Daniel, I'd be particularly interested in any solutions which work with grad filters (other than the FK-100).
Daniel, I'd be particularly interested in any solutions which work with grad filters (other than the FK-100).
I've done a quick visual test (no chromes or Polaroids yet) of the 72XL with the Lee FK-100 filter holder. My overall opinion is that Lee has pretty much solved most of the problem of using 4" filters on this BIG piece of glass.
My estimate is that the 72XL without any filters attached allows close to 50mm of rise with the ground glass in "portrait" position before corners start to vignette. With the FK-100 attached and setup for two filters, the worst possible case is loosing about 7 - 10 mm of rise from the outer set of filter rails coming into view. If the FK-100 is configured for only one filter, it didn't appear that you lost anything. I consider the worst possible case to be where the filter holder rails are perpendicular to the major direction of movement. In this case, with portrait format and using front rise, the worst possible case is with the filter rails are horizontal. With most filters this isn't an issue because you can just rotate the holder. It only becomes an issue with grad filters.
(an aside: Filter rail stack height is critical to minimize if your going to get the most coverage with WA lenses. Every millimeter counts. The Lee system uses a fairly non-functional cap piece whose only function is to allow the screws to sit flush. I throw out this piece, and use a hand held wood working counter sink tool on the outer rail pieces to allow the screws to sit flush without the extra piece. Alternatively, you could just get some flat head screws. My preliminary estimates above were with this modification.)
Hi Dan
You might consider using filters at the rear of the lens. I bought some old new stock Sinar 3x3 filters recently and was finding a way to mount them on my 67mm diameter lenses without causing vignetting.
I posted a request for suggestions at RPELF on USENET and some clever chap emailed me and suggested that I use Xenophon rear filter holders. If you go over to Calumet's website http://www.calumetphoto.com, and type "Xenophon" as the search string you will find them. They have both 3x3 and 4x4 gel holders (picture available at the site).
I am not sure how much rear mounting a filter would affect picture quality (I haven't personally tried it yet).
Hope this might help.
Does rear mounting a filter change focus?
I remember seeing the "Xenophon" at Calumet, and thought it was interesting, but quite a bit overpriced for what it was. It also didn't appear to be an easy solution if you use multiple lenses, unless you get a "Xenophon" for each lens. Changing the depth of the holder to accomodate different lenses appeared to require a screwdriver.
At one time I thought about building a rear filter holder out of a routed out piece of wood. I would also cut different length side pieces to fit each of my lenses, and attach them to the block via embedded magnets (velcro is too sloppy).
"Does rear mounting a filter change focus? "
It does several things - none good!
A: Any filter placed behind the lens (unless designed to be part of the lens) creates a focus shift equal to 1/3 the thickness of the filter.
B: Any fingerprint will degrade the image C: Any dust degrades the image D: Any dirt degrades the image E: Any smudges degrade the image
In short there is no positive optical reason to place a filter behind the lens.
I buy the focus shift argument A if you are using filters that make it inconvenient to focus with the filters on. But the problems with B-E applies to front mounting as well! You have to exercise care to make sure the filters are clean whether you mount them in front or behind.
" But the problems with B-E applies to front mounting as well! You have to exercise care to make sure the filters are clean whether you mount them in front or behind."
Not really since the image has passed through the lens and is then "disturbed" by having to go through dust, dirt, fingerprints, etc.
Gee Bob, have you told the guys at Sinar this? They might need to know that so t hey can recall all of the Auto Shutters and Digital Shutters thay have sold over the years. But I agree completely with you about the need for absolute clea nliness. The focusing difficulty is resolved by focusing with the filter in plac e.
"Gee Bob, have you told the guys at Sinar this? They might need to know that so they can recall all of the Auto Shutters and Digital Shutters thay have sold over the years. But I agree completely with you about the need for absolute cleanliness. The focusing difficulty is resolved by focusing with the filter in place. >
You may not remember but when the shutter first came out that rear mount was for gels not acrylics (which really didn't exist then.
And whether or not Sinar has a rear mount does not mean it is a g
ood place to put filter
Bob outside of the cleanliness issue (which is addressed by practicing good phot o hygiene) and the focus shift issue (addressed by focusing with the filter in place (or am I missing something else here?)) whta other issues would make this a bad idea? I ask this out of a case of genuine perplexedness as when I was doing my apprenticeship this was a question that came up and was told that placi ng a filter there eliminates flare and some other issues. As you already know I am a big fan of Heliopans glass filters so i am not trying to find a "cheap" sol ution".
Posting Permissions
Reply With Quote
Bookmarks