'Clingfilm' as a pellicle mirror?

Discussion in 'Beginner Questions' started by rodeo_joe|1, Jun 19, 2021.

  1. I have a use for a pellicle mirror, about 4" x 5" in size. It's to be used to shoot through at 45 degrees while also acting as a light reflector.

    I already Googled it, and got a hit on using food wrap as a replacement for the pellicle mirror in a Sony camera; where it worked quite well by all reports.

    I figure that its use in front of a sensor might be more demanding than simply pointing a lens through the stuff.

    Another suggestion was to use the protective film used for phone and tablet screens. But it seems to me that a thinner film would be better.

    So, has anyone tried shooting through clingfilm? Or any other readily-available thin plastic.

    BTW. I know this isn't strictly a beginner question, but I thought this forum might attract the most replies.

    There's also one-way mirror film sold for coating windows, but this might be too reflective for the above purpose. Could be useful for healing up the shooting hole in a light-tent though.
     
  2. I've made replacement pellicles for autocollimators the old fashioned way. Get yourself some traditional clear nitrocellulose airplane dope and a tray of clean water. I haven't done this for years, but assume you can still buy it. I don't know if modern NC lacquer would work, but it might. Use an eyedropper to deposit some dope in the middle of the tray. It will spread out into a very thin layer and dry. Make a wire loop to go under it and slide it out/off the water. Framing and installation are tricky as the thing is so fragile, but it's doable. I've only done a few inches, not so large as 4x5. This is about the ultimate in thinness and avoiding double reflections.
     
  3. Thanks for that Conrad. An interesting method, but I was hoping for something more 'off-the-shelf'. Plus there are very few Aero Modelling stores around where I live and I'm not even sure if the Health & Safety Gestapo allow such volatile stuff to be sold nowadays.

    The fragility concerns me too. It's to replace a contrast-control mirror in my film copier. The original was a fairly expensive sheet of thin glass that gets easily cracked, and was missing from my copier unit when I bought it. Whereas something like cling film... easily found and replaced.

    But thanks again. It's something to keep in mind.
     
  4. You can get optically clear Mylar film as thin as 0.48 mil, but I don't know how easy it is to get less than a rail car full. You might call an industrial supplier and see if you can wrangle a sample. Thicker is easier and probably available on Amazon or other places. The food wrap on huge rolls used in supermarket meat departments might be of better quality than the common off the shelf stuff. Time for steak tonight?
     
    steven_endo likes this.
  5. Aha! Now packaging film might fit the bill. I've struggled to tear it off countless food items, and usually end up taking a sharp knife to it.

    Cheers Conrad. Stay safe.
     
  6. Industrial pallet wrap film might fit the bill?

    Ask around locally and see if someone will give you the end of a roll?

    Ours now has the company logo printed all over it, so not so useful...
     
  7. The problem with flexible stuff is that it is flexible. It needs to be as flat as can be.
    Using a piece of 1 or 2 mm glass will probably be the best option anyway. Sagging and wrinkled film will cause uneven illumination (highlights) in your contract reducing lighting, and cause optical aberrations in the image.
    For small formats a piece from a glass slide frame will do quite well.
     
  8. I came across some glass mobile-phone screen protectors. Two for £1 (for obsolete phone models) at a charity shop. I bought two packs - 4 sheets of glass.

    I wrecked one piece trying to find the best method to cut it to size, but another is now re-sized and fitted in the contrast control unit of my Illumitran copier.

    Thanks for all the suggestions.

    After considering the optics involved, it seems the glass thickness isn't too important after all. The image is only deflected slightly by passing through the angled glass, and a double image isn't produced (except in the white-light reflection, which isn't an issue). So no need for absolute thinness.
     
    Last edited: Jul 19, 2021 at 7:24 AM
    NHSN likes this.
  9. Hmmm... I wonder if those glass plates could be coated with emulsion and a line of mid-format cameras developed to use them? Way thinner and more rugged than traditional glass plates. :D
     
    steve_gallimore|1 and NHSN like this.
  10. Quite likely. They're already toughened with a (self-healing apparently!) plastic coating on one side.

    I discovered you have to apply the glass cutter to the genuine glass surface and then carefully cut through the plastic coating once the glass has parted. It takes a nicely sharp carbide tipped scribe to cut the glass neatly BTW. While not applying too much pressure.
     

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