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03-31-2008, 07:12 AM   #1
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Shadow created by lens

Hello,

I have just purchased a Sigma 24-70 f2.8, for my K10D.
During the test I was shocked to see a Black shadow area at the bottom centre of all the pictures I took using the built in flash. I though that I should return the lens, but since it was night time decided to investigate the matter. Then I found out that the shadow was only when I used the lens between the zoom ranges of 24-35, and anything above this shadow was not there. Then when I checked the Camera again I could clearly make out that this shadow was caused by the lens. This particular lens has a very wide front portion which was obstructing the light from the built in flash when used at wide angles. Shadow is not there when I use a hot shoe mounted Sigma 500 DG Super, as the height of the flash head takes cares of the large lens diameter. Did any one else face similar problems? Is this a design mistake from Sigma?
Thanks,
Kris

03-31-2008, 08:08 AM   #2
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This is something to take into consideration with many different wide angle lenses. My 16-50 f2.8 does the same thing. Its just the fact that the lens is so big. They even mention this in many common lens reviews. If you plan on doing flash photography with that lens you'll either have to avoid those zoom settings or use an accessory flash.
03-31-2008, 08:26 AM   #3
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QuoteOriginally posted by photomad_2007 Quote
Hello,

I have just purchased a Sigma 24-70 f2.8, for my K10D.
During the test I was shocked to see a Black shadow area at the bottom centre of all the pictures I took using the built in flash. I though that I should return the lens, but since it was night time decided to investigate the matter. Then I found out that the shadow was only when I used the lens between the zoom ranges of 24-35, and anything above this shadow was not there. Then when I checked the Camera again I could clearly make out that this shadow was caused by the lens. This particular lens has a very wide front portion which was obstructing the light from the built in flash when used at wide angles. Shadow is not there when I use a hot shoe mounted Sigma 500 DG Super, as the height of the flash head takes cares of the large lens diameter. Did any one else face similar problems? Is this a design mistake from Sigma?
Thanks,
Kris
this is not a mistake

this is the limitation of the built in flash
03-31-2008, 08:26 AM   #4
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This isn't a design flaw in the lens and is common to many lenses when a bulit in flash is used. That is also true across camera brands.

The issue is the height of the built in flash on the camera. It simply is not high enough for the flash light emitted to clear the size of the lens. So when using the flash you to know that many wider angle lenses will do this with the small on board flash. The design of the wider angle zoom lenses can't really change with the physics involved. A fast wide zoom will need a larger diameter lens barrel and that will block some of that light on the bottom of the picture frame.

03-31-2008, 09:55 AM   #5
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Buy an external hot shoe flash. No shadow and pictures will look MUCH better when you bounce the flash off of something (ceiling/wall/etc....)
03-31-2008, 10:36 AM   #6
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QuoteOriginally posted by photomad_2007 Quote
Hello,

I have just purchased a Sigma 24-70 f2.8, for my K10D.
During the test I was shocked to see a Black shadow area at the bottom centre of all the pictures I took using the built in flash. I though that I should return the lens, but since it was night time decided to investigate the matter. Then I found out that the shadow was only when I used the lens between the zoom ranges of 24-35, and anything above this shadow was not there. Then when I checked the Camera again I could clearly make out that this shadow was caused by the lens. This particular lens has a very wide front portion which was obstructing the light from the built in flash when used at wide angles. Shadow is not there when I use a hot shoe mounted Sigma 500 DG Super, as the height of the flash head takes cares of the large lens diameter. Did any one else face similar problems? Is this a design mistake from Sigma?
Thanks,
Kris
One thing I have not seen mentioned in the other posts: Did you have the lens hood on? If the hood is on, it seems most lenses will cause the flash shadow.
03-31-2008, 07:30 PM   #7
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I have read many reports about the shading of the built in flash on virtually all DSLRs (not just pentax) with wide angle lenses and espedcially the lens hoods.


I have not experienced this on my cameras because I always use a shoe flash, not the built in.

I did see it on my Kodak DX7590 when I attached a 0.45x wide angle adaptor when I used the built in flash, for the same reason
04-01-2008, 01:03 AM   #8
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QuoteOriginally posted by photomad_2007 Quote
Hello,

I have just purchased a Sigma 24-70 f2.8, for my K10D.
During the test I was shocked to see a Black shadow area at the bottom centre of all the pictures I took using the built in flash. I though that I should return the lens, but since it was night time decided to investigate the matter. Then I found out that the shadow was only when I used the lens between the zoom ranges of 24-35, and anything above this shadow was not there. Then when I checked the Camera again I could clearly make out that this shadow was caused by the lens. This particular lens has a very wide front portion which was obstructing the light from the built in flash when used at wide angles. Shadow is not there when I use a hot shoe mounted Sigma 500 DG Super, as the height of the flash head takes cares of the large lens diameter. Did any one else face similar problems? Is this a design mistake from Sigma?
Thanks,
Kris
I believe that guys above me explained reasons for the shadow clearly. So nothing to worry IMO. But if you'd still like to get rid of that particular lens, let me know please, I'd be interested

04-01-2008, 05:03 AM   #9
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I have to say with or without the lens hood you get the same thing with the 16-45. The others all explained how to avoid. Sigma 500 Super works for me.
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