Fuji Velvia or Provia for portraits?

[koraks]

Thanks for the explanation and I'm grateful for the little discussion between the two of you, as it suggests it does work differently than I had expected (my expectation paralleled that of Pere). I need to try this - which will evidently be challenging with one enlarger, but I'm going to give it a shot. And yes, I understand the flash exposure needs to be color balanced.
Interneg, if you reflect on the difference between pre- and post flashing, what would you say the difference is? I would expect not much difference at all, but that's based on just logic, not experience.

[interneg]

Thanks for the explanation and I'm grateful for the little discussion between the two of you, as it suggests it does work differently than I had expected (my expectation paralleled that of Pere). I need to try this - which will evidently be challenging with one enlarger, but I'm going to give it a shot. And yes, I understand the flash exposure needs to be color balanced.
Interneg, if you reflect on the difference between pre- and post flashing, what would you say the difference is? I would expect not much difference at all, but that's based on just logic, not experience.

You might want to try the RH Designs paper flasher - though you'd need a set of colour printing filters for it & those are probably the trickiest thing to find - I've heard of opal diffusion being used under the lens with the neg still in the enlarger & that should potentially work quite well too.

To simplify it to extremes, you'd use a pre-flash if your shadows are crushing together, but your highlights are about right; and a post-flash if you've got nice punchy shadows with good separation, but your highlights are flying off the scale/ are too awkward to burn in - to give an idea, I was making some BW prints this afternoon, G4.5 gave amazing, punchy, separated shadows at 16s exposure, but the highlights would have needed at least a stop of burning with awkward fenceposts that would have been almost impossible - 2s of post-flash white light from an enlarger with head at top of column & a 50mm at f16 brought everything together perfectly. I graduated in the exposure, keeping the flash away from the foreground area that I wanted to keep the intensity of the core exposure in - essentially it's controlled fogging. You don't need a fancy enlarger for this sort of pre/post-flash - if you can find an LPL or cheapo medium format Durst with a colour head you'll be set.

[koraks]

For now, all I have in color is a simple Durst M305; I still need to figure out a way to do color with my 138. Color heads for that one are hard to come by around here, so odds are I'll have to cobble something together.

Anyway, I did a quick round of testing, and I have to admit that to my surprise, you are entirely right about the difference between pre- and post flash. To my surprise, as I honestly would have thought it didn't matter one jota if the flash exposure occurred before or after the main exposure, but what do you know, it makes quite a pronounced difference indeed. Goes to show I've got a lot to learn still.

I did 3 prints of the same negative, in the same chemicals, etc. The main exposure was also identical for all three exposures, which I color balanced by eye (turned out to be Y55/M60 6 seconds f/11 on Crystal Archive II 13x18cm paper from a normally processed Fuji Superia or C200 negative exposed at about EI100). The pre-flash and post-flash were also identical exposures, 1 second at f/16 (so roughly 8% of the main exposure) through the clear, but masked, leader of the film. I left the filter settings in place, which means the flash exposure was not perfectly balanced and tended towards green.
The regular exposure without flash looks normal for a sunlit +1 stop overexposed frame. Nothing blown out in the highlights, deepest shadows barely contain detail, but it's there.
The pre-flashed print shows more muted highlights. Shadows haven't changed much at all. Color balance is of course off a bit. In terms of contrast, one paper grade less in B&W speak sounds about right to me.
The post-flashed print also shows more muted highlights - more so than the pre-flashed print. More importantly, shadow contrast seems to be increased a bit as well. Color balance is also off and different from the pre-flashed print.

I also made a print in which I pre-flashed half of the frame and left the other half alone, then followed with a normal exposure. The difference is blatantly obvious in the highlights, but not the shadows.

All considered, it looks very much like the way you described it. I'll have to look into it further to get proper control of it, but at least, it evidently does something.

[interneg]

For now, all I have in color is a simple Durst M305; I still need to figure out a way to do color with my 138. Color heads for that one are hard to come by around here, so odds are I'll have to cobble something together.

Anyway, I did a quick round of testing, and I have to admit that to my surprise, you are entirely right about the difference between pre- and post flash. To my surprise, as I honestly would have thought it didn't matter one jota if the flash exposure occurred before or after the main exposure, but what do you know, it makes quite a pronounced difference indeed. Goes to show I've got a lot to learn still.

I did 3 prints of the same negative, in the same chemicals, etc. The main exposure was also identical for all three exposures, which I color balanced by eye (turned out to be Y55/M60 6 seconds f/11 on Crystal Archive II 13x18cm paper from a normally processed Fuji Superia or C200 negative exposed at about EI100). The pre-flash and post-flash were also identical exposures, 1 second at f/16 (so roughly 8% of the main exposure) through the clear, but masked, leader of the film. I left the filter settings in place, which means the flash exposure was not perfectly balanced and tended towards green.
The regular exposure without flash looks normal for a sunlit +1 stop overexposed frame. Nothing blown out in the highlights, deepest shadows barely contain detail, but it's there.
The pre-flashed print shows more muted highlights. Shadows haven't changed much at all. Color balance is of course off a bit. In terms of contrast, one paper grade less in B&W speak sounds about right to me.
The post-flashed print also shows more muted highlights - more so than the pre-flashed print. More importantly, shadow contrast seems to be increased a bit as well. Color balance is also off and different from the pre-flashed print.

I also made a print in which I pre-flashed half of the frame and left the other half alone, then followed with a normal exposure. The difference is blatantly obvious in the highlights, but not the shadows.

All considered, it looks very much like the way you described it. I'll have to look into it further to get proper control of it, but at least, it evidently does something.

Glad to hear it's working for you! Post-flash can be drastically less subtle than pre-flash - & it is important that the latter be fairly carefully controlled as it otherwise becomes a fogging exposure rather than a pre-flash.

& If you're looking for colour heads for the 138, the good news is that it's not a difficult enlarger to adapt to - another 138 user here (and DeVere 504), but with a DeVere dichroic on one of the 138 chassis, the other 138 still having its condenser head attached - that being said, I much prefer the DeVere 504 in some ways, but the 138 is very useful for wall projection etc. Kienzle & Heiland make new colour heads for the 138 & I imagine John Boyce at Odyssey Sales would likely happily sell you a 5x5" or 5x7 dichroic DeVere head & quite possibly have hardware to adapt it.

[koraks]

The 138 was a gift and even just to honor the fact that it was given to me and the person who entrusted me with it, I'll continue to use it. More importantly, it works quite well for me and I have very little reason to upgrade, even though I'm sure there are yet more convenient options out there. Like you said, it's fairly easy to adapt/modify due to its straightforward design. I'm currently running it with an Ilford 500 system (another gift). I half a half-assed plan to construct an RGB LED head for it. Yes, I'm aware of the availability of Heiland's (undoubtedly excellent) heads and the other options on the second hand market - but a friend describes me as a 'bottom feeder' and I think I'm going to honor title that as well - I worked hard to deserve it Ah, it's just one of those things I have to look into one of these days. Last year I spent my time getting the basics of color printing down; it's only now that I seriously consider going larger as I feel I'm getting the hang of it and it's something I'll probably stick with as long as materials are available.

[Drew Wiley]

I wouldn't contemplate an LED additive system for actual color printing unless the prints are going to be small and you have enlarging lenses with very
wide max apertures. VC paper printing might work.

[koraks]

I thought about that, Drew, and it's one thing I need to test. These days there are quite powerful LED sources and I figured that since I generally print color no larger than 24x30cm (not inches!), I might just get away with it. But I agree that it's an ope question for now.

[interneg]

I wouldn't contemplate an LED additive system for actual color printing unless the prints are going to be small and you have enlarging lenses with very
wide max apertures. VC paper printing might work.

The Heiland system has plentiful light output - by all accounts at least equalling the output of the units they're designed to replace - Ilford had tested one & found it performed very closely to the MG500 unit - in other words, the 4x5 unit equates to about 600w of additively filtered MOSFET switching tungsten halogen. Given that most chromogenic papers today are pretty fast, I think the bigger issue is choking off the light output. I think you're underestimating the level of thought that has gone into designing them.

[Pere Casals]

It's pretty clear you've never actually used a pre- or post-flash exposure. The effects I mentioned are very, very obvious if you use a pre- or post-flash. More to the point, you don't pre-flash until you see density, you pre-flash until just before you see density. It's all there in Ctein's book, complete with step wedges - of course there's some effect in the highlights, but nothing like as much as a post-exposure flash or various masking techniques. Pre- and post-flashes are not difficult techniques to try.

I've been using preflash.

You were saying the same as Ctein Page 100 (http://ctein.com/PostExposure2ndIllustrated.pdf)

But 8-1 Figure (Page 100) shows (IMHO) that the middle fogged strip has better highligh separation.

I had been thinking in that effect... perhaps it depends in how fogging technique is used, and on how general exposure is corrected if fogging. What I found in my personal tests is that if fogging just the amount to overcome the "paper inertia" then any amount of highlight detail in the negative builts density, allowing separation in extreme highlights, while having little impact in the shadows.

Anyway I found better to use a right grade for general exposure, and then dodging/burning locally under the right contrast filters.

[interneg]

I've been using preflash.

You were saying the same as Ctein Page 100 (http://ctein.com/PostExposure2ndIllustrated.pdf)

But 8-1 Figure (Page 100) shows (IMHO) that the middle fogged strip has better highligh separation.

I had been thinking in that effect... perhaps it depends in how fogging technique is used, and on how general exposure is corrected if fogging. What I found in my personal tests is that if fogging just the amount to overcome the "paper inertia" then any amount of highlight detail in the negative builts density, allowing separation in extreme highlights, while having little impact in the shadows.

Anyway I found better to use a right grade for general exposure, and then dodging/burning locally under the right contrast filters.

Perhaps marginally (fractionally) better highlight separation - but because of the boost in effective speed from the flash, highlights will come in faster anyway, just not necessarily better separated - my results match Ctein's very closely & the shadow separation is definitely stronger than any improvement in the highlights.