Sigma 85mm front focusing on K-5 body.

Class A · 06-02-2011, 05:37 PM

Originally posted by creampuff

Sorry but before you go off and attempt to hypothesize, do you even have a fast Sigma prime mated to a K-5 to begin with?

If you think that my comments become invalid because I don't own a K-5 + Sigma 85/1.4, that's your prerogative.

I wouldn't be qualified to write a "hands on" report on the above combination, but surely some of the knowledge I acquired with other equipment transfers to this discussion. Do also think that my AF adjustment hints do not apply to the K-5 because I don't own a K-5?

Furthermore, assuming that what I read about the K-5's focus problems is not just all lies, it seems plausible to suggest a connection.

If you read my posts again you'll notice that I offered explanations without implying that I'm a 100% sure that they apply in this particular case.

If I had a problem with some equipment, I'd prefer the advice from someone knowledgeable about the principles any day over someone who just happens to own the same equipment.

P.S.: You apparently overlooked a question I asked: "How do you explain that the OP's shots of brick walls and other 3D objects are fine?". How do you combine that observation with your theory that the lens needs a recalibration? I'm not saying that it is impossible that the lens needs recalibration but given the fact that it focuses fine on many objects other than faces, seems to suggest that other explanations should be explored as well.

simico · 06-03-2011, 01:10 AM

Originally posted by outsider

The k-5/sigma has broken my heart so many times with front focus, blurry eyes and sharp noses, that I even considered getting rid of my k-5

Although I don't have 85 f/1.4 lens, I can run into this issue with the 30 f/1.4, 100 f/4 and 50-150 f/2.8 when shooting wide open and from close distance with the latter two lenses. I usually try to focus on the outer lower corner of the eye to make sure that neither the nose nor the eyebrows & eyelashes are included in the af area. Or I just manual focus if the shooting pace and subject allows (definitely not my little daughter lol). But I'm just a hobby crapshooter so what do I know

outsider · 06-09-2011, 02:46 PM

You guys should do a test of say, 10 shots with the k-5, any lens of someones head, at a wider aperture (so it will be easier to tell when it front/misses focus). Stand far back enough to get the entire head into the frame (just as I like to do with portraits). Aim at an eye and see how many times the k-5 will acknowledge the eye as the target. I now confirmed that this same issue is happening with my tamron 70-200. If you get close enough, the k-5 has little problem nailing the eye, but you don't want to shoot that way all the time. The k-x blows the k-5 out of the water for pinpointing small areas of focus. I can stand back nearly 10 feet shooting at 1.4 with the k-x/sigma 85 and nail the eye at least half the time. Sadly, this is what I use most of the time when out shooting people. I miss the 14bit redering but i've no choice at the moment.

WerTicus · 06-09-2011, 08:43 PM

my 55* which i just sent back would back focus majorly at longer distances and for close ups was perfectly fine. Ughh quality control on this level of lens should be perfect.

mikknu · 06-10-2011, 03:24 AM

Originally posted by outsider

My sigma 85mm 1.4 is front focusing like H*ll on the K-5 and I can't understand why. This only happens when I'm shooting closeup faces. Half of the shots are unuseable and the other half are just good enough to sharpen and keep. A few are just perfect, but not many. It has no problem with the brick wall test or just about anything else. It's as though it gets confused, stops, beep confirmation and most times I can't see well enough to tell if it's actually spot on until viewing the pictures on a monitor. I have no problems while using the k-x, it's a dream. I've tried everything except focus adjustment, but I don't think that's the problem. It seems as though the point focus is significantly larger area on the k-5 than the k-x. Many times the focus will stop at the frame of someone using glasses, rather than the eye itself. Very frustrating. I've noticed that the sigma focuses much more surely on the k-x than k-5, even in low light. Sometimes the sigma just stops in low light on the k-5 without catching focus and no beep confirmation. Maybe this is just an adverse occurance with these two. Any suggestions?

I've had a similar experience with my K-5 and my recently purchased sigma 30mm 1.4 lens. I couldn't get any decent focus unless I got up as close as the lens allows, which is 40cm. It mainly seemed to be BF'ing. Camera and lens are currently being calibrated. If you are interested, I can tell if calibration have helped anything, once I get it back, I just don't know when that will be right now.

outsider · 06-11-2011, 06:29 PM

Originally posted by mikknu

I've had a similar experience with my K-5 and my recently purchased sigma 30mm 1.4 lens. I couldn't get any decent focus unless I got up as close as the lens allows, which is 40cm. It mainly seemed to be BF'ing. Camera and lens are currently being calibrated. If you are interested, I can tell if calibration have helped anything, once I get it back, I just don't know when that will be right now.

Nice. That would be great! Let me know!

pilgrimingvine · 06-11-2011, 09:01 PM

Had a Sigma 50 f1.4 that front focused. At 1.4, it front focused ~2-3mm with AF Fine Tune set at -10. That was negligible in real world situations for me since I hardly shot wide open. At smaller apertures, it really wasn't an issue.

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06-02-2011, 05:37 PM	#16
Class A Pentaxian Join Date: Aug 2008 Location: Wellington, New Zealand Posts: 11,251	Originally posted by creampuff Sorry but before you go off and attempt to hypothesize, do you even have a fast Sigma prime mated to a K-5 to begin with? If you think that my comments become invalid because I don't own a K-5 + Sigma 85/1.4, that's your prerogative. I wouldn't be qualified to write a "hands on" report on the above combination, but surely some of the knowledge I acquired with other equipment transfers to this discussion. Do also think that my AF adjustment hints do not apply to the K-5 because I don't own a K-5? Furthermore, assuming that what I read about the K-5's focus problems is not just all lies, it seems plausible to suggest a connection. If you read my posts again you'll notice that I offered explanations without implying that I'm a 100% sure that they apply in this particular case. If I had a problem with some equipment, I'd prefer the advice from someone knowledgeable about the principles any day over someone who just happens to own the same equipment. P.S.: You apparently overlooked a question I asked: "How do you explain that the OP's shots of brick walls and other 3D objects are fine?". How do you combine that observation with your theory that the lens needs a recalibration? I'm not saying that it is impossible that the lens needs recalibration but given the fact that it focuses fine on many objects other than faces, seems to suggest that other explanations should be explored as well.

06-03-2011, 01:10 AM	#17
simico Veteran Member Join Date: Jan 2009 Location: Budapest Posts: 821	Originally posted by outsider The k-5/sigma has broken my heart so many times with front focus, blurry eyes and sharp noses, that I even considered getting rid of my k-5 Although I don't have 85 f/1.4 lens, I can run into this issue with the 30 f/1.4, 100 f/4 and 50-150 f/2.8 when shooting wide open and from close distance with the latter two lenses. I usually try to focus on the outer lower corner of the eye to make sure that neither the nose nor the eyebrows & eyelashes are included in the af area. Or I just manual focus if the shooting pace and subject allows (definitely not my little daughter lol). But I'm just a hobby crapshooter so what do I know

06-09-2011, 02:46 PM	#18
outsider Veteran Member Join Date: Jan 2011 Photos: Albums Posts: 416 Original Poster	You guys should do a test of say, 10 shots with the k-5, any lens of someones head, at a wider aperture (so it will be easier to tell when it front/misses focus). Stand far back enough to get the entire head into the frame (just as I like to do with portraits). Aim at an eye and see how many times the k-5 will acknowledge the eye as the target. I now confirmed that this same issue is happening with my tamron 70-200. If you get close enough, the k-5 has little problem nailing the eye, but you don't want to shoot that way all the time. The k-x blows the k-5 out of the water for pinpointing small areas of focus. I can stand back nearly 10 feet shooting at 1.4 with the k-x/sigma 85 and nail the eye at least half the time. Sadly, this is what I use most of the time when out shooting people. I miss the 14bit redering but i've no choice at the moment.

06-09-2011, 08:43 PM	#19
WerTicus Veteran Member Join Date: Mar 2009 Location: Perth Australia Photos: Albums Posts: 1,514	my 55* which i just sent back would back focus majorly at longer distances and for close ups was perfectly fine. Ughh quality control on this level of lens should be perfect.

06-10-2011, 03:24 AM	#20
mikknu Forum Member Join Date: Dec 2010 Location: Silkeborg, Denmark Posts: 82	Originally posted by outsider My sigma 85mm 1.4 is front focusing like H*ll on the K-5 and I can't understand why. This only happens when I'm shooting closeup faces. Half of the shots are unuseable and the other half are just good enough to sharpen and keep. A few are just perfect, but not many. It has no problem with the brick wall test or just about anything else. It's as though it gets confused, stops, beep confirmation and most times I can't see well enough to tell if it's actually spot on until viewing the pictures on a monitor. I have no problems while using the k-x, it's a dream. I've tried everything except focus adjustment, but I don't think that's the problem. It seems as though the point focus is significantly larger area on the k-5 than the k-x. Many times the focus will stop at the frame of someone using glasses, rather than the eye itself. Very frustrating. I've noticed that the sigma focuses much more surely on the k-x than k-5, even in low light. Sometimes the sigma just stops in low light on the k-5 without catching focus and no beep confirmation. Maybe this is just an adverse occurance with these two. Any suggestions? I've had a similar experience with my K-5 and my recently purchased sigma 30mm 1.4 lens. I couldn't get any decent focus unless I got up as close as the lens allows, which is 40cm. It mainly seemed to be BF'ing. Camera and lens are currently being calibrated. If you are interested, I can tell if calibration have helped anything, once I get it back, I just don't know when that will be right now.

06-11-2011, 06:29 PM	#21
outsider Veteran Member Join Date: Jan 2011 Photos: Albums Posts: 416 Original Poster	Originally posted by mikknu I've had a similar experience with my K-5 and my recently purchased sigma 30mm 1.4 lens. I couldn't get any decent focus unless I got up as close as the lens allows, which is 40cm. It mainly seemed to be BF'ing. Camera and lens are currently being calibrated. If you are interested, I can tell if calibration have helped anything, once I get it back, I just don't know when that will be right now. Nice. That would be great! Let me know!

06-11-2011, 09:01 PM	#22
pilgrimingvine Forum Member Join Date: May 2011 Location: Vancouver Photos: Gallery Posts: 54	Had a Sigma 50 f1.4 that front focused. At 1.4, it front focused ~2-3mm with AF Fine Tune set at -10. That was negligible in real world situations for me since I hardly shot wide open. At smaller apertures, it really wasn't an issue.