Perceptol speed loss

I'm about to try FP4 and PanF 50 in Perceptol for the first time, but I read that this results in a speed loss. Its probably obvious, but I don't understand exactly what that means. Do I need to give the film an extra stop of exposure, or more development? Or both?

You need to drop the speed to 25 EI ideally and process for 9 minutes in Perceptol FS, or go to the Ilford website and download the Pan F datasheet for the times in dilute Perceptol.

Ian

Expose the film as if it was half the "box speed" and develop normally.

This assumes you want the fine grain that Perceptol is recommended for. I don't know what would happen if you expose the film by the box speed and push develop in Perceptol...

Suggest reading the data sheet for each film eg

http://www.ilfordphoto.com/Webfiles/2006216115811391.pdf

A suggestion with Perceptol is to use at 1+2 although Ilford don't list this dilution it works extremely well and is more economic than FS or 1+1, I'd use 12½ minutes at 20°C as a good starting point.

Ian

Recently discussed:
(there was a url link here which no longer exists)

It's been awhile since I used Perceptol. But what worked well for me was half of box speed, in other words, ASA 50 for FP4, and 25 for Pan F.
In terms of dev time, it's analogous to D76 or ID11, and therefore dependent upon whether you use it straight or 1:1.

Half-speed for FP4 should be 64, but it's just me being pedantic.

Thank you for your advice. I was wondering if I needed to do give any extra exposure on top of what I already do, but it looks like the dev times take the speed loss into consideration. I'll do half box speed then follow the normal dev times given by Ilford, then adjust for subsequent films if necessary.Cheers!

the biggest speed loss with perceptol happens when you dilute it from stock. You get sharper grain but lose speed.

RobC said:

the biggest speed loss with perceptol happens when you dilute it from stock. You get sharper grain but lose speed.

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This puzzles me since I have not seen a drop in the speed department with Perceptol 1+3 or 1+2. Maybe I'm doing something right for a change. Even Barry Thornton never mentioned a speed loss with diluted Perceptol compared to full strength. He did say the grain would not be as fine with diluted, but no speed loss. I've used this developer often so I'm not just blowing smoke here. John W

that was my experience when I used it quite a lot. Ones persons speed loss is not necessarily the same as anothers. It depends how you do your testing and the criteria you apply. Generally diluting developer lengthens the toe. For some people the reduced shadow separation that causes is acceptable but to me it wasn't so I usually shot HP5 at 160 when using Perceptol and devloping 1+2. Mind you, I was tailoring dev for the zone system which IMO requires a lower CI than what is considered "normal". So there you have it, thats how it worked for me. As always YMMV. And as always, everyone does it their way so its nearly always best to take it with a pinch of salt and work out your own personal way of doing it.
Thats confusing for newbies asking about it I know but really if you are just starting out you should be using whatever the manfacturer recommends for optimum results and adjust to taste thereafter.

p.s. I take whatever Barry Thornton said with a very large pinch of salt.

No speed loss if you dilute 1:1. But you will probably need to adjust your time a bit longer or temp a bit higher, which affects overall contrast,
including highlight density. 1:2 seems a stretch, like Rob just implied. As the saying goes, expose for the shadows, develop for the highlights.

DREW WILEY said:

No speed loss if you dilute 1:1. But you will probably need to adjust your time a bit longer or temp a bit higher, which affects overall contrast,
including highlight density. 1:2 seems a stretch, like Rob just implied. As the saying goes, expose for the shadows, develop for the highlights.

Click to expand...

If there is no speed loss at 1:1 can you clarify what you mean by "1:2 seems a stretch " I think you are saying that there are losses/problems at 1:2 but clarification will be welcome.

I note that Ilford gives times for 1:3 for some films at full box speed without indicating any drawbacks while for other films, namely the faster ones such as HP5+ there is a slight loss of speed. In the case of HP5+ it is a drop from 400 to 320. It would appear that with the faster (400) films exposure at box speed instead of the reduction Ilford recommends, might involve a slight loss of shadow detail even at 1:3 but with slower films such as the 125, 100 and 50 there appears to be no disadvantages

My later conclusion may be wrong of course

Thanks

pentaxuser

Although I've not used a huge amount of Pan F Plus I happened to come across some of my 9 1/2" x 12" test prints recently from 35mm Pan F Plus negatives, processed in Perceptol 1+3 dilution (25 EI). It really is a very high quality combination.

Tom

If preceptol is the developer for film(fp4) then what's the dev-paper combination for a print then?
I'm assuming the current discussion is about getting better (final) prints with the combination(overall)?

I haven't tried fp4 with preceptol, but I tend to like it better than Delta 100 with xtol.(can't quite put a finger on why)

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