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almostpilot
30-Apr-2018, 09:22
Hello,
I guess this has been covered before and I am grateful if someone will point me to the correct thread, because so far I have not been able to find the answers I am needing.
I have a lovely english half plate mahogany camera, and I normally use it with a 5x4 reducing back. It's a great back which fits the camera without any alterations to the original spec whatsoever. However my reducing back is made with a very heavy cast iron darkslide holder so I want to go back to use the original GG and the half plate mahogany slides. I have two. Book form.
I understand that these were made for glass negs so I need to use a cut-to-size perspex/glass piece onto which i must attach the film. So as to replicate the thickness of the glass negs I presume.
My questions are:
how thick should this piece of perspex/glass be? I have been told 0.5 mm... is that right?
and how to attach the film to it? What is this "jam" method I read about?
Some american threads mention "film sheaths" (there are several for sale on ebay usa but none in uk) are these a possible solution?
Any advice much appreciated.
PS
I also want to do daguerreotypes with these darkslides. I think a half plate size daguerreotype should be a wonderful thing to hold...

Nodda Duma
30-Apr-2018, 09:29
Use whatever thickness glass is needed to build up to a 0.050 thick glass/film stack. When I started making dry plates, pretty much all the plates from that era were that thickness so I went with that. (0.050 = 1.27mm)

Jim Jones
30-Apr-2018, 09:42
Perhaps film sheaths could be improvised from thin aluminum sheets. One source of fairly inexpensive aluminum sheets is sold for flashing at hardware stores.

RJ-
30-Apr-2018, 09:47
"I understand that these were made for glass negs so I need to use a cut-to-size perspex/glass piece onto which i must attach the film."

- This is where jam gets sandwiched. It enables the adherence of the film sheet to a cut glass surface. You can use anything; preferably without seeds or chunks of marmalade orange rind.

The replication of the glass plate thickness to attain the same focussing sharpness on the image plane (ground glass) is a little hit and miss. As Jason suggests - 0.050inches makes more sense; 0.5mm glass will shatter.

In England, it's easier to source 18mm, 20mm, 22mm glass - which you can bevel around the perimeter or request at the time of cutting (approximately <0.80 per sheet for a whole plate size from any glass specialist/mirror shop). This is the foundation for bringing the thin sheet of film into the same critical measurement range as the ground glass for focussing the image. I've settled on bevelled 18mm, always bevelled. The cheaper non-bevelled alternative might require a First Aid kit in the darkroom.

The sheath adapters exist for a number of formats. I've not seen a 5x4 inch one for years after parting with one. The sheath is built from black sprayed aluminium with 3 metal lips, approximately 3mm, which enables the sheet of film to be held in place within a book form holder. Neither have you named your lovely mahogany camera (a Gandolfi perhaps?) which had some standardisation across its cameras for these now eccentric plate holders - easier to find in the half-plate form.

www.mrcad.co.uk in London held the last reserve of these which I could find, otherwise the only feasible non-custom solution is to acquire as many as possible online to filter out the appropriate one required.

The Deptford Sheet metal factory crafted around 20 whole plate customised ones around 15 years ago for me. As Jim suggests - thin aluminium works and easily holds black radiator paint. The company still exist and no doubt you could achieve it DIY. The factory however will need to draft a CAD or design to allow them to follow, ideally making one draft template to check out.

http://www.deptfordsheetmetal.com/


Kind regards,

RJ

Andrew Plume
30-Apr-2018, 13:31
RJ, Hi

"..............I've not seen a 5x4 inch one for years after parting with one............."

You're in luck, PM on the way

regards

Andrew

Steven Tribe
30-Apr-2018, 14:40
Manufactured film sheaths are not necessary with book type holders. You just need a stiff distance piece (plastic or metal sheet) the same size as the film - to place on top of the film. This is held in place by the central spring when the "book" is closed.

RJ-
30-Apr-2018, 16:15
Book form plate holders come in different non-standardised thickness Steven.

The difference in tolerances and the design of the book form holder, risks having the film dislodge and whipped out of the book form holder during exposure making. Even cherry jam isn't strong enough sometimes.

This is why the metal sheath system has a particular advantage over a plain sheet of glass, plastic, or metal. The lipping traps the film in place, allowing the mahogany wood to glide over.

Kind regards,

RJ

RJ-
30-Apr-2018, 16:16
RJ, Hi

"..............I've not seen a 5x4 inch one for years after parting with one............."

You're in luck, PM on the way

regards

Andrew


Hi Andrew -

This is AlmostPilot's thread - I'm sure he might appreciate the heads up!



RJ

B.S.Kumar
30-Apr-2018, 19:16
I offered to get some made: http://www.largeformatphotography.info/forum/showthread.php?145203-Film-Sheaths-and-Adapters-for-Plate-Holders

almostpilot
1-May-2018, 02:05
Thank you very much for the responses.
My camera is called The Guilford. Made in London and Leeds.
Still a bit confused here but I know well Alex at MrCad so i will take a stroll there with my darkslides and see what he has to say.
I was planning to get some black pexpex and cut to size. I have used this before with success on other projects (pinhole cameras) With regards to the "Jam method" if you use it do you then pre soak the film to get rid of the jam prior to developing?

RJ-
1-May-2018, 03:28
I offered to get some made: http://www.largeformatphotography.info/forum/showthread.php?145203-Film-Sheaths-and-Adapters-for-Plate-Holders


Hi Kumar,

That's a fascinating proposal. I love the upcycling principle, bringing life back and extending the use for the late 19th century/earl 20th century plate cameras.

I hope it succeeds. Had you not flagged this up, I'd never have known that this venture for film sheath making was being piloted (I've already worked out my film sheath work flow for some time now).




My camera is called The Guilford. Made in London and Leeds.


...errr good luck!




I was planning to get some black pexpex and cut to size. I have used this before with success on other projects (pinhole cameras) With regards to the "Jam method" if you use it do you then pre soak the film to get rid of the jam prior to developing?

Hi again,

I wonder if you've considered the electrostatic issues with using perspex and non-glass or non-metal and the effect of dust and charged debris on your film emulsion.

Pre-soaking film for adsorption contact consistency between the dry film emulsion and a solution is standard practice surely? It is possible for you to use the jam in the developing solution. My guess is that it would create a sweet developer.

Kind regards,
RJ

Steven Tribe
1-May-2018, 07:54
Book form plate holders come in different non-standardised thickness Steven.

The difference in tolerances and the design of the book form holder, risks having the film dislodge and whipped out of the book form holder during exposure making. Even cherry jam isn't strong enough sometimes.

This is why the metal sheath system has a particular advantage over a plain sheet of glass, plastic, or metal. The lipping traps the film in place, allowing the mahogany wood to glide over.

Kind regards,

RJ


I beg to disagree with most of what you have written.

Back loading film into the rectangular space where the glass plate used to sit, means that the emulsion is exactly right position - unless the plate holders and the camera are not a match (If the position of the ground side of GG doesn't coincidence with the emulsion plane position). It is the distance of the glass/film emulsion from the flat side facing the camera that is important - not the external thickness of the plate holder.

As long as the springs are still OK, the metal plate (the size of the film) will press the film down on all 4 edges. It is a simpler operation in a changing bag/tent then mounting film in film in sheaths. Sheaths are not always in good condition- have received knocks and don't always adopt the focal plane of glass plates. If reversed, they can be used in the method I have described - as pressure plates.

almostpilot
2-May-2018, 02:53
I wonder if you've considered the electrostatic issues with using perspex and non-glass or non-metal and the effect of dust and charged debris on your film emulsion.

Pre-soaking film for adsorption contact consistency between the dry film emulsion and a solution is standard practice surely? It is possible for you to use the jam in the developing solution. My guess is that it would create a sweet developer.

RJ

Thanks RJ. Re the perspex, well a lot of cameras have plastic film pressure plates, no?
Re pre-soaking, i develop in Xtol and kodak advises against pre soaking in Xtol, so that is why i asked.
Still, no-one has really answered with details of the "jam method"
Can you?
thanks again
alex

almostpilot
2-May-2018, 02:54
@ Steven Tribe, above
Yes, I would agree with you there. I need to look at my darkslides carefully again, perhaps with someone who has used these types before. But what you say makes sense to me.

Steven Tribe
2-May-2018, 14:31
I'll see if I can make some x-section sketches tomorrow - but I have poor drawing abilities!

B.S.Kumar
2-May-2018, 18:02
Sheaths are not always in good condition- have received knocks and don't always adopt the focal plane of glass plates. If reversed, they can be used in the method I have described - as pressure plates.

People use Grafmatics, and take care of the sheaths inside. The same principle applies, no? If the adapters and sheaths are well made, they will place the film properly.

Steven Tribe
3-May-2018, 07:32
I think sheaths are generally well made - but problems arise if there are bends. It is very difficult to remove distortions in sheet metal.

Here are some photos rather than sketches!

I have about a dozen makes of book holders - none of them are exactly the same internally. UK and continental are very similar! I have a UK in the first two photos (12x16") and a Continental one (18x24cm). The central metal plate, which prevents light penetrating from one side to another, can be attached with two metal hinges (the most common), a tape hinge (the early ones) or be completely loose and help in place by 4 catches. Each side has one or two (or more) springs which held the glass plates down on all four edges. Note that this type is only suitable for dry plates as the mahogany/walnut would be really nasty after just a few exposures! All you need is a flat and stiff plate (it doesn't have to be light tight) on top of the film which is contact with the central spring when the book plate holder is closed. One side of the book holder will have a latching system and, of course, this side has to be loaded with film and a pressure plate first. Otherwise, loading the second side will be impossible.

I think now the photos will make sense! I show both sides of these two holders. The total view photos show the central devide with springs. This plate will only fit properly on one side. The detailed shows the other side and the section of the frame where the plate (or film + backing plate) fits perfectly.

It is possible that very early book type holders were made for wet plate use. In which case, instead of the ledge all the way round, they would have silver corner pieces. I think film would sag on these.

photos won't load at the moment - so I'll try later!

Steven Tribe
3-May-2018, 09:07
photos for post #17

RJ-
3-May-2018, 16:41
I beg to disagree with most of what you have written.

Back loading film into the rectangular space where the glass plate used to sit, means that the emulsion is exactly right position - unless the plate holders and the camera are not a match (If the position of the ground side of GG doesn't coincidence with the emulsion plane position). It is the distance of the glass/film emulsion from the flat side facing the camera that is important - not the external thickness of the plate holder.

As long as the springs are still OK, the metal plate (the size of the film) will press the film down on all 4 edges. It is a simpler operation in a changing bag/tent then mounting film in film in sheaths. Sheaths are not always in good condition- have received knocks and don't always adopt the focal plane of glass plates. If reversed, they can be used in the method I have described - as pressure plates.


Hi Steve,

10 years ago I would have agreed with you, although never with as much vehemence. Your experience is provincial; mine is even more provincial against a backdrop of 100 years+ of plate photography and thus, changing methods during this time scale have existed.

In principle, the book form plate holders with the spring loaded metal bars to press on the glass plate for tension were never designed for film: they were designed for plates. There are many varieties of book form plate holders - which do not possess four metal plates as you suggest as universal - which do however, push the film against the friction plane and contact with the moving wooden darkslide.

Film adaptation to the plates, was a hack measure, which does indeed work. I've done this for years. Perhaps it is not a move I would recommend to a newcomer.

Ruining sheet film from scratching by glass plate pressing the film right up against the moving wood dark slide is a real problem. As is dragging the sheet film out (there are no sheath guide rails to hold it in place), and destroying it mid-exposure.

When we examine the construction of a modern 5x4 inch Fidelity Double Dark Slide: inside, there are lateral grooves - which act like the 3 edges of a metal sheaths, trapping the sheet film by the edges and not by apposing the film with tension against the wooden darkslide. The metal sheaths found in Grafmatics and plate holders, hold the film sheet at the edges and does not force the film against the plane of the moving darkslide. The modern DDS has more in common, with the lipping of the metal sheath for sheet film, than book form holders using metal pressure hinges to contact flatten a whole sheet of film in a holder.

A lot of work went into the development of the metal sheath for sheet film in vintage photography: which exists in 6x9cm formats [Plaubel Makina II, IIIR series strut camera from the 1939-1950s]; Baby Graphic [6x9cm]; Quarter Plate [Butchers & Houghton]; Half Plate [Thornton Pickard, Gandolfi, Lizars]; Whole Plate [Sanderson, Thornton Pickard] to name a few.

If you've not found it helpful, I can understand this, however our personal experience is provincial.

Kind regards,

RJ

RJ-
3-May-2018, 17:07
Thanks RJ. Re the perspex, well a lot of cameras have plastic film pressure plates, no?
Re pre-soaking, i develop in Xtol and kodak advises against pre soaking in Xtol, so that is why i asked.
Still, no-one has really answered with details of the "jam method"
Can you?
thanks again
alex


Hi Alex,

Sorry I've been busy helping my local minority party stage Custard's last stand in our local election.

Q1: My preferred darkslides are made of carbon fibre. Or wood. If you think about 35mm or medium format cameras - how many do you know, use perspex for the film back? It's just a consideration if you wish to enlarge or work meticulously. Which will attract more dust for you - metal, glass or perspex, when placed inside wood?


Q2: We understand development of film with a liquid, in terms of adsorption (contact with the developer). The concept of pre-soaking, breaks down the stage of contact between the film surface with an active liquid developer: a) the film is wetted by the pre-soak, with no activity b) when the pre-soaked film is then immersed in a developer, the adsorption of water has already taken place c) the active liquid developer spreads more evenly [consistently]

This is as simple as I can put it: it is first principles in any activity requiring wetting: whether this be dyeing your jeans a different colour, or marinading a Sunday roast: it is pre-soaked, to enable consistency.

In your understanding, 'Kodak advises against presoaking', it seems to create a conflict with the basic principles of presoaking. Perhaps this is a mis-reading. I understand, that not everyone has a science degree, but equally I don't believe one is needed. Researching well is one way to overcome this challenge, since I do not use Xtol anymore. So I've looked it up:

http://imaging.kodakalaris.com/sites/uat/files/wysiwyg/pro/chemistry/J-109_Feb_2018.pdf

The Kodak .pdf states "Presoaking sheets in water yields more even development" [Page 3]

I hope this answers your question.


Q3: Jam Method

Sorry - I thought I had answered it above referring to a jam sandwich metaphor.

Jam is used in a sandwich. A sandwich has two layers, and jam is the filling. When jam is spread on one side of the sandwich, it sticks both layers together. In this manner, it is possible to eat a sandwich with one hand, without it falling apart into two layers.

In some bookform plate holders where the layers are formed by a sheet of glass and a sheet of film, the jam is used to adhere the two layers. The jam is applied to the non-emulsion face of the sheet, and the exposure face of the glass slide to adhere its position. The jam is "sandwiched" by the back of the film emulsion and the glass. This temporary jam resolves the sticky situation of loose film sheets undoing within a bookform holder, not originally designed for sheet film.

It works, perhaps not elegantly, quirkily, however since a film metal sheath over a sheet of glass cannot be used without bulging the holder (wrong film-lens distance, insufficent room) and a metal sheath on its own cannot be used without wobbling loose (setting up a potentially wrong imaging plane), it works. This is the kind of bookform holder which Steve is referring to perhaps: these do not accept metal sheaths blindly without checking the plate glass backing thickness and calibrating to match.

Kind regards,

RJ

almostpilot
4-May-2018, 01:55
Just want to thank you all for he;lping me. i will absorb the info you have given me in this last round of posts and get back to you. Thank-You!
Sorry I am dealing with a very bad and serious problem encountered with SAS Photographic Auction House. I will post a new thread with information because all enthusiasts should be aware of these issues I have encountered.