Seeking high quality optical flocking for lens adapters

[dheck]

Thanks Am.

The most problematic lens / adapter combination is actually the highly regarded Tamron SP 90mm f2.5 on the A7II... it's really hazy at f2.5. Nobody else seems to have this problem so I suspect that the combination of a flat rear element and a highly reflective digital sensor in a long somewhat shiny (black anodized) mount adapter is particularly problematic. I have tested in controlled lighting, with the original hood and that doesn't fix the problem.

The real clincher was when I tried the same lens on my A mount body which has a much shorter adapter tube. That combination showed much less contrast loss at the larger apertures.

It will be an easy test to tape, flock or even paint the inside of the E mount adapter and see if that helps.

Cheers!
Daniel

[jjphoto]

Thanks Am.

The most problematic lens / adapter combination is actually the highly regarded Tamron SP 90mm f2.5 on the A7II... it's really hazy at f2.5. Nobody else seems to have this problem so I suspect that the combination of a flat rear element and a highly reflective digital sensor in a long somewhat shiny (black anodized) mount adapter is particularly problematic. I have tested in controlled lighting, with the original hood and that doesn't fix the problem.

The real clincher was when I tried the same lens on my A mount body which has a much shorter adapter tube. That combination showed much less contrast loss at the larger apertures.

It will be an easy test to tape, flock or even paint the inside of the E mount adapter and see if that helps.

Cheers!
Daniel

Correct me if I'm wrong but doesn't that lens have an issue with a hot spot (Google it)? A flare spot is essentially a form of flare and depending on the aperture and magnification it can either appear as haze or a light spot in the shape of the aperture in the centre of an image.

An example of a flare spot. The spot is visible at F8 but is just haze at F2.8.


Are you having flare issues with other lenses using the same adapter or only/mainly with the Tamron? Maybe the lens is the issue as much as the adapter itself, which is not to say you shouldn't try to improve the adapter.

[dheck]

Thanks John,

You're right about that lens and its hotspot issues. That's actually the reason I thought it might be particularly prone to adapter internal reflection as well... I'm seeing the problem even in moderate lighting conditions whereas the hotspot afaik seems to require a very bright lightsource in or near the field-of-view.

Most lenses have reduced contrast wide open, of course, so I've certainly observed it with many of my other adpated lenses to lesser degrees. Honestly don't know to what extent that may be exacerbated by lens adapters, but I'm curious to find out!

I'll try something on the weekend and see how it goes!

Cheers,
Daniel