Vignetting? Feeble strobes? User error?

[d^2b]

I am using the OM 12-45 pro with an AOI DLP-04 semi-dome port, and I have noticed some dark corners at 12mm.

This example is at f8. The camera (OM1) reports a focus distance of 0.28m and ISO500. I guess it could well be that my 2 Sea&Sea YS-01's are not throwing enough light, but if I am just doing something silly I'd like to know.

 

[Nemrod]

IMO, that is vignetting of the lens by the dome port. You will need to do two things, zoom in slightly to eliminate the dark corners or crop it out and you may consider disabling IBIS or ILS. You might also check that the lens shade is correctly installed and aligned.

 

[rjack321]

I am going with the 110 degree spread of the YS01's isn't enough for a 12mm wide angle. Are you using the diffusers on the strobes?

 

[cerich]

it's 12mm shorter than the 12-50 that that port does say is good for, the rest of the lenses that port is good for are 14mm up other than 9-18 that is 6mm shorter than12-45. The lens is too far back for that port at 12mm. You might be able to literally cut off some of the lens shade

 

[Barmaglot]

The vignetting in top corners is just water - it has nothing to do with strobes. My vote is on the dome (extension slightly too short) or a misaligned dome shade.

 

[d^2b]

I am going with the 110 degree spread of the YS01's isn't enough for a 12mm wide angle. Are you using the diffusers on the strobes?

Yes, I do have the diffusers on the strobes.

 

[Nemrod]

When vignetting only appears on one side or one corner there can be a misalignment of the lens/camera/shade to the port or the IBIS /ILS has shifted to be slightly out of center. Usually there is enough forgiveness in the optical alignment that this does not cause vignetting but if everything is on the edge, then sensor shift or lens shift can show up as a dark edge or corner.

I do not think the dark corner in clear water has anything to do with the strobes.