Dmax for my Minolta Film Scanner vs. Epson 4990 ?

Hi all,

I'd appreciate some advice. About two years ago, I bought a Minolta DiMAGE
Scan Dual III film scanner for scanning of 35mm color transparencies, B&W
negatives and color negatives.

I'm now considering buying an Epson 4990 scanner for scanning my 4x5 film
(again, both transparencies and negatives).

The specs on the two units are as follows:

=====

Minolta DiMAGE Scan Dual III

Optical Resolution: 2,820 DPI
Color Depth: 16 bit
Dynamic Range (Dmax): 4.8 (calculated)

=====

Epson 4990

Optical Resolution: 4,800 x 9,600 DPI
Color Depth: 48 bit
Dynamic Range (Dmax): 4.0

=====

I'd like to sell my Minolta and do ALL my scanning with the new Epson. The
Epson has much better resolution and color depth, but the Minolta has much
better Dmax rating. With the exception of Dmax, the Epson is a clear
winner. Does anyone have any experience with these types of devices to help
me understand if the Epson (with it's lower Dmax rating) can produce 35mm
scans equal to, or better than, the Minolta. Thanks in advance for any
advice.

Terry

> Minolta DiMAGE Scan Dual III
>
> Optical Resolution: 2,820 DPI
> Color Depth: 16 bit
> Dynamic Range (Dmax): 4.8 (calculated)
> =====
> Epson 4990
>
> Optical Resolution: 4,800 x 9,600 DPI
> Color Depth: 48 bit
> Dynamic Range (Dmax): 4.0
> =====
>
> I'd like to sell my Minolta and do ALL my scanning with the new Epson. The
> Epson has much better resolution and color depth, but the Minolta has much
> better Dmax rating. With the exception of Dmax, the Epson is a clear
> winner. Does anyone have any experience with these types of devices to help
> me understand if the Epson (with it's lower Dmax rating) can produce 35mm
> scans equal to, or better than, the Minolta. Thanks in advance for any
> advice.

I think another critical issue is the (calculated) note after the
Minolta's 4.8 Dmax. I'm pretty sure that means it's based on the number
of output bits, not the real Dmax. Scanners with 16 bit output have a
theoretical maximum Dmax of 4.8 but the sensors rarely (never) meet
that limit. From what I've read, most scanner manufacturers have gone
to this system which over-states their Dmax. But once one did it, the
claim is they all had to. If the Epson has 16 bit output then they're
NOT using the "theoretical value" which should be called "BS value"
instead. That gives some hope that you might actually see a Dmax of
4.0.

I have a DiMAGE Scan Elite 5400 II which also has a "BS value" of 4.8.
While I've been told the scans don't meet that value (and no film I
know of has that much range anyway), it gives me great scans with lots
of shadow detail that can be brought out in PhotoShop or other
programs. While looking for some web sites that discuss these issues, I
found

http://www.scantips.com/basics14.html

which seems to do a good job.

Hoping this helps.

Martin