-2014, 08:03 AM
|
| |
Actually, PDAF is a mathamatical process, although the calculated result is not perfect. This means, the direction the AF has to move should be detected every time (if there is enough light and something to focus on) and the amount of movement required to reach focus should be pretty close. You make it seem a bit like a trial-and-error method which it is far from.
Well, getting rid of microcorrections totally is probably impossible. That would mean a perfect AF and I doubt that we will ever get there. We are getting off-track here a bit, but this is an interesting discussion, so I don't mind having it, as long as it stays a discussion and noone starts to rant because I critisised Pentax.
Canon and Nikon seem to be doing a better job with their AF. I don't know how or why, but I could venture a guess. The first time the PDAF take a measurement the amount of required movement may not be to exact. This depends on how far off focus the lens is. Imagine, the lens is completely off focus. One way to get an exact hit would be to take a measurement, calculate, move to that rough position and take another measurement and so on, until you hit focus. This method would probably require three or so corrections. You could of course keep taking measurements while the focus is moving and thus get several calculated focus positions, each getting closer to perfect. If this system works well, you should be close to being able to focus in what seems like one movement (and possibly is).
But I actually don't expect my K-3 to be that good. It would be fine with me if the PDAF worked like the contrast AF, with the advantage of knowing the right direction. In my post from March 16th I put in a link to two sound files. Firefox can play there directly. Listen to the contrast AF and notice how quick is it when if moves in the right direction. There is one correction at the end and it's fast, while the PDAF has three corrections which feel a bit slower too. On average, PDAF is slower than contrast AF and that's just weird.
Regards,
Chris
|
|
Forum: Troubleshooting and Beginner Help
03-31-2014, 03:38 AM
|
| |
Although I am thankful to any person who wants to help me out whem I write about a problem, I sometime do wish they would read the thread or at least the original post. Had you (and cjsong) done that, you would know, that this is not about the focussing motor. While admittedly the DA18-135 doesn't have the fastest motor I have seen, it would be plenty fast enough for me if the focussing would consist of one movement and a lock. What really costs time are those microcorrections (and the pauses between those). Because of them BTW, the Sigma 85mm and the 50mm EX primes are not faster than the kit lens - at least I can't tell the difference when using them.
Concerning the lenses you suggested...
None of them are of any real use to me because the focal lengths are way too long for for what I am doing. As I wrote in my OP, the subjects I am shooting are in some cases less than 1m from me and usually no further than 10m, the most common field being between 2 and 5m. Not all sports are outside and across a giant soccer or baseball field. :p Although I have and use prime lenses, they are of little use in this setting. I am pretty much stuck to the place I am sitting. Standing up is not an option because the audience could be a little annoyed with me if I get in their line of sight. I just can't move around enough to get anything with my primes. I have borrowed a DA*16-50mm 2.8 for next weekend. I am going to give it a shot, but I am not sure if that will be ideal for me, especially because the 50mm at the long end does seem a little short.
Kind regards,
Chris
|
|
Forum: Troubleshooting and Beginner Help
03-16-2014, 01:44 PM
|
| |
Good evening, everybody!
Thank you all for your kind words and understanding!
Before I get started, one comment @loganross:
You are describing a completely different issue in your notes, if I didn't misunderstand you.
To the subject at hand...
This took pretty long, but I have my camera back (again). The first time I sent it directly to the Pentax service, this time to my dealer. I actually got it back last Monday but didn't have any time to play with it until today. I'm kinda a working guy. :D
I won't go over what happened the first time (when I sent the camera directly to Pentax). This time I sent it to my dealer. They checked it out, confirmed what I described in my email and sent it on to Pentax for verification. My dealer did compare my camera with a demo model the keep in the store and told me that although they saw what I did, their demo model worked just like mine. :eek:
On Monday when my camera was in the mail, I checked and found a service report from Pentax. They had aligned the lens (I wonder why that was necessary again), cleaned everything but could not find anything wrong with the camera (body) itself: Working within normal parameters. As a bonus, my dealer included their demo K-3 for me to try out and compare my camera too. I also got an offer that I could send back the camera if I still am not happy.
I sat outside on my porch again and did my little back and forth test again - and I recorded the sound again (sorry, had to use ogg this time):
http://media.advico.de/audio/kit_2014-03-16_phase.ogg
http://media.advico.de/audio/kit_2014-03-16_contrast.ogg
This is once again the kit lens (18-135mm), set at ~100mm, f/5.6, PDAF set to spot. I didn't bother with any of my Sigma lenses. For some reason, I decided to play with the live view and noticed something strange: It's bloody fast - and it sounds right! There are no micro-corrections using the contrast-AF. The lens just moves and locks. Ok, when I change focus from from near to far the camera moves the lens in the wrong direction and then back again. But even this feels pretty fast considering the "distance" the lens has to move.
Using my audio editor I got the focus times again (W is worst case, B is best case). Because I can't hear me pushing the shutter button, all timing is done from the first moment I can hear (or see in the graph) the focus motor running until right before the camera beeps. This means, the actual beeping is not included in the timing. This probably wouldn't add much (I didn't bother to check), but I left it out anyway.
PDAF
W: 1s, B: 0.55s
Contrast-AF
W: 0.9s, B: 0.37s
I think these times are quite remarkable! Although this is actually not the issue here, I think the contrast-AF times are quite excellent. At the same time, I think it is borderline shocking that the PDAF is slower than the contrast-AF - which is actually a first for me. I have not read, seen or heard one single review where something similar was described. This has me pretty much speechless.
I took the extra K-3 out on the porch with me. While I didn't record it's focussing like I did with mine, I can tell you that it felt exactly the same. The PDAF made the same micro-corrections, the contrast-AF was smooth.
All that being said, I have to conclude that my K-3 is not faulty. I am very happy to argue this point, but currently, the evidence (two trips to the Pentax service and a second K-3 that feels just the same in direct comparison) pretty much points to the K-3 (as a model) having a pretty slow PDAF, which is outperformed by the device's own contrast-AF.
Giving the camera back is not really an option to me. I have those two Sigma lenses and the Flash for Pentax. The shop that sold the camera didn't have the other stuff I wanted, so I got that elsewhere. That shop probably will not take the lenses and other stuff back after about 4 weeks, but I guess I could try if push comes to shove.
Currently, there is no other camera that I really want. None other has the internal image stabilizer, the LPF simulator or the magnesium alloy body. The D7100 has a little bit of magnesium, the 70D has none. The D800 could be an alternative, but it's in a completely different class and costs much more, which pretty much goes for the 5D aswell. The K-3 was pretty much the best I could get for my budget and what I wanted it for - save the AF.
I'd really like to read your opinions on these recent developments. If my camera is really within the usual parameters, I just don't understand why not a single review said something about the AF being this slow. One guy even used the K-3 for shooting wildlife! DigitalRevTV (YouTube) compared the D7100 to the K-5 II and said the Pentax AF outperformed the D7100's in low light - and these are pretty much Nikon guys! What am I doing wrong? At the moment, I'd just about listen to anything that sounds reasonable reasonable. :o
Kind regards,
Chris
|
|
Forum: Troubleshooting and Beginner Help
02-25-2014, 02:17 AM
|
| |
Well, as I wrote, the camera already was with the Pentax service. They sent it the body back saying there is nothing wrong with it, only the lens was dealigned (or so they say). Currently the whole kit is with my dealer and I am hoping that she sees the situation the same way you do.
What really gets me in this discussion is the huge delta of what people are saying about my observations. While you (and others) say that there is something wrong with my camera, others in this thread seem to find that 1 second or even 1.3 seconds of focus time (which is 5 times the amount you "set") is not only normal but apparently totally acceptable. That's the reason why I kept this thread going for so long and why I felt so unsure about what to do. The response was so mixed. I'd like to know your thoughts about this (especially why the viewpoints are so different)!
BTW. A regular focus time of more than 1s would be completely unacceptable for me when I spend more than 1000 Euros on an SLR body, regardless of whether that is normal or not. In a way, I guess I have fallen in love with my K-3 a little. It feels good, it's good to operate, it feels very sturdy and has some great features. I am actually very relieved that my model is broken, because that means I can keep all those goodies without having to worry about the slow AF.
I get the point you are making. Still please remember that I was comparing my K-3 to the EOS 700D, not the 70D, which is quite a different class of camera!
Having a real pro-grade Pentax (full frame competitor of the D4 or EOS 1D X) would be great. Even the mid-level SLRs from Nikon and Canon have profited from having these "big brothers". Additionally, the prestige of such a camera would really boost the sales (IMHO) of Pentax SLRs. At the dancing tournament I wrote about, I was the only one there with a Pentax (which in a way is kinda cool too) and I saw a lot of cameras there - even one jerk trying to show off his Hasselblad. :p YouTube is also a good indicator. If you search for the Nikon D7100 or Canon EOS 70D (which have not been around much longer), you are completely smothered by reviews and comparisions. For the K-3 I can see something like three or four real reviews (where people actually use a production model) and not a single real comparison. Boosting the sales could be a good idea. But, I'm getting side tracked here. :o
Once I hear from my dealer, I'll let you guys know.
Kind regards,
Chris
|
|
Forum: Troubleshooting and Beginner Help
02-23-2014, 05:12 AM
|
| |
Yeah, I kinda forgot to mention something. My bad. :o It was rather late yesterday when I wrote that post. ;)
I have already contacted my dealer. She requested that I send the whole kit to Hamburg where one of the companies that does Pentax service in Germany is. I got it back after a little less than a week. Result: The kit lense was realigned on warranty. Nothing was done with the camera body because the technician says it's within the specs set by Pentax (Ricoh). The focus speed with the kit lens did improve quite a bit. It is now about as fast as the Sigma is. To me this is still miles away from blazingly fast - and a long way away from the speed with which the EOS 700D focuses (I'd say about a factor 3).
I called my dealer and told her as much. She said it's possible the technician made a mistake and asked me to return the camera for an exchange. The camera is currently with her and I am hoping to have the replacement by the end of the week. What I tried to get from you guys (I guess) was a clear conscience. I just wanted to have the feeling, I am not just the most ball-busting customer this shop has in 2014 but that I really do have a defective camera and a valid claim.
Sorry for being so unclear!
Cheers!
Chris
|
