Do skylight/UV filters degrade the image?
I realize this can be a hotly contested topic, and I don't intend to re-start a thread that may have already been debated and that everyone is sick of, but I thought I'd ask the Nikonian experts. : ) Is it a good idea to always use skylight, UV or haze filters with Nikkor lenses?
I have always used skylight filters on all my lenses, kind of like a permanent lens cap you can shoot through. I've also always discounted the opinions of some who would suggest that one should never use any filters unless they have a specific purpose in mind. Recently, however, I came across a post on another forum (which shall remain nameless) where a person suggested that some UV filters are such poor optical quality that they can cause autofocus mechanisms to fail to lock. What I'm wondering is, if a filter can cause a lens to fail to autofocus, could it also cause it to focus incorrectly?
I am asking because since switching to Nikon from C*n*n this past spring, I have noticed that some of my landscape photos seem slightly soft at infinity. I noticed it first with my 28-80 AF-D, then later with my 50mm f/1.8. Could a marginal quality or not quite 100% squeaky-clean skylight filter be causing the autofocus to lock at some distance other than infinity? Is the filter just dirty enough to cause the softness? Or maybe I should be shooting landscapes using manual focus?
I am referring to skylight and UV filters manufactured by Tiffen and Hoya.
#1. "RE: Do skylight/UV filters degrade the image?" | In response to Reply # 0JM Registered since 01st Mar 2007Fri 19-Oct-01 12:18 AM
Even the cheapest UV filter should not interfer with your AF, but having said that the follow-up would be ...within reason.
Your using the filter as a lens cap could be leading to your overlooking a dirty filter but I would look for other problems as well. Do you ever get sharp focus from your lenses when opened to the same f-stop as the soft focus results? Are you shooting wide open aperture or do you stop down to the sweet spot in the middle range (f5.6-11 on most lenses)?
If you follow most reveiws they all show varying degrees of softening of the image when wide open as this uses more of the edges of the glass. By stopping down your using the center which is the most exact area of the lens. If you have good results at the same settings as poor shots then you might have aproblem in more than technique.
#2. "RE: Do skylight/UV filters degrade the image?" | In response to Reply # 0geo Basic MemberFri 19-Oct-01 02:34 AM
LAST EDITED ON Oct-19-01 AT 06:35 AM (GMT)
I remember that a few years ago I came into a MTF test of the Zeiss Contax G-series Hologon 16mm. f/8, published on an Italian magazine. The test was performed with and without the center filter originally supplied by the manufacturer. Center filters are filters "concentrically graduated", designed to be used on extreme wideangles to compensate the brightness diminution from center to the edges (vignetting). The results were sensibly different, expecially at the edges, curiously since that filter's edges are transparent.
On the user's manuals of lenses using drop-in filters, such as Nikkor long telephotos, there is invariably written: "do always use a filter in the filter holder; it is part of the optical scheme". Therefore, I assume that also putting a filter in front of a lens changes the optical scheme.
Logic says that anything between the lens and the subject can do nothing but worsen the light transmission and therefore the transmission of informations.
For these reasons, I only use filters when I really need them. Nevertheless, I have no notion of extensive tests on this subject, and nor I did perform any. Of course, performance diminishing should depend on lens quality, film quality, accuracy of shooting technique and enlargement of one's images.