Lens/Flash Incompatbility?

Parallax · 06-08-2008, 06:59 AM

O.K., This one has me stumped. I have a K20D and recently got the Sigma 105/2.8 macro. The built in flash exposes properly with all of my lenses except the Sigma. Flash shots with that lens are unusably underexposed at all distances. I have tried several modes, shutter speeds, ISO settings and trailing curtain sync all with the same results. The problem also exists exactly the same with my 360 flash using P-TTL mode but things are properly exposed using Auto and Manual modes. Any theories?

Wheatfield · 06-08-2008, 08:06 AM

Yup, the Stigma lens isn't transmitting proper information. This kind of problem is why I stay away from their equipment.
Note, the 105mm lens is probably going to vignette the built in flash, which is just adding to the problem.

Parallax · 06-08-2008, 10:35 AM

I hadn't thought of that, but that would explain it. It isn't a big deal as it is not one that I would use very often with flash and for the few occasions I do need flash I can use the 360 on auto and get what I need. The IQ is superb so the lens is a keeper, but if these issues are common to sigma I may avoid others in the future. Thanks for the reply.

Jim

06-08-2008, 06:59 AM	#1
Parallax Senior Moderator Loyal Site Supporter Join Date: Apr 2008 Location: South Dakota Photos: Gallery Posts: 19,332	Lens/Flash Incompatbility? O.K., This one has me stumped. I have a K20D and recently got the Sigma 105/2.8 macro. The built in flash exposes properly with all of my lenses except the Sigma. Flash shots with that lens are unusably underexposed at all distances. I have tried several modes, shutter speeds, ISO settings and trailing curtain sync all with the same results. The problem also exists exactly the same with my 360 flash using P-TTL mode but things are properly exposed using Auto and Manual modes. Any theories?

06-08-2008, 08:06 AM	#2
Wheatfield Moderator Join Date: Apr 2008 Location: The wheatfields of Canada Posts: 15,986	Yup, the Stigma lens isn't transmitting proper information. This kind of problem is why I stay away from their equipment. Note, the 105mm lens is probably going to vignette the built in flash, which is just adding to the problem. Last edited by Wheatfield; 06-08-2008 at 07:31 PM.

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06-08-2008, 10:35 AM	#3
Parallax Senior Moderator Loyal Site Supporter Join Date: Apr 2008 Location: South Dakota Photos: Gallery Posts: 19,332 Original Poster	I hadn't thought of that, but that would explain it. It isn't a big deal as it is not one that I would use very often with flash and for the few occasions I do need flash I can use the 360 on auto and get what I need. The IQ is superb so the lens is a keeper, but if these issues are common to sigma I may avoid others in the future. Thanks for the reply. Jim