Dracaena, Rainy Day

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Maris
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Joined: 27 Jul 2012, 16:02
Location: Noosa

Dracaena, Rainy Day

Postby Maris » 17 May 2023, 12:51

Image
Dracaena, Rainy Day
Gelatin-silver photograph on Ultrafine Silver Eagle VC FB photographic paper, image size 21.5cm X 16.3cm, from a 4x5 Kodak Tri-X negative exposed in a Tachihara 45GF field view camera fitted with a Nikkor-W 210mm f5.6 lens.

The Tachihara camera only has 330mm maximum bellows extension and all of it was used for this close-up. An extra stop and a half was added for bellows extension factor and the exposure was longer than preferred. Fortunately the breeze held off. Doesn't usually.

Mick Fagan
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Joined: 24 Sep 2015, 21:20
Location: Melbourne

Re: Dracaena, Rainy Day

Postby Mick Fagan » 19 May 2023, 19:57

Pretty cool effort there Maris, what with maximum bellows extension and what looks like not really bright light that possibly put you into reciprocity territory.

The water droplets really make this and the lack of wind allowed you to get sharp edges on the droplets and thereby better definition of them.

I wonder if using Ilford's reciprocity chart would work with Tri-X? It works very well with FP4+, and maybe just maybe it may be close to either FP4+ or HP5+ with a small bit of experimenting.....

https://www.ilfordphoto.com/wp/wp-conte ... sation.pdf

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Maris
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Joined: 27 Jul 2012, 16:02
Location: Noosa

Re: Dracaena, Rainy Day

Postby Maris » 22 May 2023, 13:01

Mick, large format photography tends to long exposure times at small lens apertures so I've wasted more time than strictly necessary in studying film reciprocity failure. Taking the Kodak data table for reciprocity failure of TXP320 and reducing it via some logarithms and exponents like the Ilford method I get:For TXP320 "measured exposure time" raised to the power 1.54 delivers "reciprocity compensated time".

This seems to hold quite well for exposure times longer than about 10 seconds. Kodak suggests stronger correction for times just beyond 1 second: 2s measured - give 5s, 5s measured - give 20, and so on. I'm not sure I truly believe it. Testing would confirm but too lazy to test.
Because the bright parts of an image "fail" less than the dark parts film contrast increases as exposure times lengthen. Kodak suggests reduced development to defeat contrast build up: 10% less for 1s, 20% less for 10s, 30% less for 100s, and so on. Testing would confirm but again too lazy.

In practice instead of chasing shadows I use reciprocity correction to support a detailed highlight (maybe Zone VII) and let the dark stuff go black. That's what a dim scene looks like anyway: glimmering highlights, empty shadows. Seems plausible.

Mick Fagan
Posts: 425
Joined: 24 Sep 2015, 21:20
Location: Melbourne

Re: Dracaena, Rainy Day

Postby Mick Fagan » 22 May 2023, 18:58

Aha, quite detailed reciprocity details there Maris. Kodak have at times surprised me with many films and their longer than one second measured exposure versus required exposure requirements. Ektar 25 professional was relatively unique, as no reciprocity adjustments were needed until 10 seconds measured exposure happened. So even with it being two stops slower than Ektar 100, it was able to gather light more easily and better than the faster film.

The biggest surprise to me was with Ektar 25 professional C41 film, we used it at work for a very big advertising campaign for Kodak Australasia. We literally made same size full length portrait colour prints of people. These were then sealed and displayed by attaching one to every post on the walking bridge to the Australian Tennis Open.

This was really interesting as all of the portraits were taken with 135 film and enlarged directly from a 10"x10" DeVere horizontal enlarger. After the tennis had finished, the whole lot went on an advertising tour of the country. With each portrait we were given the height measurement of each subject, to ensure we actually made the pictures same size.

As we used 6' wide colour negative paper, it wasn't a cheap exercise even if Kodak supplied the roll(s) of paper. Which came in what looked like a lead coffin. The paper size was 6' wide by 100' long and our paper processor was only 2" wider than the paper, which was alright for these as we spliced the paper in the dark by cutting about 2' of paper from one side and used those cut-offs for test strips.

We actually wanted Ektar 25 professional as a 4x5" sheet film, we had plenty of museum stuff happening on the side and this film would've been perfect, but it was only ever supplied as roll film.

Getting back to your figures, 1.54 sounds about right, but yeah, the contrast change can be something else again.


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