Using Rodinal to Push Portra 400

[Rudeofus]

In any case, the 'predev' idea is to use only mild b&w development before continuing normal C-41. So it should be fine as long as you're not developing a full negative etc.

Obviously you don't want to develop much in this predev step, or you wouldn't get a color image. What you do want, though, is enlarge the smallest latent image specks in order to make them more easily developable by the CD. For this reason I wondered whether Michael's LC devs would be a better choice than Rodinal which loses a stop of ISO speed to begin with. We may have to dilute Michel's formula quite a bit, but it should work better. All my statements are worthless, of course, unless I have experimental data to back up my claims.

The pre-dev only gives a small improvement, but I imagine that improvement would increase with a C-41 push and would stack well with pre-flash to get a little bit more out of it.

Since both techniques trigger different effects, they should add up nicely. Preflashing (ideally) creates a bunch of stable but not developable image centers (typically clusters of two Silver atoms) which are then enlarged to fully developable (>= 3 Silver atoms per cluster) by the actual exposure. The predev step only works with developable image centers, but boosts their development speed, which in turn allows their full development before overall image contrast runs away.

 

[Athiril]

The predev helps develop additional shadow detail that normal process cannot, but I don't know whether it will develop additional shadow detail that a C-41 push cannot also reveal. Though it'd be interesting to see if it helps improve the grain as much as it did in the normal process combined with a push and pre-flash.

 

[Truzi]

It can due to the reciprocity failure characteristics of your film.

PE

Thanx, I'd not though of that - and the way you answered actually made me think through it for a few seconds, I'll remember it better this way.

 

[flavio81]

Preflashing (ideally) creates a bunch of stable but not developable image centers (typically clusters of two Silver atoms) which are then enlarged to fully developable (>= 3 Silver atoms per cluster) by the actual exposure. The predev step only works with developable image centers, but boosts their development speed, which in turn allows their full development before overall image contrast runs away.

Genius! This is genius!

So, to summarize, in the case of Portra 400:

- We will preflash, say, for example, by putting a white sheet of thin paper on the lens. But we will meter so, when light goes through the lens, the exposure is equivalente to 6 stops below middle gray for ISO 400. (Please confirm if with "middle gray" you mean the same as the 18% gray card...)

- We develop the film in C41 but with about 6 minutes first development time

- The result is effective speed of 3200.

Please confirm!

 

[baachitraka]

I presume we have to set the meter to E.I. of 12800 for pre-flashing and E.I. 3200 for normal exposure, with Portra 400.

 

[Photo Engineer]

The thing that bothers me is the predevelopment with a B&W developer. It should only develop silver and that silver should be removed by the bleach leaving no overall change other than the normal C41 developer used at about 2x the normal time. So, it would be interesting to see if this would work without the predevelopment.

PE

 

[Rudeofus]

The thing that bothers me is the predevelopment with a B&W developer. It should only develop silver and that silver should be removed by the bleach leaving no overall change other than the normal C41 developer used at about 2x the normal time. So, it would be interesting to see if this would work without the predevelopment.

I voiced some theory how this could work before, but have no practical data to back up my claim. Posted images alone won't tell the whole story, because shooting Porta400 @Ei3200 does not necessarily mean the same thing for everyone: the result very much depends on where you point your light meter at.

@flavio81: nobody claims that some mysterious procedure turns Portra 400 into a true ISO3200 color negative emulsion. What is claimed, is that you can shoot Portra 400 at EI3200, and get useful negatives if that procedure is followed, or let's rather say: get better negs at EI3200 with the procedure than without the procedure. There is a huge difference between these two statements, because the latter one doesn't require normal contrast, three straight characteristic curves in lock step, shadow detail only considered above b+f+0.1, ....

@baachitraka: 6 stops above Ei400 is EI25600 ...

 

[Xmas]

The thing that bothers me is the predevelopment with a B&W developer. It should only develop silver and that silver should be removed by the bleach leaving no overall change other than the normal C41 developer used at about 2x the normal time. So, it would be interesting to see if this would work without the predevelopment.

PE

Hi Ron

A Cruella de Ville suggestion?

But I use single coated lenses (with efficient hoods) on bright and sunny days to try and get some more detail in shadows from the concurrent flash of the inherent single coated flare. Pastel shades in colour film as well. Tones down high lights too.

One would get more flash with more contrast so it is adaptive to a degree.

Noel

 

[Photo Engineer]

Noel, I am not sure I follow your answer.

 

[Athiril]

Genius! This is genius!

So, to summarize, in the case of Portra 400:

- We will preflash, say, for example, by putting a white sheet of thin paper on the lens. But we will meter so, when light goes through the lens, the exposure is equivalente to 6 stops below middle gray for ISO 400. (Please confirm if with "middle gray" you mean the same as the 18% gray card...)

- We develop the film in C41 but with about 6 minutes first development time

- The result is effective speed of 3200.

Please confirm!

You could just take a photo of an out of focus white sheet of paper, or through it, regardless, but yeah same as 18% grey essentially, a camera meter should set it to 18% grey. So if my camera is set to ISO 400, and is metering 1/8th, I'll count down 6 stops and use 1/500th as the pre-flash.

6 stops is the starting point. There may be inherent error in my AE-1 meter, shutter speed, and differences between Superia 800 and Portra 400 in minimum exposure that can be developed in a push relative to their box speed etc. So I would test a roll or at least a partial roll with bracketed pre-flash, ie: 7 stops, 6.5 stops, 6 stops, 5.5 stops, etc, as well as one with no pre-flash. I'd test it with your EI 3200 or 6400 exposure stacked on top.

6 minutes is the time I used. You can adjust that if you want, but a strong push like this I definitely recommend to make use of the pre-flash.

As for effective speed, I haven't tested Portra 400, that technically depends on how much shadow is actually now recorded, but on Superia 800, EI 12800 was useable, 6400 also looked good, there was a huge jump between no pre-flash and the right amount of pre-flash (it's on the first page).


Also it'll be grainy.

 

[Athiril]

The thing that bothers me is the predevelopment with a B&W developer. It should only develop silver and that silver should be removed by the bleach leaving no overall change other than the normal C41 developer used at about 2x the normal time. So, it would be interesting to see if this would work without the predevelopment.

PE

I havent tried combining the b&w predeveloping with the push and preflash. Only on its own with normal processing.

It gave a small boost to shadow detail and an improvement to grain in underexposed images. Not any perceptible change in normally exposed images except for the colour balance shift.

The predevelopment is providing a different base for the C-41 to develop off of.

 

[flavio81]

You could just take a photo of an out of focus white sheet of paper, or through it, regardless, but yeah same as 18% grey essentially, a camera meter should set it to 18% grey. So if my camera is set to ISO 400, and is metering 1/8th, I'll count down 6 stops and use 1/500th as the pre-flash.

6 stops is the starting point. There may be inherent error in my AE-1 meter, shutter speed, and differences between Superia 800 and Portra 400 in minimum exposure that can be developed in a push relative to their box speed etc. So I would test a roll or at least a partial roll with bracketed pre-flash, ie: 7 stops, 6.5 stops, 6 stops, 5.5 stops, etc, as well as one with no pre-flash. I'd test it with your EI 3200 or 6400 exposure stacked on top.

6 minutes is the time I used. You can adjust that if you want, but a strong push like this I definitely recommend to make use of the pre-flash.

As for effective speed, I haven't tested Portra 400, that technically depends on how much shadow is actually now recorded, but on Superia 800, EI 12800 was useable, 6400 also looked good, there was a huge jump between no pre-flash and the right amount of pre-flash (it's on the first page).


Also it'll be grainy.

Thank you VERY much Athiril, that was very clear.

BTW, i always found the AE-1 meter very accurate, same with the A-1 meter. I've used those two cameras a lot.

 

[baachitraka]

I voiced some theory how this could work before, but have no practical data to back up my claim. Posted images alone won't tell the whole story, because shooting Porta400 @Ei3200 does not necessarily mean the same thing for everyone: the result very much depends on where you point your light meter at.

@flavio81: nobody claims that some mysterious procedure turns Portra 400 into a true ISO3200 color negative emulsion. What is claimed, is that you can shoot Portra 400 at EI3200, and get useful negatives if that procedure is followed, or let's rather say: get better negs at EI3200 with the procedure than without the procedure. There is a huge difference between these two statements, because the latter one doesn't require normal contrast, three straight characteristic curves in lock step, shadow detail only considered above b+f+0.1, ....

@baachitraka: 6 stops above Ei400 is EI25600 ...

I want to calculate for six stops but I do not know why I end up at five.

 

[Athiril]

Ftr 6 stops is 64x difference. So if box speed measures 1/10th then it becomes 1/640th