FA 31mm what's wromg with my lens??? please please help

pHREDD D · 04-22-2010, 05:28 AM

just brought this AIS (Australia - CRK) a couple of weeks ago had major problems adjusting the AF focus for close ups ie flowers (+70 on my KX) but now my landscape photos are just crap!!!!!!!!!!! I can get better images with my FA 50mm wide open. Below is a crop on where the focus should be plus a link to the full size photo. Is this an out of focus photo or just a bad lens?

Please help I bought this lens for my holidays in a few weeks and have no idea about why these photos are poor quality. (with all my lens I do a focus test on a focus chart then brick wall tests all with great results... except of course the only lens I really don't need but just had to get! (perhaps this a cure for LBA...)

full size image link...
http://phreddy.zenfolio.com/img/v7/p1023242447.jpg

another full size image link
http://phreddy.zenfolio.com/img/v9/p804412874.jpg

To be honest I am at my wits end about this lens so any comments suggestions would be most welcome.

axl · 04-22-2010, 05:37 AM

I would say it's front focused.
To my eye the focus is actually just below the road below the boat.

BR
Peter

farfisa · 04-22-2010, 05:44 AM

Are you using a filter?
Sometimes filters can degrade the image quality.

I see these are at f/2.4 and f/1.8, so focus is pretty critical too, but I really can't tell where the focus is in the first one. The second shot appears pretty close, but at 1.8 the depth of field is pretty thin so you could be a touch in front and it'll screw up the whole image.

Good luck with it!

axl · 04-22-2010, 06:08 AM

Originally posted by farfisa

Are you using a filter?
Sometimes filters can degrade the image quality.

I see these are at f/2.4 and f/1.8, so focus is pretty critical too, but I really can't tell where the focus is in the first one. The second shot appears pretty close, but at 1.8 the depth of field is pretty thin so you could be a touch in front and it'll screw up the whole image.

Good luck with it!

I don't think it's a filter.
In the second shot the focus appears to be just in front of the twigs on the mall.

Basing on those two shots, I believe his lens does front focus....

aleonx3 · 04-22-2010, 06:53 AM

It is difficult to determine the problem (if any) based on those shots. For focal length 31mm at f4 aperture the hyperfocal length is about 40 feet. Focus on any objects beyond the hyperfocal length - you should be able to determine if the focussed object is sharp or not (ff or bf).

JeffJS · 04-22-2010, 07:53 AM

I'm not seeing anything in focus in either shot.. Have you tried turning off the AF and going manual focus just to determine it is Not the lens? You say you adjusted the AF +70 for doing Closeups of flowers. What happened with the Rest of your lenses? Does the Kx support AF adjustment or did you use a hack?

Parallax · 04-22-2010, 08:34 AM

Originally posted by JeffJS

I'm not seeing anything in focus in either shot.. Have you tried turning off the AF and going manual focus just to determine it is Not the lens? You say you adjusted the AF +70 for doing Closeups of flowers. What happened with the Rest of your lenses? Does the Kx support AF adjustment or did you use a hack?

Sounds to me like he used a hack to get the lens to focus closer than it's natural minimum and now it won't focus to infinity in AF.
Just a guess.

SpecialK · 04-22-2010, 09:09 AM

Something is wrong in both shots.

I'd test it again by shooting along a brick wall or something with an identifiable focus spot to see where it is actually focusing.

JeffJS · 04-22-2010, 09:40 AM

Originally posted by Parallax

Sounds to me like he used a hack to get the lens to focus closer than it's natural minimum and now it won't focus to infinity in AF.
Just a guess.

You're probably right and that's why I asked if the lens can be focused without the AF getting in the way.. FWIW, I think AF is really a poor way to Test a Lens for sharpness. Turn off the AF and see if the lens can be focused and give a sharp photo At All. THEN give the best calibration possible (which should be done at a moderate distance).

aleonx3 · 04-22-2010, 09:51 AM

Arh, I didn't read the OP carefully, if anything at all, try to undo what have been done before, reverse the +70 focus adjustment and see if that help. It almost sounds like something similar to putting on extension tube and not adjusting to the focusing distance.

Just curious about the focus adjustment, is the adjustment on a per lens base or for every lenses?

nulla · 04-22-2010, 12:34 PM

Also what settings have you for AF?

Seems to be front focusing

Voe · 04-22-2010, 03:41 PM

Originally posted by pHREDD D

I can get better images with my FA 50mm wide open. Below is a crop on where the focus should be plus a link to the full size photo. Is this an out of focus photo or just a bad lens?

To be honest I am at my wits end about this lens so any comments suggestions would be most welcome.

You pretty much experience what I went through with my first 31mm Limited when I got it in August 2009. Lens was one of the first "Assembled in Vietnam" series.

When I posted my findings most of the people here said that I'm wrong or it's a matter of back or front focusing.

Nevertheless I returned it to B&H Photovideo and requested an exchange for one "Made in Japan". When it arrived I could finally see why people say this lens is sharp even wideopen.

With time many people on the forum started experiencing the same issue with 31mm Limited lenses "Assembled in Vietnam". I personally know two forum members in Melbourne who had the same problem.

If you can contact CRK and ask them to send it back to Japan for adjustment as it appears that the lens has a decentered optics.

The lens is great and is a keeper. If nothing works, sell it and buy a mint second hand made in Japan.

Good luck.

pHREDD D · 04-23-2010, 12:46 AM

I've reset the AF adjustment - taken more landscape and portrait photos and wide open they are the worse quality I have ever seen. Looks like this lens won't be going on holidays next month...

iFoto · 04-23-2010, 01:42 AM

Originally posted by pHREDD D

full size image link...
http://phreddy.zenfolio.com/img/v7/p1023242447.jpg

another full size image link
http://phreddy.zenfolio.com/img/v9/p804412874.jpg

you can look up at flickr how your photos should look like Kx + 31mm
31mm - Flickr: Search

in the first one the focus is on the grass in the front
but the second one doesn't look like front focus

both photos are way too soft
and it produces massiv green edges - this should not be like this

i personally found the 31 is not the "magic best off all super lens" as a lot of people
think of it - maybe it is, because even the standard-lenses are allready quite good

but it is a very good lens - resolution is very high, bokeh is outstanding and the colours are great

test it with different settings on one shot - starting with "auto" and than move on with manual settings
if the results all look that bad send it back

**Ash** · 04-23-2010, 02:19 AM

Totally unexpected from a lens of this class.
My own copy is absolutely stellar in performance and has an HMC in front of it without any noticeable effect.

Mate, get it looked into with another camera and see if it's an intrinsic lens problem or some focusing issue between the lens and camera.

04-22-2010, 05:28 AM	#1
pHREDD D New Member Join Date: Dec 2008 Location: Adelaide Posts: 24	FA 31mm what's wromg with my lens??? please please help just brought this AIS (Australia - CRK) a couple of weeks ago had major problems adjusting the AF focus for close ups ie flowers (+70 on my KX) but now my landscape photos are just crap!!!!!!!!!!! I can get better images with my FA 50mm wide open. Below is a crop on where the focus should be plus a link to the full size photo. Is this an out of focus photo or just a bad lens? Please help I bought this lens for my holidays in a few weeks and have no idea about why these photos are poor quality. (with all my lens I do a focus test on a focus chart then brick wall tests all with great results... except of course the only lens I really don't need but just had to get! (perhaps this a cure for LBA...) full size image link... http://phreddy.zenfolio.com/img/v7/p1023242447.jpg another full size image link http://phreddy.zenfolio.com/img/v9/p804412874.jpg To be honest I am at my wits end about this lens so any comments suggestions would be most welcome.

04-22-2010, 03:41 PM	#12
Voe Veteran Member Join Date: Dec 2006 Location: Sydney Photos: Gallery Posts: 719	Originally posted by pHREDD D I can get better images with my FA 50mm wide open. Below is a crop on where the focus should be plus a link to the full size photo. Is this an out of focus photo or just a bad lens? To be honest I am at my wits end about this lens so any comments suggestions would be most welcome. You pretty much experience what I went through with my first 31mm Limited when I got it in August 2009. Lens was one of the first "Assembled in Vietnam" series. When I posted my findings most of the people here said that I'm wrong or it's a matter of back or front focusing. Nevertheless I returned it to B&H Photovideo and requested an exchange for one "Made in Japan". When it arrived I could finally see why people say this lens is sharp even wideopen. With time many people on the forum started experiencing the same issue with 31mm Limited lenses "Assembled in Vietnam". I personally know two forum members in Melbourne who had the same problem. If you can contact CRK and ask them to send it back to Japan for adjustment as it appears that the lens has a decentered optics. The lens is great and is a keeper. If nothing works, sell it and buy a mint second hand made in Japan. Good luck. Last edited by Voe; 04-22-2010 at 03:48 PM.

04-23-2010, 12:46 AM	#13
pHREDD D New Member Join Date: Dec 2008 Location: Adelaide Posts: 24 Original Poster	thanks Voe. I've reset the AF adjustment - taken more landscape and portrait photos and wide open they are the worse quality I have ever seen. Looks like this lens won't be going on holidays next month...

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04-22-2010, 05:37 AM	#2
axl Veteran Member Join Date: Mar 2007 Location: Nove Zamky, Slovakia Photos: Gallery \| Albums Posts: 7,183	I would say it's front focused. To my eye the focus is actually just below the road below the boat. BR Peter

04-22-2010, 05:44 AM	#3
farfisa Veteran Member Join Date: Nov 2008 Location: Toronto, Canada Photos: Gallery Posts: 1,274	Are you using a filter? Sometimes filters can degrade the image quality. I see these are at f/2.4 and f/1.8, so focus is pretty critical too, but I really can't tell where the focus is in the first one. The second shot appears pretty close, but at 1.8 the depth of field is pretty thin so you could be a touch in front and it'll screw up the whole image. Good luck with it!

04-22-2010, 06:08 AM	#4
axl Veteran Member Join Date: Mar 2007 Location: Nove Zamky, Slovakia Photos: Gallery \| Albums Posts: 7,183	Originally posted by farfisa Are you using a filter? Sometimes filters can degrade the image quality. I see these are at f/2.4 and f/1.8, so focus is pretty critical too, but I really can't tell where the focus is in the first one. The second shot appears pretty close, but at 1.8 the depth of field is pretty thin so you could be a touch in front and it'll screw up the whole image. Good luck with it! I don't think it's a filter. In the second shot the focus appears to be just in front of the twigs on the mall. Basing on those two shots, I believe his lens does front focus....

04-22-2010, 06:53 AM	#5
aleonx3 Veteran Member Join Date: Jul 2007 Location: Brampton, Ontario Photos: Gallery \| Albums Posts: 3,996	It is difficult to determine the problem (if any) based on those shots. For focal length 31mm at f4 aperture the hyperfocal length is about 40 feet. Focus on any objects beyond the hyperfocal length - you should be able to determine if the focussed object is sharp or not (ff or bf).

04-22-2010, 07:53 AM	#6
JeffJS Inactive Account Join Date: Aug 2008 Location: Michigan, USA Photos: Gallery \| Albums Posts: 7,484	I'm not seeing anything in focus in either shot.. Have you tried turning off the AF and going manual focus just to determine it is Not the lens? You say you adjusted the AF +70 for doing Closeups of flowers. What happened with the Rest of your lenses? Does the Kx support AF adjustment or did you use a hack?

04-22-2010, 08:34 AM	#7
Parallax Senior Moderator Loyal Site Supporter Join Date: Apr 2008 Location: South Dakota Photos: Gallery Posts: 19,332	Originally posted by JeffJS I'm not seeing anything in focus in either shot.. Have you tried turning off the AF and going manual focus just to determine it is Not the lens? You say you adjusted the AF +70 for doing Closeups of flowers. What happened with the Rest of your lenses? Does the Kx support AF adjustment or did you use a hack? Sounds to me like he used a hack to get the lens to focus closer than it's natural minimum and now it won't focus to infinity in AF. Just a guess.

04-22-2010, 09:09 AM	#8
SpecialK Pentaxian Join Date: Dec 2006 Location: So California Photos: Gallery Posts: 16,481	Something is wrong in both shots. I'd test it again by shooting along a brick wall or something with an identifiable focus spot to see where it is actually focusing.

04-22-2010, 09:40 AM	#9
JeffJS Inactive Account Join Date: Aug 2008 Location: Michigan, USA Photos: Gallery \| Albums Posts: 7,484	Originally posted by Parallax Sounds to me like he used a hack to get the lens to focus closer than it's natural minimum and now it won't focus to infinity in AF. Just a guess. You're probably right and that's why I asked if the lens can be focused without the AF getting in the way.. FWIW, I think AF is really a poor way to Test a Lens for sharpness. Turn off the AF and see if the lens can be focused and give a sharp photo At All. THEN give the best calibration possible (which should be done at a moderate distance).

04-22-2010, 09:51 AM	#10
aleonx3 Veteran Member Join Date: Jul 2007 Location: Brampton, Ontario Photos: Gallery \| Albums Posts: 3,996	Arh, I didn't read the OP carefully, if anything at all, try to undo what have been done before, reverse the +70 focus adjustment and see if that help. It almost sounds like something similar to putting on extension tube and not adjusting to the focusing distance. Just curious about the focus adjustment, is the adjustment on a per lens base or for every lenses?

04-22-2010, 12:34 PM	#11
nulla Veteran Member Join Date: Jul 2008 Location: Melbourne Australia Posts: 1,560	Also what settings have you for AF? Seems to be front focusing

04-23-2010, 01:42 AM	#14
iFoto Senior Member Join Date: Feb 2008 Photos: Gallery \| Albums Posts: 177	Originally posted by pHREDD D full size image link... http://phreddy.zenfolio.com/img/v7/p1023242447.jpg another full size image link http://phreddy.zenfolio.com/img/v9/p804412874.jpg you can look up at flickr how your photos should look like Kx + 31mm 31mm - Flickr: Search in the first one the focus is on the grass in the front but the second one doesn't look like front focus both photos are way too soft and it produces massiv green edges - this should not be like this i personally found the 31 is not the "magic best off all super lens" as a lot of people think of it - maybe it is, because even the standard-lenses are allready quite good but it is a very good lens - resolution is very high, bokeh is outstanding and the colours are great test it with different settings on one shot - starting with "auto" and than move on with manual settings if the results all look that bad send it back

04-23-2010, 02:19 AM	#15
Ash Loyal Site Supporter Join Date: Mar 2007 Location: Toowoomba, Queensland Photos: Gallery \| Albums Posts: 23,920	Totally unexpected from a lens of this class. My own copy is absolutely stellar in performance and has an HMC in front of it without any noticeable effect. Mate, get it looked into with another camera and see if it's an intrinsic lens problem or some focusing issue between the lens and camera.