Official recommendation for Kentmere400 in Perceptol, why?

[Juan Valdenebro]

After using Perceptol happily with several films, I feel metol developers are the real thing, and we can decide to lose some image quality to gain a stop of speed using standard MQ developers, or lose even more IQ and go for one more stop of speed with a speed enhancing developer, just to describe things quickly.
In the past I did test K400 (never liked it too much, really: not as much as best films) in MQ and speed developers, and in Rodinal, but never in a metol developer, so this time I ordered some K400 rolls among my more usual films, wanting to see K400 at EI200 in Perceptol Stock, not diluted, as grain is really present in that film, and I won't need contrast control: no direct sunlight. I just want to make the film work better than I was able before, talking about image structure... Not being a too modern type of grain film, it's possible to imagine Perceptol stock helping it at EI200 for portraiture.

But the only recommendation by the manufacturer, for Perceptol, is 1+1 (EI320) with a time above 20 minutes... I wonder what's the reason (or reasons) for that.

Stock is not even recommended, and it would of course make a shorter and more convenient development time: I'm surprised... Why could that be?

Maybe they don't expect people to really use Perceptol stock in general, but only 1+1?
Maybe the film doesn't look good after stock?
Or could it be they didn't want to say the film requires EI200 in any developer?

Perhaps some forum members can understand (or imagine) and share a few possible reasons.

Thanks.

 

[laingsoft]

I think If I'm remembering correctly from Mason, the general idea was that as you dilute the developers more, highlights develop more slowly, meanwhile for midtones and dark areas, the development speed doesn't drop off as quickly. As for why ilford would reccomend an ilford product? I think that's clear. As for the 1:1, Perhaps it's because kentmere film has a tendency to take on an odd muddy, flat tone? At least that's been my experience with it. Maybe perceptol solves that?

 

[Juan Valdenebro]

One thing I'm sure of is K400 looks better when it receives more light than box speed. I didn't find it as fast as HP5+.
Once I was testing it for EI640 in ID-11, after I didn't like it at EI1600 in Microphen. That was the last roll of K400 I did, some years ago.
I was testing it with a Nikon SLR, and as my girlfriend told me that day she wanted to do some photographs of her daughter, I thought "I'll give her the second half of that K400 roll at EI640 because with that camera she can use AE without including white walls or overcast skies inside the frame..."
I was there while she did the portraits, and when the roll was finished and I had the camera back, I saw I had handed her the camera when it was not set to A yet, so the camera was not ready for the type of use I had told her it was totally ready... I went pale thinking of all the spoiled portraits, because the camera was set to the mechanical 1/250 speed instead of A. After the first moments of guilty anguish, she told me she had done all frames at f/4 (with the 105mm), so, as light had been stable (a thick huge cloud) we discovered -yet under the same light- all portraits had been accidentally exposed at EI250: I remember it well because EI and shutter speed were the same... So I cut that roll in two and developed that second half for EI250 in ID-11 1+1: that's the K400 I've liked the best: sharp, clean tone, and with very small grain, and it was 1+1, not stock... So I've thought for long Perceptol Stock must be the best for K400 at EI200.

 

[Juan Valdenebro]

I just saw both for HP5+ and D400, when Ilford talk about EI320, the same happens: Perceptol is recommended 1+1, but not stock. Interesting.
If the official time for K400 at EI320 in Perceptol 1+1 is 23 minutes at 20C, I'd say for stock at EI200, considering HP5+'s behaviour (closest film), 14 minutes at 21C would be a good starting point for testing.