question about filters and IQ

Started Aug 5, 2014 | Discussions thread
Bob Sal Senior Member • Posts: 1,529
Re: question about filters and IQ

Dr JLW wrote:

The only filter I use on modern lenses is a polarizing filter. really old lenses benefited from UV blockers but virtually all lenses made since about 1970 block UV.

I like ht idea of using a protective filter in a nasty environment, rain, spray, blowing dust and sand or at a beach but I usually just use a shade. I rarely take out my camera in such circumstances. I tend to keep my photographic stuff and not resell it.

Camera now evolve faster than the environment can erode the surfaces of my lenses.

For the most part I don't keep a filer o nmy lenses but I only buy cameras and lenses with a filter ring and usually one size so I can use the ring for close up lenses and shades.

Buying a clear filter with the lens is usually a waste of money, small but better spent on a polarizer,a shade.or a close up (color corrected).

Anything made from glass will block UV. But not all UV. As you go to higher elevations you need greater UV correction, when you shoot on overcast days you need more UV correction. When you shoot on snowy days, especially into shadows you need more UV correction.

UV filters have a slight yellowish tint, unless you need heavy UV correction at altitude for aerial B&W when you would have a quite definate yellow tint.

If you use the heavier yellow then your shots would be yellowish overall when not at altitude and when shooting in color.

A lens coating might block some UV but no consumer or professional lens coating can block all UV. Hence a quality UV filter can be necessary for best color and best haze cutting over the widest range of lighting and altitudes.

Even a clear protection filter (clear glass) will have some minor UV protection since it is glass, but it will not be as effective as a UV filter in cutting haze and reducing the blue in deep shadows, etc.

And, before you claim it, sensors are able to give better colors and haze penetration with a quality UV filter.

A filter protects the lens from anything blowing/floating towards the lens directly. Also from peanut butter and jelly sticky curious fingers. A lens hood would block anything coming at an angle but will do no protection for anything coming directly in to the front of the lens.

And a lens hood on a zoom lens is essentially worthless at doing what it was supposed to do since it has to not vignette at the widest focal length of the lens. Therefore its' opening is far too wide at the longer focal length settings on the lens and does not properly protect against flare from light coming in that too large an opening. If your lens hood is adjustable in coverage like a Kaiser 3 in 1 hood then it would be more effective in blocking flare at multiple focal lengths then the fixed length hoods.

Lastly a close up lens (except possibly multi element achromatic ones) are the last thing you want to use with an interchangeable lens camera if you do not want to sacrifice optical quality. The only benefit of a close-up lens is that you can focus closer without a loss in light.

Extension tubes or a bellows or a reverse ring will give far superior optical performance, all - except for the reverse ring - will allow various magnifications and camera/subject distances. The drawback is that since you are increasing the lens to image plane distance you will have to increase exposure time to make up for the loss in light. Modern cameras will correct for this automatically, these are also bulkier then a close-up lens but the results are so much better that that is usually not a problem. The close-up lens might also be easier to hand hold initially.

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