Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
08-28-2010, 06:45 PM   #1
Veteran Member
JonPB's Avatar

Join Date: Sep 2008
Location: Portland, OR, USA
Photos: Gallery | Albums
Posts: 430
Help: automatic lens?

Hello all. I seek advice.

My time spent out with a camera has declined substantially. Between increasing work and family obligations, my ability to go out and fiddle with the craft of photos has declined. I've identified my primary frustration when taking pictures as the number of failed images from burned highlights and out of focus subjects. I think if those become easier, I'll be more satisfied with my products--and more encouraged to get out there.

I almost entirely use manual lenses (mostly Takumar, a few SMC-M). My GX10 (i.e. K10d) doesn't meter them well, and the focusing screen doesn't do well for large apertures. Histograms and zoomed reviews only seem to get me so far.

I'm thinking of buying some automatic lenses. Then my camera would understand better what I'm trying to do and would help me out--allowing me to focus on subjects and light and composition, which are the things I really enjoy. Of course, I don't expect the silicon to keep me from having to think, but to make fatal mistakes less common. I'd love to get a DA 70mm--just the right focal length for my tastes--but don't have the money to buy one if it is just going to sit on the shelf.

So I'd like your thoughts on the matter, if you'd be willing to share.

I'm tempted to get a cheap automatic lens and see how it works for me. Namely the SMC-F 35-70/3.5-4.5. I like the 50-105mm range for many of my pictures, and, if that lens takes me in the right direction, I'd want to get the DA 70mm. Does that make sense to you? Any other lenses you'd recommend instead?

Alternatively, am I just poor at the technical skills of exposure and focus, and need more practice to improve? Would you recommend a light meter and/or SMC-A lenses to help out with the exposure, and perhaps a split-prism screen and/or O-ME53 to help with focus?

Thanks for your thoughts!

08-28-2010, 06:57 PM   #2
Administrator
Site Webmaster
Adam's Avatar

Join Date: Sep 2006
Location: Arizona
Photos: Gallery | Albums
Posts: 40,957
If you like to manually focus but are just sick of poor exposure, then I'd recommend you get some A lenses, such as the A 70-210mm(which, IMO is rated lower than it deserves to be).

However, fully automatic lenses are also nice. Since you've been using manual lenses, you're probably used to the aperture ring. I'd therefore also recommend F and FA lenses over DA lenses, just because they have the added flexibility of the aperture ring in case you need it. My favorite lens is the FA* 85mm, which is a true beast, and pretty much has is all. Fantastic photos can be taken with it.

The FA limiteds are also nice- check them out in our lens database: Pentax FA Series Prime Lens Reviews and Specifications - Pentax Lens Review Database

Adam
PentaxForums.com Webmaster (Site Usage Guide | Site Help | My Photography)



PentaxForums.com's high server and development costs are user-supported. You can help cover those costs by donating. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

08-28-2010, 07:12 PM   #3
Inactive Account




Join Date: Aug 2008
Location: Michigan, USA
Photos: Gallery | Albums
Posts: 7,485
The F 35-70 is actually what I call a sleeper lens. IMO, it's one of the better of that line in a Zoom lens. It will never come close to the DA70 of course but who would expect it to. However, The Taks and the M's are also very fine lenses. If you describe your technique a bit, we can tell you where you're going wrong.

08-29-2010, 04:05 PM   #4
Veteran Member
JonPB's Avatar

Join Date: Sep 2008
Location: Portland, OR, USA
Photos: Gallery | Albums
Posts: 430
Original Poster
Adam and Jeff: thank you for your comments.

Upon reflection, I have been taking (or trying to take) more images of moving subjects lately: people, wildlife, and the like. When it comes to static subjects, I'm able to chimp away and find the right exposure, and then snap away a few times until I get the focus where I want it. But moving subjects require either more anticipation or quicker operation.

Maybe I should work on estimating brightness. Currently, I don't look at a possible frame and think "EV5" or whatnot. Rather, I chimp and adjust aperture and shutter from that baseline in relative terms: larger/smaller aperture, slower/faster shutter, higher/lower ISO. Perhaps if I'm able to estimate exposure before lifting the camera to my eye things will be easier.

I've enjoyed A-series lenses. I currently own an A35-70/4, which has let me see that I like the ~70mm focal length for walking around; I've had an A50/1.7 and A28/2.8. Never had any exposure problems, aside from "what was I thinking?" moments, with the A series.

Focus, though, has always been guess-and-check. I've probably taken 3000 exposures trying to teach myself to read focus accurately: static, bright, high contrast subjects with nothing to worry about besides nailing focus. It seems fairly random whether I'll get a bit back, a bit forward, or good enough focus--even when using focus confirmation--with f/4 or faster apertures. I understand that split-focus screens help, but that they interfere with metering. I understand that the O-ME53 helps, but I wonder if the screen itself is capable of displaying the true focal point regardless of magnification.

I realize I'm talking about throwing my hands in the air, admitting ignorance, and letting the camera do (most of) the thinking for me. I'm open to being persuaded to stick in the manual realm: that certainly is more satisfying, when it works. When it doesn't work, though, I normally don't realize that until I'm home and the opportunity has passed.

Anyhow, I'm open to suggestions for other equipment--does the K-7 meter or focus substantially better with manual lenses than the K10D? would a light meter and new focusing screen make things easier with my existing lenses?--but I think that a new lens is the way to go. Perhaps if only to complement my manual lenses.

I'm going to nix the FA* 85, because I'd need to save up for it for some time and I'd rather be out shooting during that time.

I could be persuaded of the FA77 over the DA70, although I lean toward the DA70 for its edge-to-edge sharpness. I like abstract compositions and frequently value sharpness in the corners as much as in the center. And, heck, it would be easier to justify the FA* 85 later if it is 15mm away rather than 8mm from my current-best automatic lens.

Or should I get a bridge lens? Perhaps my exposure problems are due to liking high dynamic range images (even though I don't like most HDR-processed images), where the lens is not to blame. Get a cheap lens--e.g., F35-70/3.5-4.5--and see whether that gets me closer to where I want to be, or whether my technique is really to blame, for 10% of the cost of a DA70.

Or just buy the DA70 because that's what I think I'll buy eventually anyhow.

I write too much. If you've read this far, even if you don't reply, I appreciate that.

Cheers!

08-29-2010, 05:15 PM   #5
Pentaxian
Lowell Goudge's Avatar

Join Date: Jan 2007
Location: Toronto
Photos: Gallery | Albums
Posts: 15,312
have you consiered getting an *istD screen for your K10 (equivelent) the metering is greatly improved

also,with manual lenses you should plot the metering by shooting either a paved road or block wall uniformly lit, and measure the histogram in the middle 10% of the area.

this helps you to understand what you need to do with exposure compensation to get the metering right
08-29-2010, 07:26 PM   #6
Inactive Account




Join Date: Aug 2008
Location: Michigan, USA
Photos: Gallery | Albums
Posts: 7,485




This character represents my only try and (somewhat) success with moving subjects using the K10d. They were taken with the Tamron LD Di 70-300. Av mode, pre-focus on an area and wait for him to come into frame. These photos were taken before I learned about Focus Trap (or Catch In Focus, which wouldn't have worked with the Tamron anyway). I think that camera had a perpetual front focus problem with some lenses though.

If he was moving slow and towards me, it of course was a lot easier



But at full haul, it was point, shoot, and hope.



Exifs for above photos are in tact.

Fast forward a few years to the K7 and long after my discovery of the focus trap.





Sears 55mm f1.4 (1/800) and Vivitar 28mm f2.5 (1/1600) respectively, both M42 lenses, full manual mode (taken one week apart).

One truth I've found is that typically, lighting conditions don't change from shot to shot. That knowledge allows me to to preset the exposure and concentrate on focusing. While the above shots are far from what anyone would call perfect, for me, they are great as they are among the first, I was able to get with him at a full run. I have several hundred failed attemps if not at least a thousand (if these were film, the cost of trying would have broken me).

My next nemisis, photographically, is the bird in flight.. I've captured exactly one that I was happy with. Happy meaning, I could tell that it was a bird, and what type of bird. I'm not a big fan of birds, in fact, I kind of hate them. However, being able to stop the action of something that moves at a pretty good clip and changes direction on a whim is something I've always admired in other people's photos.

K7, DA*300, f4.5. 1/800 sec



08-29-2010, 08:05 PM   #7
Inactive Account




Join Date: Aug 2008
Location: Michigan, USA
Photos: Gallery | Albums
Posts: 7,485
Now that I've finished boring you with my attempts at moving subjects....

Blown Highlights.. I like to use Spot metering almost exclusively. As I said in my other post, one truth I've learned is that exposure doesn't really change much from shot to shot (until location or conditions really change). Once I have that set to my satisfaction, I tend to leave it alone when I've gone manual (M mode). If I have a partly cloudy sky, I'll meter a dark part of a cloud just to get my exposure, set the camera for that, and leave it. If there are no clouds, then I'll use the concrete sidewalk or even the grass (non shaded). That is by no means perfect but it gives me a decent base to make adjustments later (I also shoot RAW+ all the time). Nothing is so blown out that I cannot recover it in post processing.

Focusing screens.. I had a Katzeye on my K20d and the O-ME53. I think I actually had the eyepiece on my K10d as well but the screen was first on the K20d. I didn't notice any real problems with metering on the K20d (but it has a better metering system to begin with). The eyepiece does magnify somewhat but it also blocks part of the viewfinder when looking straight through. The focusing screen didn't have any of the add-on options but was the base $100 model. I Think, the Optibrite treatment will affect metering however. Anyway, what I found in using the combo is that it was helpful but there were still situations where it failed me. To use a split screen, you have to be able to Perfectly line up the two halves of the screen focus area. Sometimes my eyesight isn't good enough for it and additional magnification is required to be dead on accurate. Changing the screen sometimes requires adding or changing the shims to make sure it's at a proper distance from the mirror. So if you go for that, keep it in mind.

I really enjoy using manual lenses on the K7 and to date, haven't felt the need to go split screen. I do think it's much more refined as far as focusing and metering than the K10d. Add Live view to that so I can magnify (a Lot) if I need to when I'm having trouble nailing focus in the viewfinder (which has my O-ME53 on it).

If you are having trouble focusing with auto focus lenses, consider the idea that your camera needs to be adjusted. If you are relying on the AF sensor to tell you that your manual lenses are in focus, again, consider a camera adjustment. If you are getting poor results consistently based on the focus screen, it's possible that the screen needs to be adjusted.

Lenses.. If you are thinking Limited Primes, resistance is futile. Once that thought enters your head, you'll end up with them anyway. If you Really like the 70ish mm range, one lens you might consider (since you are talking upper end anyway) is the DA*50-135. Arguably, one of the best Pentax zooms out there. If SDM worries you, keep your camera at firmware v1.20 to keep SDM turned off.

08-30-2010, 02:46 AM   #8
Ira
Inactive Account




Join Date: Mar 2009
Location: Coral Springs, FL
Photos: Gallery | Albums
Posts: 5,218
QuoteOriginally posted by JeffJS Quote
As I said in my other post, one truth I've learned is that exposure doesn't really change much from shot to shot (until location or conditions really change). Once I have that set to my satisfaction, I tend to leave it alone when I've gone manual (M mode). If I have a partly cloudy sky, I'll meter a dark part of a cloud just to get my exposure, set the camera for that, and leave it. If there are no clouds, then I'll use the concrete sidewalk or even the grass (non shaded). That is by no means perfect but it gives me a decent base to make adjustments later
I've been living by a similar practice the last few months, and it makes a world of difference--you don't have to drive yourself crazy getting a new meter reading for every single shot in M, and you can concentrate on quicker focus and pulling the trigger.

Also important, in M mode, you want to meter for the best part of your scene ANYWAY, and in many scenarios, you're not going to meter for the correct part of the scene (your subject) when it's something moving real quickly, and also not in the center of the frame.

08-30-2010, 04:05 AM   #9
Veteran Member
JonPB's Avatar

Join Date: Sep 2008
Location: Portland, OR, USA
Photos: Gallery | Albums
Posts: 430
Original Poster
Quick thoughts before going to work:

Lowell, are the *ist D screens readily available? I wasn't able to find any in a brief search.

Last night I tried some test shots at 50mm with my A35/70 and DA18-55. I hadn't thought of toying with autofocus with that lens, because it isn't a range I use much (or, rather, provides me f/5.6 in the portion of the range that I like). I found AF to be quicker and consistently okay. I found MF to be slower, more likely to miss, but sometimes perfect. Like a lot of people here, methinks, "sometimes perfect" is more attractive than "consistently okay." But this perhaps points to an AF problem.

I think I'll try out several lenses with trap focus and see whether the camera consistently back- or forward-focuses. Perhaps I'll re-install the focusing screen; that's something I hadn't considered, so thank you, Jeff.

How do the FA limiteds feel when manually focusing compared to the A series? I don't expect them to touch Takumars, but perhaps they're on par with the A's? If AF is consistently okay rather than consistently spot on--it should be measuring where the red indicator blinks, right?--then I'd rather be able to make my own adjustments when I have the time to do so.

The DA*50-135 is a very attractive lens in every respect except size. I'm okay with carrying a camera, but not lugging--especially when hiking.
08-30-2010, 04:25 AM   #10
Senior Member




Join Date: Jan 2009
Location: Perth, Australia
Photos: Gallery | Albums
Posts: 180
I would recommend getting the F 35-70mm. It costs USD 40-50 for a good copy, sometimes even cheaper on ebay.

At least you'll get the feel before spending more on FA limited lenses.
And you can always sell the F 35-70mm for the same price you bought it at when you are not using it anymore.

The F 35-70mm has the right amount of color, contrast and sharpness to begin with. Moreover, the price is right (for me at least)
08-30-2010, 06:33 AM   #11
Inactive Account




Join Date: Aug 2008
Location: Michigan, USA
Photos: Gallery | Albums
Posts: 7,485
QuoteOriginally posted by JonPB Quote
Quick thoughts before going to work:

Lowell, are the *ist D screens readily available? I wasn't able to find any in a brief search.

Last night I tried some test shots at 50mm with my A35/70 and DA18-55. I hadn't thought of toying with autofocus with that lens, because it isn't a range I use much (or, rather, provides me f/5.6 in the portion of the range that I like). I found AF to be quicker and consistently okay. I found MF to be slower, more likely to miss, but sometimes perfect. Like a lot of people here, methinks, "sometimes perfect" is more attractive than "consistently okay." But this perhaps points to an AF problem.

I think I'll try out several lenses with trap focus and see whether the camera consistently back- or forward-focuses. Perhaps I'll re-install the focusing screen; that's something I hadn't considered, so thank you, Jeff.

How do the FA limiteds feel when manually focusing compared to the A series? I don't expect them to touch Takumars, but perhaps they're on par with the A's? If AF is consistently okay rather than consistently spot on--it should be measuring where the red indicator blinks, right?--then I'd rather be able to make my own adjustments when I have the time to do so.

The DA*50-135 is a very attractive lens in every respect except size. I'm okay with carrying a camera, but not lugging--especially when hiking.
To use focus trap on your GX10, you'll need to use manual lenses. It only works in AF-S. Just wanted to make you aware of that. There are little tricks you can use with Any lens. M42 lenses have to have foil piece installed to short the contacts. Autofocus lenses, you can hold down the lens release button while holding the shutter button down. Bit of a balancing act but it works (even with your kit lens).

The FA Limited lenses are not quite as damped as your A lenses in the focusing ring. The are probably closer to your kit lens but more damped than the regular FA lenses. My 2 DA limited lenses feel about the same.

I guess on a long hike, every ounce matters but I don't find the DA*50-135 that heavy. One very nice feature about it over other zooms, is that it's all internal. The lens does not extend at all with zoom and focus.

08-30-2010, 07:16 AM   #12
Pentaxian
Lowell Goudge's Avatar

Join Date: Jan 2007
Location: Toronto
Photos: Gallery | Albums
Posts: 15,312
QuoteOriginally posted by JonPB Quote
Lowell, are the *ist D screens readily available? I wasn't able to find any in a brief search.
The honest answer is I am not sure, but you could try getting one from pentax or anyone who has taken out the screen from the *istD or DS (they are the same) and see if they are willing to part with the screen.

As for split image and metering, spot metering can be messed up a little.

now that I am back home, I can post the curve I did comparing my F1.4 50mm K mount on the *istD, K10D K7D and the K10D with *istD and split image screens.



I try to test all my lenses, but it gets hard with 30 lenses when you add a new body or change focusing screens, because you have 30 lenses to retest with the new arrangement.

the test is to use a block wall or paved surface, evenly illuminated by sunlight, and then measure the greyscale value for the central 10% in my photo editor (PSP X3 currently)

this allows me to understand exactly what each lens does, and then when shooting I have a much better ability to get it right first time.

I like split images, and specifically diagonal ones, but note, according to Rachel Katz they are not as accurate, I think because of the slope of the slit on a line, it is harder to get exxact focus on either vertical or horrizontal.
08-30-2010, 05:13 PM   #13
Veteran Member
JonPB's Avatar

Join Date: Sep 2008
Location: Portland, OR, USA
Photos: Gallery | Albums
Posts: 430
Original Poster
Lowell, that chart is fascinating. If I'm reading it correctly, the istD screen has about half the variation in metering as the stock K10D screen. And the K7 has far more deviation than the istD, although is still better than the stock K10D.

I'm curious: when you take the test images to plot exposure against aperture, do you take an image with an A or newer lens? It would be interesting to see how those lines compare against the camera metering when it knows the aperture.


Jeff, trap focus seems to work very well with my A lens. I'll have to play with making it work on my Takumars.

That the DA*50-135 weighs more than my camera puts me off a bit. I'd love to have the weather sealing.


I've been thinking about this too much. Bodhi, you're absolutely right: one can sell a lens for roughly what one paid for it, if well taken care of. I think I'll pull the trigger on that DA70 in the marketplace...
08-30-2010, 05:18 PM   #14
Inactive Account




Join Date: Aug 2008
Location: Michigan, USA
Photos: Gallery | Albums
Posts: 7,485
Talk to IRA about your M42 lenses. He's the resident expert around here. I own a grand total of 4 and have never felt the need to do focus trapping with them (I also don't use them very much).

08-30-2010, 06:43 PM   #15
Pentaxian
Lowell Goudge's Avatar

Join Date: Jan 2007
Location: Toronto
Photos: Gallery | Albums
Posts: 15,312
JonPB
I tested my sigma APO 70-200f2.8 Ex and it had a total variation of perhaps +/- 20 greyscale which is less than +/- 1/2 stop my tamron 28-75 drifts upward in A mode suggesting the aperture is not really accurate in the lens
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
and/or, da, exposure, focus, k-mount, lens, lenses, light, meter, pentax lens, pictures, slr lens, subjects
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
K-7 automatic Lens Correction? shang Pentax DSLR Discussion 3 07-16-2010 01:49 AM
Problem with automatic lens tfischer Troubleshooting and Beginner Help 10 03-25-2010 05:18 PM
Automatic lens distortion correction example PentaxPoke Pentax SLR Lens Discussion 6 02-03-2009 05:39 PM
automatic focus problems 16-45 lens vladimir Pentax SLR Lens Discussion 1 10-07-2007 08:17 PM
Sakar 50mm 1.7 automatic lens? wipearl Pentax SLR Lens Discussion 0 02-17-2007 04:57 AM



All times are GMT -7. The time now is 09:49 PM. | See also: NikonForums.com, part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top