Multiple Sample & Image Softness

[Stantheman]

Hi!

I have an Epson 750 pro that I use to scan slides and negatives (dry). Recently I've fooled around a little bit more trying to increase image sharpness. I used to multi sample everything with auto sharpen but found that a single pass without autosharpen is *almost* as sharp as a scan from a dedicated fuji scanner at my camera store (which the quality of I'm very happy with and can enlarge to 20x30). Multi pass does not seem to provide any benefit and leads to considerable image softness. Auto sharpen on a single pass does not reliably provide an increase in sharpness.

I will say that the color gradations from my scan is much superior to the store scan and makes up for the slight perceptible loss in sharpness.

So my question is:
1) Is this normal? Shouldn't multi sample provide an image of the same sharpness?
2) What is the purpose of mutli sampling if the color range is close it the same as a single pass but the image is much softer? 

the above is in reference to trials I've done on 35mm Ektar 100 negative.

[LSI_Ketelhohn]

Dear Stantheman,

MultiSampling is meant to reduce nice caused by the scanner sensor.
The function has nothing to do with sharpness other than that areas will have a smother look because less noise pixels are present.
We have a second function MultiExposure which in addition enhances the dynamic range

Sharpness on the V750 can only be influenced by choosing the correct scanmode and using the sharpening filter.

For film placed directly (unframed!) on the glass the "transparency full area" has to be chosen.
For the normal transparency mode a frame-holder must be used.
The V750 has two fixed focus planes (one on the glass plane (full area) and one at the expected film hight using the frame holder (normal).
Other than that the focus can not be influenced.

The sharpness filter uses special sharpening tables tailored to the device.
But correct placement of the film is necessary for a good result.

kind regards,
Arne

[degrub]

If i remember correctly, the V750 holders have adjustments to move the elevation above the glass slightly in case focus is not dead on. A web search will turn up info on how to do the adjustment. Here is one -

http://photo.net/digital-darkroom-forum/00HuCs

Also, consider a different holder as mentioned in the above.

The other issue i have heard about is "fogging" of the "glass" bed from plasticizer inside the casing. There are some web pages around that describe how to clean.

http://www.largeformatphotography.info/ ... p?p=500549

Frank