Thanks for the exposure explanation. Translucent petals, light fall-off
and darkening the dark bits explains it for me. If the flower was 0.5
meter from the flash (just a wild guess) the light of the flash at 1
meter would already be down 2 stops.
Chuck Norcutt
Fernando Gonzalez Gentile wrote:
> Could be so, in fact I hope so.
>
> I stopped talking pictures since January, around the days of the last
> TOPE I very slowly started again.
> Faced Vuescan, trying to translate how does it present the figures,
> especially 'curve low' and 'curve high'. It seemed that I had almost
> understood it, but when scanning this one I was in fact only
> experimenting.
>
> I can explain only some of the results:
> 1- Chuck: No, I didn't use a black backgound, neither is it completely
> due to light fall-off 'though I took it into account when making the
> picture: it was -1/3. In spite of this, if you transilluminate the
> Provia strongly enough, there's a lot of background detail. I adjusted
> the 'curve low' figure in Vuescan but they remained fairly visible.
> Adjusted Levels in PS (the histogram in Vuescan and CS3 don't match,
> despite they're both set for aRGB) and the background darkened a
> little more, but still visible.
> 2- regarding the use of only one T32 mixed with very little ambient
> light, there might be at least two issues to take into account: a) the
> flower is not completely opaque, it lets flashlight go through its
> petals and difusses it into countless directions. b) the raindrops are
> reflecting light, not only the big raindrops but the whole wet
> surface. c) there was, in fact, some ambient natural light which
> served as 'fill'.
> 3- as for sharpness: a) the T32 covers a 24mm fov (yes, it does ;-) )
> and I was using a 135mm fov; b) during post processing, and this
> puzzles me, the 16 bit .tiff was sharp but not cracking-sharp. I had
> sharpenned using NI setting 'reduce noise and sharpen slight out of
> focus image setting' and then, just for fun used Intellisharpen at a
> small amount: 10% but 75% 'sharpen small detail'. I felt happy with
> the resulting .tiff, and background detail was preserved.
> Then, I downsized to 1280 using SI2, still at 16 bit in aRGB, worked fine.
> Then converted to sRGB, then to 8 bit, finally to .jpg. And it cracked
> sharp, without artifacts. Backgound detail became barely visible, but
> if you let the monitor to warm up enough and look at it into a dark
> environment and view it on black, it's still there.
> Furthermore, untill recently Flickr allowed me to upload at 1280, but
> it's now resizing to 1024 no matter what I do (should I go "pro" ;-)
> ).
>
> Thanks all who looked and commented.
> Further thoughts are welcome.
>
> Fernando.
>
> 2010/6/30 Ken Norton <ken@xxxxxxxxxxx>:
>> It looks like you may be finally gotten
>> your scanning process down.
>>
>>
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