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08-21-2010, 07:50 PM   #1
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Focusing manual lenses on DSLRs

I have read a few threads on how to focus manual lenses on DSLRs, but am still not getting it right. Here's what I have done:

1) corrected my diopter in the viewfinder. the LEDs are crisp with my glasses on and 3 clicks from the right.
2) Focus lens to intended point.

I have been using an istDS and an A 50/2. On landscape or other, I have no problem. Close up, I have large issues. The example below was shot with a offhand, at f/22, 1/3000, asa 200. The item I was trying to make most crisp was the letters "BB" (this is a rare and unique vintage item, and that is the unique identifier of that). I also did some shots from a few feet away, with a tripod, same setting and also w/mirror lock-up, and they were also a few inches off in focus.

Instead, the area of actual focus was about 1.5" below where I focused and what was apparent in the viewfinder. It was down, in the pebbling of the grain of the cardboard box. With a film camera, I would not have expected this outcome.

So my questions are:

1) Was I wrong to use such a low asa, and I should have used a higher one and slower shutter speed?
2) Is close-up focusing this lens just a bad idea? (I have a macro lens purchased but not here yet, but I will still want to focus this lens close-up occasionally).
3) Is this an example of "tolerance stacking" and I just need to learn to compensate with this particular lens?
4) Would a Katzeye or similar help me catch this, or it's in the lens and at these settings that would have not mattered?




Last edited by Oro; 08-21-2010 at 07:58 PM.
08-21-2010, 08:36 PM   #2
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I think it's more common for AF to be off than for there to be misalignment that causes MF to be off. I would try some additional controlled tests with a different lens, to see if the issue is the same with other lenses. Use a high enough shutter speed or a sturdy tripod so that motion isn't an issue.

I have no idea what you mean by "offhand", but it's almost certain that if you weren't using a tripod, the camera moved after focusing.

I'm thinking that if you shot another picture from several feet away at f22, it would be almost impossible to tell if the focus was a "few inches" off. It woud have to be pretty far off for you to notice under those conditions.

The issues here are independent of film vs. digital.

Paul
08-21-2010, 08:46 PM   #3
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On my *istD, I did have issues focusing manually. I don't think as bad as your having, but once I switched to a Katzeye, I rarely missed focus.
08-21-2010, 11:25 PM   #4
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QuoteQuote:
I have no idea what you mean by "offhand", but it's almost certain that if you weren't using a tripod, the camera moved after focusing.
"Offhand" shooting means shooting something without an external rest, in this case, not on my tripod. It is a term more often used in firearms shooting than photography, so it may not be as common in photography, sorry. I was braced, so if the focal distance changed, it would have been by only a few millimeters, not an inch or more.

I wanted to go repeat the test with other lenses, but I did not realize this was going on until after dark when I downloaded the camera. And this is western WA and the sun is not schedule to re-appear until Tuesday (maybe I'll get lucky in the next few days). So re-doing it is not immediately possible. Very frustrating.

I wonder if it is something with my glasses because my vision is outside of what can be corrected by the diopter range of the viewfinder. I'll try re-adjusting everything and experimenting indoors, albeit I'll have to shoot at open lens settings. This body is going to be used 90% or more with fixed length lenses, so I will work to sort this out.

08-22-2010, 02:03 AM   #5
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How far from the subject were you. The minimum focus distance of the lens is 0.45 metres.
08-22-2010, 03:01 AM   #6
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Are you sure you have the view finder right? I thought I had mine correct until I used a focusing chart and a tripod to check it. I found out that I was one click off. Just enough to give similar problems to what you are having.
Focus to the zero point on the chart, down load picture and double check the actual focus point. Adjust the viewfinder and re shoot. Simple to do, absolutely drove me nuts until I found the problem.
Before I had just used an AF lens and adjusted the viewfinder by eye after letting the camera focus the lens, and I got it wrong...
08-22-2010, 06:55 AM   #7
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If your focused correctly, I would think your focus confirmation would give you a thumbs up. Did you get confirmation from the camera?
08-22-2010, 11:13 AM   #8
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QuoteOriginally posted by Oro Quote
I have read a few threads on how to focus manual lenses on DSLRs, but am still not getting it right
Keep searching and see if you can find any where I posted about the issue of the viewfinder showing too much DOF. That's your problem here - you are being fooled by the viewfinder into thinking your subject is in focus, when in fact it isn't. The solution is to experiment and practice so you don't judge focus by looking just at your subject but also at what's in front of or behind it, and in quite a few previous posts on the subject, I've outlined methods for doing this using a sheet of text.

QuoteQuote:
With a film camera, I would not have expected this outcome.
Recent film cameras without split prism focus screen probably would have actually behaved the same way - the issue is focus screen that are optimized for use with slow zooms rather than fast primes. but it's true you wouldn't see it on older film cameras, or cameras of any type with split prism screens.

QuoteQuote:
1) Was I wrong to use such a low asa, and I should have used a higher one and slower shutter speed?
I don't see what that has to do with focus.

QuoteQuote:
4) Would a Katzeye or similar help me catch this
Yes, but so would practice after fully coming to grips with the effect I described (viewfinder showing too much DOF).

08-22-2010, 05:00 PM   #9
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If DOF doesn't matter, then use f8 or f11.

If the shutter speed is too high, compose your picture in a darker environment, maybe indoors with natural light.

Give you camera to someone else to see how they go to rule out your eyesight !

Good luck.
08-24-2010, 05:04 AM   #10
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In reading this I have a few questions

First of all you say the diopter is all the way to one side but your eyesight is bad enough that this is
Not perfect

Are you wearing glasses when you shoot? I find setting the viewfinder for glasses is better than shooting with glasses
Off

Second f22 and 1/3000 at iso 200 is very bright conditions. What lighting were you using

Lastly the apparent depth of field in the few finder is better than your lens in reality it is easy to get fooled on focus.
08-24-2010, 08:05 AM   #11
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QuoteOriginally posted by Lowell Goudge Quote
Second f22 and 1/3000 at iso 200 is very bright conditions. What lighting were you using
That appears to have been a typo. EXIF says f/2, and that's about what it looks like from the DOF and overall image quality.
08-24-2010, 08:59 AM   #12
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QuoteOriginally posted by Marc Sabatella Quote
That appears to have been a typo. EXIF says f/2, and that's about what it looks like from the DOF and overall image quality.
I can't see exit on my iPod

It would be better, unless the op wants really shallow DOD to trade 1/3000 and F2 for 1/400 and F8 that would solve mf errors
08-25-2010, 07:42 AM   #13
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My K7 was shipped with the wrong spacer for the focus screen : it's too thick, thus slightly back-focusing the screen against what is actually on the sensor... Or, you could say that my K7 suffers from front-focus when used manually...

So, I have to back-focus a little in order to have sharp photos...
08-25-2010, 08:44 AM   #14
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Is that actually an early (1970) series 70, or is the BB on the barrel for something else?
08-28-2010, 12:48 AM   #15
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OK, well I would like to pull out all my school boy latin and say mea culpa.

I have taken a number of other photos both with that lens, and an M 50/1.7. Everything is coming out fine. I think I am learning Marc's point (and others) about getting tricked by the apparent DOF. Also, I was not fully aware of the focus verification and am now using that to double check myself, but it is not demonstrating that I am making many errors. Yes I wanted to shoot it at F2 to just hightlight the "BB", the "22" was a typo.

I also re-set the diopter with my glasses and I only shoot with my eye correction on (glasses or contacts) and the diopter set to that. I really appreciate all the comments and went through each one to follow the point and double check myself. I just blew this, probably moving like tibbitts said, or getting fooled like Marc and Lowell said.

Also, to do photos like this better, I bought a proper M 50mm/4 macro lens which I am looking forward to getting and playing with, and also I will be installing a slit focusing screen.

QuoteOriginally posted by Parallax:
Is that actually an early (1970) series 70, or is the BB on the barrel for something else?
Technically it is a pre-70, but yes with the '70 series barrel/bushing and thus the "BB" code. It is one of the very last ones made in June of 1970. And yes, the "BB" is there because it is one of the random 1,000 production proof/test guns they sprinkled in the last few thousand of those prior to rolling out the full '70 series in July. I am a collector of '70 series/collet bushing Colt GMs. I actually have two of these particular "BB" pre-production models; definitely the rarest example of anything I own in that regard. If you are curious or knowledgeable about them, send me a pm or email, I won't force others to read (much) more of my non-photo ramblings! I appreciate your skilled observation. Here is a better pic of the gun and I have all the original documents that came with it, too. I have not owned it long; I just found it recently though I had been looking on and off for a number of years. I was dumbstruck when I found another one within a week later; it is arriving tomorrow. As you can see, I blew this photo, too - either that or photbucket has degraded it because I recall it looking much better on my computer after I cropped the RAW file... It was on a tripod, also. I am going to re-shoot some of it and the new (to me) one in the next few days and with a macro lens.


Last edited by Oro; 08-28-2010 at 12:58 AM.
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