Internal filter holders.

[David Prude]

Hello, I am a begginner to LF photography. I saw recently (but did not have time to talk to the gentleman) a man using a toyo view with a schnider lens. He seem ed to be using an internal gel filter holder with his camera.

I thus far have a tachihara 4x5 and a nikor W 105mm 5.6 lens. I was wondering if anyone knew of such a set up that would work with my camera/lens. and aprox. h ow much it will cost me.

[John Hennessy]

Calumet makes and/or sells such a filter holder. Probably only gelatin filters can be used behind the lens without causing a focus shift. Maybe acetate too I don't know.

But you should use a lens shade and shades hold filters too; so I have never seen the point of filters behind the lens.

[William Leviit]

One reason to use filters behind the lens is, the rear element in many cases has a smaller diameter than the front element. Using my schneider 360 5.6 I'd need a filter somewhere around 125mm X 125mm to fit over the front. The stand Sinar filters are 100X100 or 75 X 75mm.

How much would such a set up cost? The price of a roll of masking tape. Make loops with the sticky side out and stick them to the outside of the rear element and stick the filter on them.

[andrea milano]

Anothere serious advantage is that you don't have to worry too much of reflection(thus using compendiums to prevent it) on the filter itself. I mean, you have the most expensive piece of optics coated with multicoated antireflection layers and you put in front of it a piece of......, doesn't sound very intelligent! The front is necessay only for polarizers(can use it inside but not very practical because of the turning) or shaded(gradually increasing in density or color) filters. Some cameras or lenses provide it as a standard feature especially if extreme wideangle.

[andrea milano]

Kodak, Lee, CoKin, FATIF, They all produce filter holders wich are very useful and practical, most take gelatine or other thick material, can anyone elaborate on focus shift? I've never had any trouble with it but I am willing to learn from the learned contibutors.

[Bob Salomon]

Anything placed behind a lens produces a focus shift = to 1/3 the thickness of t he material.

This is why Hasselblad put a glass corrector plate in their Polaroid back. It he lps to bring the film plane to the same point as their roll film backs.

Some think that the glass plate is to hold film flat but since there is no press ure plate in a pack back this obviously isn't true.

[William Leviit]

Concerning focus shift, one way to get around it is to focus with the filter in place. BTW, Sinar shutters are made with a filter holder behind the lens.

[Sal Santamaura]

Whether or not such a setup would work with your camera/lens, you'd better be shooting roll film with it. The 105/5.6 Nikkor W won't cover 4x5.

[Dave Willison]

Calumet offers a Xenophon Gel Holder for about $40. It fits behind the lensboard and attaches with velcro. The holder comes in two sizes for 3" and 4" filters. Calumet also sells gelatin filters and self-adhering cardboard filter mounts that fit the system. The filter holder adjusts its depth from the lensboard by loosening two small screws. According to the Calumet catalog, the behind-the-lens filter helps reduce dust, etc. from getting on the lens. It also claims to reduce the flare associated with front-mounted lenses.

I've used the holder on a Calumet woodfield which is the same design as the Tachihara. I've never noticed problems with focus shift, but there are other limitations. First, if the holder is not lined up correctly over the rear lens element, vignetting is possible. Second, if you focus with the holder in place to avoid focus shift, you will get a much dimmer image on the ground glass. Dim images are more common with wide angle lenses and the problem gets worse if you use heavy filtration like a red filter or a .9 ND. Third, the filter holder cannot be mounted via the front of the camera. On my Calumet, the front opening is round and you can't back the holder into the hole to mount the lens. What I end up doing is removing the ground glass back and mounting the filter holder to the lensboard. This becomes a game of cat and mouse with the velcro on the lensboard grabbing the filter holder and creating a mismatch between the holder and the lens element. Moreover, I run the risk of jolting the camera out of focus by removing the camera back. This is really serious "focus shift." The final downside to the holder is the depth adjustment. If you switch the system to a different lens, you will have to carry a small screwdriver to loosen the depth adjustment screws.

If you can live with these problems, the Xenophon is an inexpensive way to mount filters. Hope this helps.

.................

[Jeff Buckels]

Focus with the filter in place and forget focus shift. The dimness caused by the filtration will rarely be big deal (compose and focus w/o the filter, place the filter, then fine-tune the focus).... Gel filters are questionable in general. The reason AA and other classic B & W photographers touted them so much is because they learned their stuff in an earlier time when Wratten gel filters were the best -- period. Especially the thinnest. Most name-brand glass filters today are plenty thin and high quality. Further, ring-mounted glass filters are MUCH more convenient -- easier to store, handle and keep clean. As for mounting them, that may take some doing or maybe not, just depending on what your rear lens barrel looks like. If threaded in pretty much any way, you've got it made. If you don't have threads, there are various adaptations but you certainly can get a clip-on holder that will have threads on the other side (available from all the major outlets -- Freestyle, Calumet, Adorama, etc.). In any event, as some of the above comments show, getting a gel filter system in place behind your lens can be a bit of circus, too. -jeff buckels (albuquerque)