macro lens problem

Please can anyone help with a very strange problem. I was using a Sigma 50mm 1:2.8 DG Macro on Canon 5d mk iv Took three shots all at the same setting - all fine then took three more still at the same setting, no adjustment, exposure meter correct, and got a completely white, over exposed shot each time. I was using Manual so thought I would just try P mode to see what happened and the same, over exposed shot. Is it time for a new lens or am I missing something staring me in the face.

I've seen issues with aperture blades not stopping down when my battery was running low.

Are you using flash?

Were you trying to shoot way stopped down?


Doesn't sound like a macro specific issue to me, have you just fired off a bunch more test shots around the room?

no flash and each image was at f19 - same settings, same metering. Other lens work fine

Battery condition?

Might look at lens contacts too.

I was talking about test shots with same lens. Sometimes weird things happen and just magically go away.

battery fine apparently canon and sigma sometimes have problems on newer cameras so maybe that is it

Run two very simple tests to see if aperture stops down properly...

1. Press the Depth of Field Preview button, and look into front of lens to see diaphram close down
   
2. Put camera in Manual mode, select slow shutter speed (> 1/8 sec) and press shutter release and look into front of lens to see diaphram close down
   

Any chance you accidentally dialed in +5 EC (or something close)?

no chance !

Did you try to do to two tests -- repeatedly -- what I suggested in post 8, to see if the lens is getting signals from the body consistently to stop down the aperture?

yes tried the tests and it worked fine - then it didn't ! same image, same exposure 1st correct exposure, 2nd way over exposed (but exposure compensation gauge still showing as 0) . With diaphram tests - same problem, 1st time worked then didn't. So definitely think its a compatibility problem. Also tried same test with my Canon 100mm macro and worked perfectly each time. Anyone want to buy a Sigma macro !!!

stoat wrote in post #18598140
yes tried the tests and it worked fine - then it didn't ! same image, same exposure 1st correct exposure, 2nd way over exposed (but exposure compensation gauge still showing as 0) . With diaphram tests - same problem, 1st time worked then didn't. So definitely think its a compatibility problem. Also tried same test with my Canon 100mm macro and worked perfectly each time. Anyone want to buy a Sigma macro !!!

If a press of the DOF Preview button is inconsistent with the Sigma, yet consistent in operation with the Canon lens, it is a clear indication of some issue of the Sigma not getting the signal from the body. Got a friend or store with 5DIV, where you can try the lens on that body?