Screen Cezanne Users Unite

[Patrick Daniel]

Hi all,

First of all I would like to say that I'm so happy with all the information you're providing and with this thread in general. Thank you! Though I haven't been active before, you've been of incredible value to me and getting my Screen Cézanne up and running.

I mostly photograph 35mm and MF B/W and I'm using the Cézanne to scan my photos and print them at about 1m in size for exhibitions. Which is possible thanks to the extreme quality of the scans which are bitingly sharp!

However, lately I've been noticing that my scans are not that sharp anymore! I used to scan at 5300 dpi for 35mm, which produced great results but nowadays I have to scale back to about 4000 dpi to get the same result I used to have.
I have cleaned the mirror, cleaned the scanning bed, reset everything to default values, but nothing seems to help.

Now I can stay at 4000 dpi and be happy with the quality I have but I'm afraid that the quality will go down more. Moreover, since I'm printing large, I want to squeeze out as much resolution that I can.
Would you have any suggestions on what could be the cause? I'm always using the same film (Kodak Tri-X) pushed to 1600 and using HC-110 to develop.

Thanks so much in advance for any advice that you're able to give.

[Peter De Smidt]

Hi Patrick,

In the screen server utility, you know the one that goes "Scan started....Scan finished normally", are there any autofocus warnings? I've built a couple of my own carriers. Occasionally, when I didn't get the height right, I'd get soft scans. Looking at the server report, there was a line amounting to "unable to autofocus".

[Patrick Daniel]

Hi Peter,

Thanks for replying!
No, I don't get any warnings. It just says scan finished normally.
I've thought about the autofocus as well, but it does work when I set the resolution lower. It seems as if it's interpolating.

This is a part of a scan at 5300 DPI and here it is at 4000 DPI

[Peter De Smidt]

What holder/system are you using? The clamshell holders, a hold down plate on the standard bed, wet-mounting...?

[Patrick Daniel]

Hi Peter,

Mostly I'm using the standard bed with the big hold down plate that was supplied with it (the big one with the handles) as that allows me to load a whole roll of film in one go.
I've tried using the clamshell holders as well and also the smaller hold down plate with the 35 mm template, but all with the same result.

Weird thing is that it used to work, but now it doesn't anymore while I haven't changed anything in my setup. Is there a possibility that the bulbs are wearing out?
I know it sounds silly, but I think I've tried everything else.

[Peter De Smidt]

Hi Patrick, yes, that's a possibility, and I agree with you that the situation is strange.

You're certain that in-scanner sharpening was turned off for all scans?

[Patrick Daniel]

Hi Peter,

Yes I'm pretty confident about that unless there is an option that I have overlooked. Normally I always check that sharpening has been turned off. I have replaced the bulbs (I took the ones out for reflective when I bought it so thankfully I have something to swap out) and that at least gave some improvement in the sense that there is a bigger difference between minimum and maximum density.

With my new scan at 5300, it's still not as sharp as it used to be, but I can see that some parts are sharper than others. Which is starting to confirm my earlier suspicion that negatives placed in the middle were sharper than the ones at the sides. I've had this since I bought it
There are some scratches on the scanning bed as well which always worried me a bit. I suspect that they and maybe contamination of the scanning bed are causing the unsharpness. I'll try cleaning it and see if that improves anything.

Out of curiosity, what have you used for your scanning bed? Optical glass? I can get museum glass but I don't know if that's good enough?

[Patrick Daniel]

Ok, so I've cleaned the bed thoroughly and triple checked that it was absolutely spotless. It's really crystal clear now!
I've done three passes, at 4000 spi, 5300 spi and at 6000 spi, since I read that you do that as well for 35mm.

Here are the results: 4000 spi 5300 spi and at 6000 spi

I have done nothing to the files and had sharpening turned off for all of them. Out of these three 4000 seems to be the sharpest by far. are the results I'm getting at 5300 and 6000 normal?
I've also been thinking that the steel bars on which the mechanism slides maybe need re-lubrication?

[Peter De Smidt]

I either wet-mount to the standard bed, or I wet-mount to a glass carrier tray from an Agfa T2500. I built a carrier that the tray sits in. If you go with smooth glass, you'll probably get Newton's rings. The interaction between grain and any system seems complex. Do the results apply to different film, density ranges.......? You're on the right track. Test for yourself. I doubt that lubricating the rails will help this issue. If you do, use a light machine oil, put a tiny bit on a lintless cloth, and rub up and down the rails a few times. Too much oil would be a bad thing.

[Corran]

IMO what you are seeing is grain, grain aliasing, and the difference between smooth and sharper grain. The difference is minimal though. Any change in the bounding box, resolution, or location of the negative could also change things slightly.