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11-07-2011, 06:58 AM   #16
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This copy of the FA77 has a AF fine adjustment of +10. This was done while under good sun light on a tripod. And I found +10 to be the sharpest.
I have since done a firmware update (to 1.03) without resetting the AF fine adjustment.

Tomorrow I will test again under good and bad lighting to see if the AF fine adjustment had shifted.

11-07-2011, 06:59 AM   #17
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Thanks.
11-07-2011, 07:03 AM   #18
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QuoteOriginally posted by rawr Quote
Great sharp images. No FF visible

Gee, how old would that Dragon Lady be?
Thanks .
I think it's 1968
11-07-2011, 07:04 AM   #19
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I think that this focus issue is a sporadic problem, effecting some cameras a lot and other cameras not at all. My K5 has no issues that I can tell -- seems spot on even in very low light, but I know that there are others who continue to have problems, even after the most recent firmware update.

11-07-2011, 07:22 AM   #20
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QuoteOriginally posted by Katsura Quote
AF Point Mode: Select
I think this may be important. You may not have had the AF point set at Fixed Center, but somewhere else entirely based on a manual AF point selection. Where does PhotoMe graphically indicate the AF point was? (visible in the thumbnail in PhotoMe).

I'd also clear your AF adjustments and do them again, maybe using a tool like the DataColor SpyderLensCal.

BTW the EXIF indicates there was PLENTY of light in that scene for the AF to work properly. Not a single segment of the scene was illuminated below 3.6EV.

Last edited by rawr; 11-07-2011 at 07:28 AM.
11-07-2011, 07:25 AM   #21
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I bought a K-5, noticed obvious misfocus in tungsten light. I loaded V1.03 and tested vs. my K-x and K20D, in dim tungsten lighting. Both older cameras focussed perfectly, the K-5 showed no change, severe front focus in tungsten light, perfect focus in natural light. I returned it, I'll wait for the next body.

Low light test photos and exif here: https://picasaweb.google.com/100586096103361553535/LowLightTest?authkey=Gv1sRgCKfrw5i3lJihcQ#
Click on the magnifying glass for higher resolution.
11-07-2011, 07:29 AM   #22
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QuoteOriginally posted by rawr Quote
BTW the EXIF indicates there was PLENTY of light in that scene for the AF to work properly. Not a single segment of the scene was illuminated below 3.9EV.
The K-5 I had for a short time misfocussed due to wavelength, not intensity. It focussed well in very dim natural light, and consistently front focussed in tungsten light.
11-07-2011, 07:35 AM   #23
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QuoteOriginally posted by rawr Quote
I think this may be important. You may not have had the AF point set at Fixed Center, but somewhere else entirely based on a manual AF point selection. Where does PhotoMe graphically indicate the AF point was? (visible in the thumbnail in PhotoMe).

I'd also clear your AF adjustments and do them again, maybe using a tool like the DataColor SpyderLensCal.

BTW the EXIF indicates there was PLENTY of light in that scene for the AF to work properly. Not a single segment of the scene was illuminated below 3.6EV.
100% the centre AF point. Of that I am certain.
Could to do more with mixed lighting rather than low illumination.

11-07-2011, 07:41 AM   #24
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IMO, AF Fine adjustments are better adjusted against objects further away than the usual working distance of focus charts - the small alignment changes are tiny and may not even show up on close focused objects while every stop of the change will be very noticeable on objects further away.
11-07-2011, 07:54 AM   #25
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QuoteOriginally posted by Katsura Quote
IMO, AF Fine adjustments are better adjusted against objects further away than the usual working distance of focus charts - the small alignment changes are tiny and may not even show up on close focused objects while every stop of the change will be very noticeable on objects further away.
I believe they suggest minimal subject distance and widest aperture to minimize depth of field. Longer subject distances increase the DOF, therefore are less precise.
11-07-2011, 01:56 PM   #26
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QuoteOriginally posted by Katsura Quote
100% the centre AF point. Of that I am certain.
Interesting. Did you simply select CEN, or use SEL then select a centre spot?

QuoteOriginally posted by audiobomber Quote
minimal subject distance and widest aperture to minimize depth of field. Longer subject distances increase the DOF, therefore are less precise.
Indeed. At 5 metres with the FA77 at f2 you are getting DOF of about 33cm, and at 8m @f2 about 86cm.
11-07-2011, 10:37 PM   #27
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I just did some quick tests on AF adjustment and now I am even more concerned..
Under good natural lighting today:

When subject is about 2.5 meters away (and under), AF Micro adjustment of +10 gives shaper result than 0.
When subject is around 6 meters away, AF adjustment off/ position 0 gives shaper result than +10.
When subject is closer to infinite focus, AF adjustment 0 gives clear results while AF adjustment of +10 is very very front focused.

It seems the focus adjustment is a non linear variable in this equation. it seems to be a tolerance adjustment that is multiplied to whatever the factory AF value.

So, this may not be a low light focus issue but rather AF micro adjustment behaves differently upon the focus distance.

I will need to do a much more detailed test to see if there is a sweet spot or a value that is acceptable for both short and long focus distance.
I have a bad feeling if ALL my lens exhibit this behaviour.

I think I mostly never noticed it before because the 77 is my close crop portrait lens and all previous subjects have been fairly close!
11-07-2011, 10:50 PM   #28
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I was shooting AF, as I always do. Just establish focus with the rear AF button, stay on the subject and press the shutter when its interesting. Lighting like that will drive the camera nuts because the meter is clueless which is why manual exposure is important. Regardless of purpose, good exposure is a requirement for good photographs.
11-07-2011, 11:14 PM   #29
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I am not questioning why the exposure of my shots are crap - I know they are crap, I will try harder next time . And AF button/ recompose would not have helped in this instance, but thanks for reminding me how to do it.

Thing is, I started to figure out that AF micro adjustment affects (my particular copy of ) the lens and camera depending on the focus distance in this case.

Time to reset all the AF adjustment data and do some proper re-calibration and I will post my findings here.

thinking back, I remember someone posted saying that, before he updated his firmware, he needed dial in +10 or similar to get accurate focus, but after an update, the perfect focus is achieved at adjustment 0 - sounds like this could be the same case for me, why this is, I don't know, but at the end of the day if my lens focus properly I won;t care too much.
11-07-2011, 11:40 PM   #30
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Maybe I'm lucky or naive but I've never seen the need through one K10, two K20's and two K-5s to fool with focus adjustments. Its essentially a electro-mechanical closed loop servo system. The camera moves the lens until the camera sensor determines it's in focus. AF systems will get fooled by low contrast and very low light. Most stage lighting is hot lights, tungsten balance and the only issue I've ever had is very low light mostly with the Jazz company, they love the dark.

Most stage lighting is EV 7 or 8 so from Sunny 16 aka EV15, you just have to compensate 7 or 8 stops, With the K-5's, I just start at ISO 3200 which is 5 stops, go to f4 which is 4 more and up on shutter speed to 1/250 or 1/320to capture motion and you're in the ball park. The K-5 has a great dynamic range so there is plenty of exposure wiggle room which is good because there is no way to keep a completely accurate exposure on a dancer under stage lighting. No way. Beyond that, I have a callous on my right thumb from staying on the AF button all performance.

It took me a long time to start to be consistent and it wasn't the gear, it was me. Here is one I shot last year with K20's. 3D Project Straight Up Christmas - A Trans Siberian Tale - Images | Brooke Meyer This year, I know what not to do.
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