How to process100 ISO rated at 50 ISO in stand development ?

[sapata]

Hi,

I'm intending to pull a Delta 4x5 100 ISO to 50 ISO (or even 25 if it's possible) to be able to use my Magic Lantern lens.

I normaly process with Rodinal 1:100 solution for 1 hour stand development and it works great but haven't got a clue how to process if it's been rated at 50 or 25...

Many thanks !

[JRFrench]

Hi Mauricio, I am at a similar juncture, having an f3.5 magic lantern lens and no shutter for it.

My first try was paper negs and a 'hat' shutter, I miss-calculated this tho and it was still really overexposed.

My next try is going to involve putting two polarizers on my digi-cam, and rotating them against each other until the meter in the camera reads 1s or 1/5s at f3.5 and iso 100, then tape the polarizers together and transfer them to the magic lantern lens, providing an adjustable ND filter. Will probably give it a go this weekend, should be interesting.

On your original question, that development would probably be ok for Delta @50, with the compensating nature of Stand development. I shot some fp4 at around 12 or 24 asa and processed it in rodinal 1:200 for an hour stand and it turned out 'ok'. Strong image, but a bit of a distressed look.

[jnantz]

hi mauricio

i hate to suggest this
but it might be a bit of trial and error to
find out the optimal time.
i stand develop roll film in a concoction of
caffeinol C with print developer mixed in,
and only a few times have i done this with sheet film in an FR tank.
it has taken a good long year for me to know around-when to
pull my 2 stops over exposed film ( out of the soup )
... and even then sometimes i am a little off.

you might shoot several sheets of the same image and experiment a little
with 1 dilution you want to use as your "standard" ...

good luck ( and don't forget to have fun )
john

[Jay DeFehr]

Mauricio,

I infer from your post that you need a ISO 50, or better yet, ISO 25 speed film because you want to use your lens wide open, perhaps because it has no stops, and not that you want to pull your film to deal with a very high contrast subject. If I'm right, your approach is problematic, and will likely produce dense- very dense negatives, of low contrast. Two solutions suggest themselves that don't involve changing your normal processing routine: 1) buy some ISO 25 film. 2) Use ND filter to reduce the exposure. If you're determined to use ISO 100 film at EI 25-50, stand development is a poor choice for processing. I think the best way to lose speed with Rodinal would be to use a 1:25 dilution and continuous agitation, just the opposite of stand development.

[Walter Calahan]

You shouldn't have to reduce your development time too drastically, but as with all things "chemistry" I'd run a series of tests at 5% reduction in time for test until you find the contrast range in your negative you like.

Remember, exposure controls density, and development controls contrast. So you are lowing the contrast of an overexposed negative. A negative that is overexposed tends to go flat.

[Lachlan 717]

I'm intending to pull a Delta 4x5 100 ISO to 50 ISO (or even 25 if it's possible) to be able to use my Magic Lantern lens.

As I have a similar issue with a quick Petzval (although I use a Sinar Shutter that only fires up to 1/60th sec), I was thinking about getting some Efke 25 asa film.

Perhaps you could look at that film? Otherwise, I second the ND filter. Easy enough to get a Lee/Cokin square filter and Blu-Tac it in place.

[sapata]

Thanks guys... I'll consider all the suggestions.

Jay, you're right... It's a Margic lnatern lens with no stops and more or less F4.5 aperture. The reason I wanted to pull is because at the moment is the only film I have. I had a look on the internet to buy ISO 25 but it's quite dificult and when I find it's very expensive.

Maybe I should do some tests with exposure time and development using a roll film back...

Regarding the ND filter, which one would you recommend ?

[Lachlan 717]

There's a guy on eBay in Oz who sells Efke 25. It'd be about US$1 per sheet.

[Jay DeFehr]

Mauricio,

I'm not very familiar with the different brands of ND filters, so I can't recommend one. If you're just itching to see what kind of image your lens produces, and you're not picky about the final product, you could use some RC enlarging paper (it's very slow, indeed. John Nanian is the expert here.) and scan the resulting negative print, invert it in your editing software, and presto! Alternatively, you could use your Delta 100 in low light, appropriate for f4.5 and a long exposure. Good luck!