wosis123
According to various, often contradictory sources, it seems that the two films are not identical after all.
When comparing the development times according to:
http://www.digitaltruth.com/devchart.php?Film=Kentmere&Developer=&mdc=Search
and:
http://www.macodirect.de/download/TA_RPX_400_dt.pdf
, I notice that, depending on the developer, the two films sometimes show hardly any difference in development time, and at other times very significant differences. How can this be explained?
piu58
[size=5][sub]I’ve already mentioned this elsewhere: I have both films here, and they’re identical. However, there may be several versions available from RPX.[/sub]
[sub]You can’t compare digitaltruth’s footage with anything else. Anyone can tinker with it here. One person might use a condenser lens, another a diffuser. The visual concepts are completely different.[/sub][/size]
TR
[size=5][sub]One person has a condenser microphone, the other a diffuser. People’s ideas about sound are all over the place.[/sub][/size]
Exactly.
It seems there’s a significant knowledge gap here for many people, as people are constantly juggling with development times: the length of the development time controls the contrast (from a certain base time onwards). Depending on your preference, you can develop for longer or shorter periods. I prefer to develop my roll films a little softer (shorter) to avoid clipping the highlights as much as possible. I have ‘tested’ my process for my material. When shortening a certain ‘standard time’ (for example, from tables) by perhaps 30%, there is no risk of any image information being lost, as some might fear.
bernhardmangelsgmxde
According to Maco (if I remember correctly):
To start with: RPX 400 is a standalone emulsion.
Incidentally: RPX and Kentmere are identical (RPX roll films were at times also listed among the Kentmere black-and-white films)
I believe RPX is now being marketed as a standalone emulsion again.
Based on users’ experiences, the situation is as follows:
Var. 1:
(see Uwe) RPX 400 and Kentmere were identical from the outset
Var. 2:
RPX 400 and Kentmere 400 were different at launch, but are now identical.
Var. 3:
RPX 400 and Kentmere were different at launch, and still are today.
wosis123
...then you could also combine Variants 2 and 3: first different, then the same, now different again...
That would turn development into a game of chance...
Gast
That’s exactly why I don’t buy Rollei film anymore!
wosis123
OK, but you could buy Kentmere, couldn't you? It's just, how do I develop it then?
Gast
http://www.kentmere.co.uk/Webfiles/20091291713401332.pdf
http://www.kentmere.co.uk/Webfiles/20091291714152280.pdf
And here:
http://www.foto-riegler.at/pdf/Kentmere_100_Entwicklungszeiten_Dev.Chart.pdf
http://www.foto-riegler.at/pdf/Kentmere_400_Entwicklungszeiten_Dev.Chart.pdf
hallertauBW
Good evening everyone,
I’d just like to add fuel to the fire. I’d also assumed that Kentmere and Rollei RPX were the same, until I read this on the label of my bottle of PXD developer....
wosis123
...the confusion continues...
I have a few rolls of Kentmere 400, bought about a year ago, which I developed in AM74, 1+9, for 7 minutes with good results. See attached example – which version of which film is this, then?
Wolf_XL
...I think – though I can’t prove it – that there was at least a change in the emulsion for the roll film. I bought my first roll of RPX 400 over two years ago as a trial pack and was very happy with it. That’s why I bought another 120 RPX 400 at the start of this year. Somehow, though, they seemed different to me – I particularly noticed an unusual density... I think I’ll dig out both films and at least measure the base fog with the densitometer...
AchimBauer
Hello everyone,
[font=arial,helvetica,sans-seriI don’t use any of the films; if I did, given all the confusion, I’d ask Roleimackohansohmahn directly in no uncertain terms what’s going on.[font=arial,helvetica,sans-seriThen there are only three possibilities: [font=arial,helvetica,sans-seri1. You get no reply[font=arial,helvetica,sans-seri2. You get the wrong reply[font=arial,helvetica,sans-seri3. You get an honest reply[font=arial,helvetica,sans-seriIn my experience with product enquiries, option 1 is the most likely.[font=arial,helvetica,sans-seriRegards, Achim
piu58
I get the feeling that things are starting to change at Maco. Officially, it’s quiet for the time being, but there has at least been one private enquiry where a sensitive issue was dealt with properly.
There’s nothing wrong with a company cutting up and selling industrial films. But somewhere, at least in the small print, there should be a reference to the source material. It comes out anyway, but before this research work is done, there’s always a phase of uncertainty, which isn’t over yet with the RPX.
I’ll take two more vials soon and put them in the PXD developer; its versatility is, after all, the film’s biggest plus. I’ll then place the step wedges on the light table and compare them.
Olivinyl
Hello everyone,
To perhaps allow for a better comparison, I have developed a recent Kentmere 400 (best before 2017) in Xtol and Rodinal.
Perhaps someone could share the data for the RPX 400 here.
Kentmere 400 in Xtol 1+1, 30/30/5 agitations at 20°C in a small Jobo tank for 11:00 minutes
26 DIN / 320 ASA, gamma 0.57
Kentmere 400 in Adonal 1+50, agitation 30/30/2, 20°C in a small Jobo tank, 14:30 minutes
25 DIN / 250 ASA, gamma 0.59
Best regards, Oliver
wosis123
The data sheet (http://www.macodirect.de/download/TA_RPX_400_dt.pdf) specifies 12 minutes for Xtol 1+1 at 400 ISO…
Olivinyl
...12 minutes is just under 400 ASA/27 DIN, but then the gamma is over 0.60... It depends on the enlarger you’re using
The curve at 11 minutes, however, is nicely on the standard curve. It’s slightly above between Zone 3 and 7.
With Rodinal 1+50 at 14:30 minutes, the curve is slightly above between 3 and 10, and the density increases slightly from Zone 5 onwards.
Gast
Hmm, can you actually take photos as well?
I tend to agree with Bruce Barnbaum on this
and would rather take photos than do sensitometry ;-)
adophil
Hmm, can you actually take photos as well?
What’s the problem? Surely not in the appropriate use of the ‘forum for topics relating to analogue photographic materials, processes and processing-specific questions’...
Olivinyl
Hmm, can you actually take photos as well?
I tend to agree with Bruce Aarnbaum
and would rather take photos than do sensitometry ;-)
I don’t see a problem with that! It’s important to find out how films react in different developers.
If a film type with an ideal curve has been developed in various developers, only then can I determine which film in which developer I like best as a print!
For ages I only developed according to the instructions on the packet and found with some films that the results weren’t perfect and needed retouching!
Now I know the gamma, the curve and the nominal sensitivity, and nothing stands in the way of the perfect negative!
Best wishes, Oli
Wolf_XL
...let’s put it this way – if I were to make Kentmere one of my go-to films, I’d only buy it if it came in an original Kentmere box – anything else would be a bit of a gamble...
