View Full Version : filter stuff
so... now i am in filter mode. i am thinking of a gel system to cut down on cost, but wonder about them affecting the image. are gels mounted on the rear glass a bother to image quality or complicate focusing or exposure more so than screw ons ? & how do they mount ? & for filters like polarizers that definitely or possibly require varying rotation for the best effect, how do they get properly aligned ? look, remove lens to adjust, look again, etc., until it is right ? filters can get expensive. i would prefer to stick to glass screw on w/ step down rings so 1 size will fit all, but oh ! the cost !! am i overlooking any other considerations i need to have in mind ?
Rear filters mean taking the lens off the camera to change filters. What sizes are you looking at? The smaller sizes can be pretty cheap used. Just look for kits or other bundles on ebay. This applies to both gels and glass filters. I bought a package of mostly sealed gels including virtually every filter Kodak ever made for a total of $10. Only 3x3 but for $10 I won't complain. OTOH who NEEDS the vast majority of the filters I got. Some are so special use that I doubt they are any use for photographs. Since getting those I've picked up all the filters I really need in glass. All are mint or better. It's not a very big number of filters but then I don't need everything in the filter catalog either.
I use gels and actually prefer them to the heavy glass filters. For a holder just get the Gel Snap holder ($20). It will fit n the front or rear since it just attaches to the lens with a big fat rubber band.
B&H Photo listing for the Gel Snap (http://www.bhphotovideo.com/bnh/controller/home?O=productlist&A=details&Q=&sku=162544&is=REG)
For 4x4 gels, get a set of frames to mount the filter in like these (set of 10 I think): Lee gel frames (http://www.bhphotovideo.com/bnh/controller/home?O=productlist&A=details&Q=&sku=87152&is=REG)
See previous threads on this forum about it here (http://www.google.com/search?q=gel+snap&btnG=Google+Site+Search&domains=largeformatphotography.info&sitesearch=largeformatphotography.info)
Take a look at Q.-Tuan Luong's article on filter use (http://www.largeformatphotography.info/filters.html) on the main page of this site, Jason. It provides a good overview of basic considerations, along with various cautions.
Personally, I use a mix of glass filters, generally in two basic sizes - 77mm and 105mm and step up rings to fit various sized lenses. I also use gel, resin and polyester filters for special purposes (e.g. IR, diffusion, etc.), using a HiTech holder system.
Screw-in polarizers can be set by viewing through the filter directly, noting the position of an indexing mark on the rim, and then resetting that position once the filter is mounted on the lens. If your polarizer doesn't have index marks, it's easy enough to add them yourself.
A few years ago I had some problems when I tried using some 81 series gels with a polariser. I was getting rainbow tones and effects on my tannies. I've since been told that this is a common problem when mixing gels with polarisers. I've now gone back to resins for my 81 series filters. HTH
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