Different saturation levels at different scan resolutions... Why?

[fivebyfour]

Folks,

I've shot a little bit of MF but work has always put paid to doing as much as I would wish.
I have a bit more free time now and have always wanted to take the plunge with LF, so Santa brought me a Sinar P and some bits and pieces as an early present.

In preparation of doing my first shoot and process etc. with the Sinar i've set off down the calibration path, scanner done, printer done, monitor done.
After calibration I ran some test scans (with some old MF negs) and have noticed a quite pronounced lift in saturation levels at 6400 in comparison to 2200 ppi.
Can anyone run me through the reasons why?

Scanner is an Epson 750 with fluid mount, using Silverfast 8 on Mac OS X.

Thanks all.
Clive.

[Jim Andrada]

Hmmm - I don't really know, what would cause that, but on the other hand, the 750 isn't really capable of getting 6400 optical (ie un-interpolated) ppi so I've never tried scanning at that resolution. There's a bit of argument back and forth, but general thought is that the 750 might top out at a true 2200 or so using the film holder and with the film in the center 5 1/2 inch or so of the scan head. Some folks scan at 3600 and down-rez and say that it gives slightly better results than scanning at, say, 2400. Personally I scan MF, 4 x 5, and 5 x 7 fluid mounted on the carrier at 2400, and Whole Plate and 8 x 10 at 1200 dry and flat on the scanner glass using the film area guide. So far I'm quite happy with the results.

[fivebyfour]

Thanks Jim.

Yes was aware of the thoughts re scanning resolutions hence why I was trying them out so I could try and see the differences for myself.
I'll probably stick with 2200 and send anything that needs top quality for drum scanning..
Will try the down-rez from 3600 as haven't looked at that yet.

Looks like everyone is stumped on the saturation thing!

Cheers
C

[Tyler Boley]

Can't speak for anyone else here, but not stumped so much as thinking there is some other problem. Have never experienced that, nor over many years of lot's of Q&A everywhere have ever heard of a similar experience, nor does it make any sense. Other than some improbable display problem with how the software is scaling to the display from different image pixel dimensions, there's no technical connection between scan resolution and saturation.
Therefore I have to assume there was probably a settings difference, or color management difference, that was not caught, between the 2 scans. I use Silverfast and have to double check my settings every scan, they tend to default to settings I don't want.
Tyler

[fivebyfour]

Thanks Tyler. Yes I noticed afterwards that settings move a little in Silverfast. Will re-scan and see what happens.

thanks
C