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Thread: Replacement 8x10 darkslides

  1. #31

    Re: Replacement 8x10 darkslides

    Update on the quest for dark slide replacement material.

    I completed a fairly dimensional test of the plastic sheet material that appeared to be a perfect candidate. I took three sheets of the material and performed three individual image making comparative tests on a holder where one side I used the original dark slide and the other side of the 8x10 holder I used the plastic replacement material. On each image I allowed each side of the holder to be open to the sun for a reasonable period of time - consistent with normal field operations. I made three separate exposures one per double sided holder, processed the negatives and put them on the light table.

    Unfortunately and much to my disappointment, even though the plastic material looks light tight, I can see areas in the replacement slide negative where the light worked its way through the dark slide material in varying proportions and had an adverse impact on the negative. This has to be a random event having to do with the manner with with this replacement material is manufactured. I was using 400 speed film and although 90% of the negative looks fine, the section that is slightly fogged is visually obvious. As a result I must conclude that the material that appeared to be so promising making a dark slide replacement is not suitable for the task at hand.

    At this stage I feel we should see if through the forum we can see if anyone has a contact with Fidelity in some way so we can attempt to gleam their material source for dark slides. The other alternative would be to see if the English company making holders and cameras has a material source. I could not see a way to communicate with them.

    I gave it a good go but the results are what they are. The material I used was a phenolic plastic material. I see this only as a temporary setback. We will collectively figure this out.

    Thanks!

  2. #32

    Re: Replacement 8x10 darkslides

    The Intrepid Camera Company has a video showing them using a CNC machine to cut dark slides. I would suspect the company uses similar proportions for dark slide thickness and producing a simple replacement dark slide for Fidelity 8x10 holders should be an easy buck for them since they are already gear up for it. Anyone have any contacts at Intrepid Camera?

  3. #33
    Daniel Stone's Avatar
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    Re: Replacement 8x10 darkslides

    I would use anodized aluminum sheet material, TBH. If this is something that we could get a group buy together on, I could see about making up a prototype for such.

    The benefit of the anodization process is that you can etch the aluminum BEFORE anodizing, so a semi-matte surface is achieved, which will help in reducing the chance of extra reflections... Matte is good IMO.
    The benefit of using aluminum is that it is more robust than the plastic, albeit it might add just a little bit more weight.

    Any takers? I can really only see this being cost-effective per-slide if we can get at least 100 pieces together.

    -Dan

    (EDIT): Upon looking through my 8x10 holders, one actually has metal slides. They are .030" anodized aluminum. They are quite rigid, and frankly, are what I could want in all my 8x10 holders if I were still shooting the format.

  4. #34
    Daniel Stone's Avatar
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    Re: Replacement 8x10 darkslides

    Here's a picture of the slide I referenced above ^^.



    Looks to be from the factory. I would go with the Chamonix-style ends(simple holes in the ends, but possibly masked on one side so there is a "white side" and a "black side". Not hard to do with the right polyester masking tape.

  5. #35
    Tin Can's Avatar
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    Re: Replacement 8x10 darkslides

    Why would black anodized aluminum be necessary? Why matte?

    Are there reflections inside a film holder?

    Would a reflective outside surface be cooler temperature?

    How many variations in size for 8X10, 11x14 film darkslides?

    Isn't a darkslide a creator of darkness and not necessarily dark?

    Or is it just 'traditional'?

  6. #36

    Re: Replacement 8x10 darkslides

    Quote Originally Posted by Randy Moe View Post
    Why would black anodized aluminum be necessary? Why matte?

    Are there reflections inside a film holder?

    Would a reflective outside surface be cooler temperature?

    How many variations in size for 8X10, 11x14 film darkslides?

    Isn't a darkslide a creator of darkness and not necessarily dark?

    Or is it just 'traditional'?
    As I see it there are four fundamental challenges with this objective given the thickness (1/30 to 1/32") of the original dark slide. 1) Must be not allow any light transmission. 2) The material and be matt black for reflection reasons. 3) Must be rigid and maintain this perfectly flat condition particularly on the bottom end for ease of insertion into the receiving flap end and 4) Must be cost effective to the consumers.

    Obviously aluminum would be a great material but getting it anodized and cut could run into large quantities to make it work. My Toyo 8x10 film holder dark slides feel like aluminum, but my Fidelity plastic ones that look exactly like the prior post I believe are plastic. I was hoping to keep the costs per dark slide under $20 but that may not be possible.

  7. #37

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    Re: Replacement 8x10 darkslides

    I had some aluminum left over from a job that is the right thickness so I made some dark slides from it and tried it. Yes it doesn't allow light through it but I had some light leaking through the light trap. It could be it's because my light traps aren't so good but I don't have leaks through the traps using garrolite xx, just through the material itself.
    Last edited by chris_4622; 26-Feb-2018 at 07:10. Reason: fixed a positive to a negative

  8. #38
    Daniel Stone's Avatar
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    Re: Replacement 8x10 darkslides

    Quote Originally Posted by Randy Moe View Post
    Why would black anodized aluminum be necessary? Why matte? You could use any material, but aluminum is relatively inexpensive(so finalized cost to customer would be lower), matte to reduce chance of increased internal reflections.

    Are there reflections inside a film holder? Yes, more than you would think

    Would a reflective outside surface be cooler temperature? No

    How many variations in size for 8X10, 11x14 film darkslides? My suggestion for 8x10 replacement slides(possibly even for 5x7 as well, seeing that these are less common and easier to replace a slide than the entire holder, compared to 4x5 where it's the total opposite, even more so for 8x10)

    Isn't a darkslide a creator of darkness and not necessarily dark? It needs to be completely opaque, for obvious reasons

    Or is it just 'traditional'? Nothing traditional about photography. I would prefer aluminum anyhow, as it has a lower tendency to generate static electricity during withdrawal and insertion, compared to plastic slides(plastic->plastic contact vs metal->plastic)

  9. #39
    Daniel Stone's Avatar
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    Re: Replacement 8x10 darkslides

    Anyone interested, I'm at my shop today and drew up some sample files. This one shown is simply made from paper, but could easily be routed out from MDF at my friend's shop so I could have a blank routing guide/template for producing these. Lemme know! On the pull slides, what do you guys think in terms of design? I want to make sure these will still allow the use of the retaining clips(although I personally prefer rubber bands :P)




  10. #40

    Re: Replacement 8x10 darkslides

    Quote Originally Posted by Daniel Stone View Post
    Anyone interested, I'm at my shop today and drew up some sample files. This one shown is simply made from paper, but could easily be routed out from MDF at my friend's shop so I could have a blank routing guide/template for producing these. Lemme know! On the pull slides, what do you guys think in terms of design? I want to make sure these will still allow the use of the retaining clips(although I personally prefer rubber bands :P)



    Awesome Daniel.

    The design of the top tabs I believe should be offset from center to one side of the dark slide so you can always get a clean grab of them to individually grab when they are offset. I am thinking about applying an exposure tab on the dark slide and returning the slide in its original orientation to maintain the offset rather than the conventional white/black system. The Intrepid video showed they decided to drill three holes in the top of the tab I guess to make it easier to hold. I was looking at the entry edge of the dark slide and it had a slight curve to it obviously to ensure a complete entry into the holder.

    I believe that if we can find a product that would function properly this would be a very good product for large format photographers. I personally take considerable care of my holders but they get considerable use and if a dark slide cracks and becomes inoperable there is no Plan B. Testing as I found out is critical to the process to ensure they work properly.




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