speculation about FA lenses on FF DSLR

[lpfonseca]

Originally Posted by Ron Boggs

For the OP, you may have seen posts about this stuff, but doubtful that you've seen CREDIBLE posts about it.

Ron, indeed I've seen some of those posts but none are credible enough so I decided to ask here. Not that my post makes it more credible but I wanted to make us think.

Originally Posted by Miserere

I pretty much agree with Ron. The only issue that might come about with "non-digital" lenses on FF sensors is that the sensors could outresolve the lens.

Miserere, I don't think that this is a problem. Most FF DSLR today have larger photosites than APS-C DSLR's so they should require less from the lens (provided that the lens can offer that resolution on the corners)

But you're absolutly right when you say we don't have a FF DSLR.

[lpfonseca]

Originally Posted by Lowell Goudge

there is the secondary issue of rear element coatings, to avoid the internal flair from the reflection off the UV and IR filter in front of the sensor, which has a higher reflectivity than film.

But this doesn't seem to be a big problem today with APS-C DSLR's. Is there a reason to think that this problem will arrise on the corners of a FF?

[Ron Boggs]

What? You mean Pentax doesn't even have a FF digital body? So everything I just posted is a bunch of conjecture? As Gilda Radner's famous character Rosanne Rosannadana would've said, "Oh, that's very different. Never mind."

[Lowell Goudge]

Originally Posted by lpfonseca

But this doesn't seem to be a big problem today with APS-C DSLR's. Is there a reason to think that this problem will arrise on the corners of a FF?

there has been some discussion on this, and you will note that all lens manufacturers have begun coating the rear elements of digital lenses, even those that are full frame to avoid this problem and the loss of contrast that can result.

That is, for exxample the difference between the Sigma APO 70-200 F2.8 EX and the Sigma APO 70-200 F2.8 EX DG. "G" means full frame but "D" means specific digital coatings (on the rear element)

[Wheatfield]

Originally Posted by Ron Boggs

No offense Lowell, but my impression is that the lens manufacturers combined with folks with too much "tech time" have created false worries--in particular worries like the need for different coatings on the rear element to reduce reflections off the IR filter. Neat theory, but Pentax multi-coating answers that concern and again--anybody ever seen problems in our brand or any other?

Well yes Ron, I have. My otherwise very excellent and much loved A100/2.8 Macro can very easily be made to show sensor flare.



It is a very real problem and is addressed by putting better anti reflective coatings on the rear element of the lens.