Sandy, does it have to be that thickness, can you tell what the application is?
Does it need to be a quartz type (UV transmission), or is the garden variety sufficient? tim
try www.fpointinc.com . I recently bought some 1mm thick glass from them.
Originally Posted by Curt
The thickness is important because I will be using the glass as a mount for scanning fluid mounted negatives. The correct point of focus for the glass of the scanner is approximately 1mm, so I want to be as close to this thickness as possible for optimum focus when I place the negative, emulsion side down, on the glass. I understand that the there is a lot of depth of field in scanner lenses so that in theory you might get acceptable depth of field from - 3mm-4mm to + 3mm-4mm from the point of best foocus but if possible I would like to be at the best point, and my tests indicate that distance is about 1mm-1.5mm over the glass of the scanner.
Are you trying to wet mount with a flatbed scanner? If so, you might try the following. Get a piece of glass approximately 8x10, or whatever fits on the scanning bed without covering the calibration area. I borrowed some glass from my 8x10 negative carrier. You will wet-mount the negative base side to the glass. I recommend Kami fluid from Aztek. You should use their mylar (or something similar), and their scanner wipes.
Before wet-mounting, though, you want to prepare the other side of the glass with a mask that'll minimize stray light. Use whatever you like. Thin, opaque black plastic works well. I leave a little space around the image edges to remain unmasked, as I find this makes it easier to keep shadow detail with Vuescan. Align the mask cut-out such that it is parallel to the edges of the glass.
On the opposite side of the glass, i.e. the one you'll be wet-mounting the film to, tape a shim(s) in each corner to hold the wet-mount carrier above the glass platen of the scanner. On my Canonscan 9950f, the best distance is to have the emulsion is .5 mm above the glass, but you should test yours to be sure. You can use small pieces of sheet film as spacers.
I recommend getting a brayer (roller) a little bigger than the narrow width of the film you'll be using. They come in hard rubber, soft rubber, or acrylic. One brand is Rollrite. I also suggest getting a tape dispenser for the Kami tape. You need special tape that isn't dissovled by the Kami fluid.
Ok, it's time for wet-mounting. I lay a scanner wipe on a flat surface which is slightly higher at the far end. Cut a piece of Mylar such that it is 2" longer and wider than the film your wet-mounting. This will give a 1 inch border around the negative. This border will help hold the negative flat.
Tape the short edge of the mylar closest to you to the glass sheet. The Mylar should be tape such that the negative or frame will cover the opening in the mask on the other side, just as one would do when putting the negative in an enlarger. Have your roller, a spare piece of acetate, canned air, and Kami fluid handy.
Tip: I don't like spraying the Kami fluid. Instead I use a squeeze bottle with a small hole. Aztek will include one with the Kami fluid.
Put the piece of acetate on the Mylar and pull the Mylar back, using the tape as a hinge. The acetate (or piece of Mylar) protects the wet-mounting sheet when you roll out the bubbles. Stand the negative on edge near the mask opening with the emulsion side facing you. Try to align the negative as best as you can, but don't get to anal as you can move it a little in a minute. Put a generous bead of Kami on the glass just on the far side of the negative. Slowly and steadily lower the negative into the Kami fluid. Now put a bead of Kami on top of the negative. Lower the mylar + acetate down and follow with the roller. The goal is to get all of the bubbles out to the edge of the film. If any bubbles remain, use the roller (or a soft squeegee, your finger or a scanner wipe to push the bubbles to the edges.) The bubbles tend to float up so angling the glass a little can help.
I then tape the far edge of the mylar down. If I'm scanning quickly and the negative is flat, I don't tape the other two edges.
Set the wet-mounting carrier down on the scanner platen, and try to align it as well as you can. If a scan pre-view shows that it's tilted, move the tray in the appropriate direction and do another pre-scan.
In my fairly short experience, some films/formats benefit from wet-mounting much more than others do.
Btw., I didn't come up with any of this. I cobbled my methods together from reading posts from people such as Ernst Dinkla and others.
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Thanks for the good infoirmation. I am actually already doing more or less what you suggest. I have been fluid mounting most of my work with both a flatbed (LF and ULF) and with a Leafscan 45 (roll film) for several months.
Last edited by sanking; 04-04-2006 at 02:22 PM. Click to view previous post history.
If you do it the way I suggest, the thickness of the glass isn't very important. Do you have any particular reason for putting the glass between the negative and scanner platen?
In any case Focal Point does carry 1mm glass in various sizes in both clear and anit-Newton glass. I think that Mike Sparks, the owner of focal point, recently made a few posts on APUG. You could always send him a PM. I've found him to be very responsive.
Originally Posted by Peter De Smidt
Two reasons. The main reason for the mounting glass between the scanner glass and negative is to put the negative at the point of best focus. The other reason is that this method of fluid mounting appears to be offer easier clean-up, since there is no possibility that the fluid will get on the surface of the scanner glass, and into the interior.
How did you figure your 'best focus distance'? It won't be the same as it would be with air.
art is about managing compromise
Originally Posted by sanking
By shimming the glass one can get the negative at the best height even though it's under the glass sheet. If you tape all of the edges of the Mylar and wipe up any excess, there's very little chance of any Kami getting on the scanner platten. If you're really worried about it, you could seal all the edges of the platten with Kami tape. Won't you have a dry glass to glass surface with your method? Might this not lead to Newton's rings?