AN Glass on Epson 4990

[Ari]

I've been wanting to scan my 4x5s full frame, but I can't do so with the holders that came with the 4990.
So I thought to get some AN glass here:

http://cgi.ebay.com/Yanke-Anti-Newton-Glass-210x250mm-8x10-Film-Scanner-/280644643112?pt=LH_DefaultDomain_0&hash=item4157b96928#ht_2354wt_1165

and scan up to four sheets, full frame, without having to open and close the scanner, change negs, etc..
The glass is 1.1mm thick.

Can anyone tell me if that is the correct thickness for the 4990 (it looks to be so), and whether or not this is a hare-brained idea before I go and buy the glass?

Also, the dimensions of the glass are 210mm x 250mm; is it better to cut a piece that will fit exactly the 4990's bed (225mm x 303mm)?

Thanks in advance.

[Frank Petronio]

You need room for tape and handling, so u do one at time. I would get it large enough to hold 8x10 plus tape and fingers. I place mine on top of pennies and have it smaller than the platen.

[Zaitz]

When I sandwich the negative between 2 8x10 pieces of glass and have the AN glass on top like the instructions say I still get bad newton rings. If I place the negative just on the scanner glass (not optimal sharpness) then they are gone.

[Ari]

I was thinking of placing the AN glass on top of the scanner bed (platen), put the negative on top of that, and then scanning.
The glass should give the same height from film to platen as does the plastic negative holder.

[Zaitz]

The instructions I have from FocalPoint say to have (from top to bottom):

an glass etched side down
negative
scanner glass

[Ari]

Isn't that the reason you are getting less than optimal sharpness, though?

[Zaitz]

Isn't that the reason you are getting less than optimal sharpness, though?

If I place a clear piece of glass on the bottom to sandwich the negative then I still get newton rings even with the AN glass on top as the instructions say. Without the extra clear glass I don't get newton rings but don't get optimal sharpness.

[Ari]

Why not leave the top open, perhaps taping down the film, as Frank suggests?
You'd be using only one piece of AN glass, and you might get both issues, sharpness and Newton rings, resolved in one fell swoop.

From the bottom up:
scanner glass
AN glass (not sure about the orientation)
negative

I'd like to know if that makes any difference for you.

[Zaitz]

Why not leave the top open, perhaps taping down the film, as Frank suggests?
You'd be using only one piece of AN glass, and you might get both issues, sharpness and Newton rings, resolved in one fell swoop.

From the bottom up:
scanner glass
AN glass (not sure about the orientation)
negative

I'd like to know if that makes any difference for you.

I figured it muck up the scan having the AN glass first! I'll try it soon.

[Ari]

Please let me know.
a) I'm curious
b) you might have a spare piece of AN glass to sell :)

[SMBooth]

tape your negative to the ANR glass then use coins to set the focus point from the platten.

[Frank Petronio]

Layer sequence is platen, film tightly taped to AN glass, glass, closed lid. Put rough side of film (emulsion) towards rough side of glass. Use pennies on corners to raise film/glass off platen so it doesn't touch. Experiment with height of pennies (two pennies, layers of tape). Scan setting as if you use a holder.

[sully75]

wait are you thinking of putting the AN glass between the negative and the scanner? That definitely won't work. The AN glass is sort of frosted, you can't scan through it.

At least, I don't think so?

Have you checked out betterscanning.com? Might make your life a lot easier.

I think you could concievably remove the scanner glass entirely, if you were in a really dust free environment.

[sully75]

Frank, you put the emulsion up? I always read to put it down. I think it matters less for color for some reason.

Basically for $120 or so, the better scanning rack would take care of all your problems. AR glass is pretty expensive so you wouldn't be saving that much money doing it yourself anyway. THe holder works really well and you can calibrate the height related to your scanner.

Also...I never used the masks they recomend, but recently I think I realized that a lot of problems I thought were in development were actually fogging from not using the masks. Scanning full frame is actually kind of hard.

[Nathan Potter]

If some types of AN glass are in the scanner optical path the etched lines in the glass can appear on the scanned image. Thus the safest arrangement is for the AN glass to be on the illumination side of the emulsion, with the emulsion facing the scanner imaging optics. For the Epson 750 and similar versions that means the AN glass contacts the smooth side of the film while the emulsion faces down toward the platen.

Some films have a rough enough emulsion so that newton rings may not be a problem when in contact with smooth glass enabling a glass sandwich to be used.

Persistent newton ring problems can be reduced or even eliminated by mounting under very dry conditions. Gently heating the film and glass ahead of time can be effective in reducing newton rings although mono layers of water vapor can reform on surfaces very quickly.

Squeezing the most out of image quality requires wet mounting, where a minimal increase in resolution will be realized with often a noticeable increase in contrast.

Nate Potter, Austin TX.

[Zaitz]

Layer sequence is platen, film tightly taped to AN glass, glass, closed lid. Put rough side of film (emulsion) towards rough side of glass. Use pennies on corners to raise film/glass off platen so it doesn't touch. Experiment with height of pennies (two pennies, layers of tape). Scan setting as if you use a holder.

Thank you. I did this and it works very well. Haven't found optimal height but it's better than on the scanner glass and no rings.