Metolal & x-ray film - CI issue

[bnxvs]

Hello.
I ran into a weird problem. I'm trying to calibrate the process of developing a Fuji HR-U (green) film in Metolal (https://www.photrio.com/forum/resources/rodinal-like-developer-from-metol.184/).
With a dilution of 1 + 50, I get a fairly high CI (see graph 2). And at a dilution of 1 + 100, on the contrary, too low a CI (less than 0,5). Moreover, with an increase in the development time from 6 to 9 minutes, the CI practically does not increase, as does the sensitivity. It seems that there is a certain density threshold in such conditions.
I took the PH measurements of both solutions:
1+50: 11,2-11,4
1+100: 10,7-10,9
What can be the options for obtaining CI in the limits 0.55 - 0.7, what do you think?

 

[Alan Johnson]

At first sight it appears that using 1+50 the development time could be reduced.
Is there some reason that would not be satisfactory?

 

[bnxvs]

Reducing the time of developing, I got a somewhat strange shape of the curve in the high zone. It was like a "hump". Unfortunately I deleted the old charts, inadvertently.

 

[Alan Johnson]

The thread "A different way to control contrast" on the UK large format forum indicates that at least with Rodinal, 1+25 may be the way to try.

 

[bnxvs]

Yes, thank you. I started with EZ Rodinal 1 + 50. It gave a good results. But metolal is easy to make for me (I have about 1kg metol). So I decided to try it.

 

[bnxvs]

At first sight it appears that using 1+50 the development time could be reduced.
Is there some reason that would not be satisfactory?

So, it seems to work out. I reduced the development time to 3.30 min. Tray. Agitation - 1 minute continuously, then for 5 seconds. every minute. 30 sec stop bath. Fast fixer - 1 minute.
I took measurements twice (2 sensitograms). In principle, the measurement results are the same (+-). It is clear that sensitivity is detected better in Metolal than in Rodinal, with acceptable contrast.
There is still a little “hump” in the middle tones, but I think this is acceptable.
Thanks for your recommendation.



FKD 13x18, mono-lens (about 250mm f/5), 4 sec. exp., v700