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Is 10 units of back focus unusual?

Sapphie
Posted 05/03/2011 - 11:51 Link
I have finally worked out that my 43mm ltd is back focusing and the '3 battery test' reveals that it needs +10 units of correction. At first I thought it was an issue with my K-5 but it is the same on my K20D.

It seems right at the limit of what we can adjust in camera.

Is there anyway to adjust the lens? I guess, if it works at +10 I should be satisfied but I am curious.

P.S. I have had the lens for a long time but am tending to use it more on the K-5 and I had noticed that some images, especially those at relatively short distances were 'soft'.

Lee
gartmore
Posted 06/03/2011 - 08:46 Link
Is this consistent with all your lenses?
Ken
“We must avoid however, snapping away, shooting quickly and without thought, overloading ourselves with unnecessary images that clutter our memory and diminish the clarity of the whole.” - Henri Cartier-Bresson -
Sapphie
Posted 06/03/2011 - 12:12 Link
Hi Ken

I really only have the 43mm and the 18-135 for my K-5. I get 'soft' shots from the latter too sometimes but am not sure if that is user error.

I tried setting the calibration with that at various focal lengths and decided that it too needed +10 for table-top battery shots at around 35mm but longer than that it seemed to make little difference.

Trouble is that with +10 on that one, my middle-long distance shots are OOF for all focal lengths.

Getting a little frustrated but am happy to be told I am doing something wrong.

Lee
beginner
Posted 06/03/2011 - 12:22 Link
Is this manual or autofocus?....Ken
K20D...ist DS ,DA18/55,DA16/45.DA* 50/135,"A"1.7 50MM..."A" 70/210..M 50mm f2...Tamron 90mm macro,28/300 Tamron,200/500 Tamron 6.9....A Pentax DA*300... Sigma10/20,FA31mm 1.8 Ltd*********,FA 77mm Ltd!
Smeggypants
Posted 06/03/2011 - 16:21 Link
I had to dial in -10 on my K20D for my DA* 50-135. It needs -5 on my K-5


My Pentax-A 50/1.2 need ore than -10 on the K20D so I ended up adjusting the overall AF in debug mode and recalibrated all the lensesso they were all within the +/-10 range.
[i]Bodies: 1x K-5IIs, 2x K-5, Sony TX-5, Nokia 808
Lenses: Pentax DA 10-17mm ED(IF) Fish Eye, Pentax DA 14mm f/2.8, Sigma 17-70mm f/2.8, Pentax-A 28mm f/2.8, Sigma 30mm F1.4 EX DC, Pentax-A 50mm f/1.2, Pentax-A 50mm f/1.4, Pentax-FA 50mm f/1.4, Pentax-A 50mm f/1.7, Pentax DA* 50-135mm f/2.8, Sigma 135-400mm APO DG, and more ..
Flash: AF-540FGZ, Vivitar 283
Posted 06/03/2011 - 16:28 Link
I had -10 on my Tamron 17-50. I put up with it for ages... no good. Sent it to Tamron and they tinkered with it. Now I'm on +1 and it's lovely and sharp.

There is nothing like lens calibration to muddy your thoughts on image quality. "is it me?" or "is the image good enough?"... you'll be asking these questions forever.

Do yourself a favour and get it adjusted. As -10 leaves you no options!!
Take care
Proud to be a Pentaxian since 1996:
Cosina C1, Pentax Me Super, Pentax MZ5n, Pentax k10, Pentax K7, Pentax K5ii, Pentax K-S2, Pentax 540 flash,
Sigma 10-20mm, Tamron 17-50mm... MF Tamron 90mm, Pentax 50mm F1.7, Sigma 50mm Macro,
Bowens lights, Yongnuo flash.
Edited by Bluewhistle2: 06/03/2011 - 16:28
Smeggypants
Posted 06/03/2011 - 17:01 Link
Bluewhistle2 wrote:
I had -10 on my Tamron 17-50. I put up with it for ages... no good. Sent it to Tamron and they tinkered with it. Now I'm on +1 and it's lovely and sharp.

There is nothing like lens calibration to muddy your thoughts on image quality. "is it me?" or "is the image good enough?"... you'll be asking these questions forever.

Do yourself a favour and get it adjusted. As -10 leaves you no options!!
Take care

Yes it does. You can adjust the overall AF if you need more
[i]Bodies: 1x K-5IIs, 2x K-5, Sony TX-5, Nokia 808
Lenses: Pentax DA 10-17mm ED(IF) Fish Eye, Pentax DA 14mm f/2.8, Sigma 17-70mm f/2.8, Pentax-A 28mm f/2.8, Sigma 30mm F1.4 EX DC, Pentax-A 50mm f/1.2, Pentax-A 50mm f/1.4, Pentax-FA 50mm f/1.4, Pentax-A 50mm f/1.7, Pentax DA* 50-135mm f/2.8, Sigma 135-400mm APO DG, and more ..
Flash: AF-540FGZ, Vivitar 283
Sapphie
Posted 06/03/2011 - 17:08 Link
Thanks for the responses; makes me feel slightly better.

My questions now are:

(a) where do I send my Pentax lenses for calibration?

(b) What do you mean, Smeggy, that you can adjust the overall AF? Is this some debug mode thing and is it available for the K5. if so, how?

Thanks, I am fed up with 'testing' and just want pictures that look sharp enough.

With a zoom like the 18-135, how should I test it? If it needs +10 at close quarters but then is OOF for distance shots, it makes me want to scream ...

And I wonder if I should have gone for another micro four thirds instead ... but those K-5 images are so nice, if only I was happy with the sharpness overall.

Lee
Smeggypants
Posted 06/03/2011 - 17:38 Link
Sapphie wrote:
Thanks for the responses; makes me feel slightly better.

My questions now are:

(a) where do I send my Pentax lenses for calibration?

(b) What do you mean, Smeggy, that you can adjust the overall AF? Is this some debug mode thing and is it available for the K5. if so, how?

On the K-5 the overall adjustment is in the same menu as the single lens adjustment. page 126 of the manual - "Apply All"

You can also do it in debug mode too on the K10D and K20D - I don't know the debug mode MODSET file for the K-5, but I suspect one exists


Quote:

Thanks, I am fed up with 'testing' and just want pictures that look sharp enough.

With a zoom like the 18-135, how should I test it? If it needs +10 at close quarters but then is OOF for distance shots, it makes me want to scream ...

Personally I think cameras should incorporate the ability to set AF adjustments for a series of subject distances, for each lens. Many lenses report the position of the focus barrel to the camera. Even though it's a tedious process I would be happy to adjust AF for various distances. After all you've only got to it once.


Quote:

And I wonder if I should have gone for another micro four thirds instead ... but those K-5 images are so nice, if only I was happy with the sharpness overall.

Lee

I doubt AF adjustments are exclusive to Pentax. I read a few Canon users moaning that the new 60D Didn't have any AF adjustment at all.
[i]Bodies: 1x K-5IIs, 2x K-5, Sony TX-5, Nokia 808
Lenses: Pentax DA 10-17mm ED(IF) Fish Eye, Pentax DA 14mm f/2.8, Sigma 17-70mm f/2.8, Pentax-A 28mm f/2.8, Sigma 30mm F1.4 EX DC, Pentax-A 50mm f/1.2, Pentax-A 50mm f/1.4, Pentax-FA 50mm f/1.4, Pentax-A 50mm f/1.7, Pentax DA* 50-135mm f/2.8, Sigma 135-400mm APO DG, and more ..
Flash: AF-540FGZ, Vivitar 283
Sapphie
Posted 06/03/2011 - 17:39 Link
Just another comment. Whilst I was doing my somewhat desperate set of 'is the middle battery in focus' tests earlier, (18-135) there was one set where they were *all* way out of focus, i.e. for 0,5 10 adjustment. I could put that down to perhaps I was kicking the tripod except the live view shot was fine. Sadly, I deleted them and haven't been able to repeat it.

And yet, a trip out to Exmoor this PM, where it was cold and windy, with '0' adjustment on my 18-135, most of the shots, even at longer focal lengths seem mostly fine ...

I am also not sure if 'AF adjusment Off', 'AF Adjustment On but 'Unset' and 'AF Adjustment On and set to 0' mean the same thing ...

And sometimes I wonder if I don't have the shutter speed high enough, or the higher ISO settings that are now so easy to use are somehow softening the image (I have all the NT things Off).

And sometimes I wonder if the SR is even battling against me - I tend to focus, recompose, hold shutter half way down and then shoot - because I am in 'old timer' mode in the days before SR when I had to try to get the camera steady before shooting.

And sometimes I just think I need to readjust to using an SLR again after mostly using smaller sensor cameras.

Is it any wonder I don't sleep well?

Lee
Sapphie
Posted 06/03/2011 - 17:45 Link
Smeggy

I didn't think that the 'Apply All' and individual AF adjustments were cumulative?

Do we have any proof that this is so, other than me doing another barrage of test (I think I might use sausages next time instead of batteries !! )

I assumed that any 'Apply All' setting was overridden by the individual setting and only used if you hadn't done an individual setting for that lens?

I do also wonder if the occasional 'reset' in this menu helps too.

I don't suppose, when it remembers for a given lens that it *is* basing that on the focal length used at the time?

Lee
Smeggypants
Posted 06/03/2011 - 17:50 Link
Sapphie wrote:
Smeggy

I didn't think that the 'Apply All' and individual AF adjustments were cumulative?

Do we have any proof that this is so, other than me doing another barrage of test (I think I might use sausages next time instead of batteries !! )


Yes they are cumulative. I've tried it - I'm currently testing to use it as a workaround for the K-5's front focussing in low light problem.


I can't use sausages. I would eat them too soon


Quote:
I assumed that any 'Apply All' setting was overridden by the individual setting and only used if you hadn't done an individual setting for that lens?

I do also wonder if the occasional 'reset' in this menu helps too.

I don't suppose, when it remembers for a given lens that it *is* basing that on the focal length used at the time?

Lee

I would very much doubt it.
[i]Bodies: 1x K-5IIs, 2x K-5, Sony TX-5, Nokia 808
Lenses: Pentax DA 10-17mm ED(IF) Fish Eye, Pentax DA 14mm f/2.8, Sigma 17-70mm f/2.8, Pentax-A 28mm f/2.8, Sigma 30mm F1.4 EX DC, Pentax-A 50mm f/1.2, Pentax-A 50mm f/1.4, Pentax-FA 50mm f/1.4, Pentax-A 50mm f/1.7, Pentax DA* 50-135mm f/2.8, Sigma 135-400mm APO DG, and more ..
Flash: AF-540FGZ, Vivitar 283
Rataegeoff
Posted 06/03/2011 - 20:48 Link
Could I show my ignorance...what is the three battery test?

Does anyone know if there is a way of making any adjustments to the AF of a KX?

If there isn't then I'll not be checking the AF! I agree about shutter speed and the clarity of the enlarged picture. No doubt at all the the SR on Pentax bodies works well but in shooting with the tele lenses I feel I see sharper results at faster shutter speeds.
K10D,KX, DA 18-55, DA 17-70 AL(IF) SDM, DA*50-135, Sigma 70-300, DAL 50-300mm, Kenko 1.5x, loads of SD cards and even more optimism
Sapphie
Posted 06/03/2011 - 20:49 Link
Hi Smeggy

In spite of my sometimes 'love hate' relationship with the K5 and (18-135mm lens), it is mostly love, or at least admiration ...

in case anyone thought I was 'having a go', which I wasn't - oh for more free time to play ...

Lee
Sapphie
Posted 06/03/2011 - 20:58 Link
3 battery test - I may have this all wrong, but place 3 batteries (AA size is ideal) on a table, at a 45 degree angle; line up your camera and lens so that they fill as much of the frame as possible, with the camera on a tripod and level with the batteries. Space the batteries far enough apart so that the central circle in the viewfinder only covers the central one.

OK, camera now on minimum aperture, choose a not too high ISO, central AF point, 2 sec timer (which also does mirror up and no SR) and try a few AF adjustments.

But only if you think you have a problem. And, even then, you may not be sure, I mean how often do you take pics like that in real life?

I am only persevering because because I think the K5 image quality is the best I have seen on a digital camera ...

I don't know what to suggest if your favourite lens is a zoom ... I am not sure myself ...

Lee

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