Glassless V700 - Bye Bye to newton ring!

[jack_hui]

Singer:

most of the time the film is not flat, put the film on the mount with the curl facing upward, then place the ANR glass on top
flatten it.

[Ash]

thanks for the pics/instructions. i've been tempted to do this, but i'd get annoyed rotating my negs since I'm using more 120 than anything else.

[sanking]

Dismantling a perfectly good scanner in order to avoid Newton Rings just seems like overkill to me.

Besides, once the glass is removed, what's to prevent the film from sagging down and falling into the opening or touching the sensor?

Also, once the glass is removed you have a much increased chance of dust getting on the mirrors, lens and CCD so my thought is that removing the glass creates more problems than it solves. If the issue is only Newton rings there are certainly several easier ways to solve the problem.

Sandy

[Eric Woodbury]

Shiny film surface to shiny glass surface= Newton Rings.

Only if the light is somewhat coherent. It is the differential path length of coherent light that forms the rings. If you replace the top glass in the scanner with diffuse glass (2447 plexi), the Newton Rings will go away. This extra layer of diffusion will diminish the light, but typically scanners have plenty of range.

[tjshot]

I was considering a similar modification on a V750 I'm going to buy.
After having borrowed/tested both a V700 and V750 on few MF and LF slides, I'm convinced that main issues with this (otherwise good) flatbed models are aberrations (LCA ang ghosting), visible at high contrast edges (low frequencies) and less so at higher frequencies (partially masked by loss of resolving power?).
This behaviour may imply problems with light diffusion and reflections between internal surfaces (base glass, mirrors, CCD glass, shiny surfaces).
If this is the case, removing the base glass would reduce aberrations and ghosting a lot, improving sharpness (low freq MTF) but not resolution (the high order rolloff of optics will mask every high freq. improovement).
Of course to really evaluate differences, a good scan target and very accurate focus plane calibration is necessary.
Did you notice any benefit in real use from suppression of aberrations on high contrast edges?
An interesting solution for 4x5 and smaller formats would be cutting a rectangular opening in a matt black plate to use as a scanning base instead of the glass; optimal would be painting internal surfaces also, to elimininate any residual light.
It did work for film enlargers back at the times, I bet difference would be relevant.

[D.Page]

I, too, have removed the top cover of my Epson V700 but to simply clean the underside of the glass platen of a fogged area and a few specks of white dust. If anyone is intent on removing the cover for any reason, please bear one thing in mind to avoid any internal physical damage. Be very careful to slot the front part of the cover onto the main body and gently ease it into position, otherwise you risk snapping one of the plastic pieces which help to keep the cover in the correct position. I didn't know it was that fragile internally, and snapped one of the pieces of plastic when reattaching my cover. No real harm done as the four top screws keeps it secure, but just so you know. I couldn't locate the broken piece and it is sitting somewhere in the bottom(!).