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Milonian
20-Oct-2016, 07:24
I was using a Hasselblad Flextight scanner the other day at the wonderful Stills Gallery in Edinburgh, Scotland http://www.stills.org/facilities and I was impressed with the simplicity of the magnetic film holders. Essentially you peel back the magnetic layer, lay the film on the metal bed and let the magnetic top layer back down, so holding the film flat. Occurred to me that if I could get a hold of magnetic sheets I could convert my old mahogany bookform plate holders so that they were film friendly.
After some "research" - quick search on a well-known auction site - I found "L" plates for UK learner drivers made from magnetic sheeting - 1 per pair including postage. Not going to break the bank. These adhere to the metal inserts in the holders.


I'm pretty happy that this will keep the film in place but the metal divider in the holder is very thin and prone to warping - it's not completely flat. So the film conforms exactly to the contours of the insert but that may not convert to absolute film flatness. So that's one problem.

Another is what I will call the "register" - can't be certain that the film sits in the correct place i.e. the same distance from the lens as the GG so this could cause focus issues - will that matter for landscapes? Will it matter more for portraits?

Any other issues I should think about - this is just so that I can use my old Century Grand 1/2 plate and maybe my Sanderson and Lancaster cameras in due course.

Maybe there are other threads on this - if so please let me know. I couldn't find any but search terms may not have been the best.

Here's a couple of pics from my phone. Any help appreciated.

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RJ-
20-Oct-2016, 14:59
"Any other issues I should think about - this is just so that I can use my old Century Grand 1/2 plate and maybe my Sanderson and Lancaster cameras in due course."


Hi,

Perhaps this resource might help guide in relation to format and glass plate adapter use:

http://photo-analogue.blogspot.com/2014/04/glass-plate-adaptors.html


Yours must be the most creative use of wearing "L" plates in your wooden camera's underwear to practice vintage plate photography.

Have you had a chance to test the exposure process of withdrawing the darkslide to check whether the sheet film is dislodged during the process? I wonder how the film adheres to the thin magnetic plate during the friction of withdrawing the wooden film darkslide sheath. In traditional glass plate to sheet film adaptation, washable culinary adhesives such as marmalade (rindless - since the rind creates lens-film distance offsets) as a temporary measure in the absence of metal sheet film adapters can be helpful. I think you've referenced half-plate and the images of your holder appear to have a similar half-plate ratio: metal sheath adapters for film are not as challenging to source as they are for whole plate film adapters although the solution is not as creative as yours.

The traditional plate film glass with the correct lens to film plane distance results in approximately 0.19inch thick glass backed emulsion being used. Your adaptation leads to a lens-film distance (which you term "register"?) which the magnetic "L" plate will fall substantially short of 0.19inch, or the equivalent thickness of Ilford HP3+ vintage plates. This thickness holds for my Sanderson whole plate camera however anything from 2mm or 0.11inches may perhaps work, depending on the circles of confusion which your photographic set-up offer. There is some scope.

You can test this hypothesis by using glass sheets of 2mm, 3mm, 4mm (if it can fit without glass being crunched) glued behind the magnetic L plate to check for critical image sharpness across the sheet film for shallow apertures to ascertain although in practice, you may find 2mm very acceptable as a thickness for the base plate/magnetic holder support for the film.

Perhaps using glue between and a 2mm base to limit the number of layers between the film and the metal dividing plate will help achieve something closer to plate plane parallelism across the image diagonal in relation to the lens-film distance. Although then the advantage of using the magnetic plate is completely lost. It will still offer less flatness than the traditional 3 way lipped metal sheath holder, which tightens the sheet of film across three of its perimeter edges to offer some albeit never completely perfect flatness.

Kind regards,

RJ

Steven Tribe
21-Oct-2016, 05:56
I have never been quite convinced that metal film sheath holders are suited to use in book type holders. This is because the original glass plates had all of their 4 edges pressed into an indent in the mahogany frame. You are totally dependent on the turned/raised edge profile on the film sheaths compensating for the thickness of the metal in the sheaths. I soon realised, in practice, that it is far easy to load book holders with film by just using the sheaths loose. The plain side fits on top of the film once this have fallen into the square hole and the locking tabs are then tirned. This requires, of course, that the springs on the hinged central plate are still present. Any metal/stiff plastic plate will suffice in lieu of sheaths. This was certainly necessary with my larger book holder formats - 24x30 and 30x40cm and 15x12" - where film sheaths were probably never made commercially.

RJ-
21-Oct-2016, 13:05
I have never been quite convinced that metal film sheath holders are suited to use in book type holders.


Hi Steve

I understand your theoretical concern. In practice, your larger format film flatness and lens-film distance for the comparative circle of confusions for your format are going to be different for a half-plate camera. I find bookform holders for whole plate very versatile. They are adept for either dry plate or film and none of the issues which you raise is apparent in my practice, however I have spent some time bedding in the vintage camera and plate holders.

Metal film sheath holders have been manufactured - and used - probably because they serve a purpose. There are an abundance of them (or were). I presumed they were not manufactured frivolously or erroneously and took on a number of them to create these images below.

Kind regards,
RJ

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Charten Wholeplate Camera, Schneider Super Angulon 90mm XL f5.6



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Charten Whole plate, Wollensak 8 1/2 inch f6.8



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Charten Wholeplate Camera, Wollensak 8 1/2 inch f6.8

Steven Tribe
21-Oct-2016, 14:41
By the time that film and film sheaths arrived on the sceen, most plate holders had become non-book types - with front loading with the dark slide pulled out. The metal sheath was secured at just two ends. I think that oldtimers with our sorts of cameras with book holders either continued with glass plates (for quality)or just used a plain metal plate to distribute the pressure evenly over film.

Milonian
21-Oct-2016, 16:11
Thank you both for comments.
While breakfast may never be quite the same from now on (!) I do think I need to "shim" the film forward (towards the lens) and the measurement provided will be useful in that respect. From there it will probably be trial and error. This might involve a piece of metal of suitable thickness glued to the existing metal divider. Another trip to eBay coming on!
The magnetic window film holder does not move at all - or at least has not moved for each trial opening of the wooden slide. The film appears to be in exactly the same position the next time the slide is withdrawn, so it seems to be fairly reliable from that point of view.
I will try to post results later.
Thanks again ����

brucep
24-Oct-2016, 05:43
I have a 6" x15" camera that I lay the film into the recess then lay sheet of black dibond over it to the thickness of the original glass plates. Dibond is both stiff and light.

Sent from my X17 using Tapatalk

Milonian
24-Oct-2016, 08:15
I didn't make it clear and perhaps should have mentioned that I'm loading 5x4 film into half plate size plate holders - or at least I'm hoping to! The reason is that I use 5x4 almost exclusively - and one day I might get good at it - so it doesn't make sense to use anything else. Also my developing tank is for 5x4 film only.
Some of my holders came with bits of card that had been used as spacers (shims) and I find that two of these in a sandwich between the metal divider and the magnetic "frame" that I have made brings the film forward towards the lens by approx. 2.3mm and has the added advantage of making the assembly more stable. The film seems to lie flatter as a result too as the card insert lends rigidity to the thin metal divider. I may experiment by gluing the card pieces together and then gluing them both to the divider.
As far as I can tell the film plane is now only the thickness of the "L" plate back (away from the lens) from where a glass plate would sit = less than 0.5mm.

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Milonian
24-Oct-2016, 08:17
I have a 6" x15" camera that I lay the film into the recess then lay sheet of black dibond over it to the thickness of the original glass plates. Dibond is both stiff and light.

Sent from my X17 using Tapatalk

I wouldn't mind seeing that camera at all!

Milonian
25-Oct-2016, 05:10
Just for completeness I have made a 1/4 plate version to fit my Lancaster Instantograph. A few pics attached. It has two old glass plates in it and no metal divider so it needs a magnetic sheet as a backing for the magnetic frame. I used a polaroid as the "film" for this purpose.
Just need to get the bellows attached to both the Lancaster 1/4 and the Century 1/2 plate, then somehow cut 5x4 film down to fit 1/4 plate holder and that should be that!

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