Questions arose about the filter I used.
Michael Demeyer said:
I would also expect the quality of the filter to matter. For example, the Zeiss filters, expensive as they are, use the same T* A/R coatings as the lens. So it seems they would be no worse than one more lens element. No?
Several people expressed a distaste for Hoya filters.
I bought 3 77 mm UV filters:
- Zeiss T* UV — $115
- Hoya Digital HMC UV(C) — $23
- B+W XS-Pro Digital UV-Haze MRC nano — $36
All prices are from Amazon US.
I set up the camera aiming at a LED flashlight a bit off-axis. The reflections from the filter that I saw were on the opposite side of the lens axis. I cropped the images to the central 9th of the image in area (central third in both height and width).
I have three conclusions:
- We can say that adding the filter is not the same as adding one more lens element. The Otus has a flock of lens elements and no reflection like all of the filter images.
- The Hoya and Zeiss reflections are about the same size, but the Hoya one is stronger. Looks like the T* costing is buying something.
- The B+W reflection is smaller in extent than the other two, but the brightest. I think the B+W reflection would be the easiest to deal with in postproduction.
I am not planning on running out and buying a bunch of T* filters.