Filter resolution issues?

[Bob Salomon]

I've kept a glass filter on every lens I've owned. When I remember to do it, don't have to rush the photograph before light changes or a breeze kicks up, and feel like going to the trouble I remove the filter before making the photograph and immediately put it back on. But I don't do it regularly. If there's any degradation of the image from a good quality clear filter except for flare issues I've never noticed it nor have tests I do every time I buy a new glass filter shown any difference.

While flare is a real issue worth thinking about in the appropriate situation , I don't think clear filters otherwise have any adverse effect on the images. Obviously this is a personal choice that everyone is free to make for themselves but given a choice between cleaning an expensive lens in adverse conditions in the field or even having to clean lenses at hom and using a $50 glass filter, I'll take the filter every time.

Also, modern, new lenses are expensive. Our current Rodenstock camera lenses currently retail from $1,600.00 ± to over $6,500.00 each. They are really not designed to be continuously cleaned, especially in the field. Cleaning techniques vary tremendously from photographer to photographer and it is not at all uncommon to see cleaning marks on lenses, be they Rodenstock, Schneider, Fuji or any other brand.

Yes, we also see cleaning marks of filters as well. But a new filter is a fraction of a new lens or a repair.

[Drew Wiley]

Keeping a filter on the lens would mean I just have to remove it in order to use the
correct filter per light balance or switching between different films etc. Filters do affect
image quality, even the best 'em, though this might not be as noticable with larger
film formats due to smaller degrees of enlargement. Lenses have to be cleaned regardless if one is around saltspray or salty fog. It gets all over everything very quickly, even several miles in from the beach. On a lesser scale it is a corrosion factor
up to twenty miles from the ocean, that is, as far as the fog reaches and then some.
The less glass cleaning the better, or course. But decent filters aren't cheap either.
I certainly don't consider them expendable.

[John Koehrer]

A dollar to a donut that few if any people can see the difference between with or without a glass filter with the nekkid eye. This is in regards to sharpness and if visible at all, gross, Really Gross enlargements.

Can't speak to resin or plastic though

No argument about some degradation from flare.

[Brian Ellis]

Keeping a filter on the lens would mean I just have to remove it in order to use the
correct filter per light balance or switching between different films etc. Filters do affect
image quality, even the best 'em, though this might not be as noticable with larger
film formats due to smaller degrees of enlargement. Lenses have to be cleaned regardless if one is around saltspray or salty fog. It gets all over everything very quickly, even several miles in from the beach. On a lesser scale it is a corrosion factor
up to twenty miles from the ocean, that is, as far as the fog reaches and then some.
The less glass cleaning the better, or course. But decent filters aren't cheap either.
I certainly don't consider them expendable.

Do you have link or a cite we could look at showing a controlled test that supports your claim that a good quality clear glass filters affects image quality (other than by flare) or should I just take your word for it despite the fact that every test I've ever conducted says the opposite?

With respect to relative cost, I just bought a B+W clear filter for an 82mm lens. It cost $70. The lens for which I bought it cost $1,800. I'll take my chances cleaning the filter rather than the lens.

[Jim Jones]

I have definitly seen reflections when using an apparently uncoated Leitz filter many years ago, so I quit using filters for protection. I did retire one 50mm Summicron due to cleaning marks incurred in the field. The cost of that lens was a small fraction of the cost of film that it exposed. If I used $1800 lenses, a filter would be a more logical option

[Drew Wiley]

Controlled link??? Get real, Brian! Yeah, I'll give you an "expert" link just as soon as you
find me just one of those flatlanders who can print half as seriously as I do, or even
knows how to define a test anywhere near my own standards. I've never damaged a
lens yet cleaning it. I learned to do that right too. More elements equals more air to
glass interfaces. Why would I pay for something like a damn multicoated dagor in the
first place to add 50% more interfaces to the formula? But its mainly in MF that the
problem becomes annoying, i,e., where you've got an itty-bitty neg that needs everything going for it possible if it's going to be enlarged much and still look snappy. LF is much more forgiving. Flare is an issue; and in the field its often hard with a deep contrast filter to see whether it need cleaning or not.

[IanMazursky]

The only time i use a UV filter is if im high up ie. top of a mountain.
Its cuts the blue enough to make it worth it. Other then that, my lenses do not have a filter attached unless i need it for something specific.

I use lens caps to protect the front and rear elements. I even put a cap keeper to tether the front and rear lens caps so i don’t loose them in the bag or over a cliff (yes that happened!).
The cap keepers may look ridiculous for but $1 at B&H, it was a good investment.

[Drew Wiley]

Amen. The argument goes full circle. Why protect a $500 lens with a $50 filter when
you can protect it with a $5 lens cap. True UV filters are a different story, and I've
got all kinds of em because different color films respond differently at high altitude.
One shoe doesn't fit all. So don't worry, Bob, I spend my share of money on high quality filters, and will no doubt continue to acquire more. If it fits the lighting and film
type, I'll leave it on the lens awhile, unless it's too dense for easy focus.

[Brian C. Miller]

Filter contrast test. If contrast is necessary to resolution, then if you must use a filter then use a multicoated filter.

I remember AA saying he used a gel filter, and tossing it and cutting out a new square when needed. He didn't point his lens directly into the sun too much, though.

[Brian Ellis]

Filter contrast test. If contrast is necessary to resolution, then if you must use a filter then use a multicoated filter. . . .

Thanks for the link Brian. However, in that test the photographer was photographing straight into a light box. So flare was obviously a major problem. So it shouldn't have come as any surprise when he found that a multicoated filter reduces contrast less than an uncoated filter when photographing directly into a bright light.

As I said before, I understand the effect of a clear filter in a situation where flare is a problem. I remove the filter in those situations. But otherwise I tend to leave the filter on most of the time. And on or off makes no difference to the quality of the image that I've observed in my photographs and in my testing. I make no great scientific claims for my testing methods but at least I've made an effort to determine whether a good quality clear glass filters adversely affects image quality as opposed to simply claiming that it does.