Sigma 50-150mm f2.8 AF doesn't work right in backlit situations?

axl · 05-30-2011, 04:07 AM

Originally posted by dadipentak

Um...mightn't the camera model be a relevant variable in this discussion?

That is very possible. Different versions of Safox might react differently under the same conditions

JHD · 05-30-2011, 04:25 AM

Originally posted by JHD

Here's something worth trying... zoom in tight, focus, and then pull back.

I should point out this is the technique used in television, both in the studio and out on location.

JHD · 05-30-2011, 04:28 AM

Originally posted by vinceloc

Hi there! I too have the same lens and have no problems shooting under similar conditions as how you were shooting. Here are some shots indoor but against strong lights which were taken at a FL around 70mm, aperture of f2.8 and ISO800 with my K200D:

I don't think the background light in these samples is comparable to the intensity of the sun in the sample posted by the OP.

vinceloc · 05-30-2011, 05:06 AM

Originally posted by JHD

I don't think the background light in these samples is comparable to the intensity of the sun in the sample posted by the OP.

Beg to disagree. The second photo shows that most of the direct sunlight is blocked out by the line of trees.

vinceloc · 05-30-2011, 05:09 AM

Originally posted by dadipentak

Um...mightn't the camera model be a relevant variable in this discussion?

Are you implying that the K200D's focusing is better than that of the K5 under these circumstances?

**dadipentak** · 05-30-2011, 06:08 AM

Originally posted by vinceloc

Are you implying that the K200D's focusing is better than that of the K5 under these circumstances?

Not at all. I just didn't see any mention of the body model and I'm under the impression that AF systems vary from model to model.

vinceloc · 05-30-2011, 06:20 AM

Originally posted by dadipentak

Not at all. I just didn't see any mention of the body model and I'm under the impression that AF systems vary from model to model.

Oh. I was under the assumption that you had also checked the EXIF and knew that the DSLR used is the K5.

**dadipentak** · 05-30-2011, 06:54 AM

Originally posted by vinceloc

Oh. I was under the assumption that you had also checked the EXIF and knew that the DSLR used is the K5.

Me? check EXIF?

JHD · 05-30-2011, 07:21 AM

Originally posted by vinceloc

Beg to disagree. The second photo shows that most of the direct sunlight is blocked out by the line of trees.

And I maintain that still is exponentially brighter than all the artificial light in the collective sum of your samples.

crossover37 · 05-30-2011, 11:06 AM

I will try to recreate the problem when I have time and I will keep you guys posted. Hopefully it's not something that will happen often.

crossover37 · 05-30-2011, 11:52 PM

Ok guys, here are some other pictures. I took these with the same intensity of backlighting and what I noticed is when I shot in landscape mode, the focus would lock correctly more often, I focused on the corner of the chair...when focusing in portrait mode, the focus was having trouble locking, it locked but was off and instead focused on the leaves as you can see in the second set of images, focus still was on the corner of the chair. I was using center focus point.

vinceloc · 05-31-2011, 12:14 AM

Hmmm. Interesting. Have you tried shooting in AV or M mode?

crossover37 · 05-31-2011, 12:17 AM

Originally posted by vinceloc

Hmmm. Interesting. Have you tried shooting in AV or M mode?

Yea, Manual is what I shoot in most of the time.

vinceloc · 05-31-2011, 12:32 AM

Sorry, I misunderstood the modes (thought it was a presetting that some models have). I notice a rather large sun flare in the portrait test photo. Did you buy the lens new or used? Your lens seems to loose a rather strong amount of contrast when shooting towards the sun.

crossover37 · 05-31-2011, 07:08 AM

I bought it used off Pentax Forums

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05-30-2011, 04:07 AM	#16
axl Veteran Member Join Date: Mar 2007 Location: Nove Zamky, Slovakia Photos: Gallery \| Albums Posts: 7,183	Originally posted by dadipentak Um...mightn't the camera model be a relevant variable in this discussion? That is very possible. Different versions of Safox might react differently under the same conditions

05-30-2011, 04:25 AM	#17
JHD Veteran Member Join Date: Jan 2010 Photos: Albums Posts: 1,406	Originally posted by JHD Here's something worth trying... zoom in tight, focus, and then pull back. I should point out this is the technique used in television, both in the studio and out on location.

05-30-2011, 04:28 AM	#18
JHD Veteran Member Join Date: Jan 2010 Photos: Albums Posts: 1,406	Originally posted by vinceloc Hi there! I too have the same lens and have no problems shooting under similar conditions as how you were shooting. Here are some shots indoor but against strong lights which were taken at a FL around 70mm, aperture of f2.8 and ISO800 with my K200D: I don't think the background light in these samples is comparable to the intensity of the sun in the sample posted by the OP.

05-30-2011, 05:06 AM	#19
vinceloc Veteran Member Join Date: Jul 2007 Location: Philippines Photos: Gallery Posts: 367	Originally posted by JHD I don't think the background light in these samples is comparable to the intensity of the sun in the sample posted by the OP. Beg to disagree. The second photo shows that most of the direct sunlight is blocked out by the line of trees.

05-30-2011, 05:09 AM	#20
vinceloc Veteran Member Join Date: Jul 2007 Location: Philippines Photos: Gallery Posts: 367	Originally posted by dadipentak Um...mightn't the camera model be a relevant variable in this discussion? Are you implying that the K200D's focusing is better than that of the K5 under these circumstances?

05-30-2011, 06:08 AM	#21
dadipentak Site Supporter Join Date: Jul 2008 Location: Baltimore, Maryland Photos: Gallery Posts: 11,590	Originally posted by vinceloc Are you implying that the K200D's focusing is better than that of the K5 under these circumstances? Not at all. I just didn't see any mention of the body model and I'm under the impression that AF systems vary from model to model.

05-30-2011, 06:20 AM	#22
vinceloc Veteran Member Join Date: Jul 2007 Location: Philippines Photos: Gallery Posts: 367	Originally posted by dadipentak Not at all. I just didn't see any mention of the body model and I'm under the impression that AF systems vary from model to model. Oh. I was under the assumption that you had also checked the EXIF and knew that the DSLR used is the K5.

05-30-2011, 06:54 AM	#23
dadipentak Site Supporter Join Date: Jul 2008 Location: Baltimore, Maryland Photos: Gallery Posts: 11,590	Originally posted by vinceloc Oh. I was under the assumption that you had also checked the EXIF and knew that the DSLR used is the K5. Me? check EXIF?

05-30-2011, 07:21 AM	#24
JHD Veteran Member Join Date: Jan 2010 Photos: Albums Posts: 1,406	Originally posted by vinceloc Beg to disagree. The second photo shows that most of the direct sunlight is blocked out by the line of trees. And I maintain that still is exponentially brighter than all the artificial light in the collective sum of your samples.

05-30-2011, 11:06 AM	#25
crossover37 Senior Member Join Date: Mar 2010 Photos: Gallery Posts: 214 Original Poster	I will try to recreate the problem when I have time and I will keep you guys posted. Hopefully it's not something that will happen often.

05-31-2011, 12:14 AM	#27
vinceloc Veteran Member Join Date: Jul 2007 Location: Philippines Photos: Gallery Posts: 367	Hmmm. Interesting. Have you tried shooting in AV or M mode?

05-31-2011, 12:17 AM	#28
crossover37 Senior Member Join Date: Mar 2010 Photos: Gallery Posts: 214 Original Poster	Originally posted by vinceloc Hmmm. Interesting. Have you tried shooting in AV or M mode? Yea, Manual is what I shoot in most of the time.

05-31-2011, 12:32 AM	#29
vinceloc Veteran Member Join Date: Jul 2007 Location: Philippines Photos: Gallery Posts: 367	Sorry, I misunderstood the modes (thought it was a presetting that some models have). I notice a rather large sun flare in the portrait test photo. Did you buy the lens new or used? Your lens seems to loose a rather strong amount of contrast when shooting towards the sun.

05-31-2011, 07:08 AM	#30
crossover37 Senior Member Join Date: Mar 2010 Photos: Gallery Posts: 214 Original Poster	I bought it used off Pentax Forums