Kentmere 100 & 400 Spectral Sensitivity

MattKing said:

Instead of being so negative by telling the rest of us that we are doing things wrong when we are confused or lose track of these matters, perhaps you can do something positive: start your own thread with organized clarifying information.
That way you or someone else in the future just needs to share a thread link.

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Done.

relistan said:

That’s not what you were doing.

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That is what I have done: Given the correct info.

relistan said:

You were making personal statements about a forum member.

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Because of long term experience with his behaviour. And my original statement to him has been respectful, and not rude. As it has been deleted by the mod., it does not matter anymore anyway........

Two years ago I got really into it. So I called Maco and Lupus.

Maco told me that the RPX 100 and 400 are new emulsions based on the original Agfa Levacusen APX emulsion produced for them by Harman. They told me they bought the rights to a lot of the Agfa Levacusen tech.

Lupus couldn’t confirm or deny but I got the strong feeling that they indeed use the Kentmere films.

Earlier this week I talked to someone who knows their shit and works with Maco. He said that Harman bought the rights to the original APX formulas and sold new films based on that to Maco. That apparently was what became Rollei RPX 100 and 400. That would explain why the curves in the spec sheets are similar. He also says that the RPX emulsions changed at some point recently. He just did tests with fresh rolls of Rollei RPX 400, AgfaPhoto APX 400, and Kentmere 400 and concluded that they’re the same emulsions. This is someone very qualified to make such test, I believe what he says. He suspects Harman decided to stop manufacturing the Levacusen emulsions because they were technically better than their Kentmere emulsion.

I’ve also talked a few times to him about other films. One interesting thing he said pertaining to this is that Ilford has more batch variation than Kodak for example. He says HP5+ is slightly more sensitive than Tri-X but varies a bit more from batch to batch. I told him about the Naked Photographer comparisons and he said that the age of the films, batch variations and variations in development may cause them to have differences in curves. The Naked Photographer also shot these video like two years ago, so there is a chance he still had the original emulsion of RPX. The packaging was certainly the old one.

VariTimo said:

Two years ago I got really into it. So I called Maco and Lupus.

Maco told me that the RPX 100 and 400 are new emulsions based on the original Agfa Levacusen APX emulsion produced for them by Harman. They told me they bought the rights to a lot of the Agfa Levacusen tech.

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I would recommend that you be more suspicious of information from either of these two companies. Neither is known for saying much other than marketing speak. That's not throwing shade, that's just what they are: marketing and sales firms.

Maco bought Agfa Leverkusen film stocks only. They packaged and sold those for awhile until they ran out.

VariTimo said:

Lupus couldn’t confirm or deny but I got the strong feeling that they indeed use the Kentmere films.

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They are definitely Kentmere films. This has been tested and confirmed by many parties. Henning also confirmed this earlier on the thread.

VariTimo said:

Earlier this week I talked to someone who knows their shit and works with Maco. He said that Harman bought the rights to the original APX formulas and sold new films based on that to Maco. That apparently was what became Rollei RPX 100 and 400. That would explain why the curves in the spec sheets are similar. He also says that the RPX emulsions changed at some point recently. He just did tests with fresh rolls of Rollei RPX 400, AgfaPhoto APX 400, and Kentmere 400 and concluded that they’re the same emulsions. This is someone very qualified to make such test, I believe what he says. He suspects Harman decided to stop manufacturing the Levacusen emulsions because they were technically better than their Kentmere emulsion.

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Not only did Maco not have the full specs or rights to them, Harman definitely did not produce anything to the specs of Agfa Leverkusen. Their sensitizers are quite different and it would have been cost prohibitive to make a completely new emulsion for just those films. Especially at the price Maco was selling them, this would have made no sense. Even ADOX, who actually did buy Agfa Leverkusen leftover chemistry and coated ADOX Silvermax/Scala 100 from it, discontinued the film when the Agfa-produced sensitizers ran out. They would have had to reformulate the film to produce it after that and they stated that the price per roll (already higher at that time than the RPX films) would not support that.

There is some indication that there may have been two generations of Kentmere films that are very slightly different. ADOX/Fotoimpex indicated someting like this in the text on their site for the CHM films. If there is any difference in RPX versions, it's likely because of that. This would not perfectly match the change on the Kentmere side because of differences in sales volumes and timing.

relistan said:

I would recommend that you be more suspicious of information from either of these two companies. Neither is known for saying much other than marketing speak. That's not throwing shade, that's just what they are: marketing and sales firms.

Maco bought Agfa Leverkusen film stocks only. They packaged and sold those for awhile until they ran out.


They are definitely Kentmere films. This has been tested and confirmed by many parties. Henning also confirmed this earlier on the thread.


Not only did Maco not have the full specs or rights to them, Harman definitely did not produce anything to the specs of Agfa Leverkusen. Their sensitizers are quite different and it would have been cost prohibitive to make a completely new emulsion for just those films. Especially at the price Maco was selling them, this would have made no sense. Even ADOX, who actually did buy Agfa Leverkusen leftover chemistry and coated ADOX Silvermax/Scala 100 from it, discontinued the film when the Agfa-produced sensitizers ran out. They would have had to reformulate the film to produce it after that and they stated that the price per roll (already higher at that time than the RPX films) would not support that.

There is some indication that there may have been two generations of Kentmere films that are very slightly different. ADOX/Fotoimpex indicated someting like this in the text on their site for the CHM films. If there is any difference in RPX versions, it's likely because of that. This would not perfectly match the change on the Kentmere side because of differences in sales volumes and timing.

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That’s just what he told me. And he’s someone I trust on a technical level and as I said before works with Maco, not for them. I don’t know if he’s right but he’s the closest thing to a reliable source I could find.

I think I'll just buy myself a good colour checker...

Andrew O'Neill said:

I think I'll just buy myself a good colour checker...

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The issue to an extent is Ilford’s batch inconstancy. That’s not a bad thing in the sense that you’ll every notice anything during normal photography but doing side by side test. The RPX could have been from another batch and stored who knows how and it’ll give slightly different hues than the Kentmere. Even if they were developed in the same tank.

VariTimo said:

The issue to an extent is Ilford’s batch inconstancy.

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I'd like to see the quality of sensitometric testing upon which that claim is made. More often than not, people are effectively testing their own systemic shortcomings than those of a given manufacturer.

Delta materials are explicitly designed to allow for batch-to-batch consistency control (ie within their structure there are adjustments that can be made for this purpose). Anything made on the rapid-mixing plant will likely be readily capable of compliance with this too (and there will very likely have been under-the-skin alterations to emulsions made on the older plant - i.e. Pan-F+/FP4+/HP5+). It would be reasonable to surmise that Kentmere emulsions are made on the rapid-mixing plant (more efficient), but without the more expensive addenda (e.g. for aspects of grain structure control, sensitisation, stronger anti-halation, pushability, reciprocity, granularity/ sharpness/ development inhibition effect control etc) or complex making processes of Delta emulsions.

Lachlan Young said:

I'd like to see the quality of sensitometric testing upon which that claim is made. More often than not, people are effectively testing their own systemic shortcomings than those of a given manufacturer.

Delta materials are explicitly designed to allow for batch-to-batch consistency control (ie within their structure there are adjustments that can be made for this purpose). Anything made on the rapid-mixing plant will likely be readily capable of compliance with this too (and there will very likely have been under-the-skin alterations to emulsions made on the older plant - i.e. Pan-F+/FP4+/HP5+). It would be reasonable to surmise that Kentmere emulsions are made on the rapid-mixing plant (more efficient), but without the more expensive addenda (e.g. for aspects of grain structure control, sensitisation, stronger anti-halation, pushability, reciprocity, granularity/ sharpness/ development inhibition effect control etc) or complex making processes of Delta emulsions.

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Very interesting points, Lachlan. Thank you.