Setting scanning resolution on the ScanMate F8+ with ColorQuartet

Hi all,

I know there are several threads here discussing these things, but Im still curious on the practicalities of in-/decreasing scanner resolution.

I just got hold of a ScanMate F8+ with the ColorQuartet software (which, when scanning 8x10" positives, is so much more convenient than the Epsons). But, in the scanner specifications it says that there is up to a maximum of 4000 dpi optical resolution (11000 interpolated). However, when I set it at 4000 in the ColorQuartet software I get a warning that it is now being interpolated... and I have to reduce the resolution to 1000dpi to not get the interpolation warning... as I understand this that means that the optical resolution is 'just' 1000dpi.

Now, I know that a lot of people say that you will set resolution or whatever for the use you intend... But I dont really know that yet so I just want the quality to be as good as possible (Im not really that concerned about big files).

I don't get why the software says the resolution is interpolated above 1000dpi when the scanner is supposed to do 4000dpi... but my concern is... What do I loose? How much larger can one print with 4000 compared to 1000? How much more can you crop? I scan 8x10" sheet film and 120 roll film.

Cheers
Peter

Peter, I've retitled the thread to indicate more clearly what your specific question is.

Good luck!

Peter,

I don't know anything about the ScanMate F8+, but it is not uncommon for scanner resolution to be limited by scan size. This has been true with several high end flatbed and drum scanners that I have used. For example, a Howtek drum scanner that I owned several years ago would scan 35mm to 4X5" at 4000 ppi, but was limited to 2500 ppi with 5X7", and 2000 ppi with 8X10".

The reason for the limit might be from either physical hardware or software.

It is possible to make an awfully good print from a scan of 8X10 original at 1000 ppi, but you would be leaving some image quality on the table with that limit as many 4X5 negatives and transparencies have more pixel quality than can be captured at 1000 ppi.

Sandy

Hi Sandy,

I was considering that possibility as well, but I did reduce the scan area to see if I could increase the scan resolution... as far as I can tell I couldn't (given that my settings were correct). Now, I'm not sure if scanning 120 film at 1000dpi is that big of a drawback... but I was expecting to scan it at 4000. Then again, as my knowledge of these things are pretty limited I dont really know what this means in practical terms..?

I'm not sure how it can be a physical hardware or software issue either... As I am able to scan all the way up to 11000dpi (I never bothered too though), which is the upper limit for interpolated resolution. I was thinking that the software was wrong - that it gave me the warning about interpolating to early, but the software knows its the Scanmate F8+...

Cheers
Peter

PS Oren - thanks and thanks.

I have never used this scanner, however the following may be helpful to figuring out what does what.

1. You can't change the effective pixel size of the CCD, unless it has a zoom lens or has multiple lenses. The blub says it has a zoom lens. So its very likely that the effective pixel size of the CCD is 1000spi if you attempt to scan an area the size of A3, this could easily increase to about 4000spi if you are attempting to cover a width about the size of 120. If you dig around you might figure if the lens moves when adjusting the scan area.

2. Many scanners use a technique called pixel shifting, sometimes under the banner of "interpolation", where by the pixels are offset so that they overlap, this allows an improvement in resolution, it may or may not make the "grain" aliasing better or worse.

I would recommend not getting too hung up on absolute numbers, and use the highest "practical" resolution that is offered. i.e. Depending on your technique this maybe well be just 2000dpi.

So, I figured it out. I tought it was the same resolution for 8x10 and 120 film. And it kind of is, and isnt... Or, what several of you suggested was right :-)

It seems to be not the size that reduces resolution but moving away from the center... so obviously when I cover the entire bed I have also 'moved away' from the center.

When i took a crop of the image yesterday I did so not in the center. And this made me think reducing the frame didnt help. Today I did crops in the center and that helped. When I moved the crop to the center it was raised to 3000 for medium format framing... if I moved that frame to the edge it would drop...

However... I still find the consequences of all this dpi stuff confusing ;-)

The F8+ has a zoom lens, therefore resolution will decrease as you cover a larger area. The later F10 model has a xy assembly which allows a fixed resolution over the entire bed.
Happy scanning, its a good machines although dense slides are so so. Masking the rest of the bed with card helps with flaring.