You can easily make a working kit yourself out of two cheap mirrors. I had a "home brewed" pair for aligning my enlarger before going all-digital, and it was VERY accurate.
Just take the glass out of any framings or whatever, then from the back scraper the protective paint and the metal from the glass in an approximate circular area in the middle of one of them. It is far harder work than you may think, but there´s really no need to be precise in this stage. Mine had a slightly egg-shaped patch with a somewhat "wooly" outline when I called it a day, and it worked well. If I were to do it again, I´d probably have a round hole cut in the glass by a professional, if only to avoid a lot of scraping work. BTW, having the reflective coating on the back of the glass is no problem either; that Hassy outfit was front silvered, but there´s no need of that.
Now, put the "holed" mirror over your lens flange, or whatever is absolutely parallel to the film plane, and the other on the painting, being very careful to press it against it. Look from the back of the camera (the finder would probably do if you are using digital). What you´ll see isn´t just a "bull´s eye", but an infinite tunnel (fuzzy-edged in my case) that curves. Just align until it looks absolutly straight, without curving away in any direction; you´ll find it is VERY sensitive.
There is no need whatsoever to find the exact center of the lens mount, or to have a perfect, sharply outlined circular hole, as long as you can see that tunnel effect clearly. Getting the mirrors absolutely parallel to the planes of the film and the subject IS important, obviously; that´s why I recommend removing any frame or casing from BOTH mirrors.
Go ahead: it´s easy, dirt cheap, and perfectly accurate!
Per Öfverbeck http://foto.ofverbeck.se
2004-02-22 kl. 06.34 skrev Walter Holt Family:
kostas,.............
Hasselblad used to sell a copying devise designed to make the film plane and the subject plane precisely parallel. It was done with two mirrors. One was placed at the center of the item you were copying and the other was mounted on a lens flange in place of a lens and had a hole in its center. The 1966 Hasselblad catalog has a picture of the unit with the following description:
I have never used or seen this Hasselblad unit but it gives you food for thought. If you are willing to experiment, a skilled glass dealer could cut you a large round mirror to hang dead center over your copy job, and a round mirror with a hole in its exact center to be glued to the surface of an old screw-in lens filter. The mirror on your camera filter would need to fill the entire filter ring.
In your camera's finder you probably want to see a perfect bulls eye target created by the two mirrors reflecting back at each other. I'm just guessing this is how it works. If it did work, you could have different sized mirrors for large and small copy subjects and your parallel set ups would be quick and easy.
Walter
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On Thursday, February 19, 2004, at 04:53 PM, kpp@xxxxxxxxxx wrote:
well here are my experience and ideas on putting a painting squarely in the picture frame...
i had a case of photographing paintings for a friend and just yesterday i photographed some test charts, only to find that squaring the rectangular frame withing the pic frame is not that easy without instrument help...
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