Copying negatives and slides on a lightpad

[purplehaze]

I recently bought a lightpad and, among other things, I would like to use it to copy some old negatives and slides with my D7100 and 105 mm macro lens. Does anyone have any suggestions as to what I should use to hold the negatives flat that won't damage the surface of the lightpad? What about the slides? Would I have to remove them from their holders? My old slides are pretty mint, but some of my dad's are a bit bent from use.

If anyone has put a lightpad to this use and has any tips for me, I'd be grateful if you'd share.

[Inkanyezi]

Slides can remain in their holders. I use the negative holder from an enlarger, but the easiest way to hold negatives flat might be to put a sheet of glass on top. The glazier should have "anti-newton" glass, that is used for framing pictures. It might be called reflex-free. It is a glass with a slightly matte surface which can lie against the negative without creating newton rings. The glazier can cut it to size and bevel the edges.

[purplehaze]

Thanks for the quick response, Urban. I am familiar with non-reflective glass, but have never heard the term "newton ring". I am going to have to look that up.

[AlwaysOnAuto]

Janis, I don't have a lightpad, but I kinda made one by using my laptop screen and projecting a picture of a flashlight on it for back lighting the slides I copied.
I used an old piece of black PVC drain pipe to shield the slide/lens from extraneous light coming in from the side.
Here's a picture of my jerry rigged affair showing my D7000 with my old Micro Nikkor 55 f3.5 lens.



I just laid the slides right on the laptop screen. Luckily the pipe was just the right size to allow the slide to sit inside it. Here's a picture of what I ended up with as an example.



Just trying to help.

[purplehaze]

Janis, I don't have a lightpad, but I kinda made one by using my laptop screen and projecting a picture of a flashlight on it for back lighting the slides I copied.

Thanks, AOA! I was just reading about this iPhone/iPad app, Free Light, that provides a bright white screen and am wondering if there is a similar app that one can use on a MacBook Pro. That would provide a nice back or side light to use in combination with the underlighting of the lightpad to shoot things like (gulp, dare I say it?) glass! Does anyone else have any suggestions for getting an all-white screen on a MacBook, other than willfully contracting a virus, say?

Edit: You can see a picture of the kind of setup I am thinking of here.

But, back to the negative copying application:

I used an old piece of black PVC drain pipe to shield the slide/lens from extraneous light coming in from the side.

Hmmm, I was just going to shoot in the basement, in the pitch dark, but I hadn't thought about the extra light spilling over from the table itself. Thanks for the idea; I may just need it.

Just trying to help.

Most helpful; thanks!

[AlwaysOnAuto]

Glad you found it helpful.
One thing I forgot to mention that I see in my picture. The white sheet under the PVC tube is a piece of mylar film. I found that without it I was getting the matrix of the laptop screen itself in my copies of the slides. It, the mylar, diffused the light and hid the matrix perfectly.
I also found the tube helped the camera meter the exposure better too.

[purplehaze]

Yes, I read about that problem. Some people apparently just use tracing paper.

[Manfred M]

The best diffuser I've found for this type of work is called "opal glass". It is clear, colour cast neutral and diffuses light quite evenly. I bought the stuff I used from a glass supplier years ago; it lasts forever if you don't drop it.

The Newtons Rings that Urban refers to are circular interference patterns caused by having two surfaces that transmit light very close together but not perfectly flat. The end result is that you get concentric rings of light and dark patterns in the image you are copying. The solution is to either use a slightly etched piece of glass that effectively disrupts the mechanism that creates Newton's Rings or to use a glassless carrier, i.e. support the slide or negative in such a way that it doesn't touch the glass surfaces.

Also remember that dust (and worse) can settle onto the glass or your slide / negative and this should be removed prior to copying, otherwise you will spend a lot of time retouching these out of your final product.

[jcuknz]

My tip on this subject is that some way you need to keep the light source from shining on the camera otherwise there is a very real danger of you getting a photo of the camera on every copy you make ... very irritating until one wises up to the problem.

[purplehaze]

I'm having trouble visualizing how that happened, John. I experimented tonight, shooting down onto the lightpad in an otherwise dark room. The lightpad is 12"x17", so quite large, and it throws quite a lot of light. I didn't have a tube to shoot into like AOA was using and I imagine some of that extra light was getting bounced back into the lens, but I shot auto exposure and only one image came out slightly over-exposed; all the others were quite good. I used auto WB, and as you old hands probably guessed, the colour rendering was not at all accurate. Now I realize I probably should have started by shooting the table and taking a white balance off it? The table is advertised as having very even lighting; I guess this would be a good way of testing it. Other than that, the hardest thing was positioning the slides to match the frame of the viewfinder (I was trying to get as close to 1:1 as possible).

Manfred, thanks for explaining the newton's rings. I have seen those.