How to cut a dark slide to acheive a narrower format

[Ken Lee]

Using my 4x5, I would like to experiment with a format that is 5 inches wide, but less than 4 inches high and crop the image in-camera. I remember reading that you can cut a dark slide, and insert it just before shooting the image - and then replace it with the full-sized slide.

My Fidelity holders are a few years old - but not having done this before, I don't know which tool to use for cutting the slide. I don't have any kind of workshop. How about several cuts with a sharp blade ?

Other than taping some opaque paper over my existing groundglass, is there any good way to mask it off, without ruining it or replacing it ?

Sorry if these questions seem lame - but I am often astounded at the resourcefulness of fellow forum members.

Thanks !

[Steve Baggett]

I did something similar to create 2 dark-slides with square openings in 2 quadrants to facilitate "zone testing" for B&W on a single sheet of film (by flipping them over I can create an opening in all 4 quadrants). What I found was that the plastic in dark slides is very brittle and it is difficult to cut with any precision. What finally worked, but not very well, was to drill a starter hole with a good drill bit and then "grind" the plastic away using a Dremel tool. Even then, the openings are a little ragged, but this did not impede my particular application. What I did discover is that when you remove part of the interior of a dark slide it will "flex" a lot when inserting and often hang on the light curtain, sometimes "scraping" it quite demonstrably. The size of the opening you are considering would make this effect even more pronounced, IMO. Darkslides seem to be designed with just enough rigidity to go in and out without too much flexing but when you have removed some of the interior space, they flex enough to "hang" quite readily. I used Fidelity "elite" holders for this experiment and, while they do work for the intended purpose, they offer a fair amount of trouble sliding in and out.

[Peter Galea]

I made a 4x10 using an old slide. It's easy, use a sharp utility knife. Make it an 1/8 inch wider so you have some clear space between exposures. On the Deardorf back I made a makeshift mask using gaffers tape on the wood as a hinge on each side and a file folder cut to 3 7/8ths x10. Just flip it back and forth to compose different sides of the film. Careful measurement, a sharp blade and willingness to sacrifice a slide is all that's needed. I like the format and the ability to vary exposure on one sheet.

[Darin Cozine]

Just an FYI, I amde one of these for my field camera (busch pressman), hoping to use it with a 65mm lens to get 6x12. unfortunately, the bellows did not allow for enough movement with such a short lens to work correctly. [sniff]

[Ralph Barker]

Unless part of the objective is to get two images on a single sheet of 4x5 film, Ken, I think it is far easier to simply use a mask on the ground glass for composition, and then crop in the enlarger. The only advantage to using a film mask would be clear borders - only important if one is making contact prints from larger negatives.

[John Cook]

The best way to trim a dark slide may be to treat it like high-pressure laminate (Formica). Several small routers are made to easily trim this material, like the ones from Porter Cable.

Find yourself a home woodworker or local cabinet shop, both of whom can probably do the job.

[Roger Hein]

Ken,

The simplest and easiest is to use a hand scoring tool/blade - the same as used for cutting thin plexiglass in picture frames. I've cut many 'masks' this way and it has worked perfectly.

[Robert A. Zeichner]

What I would suggest is getting some neutral density gel of .3 or .6 values and glue it onto the outside of your gg with tiny spots of transparent aquarium cement (silicone adhesive). You can apply the cement with a toothpick, as you will not need much to do the job. The ND gel will allow you to see what's beyond the desired ?x5 composing area, but will also provide a defined boundry. Another option might be to remove the gg and with a very sharp, hard pencil, scribe lines onto the ground surface and then make a series of angular hatch marks on the two ?" wide strips outside the composing area. This, by the way is how viewing screens in professional motion picture cameras are often treated. As another respondent pointed out, if you are not trying to make more than one image on a sheet of film, why not just mask the gg? Everytime you remove and insert a dark slide, you create an opportunity for dust to get stirred up and deposited on the film.

[David A. Goldfarb]

I've done this for 8x10" using the method described above of marking the window to be cut and scoring several times with a utility knife, and then sanded the cut surfaces with fine sandpaper to remove any burrs. The cut is very clean. The result should be an L-shaped piece, so that it will go in straight. You can also order one from Bender, if you don't happen to have a spare darkslide. In any case, take a look at the Bender website to see what the mask should look like.

[Nigel Sutton]

I bought a 2ndhand holder specifically for the purpose of making a half dark slide to make two 2x5s from a single sheet. I used a standard scalpel cutter to cut the plastic.Score it slowly, be patient. Even so, the edge will still need smoothing off. Do NOT cut a window in the dark slide but cut one side away completely, I had problems withdrawing the window cut from the holder. Leave as much of the slide as possible at the slot end, only cut away what is necessary to expose the length of the frame. This helps the half dark slide sit level but more importantly will help avoid light leaks. I then cut a piece of card (will do it with plastic later) the same shape as my GG protective sheet and cut a window to use to frame my exposures. To ensure I get the same frame for two shots I then invert the universal back on my Ebony. This way I can take two identical shots without moving the camera at all. To track the shot all my numbered holders are also marked with A and B so that I can identify the 2x5 shots. This all works really well for me, especially as I am a big fan of panoramics. Hope this helps. Regards, Nigels.