I scan my 4x5 on an Epson V750 at either 2400 or 4800 dpi, depending on the desired quality.

Obviously, the 2400 dpi files are one fourth the size of the 4800, and process much faster.

If I only want an index image, to keep track of what's on the negative, I scan @ 300 dpi.

- Leigh

Finally got back from trips and have some results from my newly acquired Epson 3200 scanner. Below is a 3200 spi scan of a negative made from a Graflex 90mm WA Optar enlarged about 6x; it's a 3x5 inch section near the corner:



And the following is a 750 dpi scan of the negative made by the pro shop in town:



The glass is very clean, no plastic gassing residue observed with laser or bright LED flashlight. Good contrast in several test scans.

A 20 x 30 inch print from my scan looks excellent. Very pleased with the results. Had to double the memory in my old XP based PC to speed up processing, but 'twas worth it to get excellent enlargements.

The difference between a 1600 dpi scanner and a 3200 dpi scanner is the very fine to extremely fine detail clarity and overall Dmax.

Gas out of the internal components will result in a slightly soft scan when you use to have a very sharp one. The LED's may cut through it better than the cold cathode fluorescent lamp did.

Enjoy!

I'm still thinking about that old Graflex 90mm f/6.8 Optar used to take the picture. While it does shift focus a bit when stopped down, it's very sharp at the center and excellent at the corners. I may ask a repair shop to check the lens and see if it may have been reassembled wrong and is why it changes focus stopped down.

http://cameraeccentric.com/html/info/wollensak_14.html
page 52 shows the lens diagram, page 53 states all exposures should be made at f11 or smaller.

Using the diagram it should be easy to determine if the elements are in the correct order but I do not know about their spacing.

Scanning tests with that Epson 3200 produced some interesting results. The negative remained in place while making scans at different resolutions. Some were resized down to half the resolution to see how that effeced overall image quality. Two scans of each type were made. Results are:

Scanned at 2400, slightly fuzzy image.

Scanned at 3200, barely sharper than the 2400.

Scanned at 3200 then resized to 1600, noticably sharper than 3200.

Scanned at 4800, same as 3200.

Scanned at 4800 then resized to 2400, sharpest image.

I know 3200 is the optical scan standard and both 2400 and 4800 are interpolations, but surprised that the 4800 to 2400 one was the sharpest.

Quote:

I know 3200 is the optical scan standard and both 2400 and 4800 are interpolations

No, up to and including 3200 is optical. Above 3200 is interpolation.
Epson smart scan wants to include a Unsharp Mask filter as its default. Other settings have a tendency to revert to default when making a change to one of the scan parameters.
Are you rechecking the other settings when changing the scan resolution?
Are you scanning in grayscale or rgb?
At what bit depth?
What resampling in photoshop? Bicubic or bicubic sharper are best.