Minolta 5400 exposure question

[JimSoto430]

I scan my slides on the Minolta 5400 in 16-bit linear mode without
making any hw or sw exposure adjustments. In PS, the scans are assigned
to the Minolta Posi Linear profile and converted to the Adobe rgb 1998
working space. The histograms at this point typically would show no
clippings, and would need minimal tonal and color corrections.

This, however, is not the case for every slide. For those that are
underexposed, or with highly saturated colors, the histograms in the
5400 Exposure Control tab would show clippings. The histograms in PS
would be shifted to the left (probably due to the profile assignment)
and the clippings would either be gone or would remain. In some cases,
it takes a few iterative exposure adjustments in the 5400 until I can
get a PS histogram without clippings. Is this the correct way to adjust
the exposure in the 5400?

Under the Exposure Control tab, there are four adjustment sliders: one
composite and three channels. Is each of the four sliders hw only
adjustment? If yes, that would imply there are three separate light
sources, one for each channel. Or is there a better explanation?

Thanks.

 

[Simon Tindemans]

In some cases,
it takes a few iterative exposure adjustments in the 5400 until I can
get a PS histogram without clippings. Is this the correct way to adjust
the exposure in the 5400?

The easiest way to adjust the exposureis to make a prescan in the
Minolta software, then go to the exposure tab, adjust if needed and then
press the 'recalculate' button. It isn't actually called that way, but
that's what it does - it is arrow-shaped. Pressing that button
recalculates the histograms using the current preview data.

Continuing to your other question, I do believe that the adjustments are
hardware-based. I say this because changing the sliders changes the scan
time. However, there is only one lamp for the RGB channels. I presume
that the RGB CCDs have an 'electronic shutter', that can turn on and off
their sensitivity without a mechanical shutter while the lamp stays on.
This shutter is adjustable for each channel individually.

Hope this helps.

Simon

 

[JimSoto430]

The easiest way to adjust the exposureis to make a prescan in the
Minolta software, then go to the exposure tab, adjust if needed and then
press the 'recalculate' button. It isn't actually called that way, but
that's what it does - it is arrow-shaped. Pressing that button
recalculates the histograms using the current preview data.

By the "'recalculate' button", did you mean the prescan button? I'm
pretty much doing what you suggested. First I prescan, then check the
Exposure Control tab's histograms, make exposure adjustments if
necessary, then prescan again to review the updated histograms, and
repeat if necessary.

Continuing to your other question, I do believe that the adjustments are
hardware-based. I say this because changing the sliders changes the scan
time. However, there is only one lamp for the RGB channels. I presume
that the RGB CCDs have an 'electronic shutter', that can turn on and off
their sensitivity without a mechanical shutter while the lamp stays on.
This shutter is adjustable for each channel individually.

The scan time change is a good indicator that the Exposure Control tab
is a hw control. Another good indicator, I think, is the rgb value
display. After adjusting the Exposure Control tab, the before and after
values in the rgb display will change as a pair. IOW, before remains the
same as after. Such is not the case if sw changes are made in the
Image-correction tab: the after value will be different from the before
value.

 

[Simon Tindemans]

By the "'recalculate' button", did you mean the prescan button? I'm
pretty much doing what you suggested. First I prescan, then check the
Exposure Control tab's histograms, make exposure adjustments if
necessary, then prescan again to review the updated histograms, and
repeat if necessary.

There's another button, on the exposure page, just to the right of the
master exposure histogram and to the left of the exposure load/save
buttons. It has a number of grey+coloured rectangles with the prescan
icon superimposed on them. Pressing the button causes the scan software
to apply the exposure corrections to the already scanned data.

It seems that the prescan is always made at a fixed exposure setting
(usually underexposed) and the histograms are calculated from this scan.

Simon