The authoritative answer on Kentmere 400 vs HP5 please!

Wow, amazing convo! Seems like most here are pushing for establishing subjective stances and not basing them on graphs, I like it!
Shooting each for 6 months, using the negs to make prints or however I want to use the photos, and then assessing myself is a great idea. I'll do that!

Lachlan Young said:

Many B&W films incorporate both anti-halation layers, and other absorber dyes to prevent internal reflection problems between layers etc. Kentmere 400 doesn't seem to have as strong a level of internal reflection prevention (which is fine if you are not expecting to give it generous exposure and curtailed processing) as something like HP5+ - this should not be a surprise as these components are potentially immensely costly custom organic chemicals. Making assumptions about today's emulsion coating structures on the basis of assertions of popular writers from the 50s/ 60s is a major error.

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I assure you that most conventional B&W films do not have the kind of anti-halation layers that C41 films have. Instead, they are coated on a grey base, which absorbs light twice, providing most of the anti-halation that is needed. The only B&W film that had a special AH layer was Panatomic-X after about 1965. This modification changed the speed from 40 to 32. I remember when this was announced (I was a teenager at the time, very keen on photography).

In this Kodak publication from 1963, the speed is still 40, so the change was indeed later (see page 44):

Can @laser possibly weigh in on the presence/function of the anti-halation dyes that seem to be present in most B&W films(and readily wash out)?

Ben Hutcherson said:

Can @laser possibly weigh in on the presence/function of the anti-halation dyes that seem to be present in most B&W films(and readily wash out)?

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Not on 35mm films. They are used on larger formats. Perhaps I didn't make that clear.

Augustus Caesar said:

Not on 35mm films. They are used on larger formats. Perhaps I didn't make that clear.

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This was probably mostly correct 60 years ago.

MattKing said:

This was probably mostly correct 60 years ago.

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I quite literally developed the first sheet film I’ve used in years today.

Meanwhile, I also processes a dozen rolls of 35mm and 120 B&W(I had a productive day…). I pre soak unless using a developer that explicitly says not to like Diafine, which was not one I used today.

The only roll that did not wash out darkly colored dyes on pre-soak was the 70mm Plus-X Aero. That’s its own beast, as it’s a pseudo-IR film(similar to the current Rollei IR offering) on clear estar. It also light pipes pretty badly, to the point that I’ve had overexposed frames bleed into the sprocket holes or even an adjacent frame. I suspect there’s little to no AH present in it, and it shows.

Any dyes that wash out aren't necessarily just AH related, but yes you see them with 35mm B&W film too.

My two cents on these two films, all from just using them, no formal analysis: Kentmere is a little contrastier than HP5, and also a little less sharp. HP5 has a much wider tonal range.
Kentmere reminds me very much of 1970s Tri-X.
It is especially nice in 120..

Camerarabbit said:

Shooting each for 6 months, using the negs to make prints or however I want to use the photos, and then assessing myself is a great idea. I'll do that!

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That would be a great way moving forward. And in fact, it's pretty much what I did, too. For my 'go to' 400-speed film, I worked my way up from Fomapan 400 to Rollei RPX 400 to HP5+. I stuck with the last one because I still feel it's worth the premium, although the subjective differences between the latter pair were rather slim. Fomapan was definitely in a different league (also price-wise) and didn't do it for me, personally. At least not for what I wanted it for, which is a decently fast walkaround film.

koraks said:

"We" do, though. Often, OP comes back and asks follow-up questions.
What generally doesn't work is if someone comes in, we barrage them with probing questions and they have to go through some kind of inquisition before any useful information is being imparted to them. That's when people tend to walk away or simply get angry. If you want examples, there are forums I can point you to where this has happened a lot, and I can tell you, it wasn't nice.

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Í don't believe it is as black and white as that There is a way to ask questíons in a way that encourages the OP to give answers from which it may be clearer what the the OP is asking and then provide answers. There are ways to ask questíons or get clarificatíon without annoying an OP


Yes it may mean that we effectively tackle the OP's issue more slowly rather give him a list of solutions with inevitably confuses not the least because it confuses him

What I do accept is that the above way ís not in our Photrio DNA part and therefore not actively pursued

pentaxuser

@pentaxuser your approach works well if you sit down with someone and/or do live chat. On a forum, it generally doesn't work out well. It just takes too long before people get answers. They've ran off to Reddit or X long before you get halfway your second round of detective work.

koraks said:

@pentaxuser your approach works well if you sit down with someone and/or do live chat. On a forum, it generally doesn't work out well. It just takes too long before people get answers. They've ran off to Reddit or X long before you get halfway your second round of detective work.

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OK You win if you know this to be the answer but it is not my experience based on another forum I am a member of . Not all forums or members of forums follow what you seem to believe are immutable laws governing all forums behaviour

We have in fact seen some attempts to address this issue here by some members but without any real success so yes I accept that we cannot change what appears to be behaviour that may have been conditioned over many years - about 22 years in our case and making a difference now may be impossible as I said before

pentaxuser

pentaxuser said:

OK You win if you know this to be the answer but it is not my experience based on another forum I am a member of .

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If it is the forum I think it is, the activity there, and the nature of the community there, is fundamentally different than what we see here on Photrio.
Even though at least two of the moderators here at least drop in there from time to time.

albireo said:

the idea of 'perceptual image structure'

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Camerarabbit said:

Seems like most here are pushing for establishing subjective stances and not basing them on graphs

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I'll take these together as they aim at the same point. In essence, resolution tests are a profoundly incomplete measure of how a film performs in the real world (in fact, even when well done, they tell you little that the MTF can't (you can forecast the results accurately if you know the test chart contrast), other than the tester's errors - e.g. in reading out at one MTF for neg films, and another for transparency - which renders the result perplexing to the mk.1 eyeball, even if the numbers are nominally 'correct') - especially compared to how using the materials in question under tightly experimentally controlled & demanding real-world scenarios can often (if done well) allow for close linkage to the much more useful MTF/ RMS granularity information which does much more to define (along with usable latitude) the ability of a given material to capture and transmit information. However, some people (usually outside of the industry) try to link up MTF to outright resolution in order to play the usual zero-sum games, rather than ever linking back to double blind tests at an array of enlargements (which of course must be done with optimised lenses, such that they don't overly influence the result). Spectral sensitivity tests also can tell some of the story, but seem rarely done (in the popular press/ influencer world) to normalise for all the potential variables. In other words, do some basic & sensible tests, but unless you can produce exceptionally well controlled data, you are never going to get close to the manufacturers (and this applies to the home developer formulators in particular - they are often unknowingly reliant on the manufacturers successfully compensating for potential end user error) test results - which I wish they were sometimes more willing to share in more detail, as it might clear up a lot of fashionable nonsense.

Anyway, even a 3x enlargement off 120 will show up the K400/ HP5+/ Delta differences - the low frequency response is clearly one of the biggest areas of difference.

Augustus Caesar said:

Instead, they are coated on a grey base, which absorbs light twice, providing most of the anti-halation that is needed.

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This is rather inaccurate - only a few rely entirely on the grey/ dyed base (usually the budget options) - many also incorporate anti-halation within the emulsions/ layer structure and/or as discrete layers (e.g. Agfapan APX 100 and successors have a discrete anti-halation layer). The grey base is almost more about preventing light-piping effects than acting as a complete anti-halation solution on many emulsions. A lack of strong anti-halation protection within a multilayer emulsion structure can become very apparent in the highlights with overexposure e.g. K400, Fomapan 400). C-41 emulsions incorporate both a discreet anti-halation layer and anti-halation within the emulsion structure as the base of C-41 is clear and would otherwise light-pipe terribly - and within the emulsion layers further anti-halation is essential as you would otherwise get each layer behaving like a mirror.

Oldwino said:

Kentmere reminds me very much of 1970s Tri-X.
It is especially nice in 120..

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Sort of - but it can also look like a bit less sharp version of a more 'modern' Delta style film too (for the record Delta 400 has a very similar curve to TX) at some points in the frequency response. Overall, something of a hybrid in some areas (which would probably have been ironed out if it was to have been a premium emulsion).

pentaxuser said:

it is not my experience based on another forum I am a member of

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How fast does it grow? How many new members does it answer questions for? How does that growth relate to the growth of attention for analog photography on YouTube, Reddit, Facebook, Instagram and the interactions that take place there to solve practical problems?
If the other forum you refer to is somehow gaining speed, then what you say must be right. If it's similar to the other forums in that it mostly caters to a relatively stable user base with a high average age, then maybe you're not getting a representative picture.

Also, it's not about "winning", not is this an either/or thing. We can offer solutions, suggestions and hypotheses and at the same time ask follow-up questions.

I assume we've sufficiently explored this tangent. If you'd like to continue or pick up this discussion yet again at a later stage, please do so by making a thread about it in an appropriate spot on the forum. Thanks.

pentaxuser said:

OK You win if you know this to be the answer but it is not my experience based on another forum I am a member of .

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MattKing said:

If it is the forum I think it is, the activity there, and the nature of the community there, is fundamentally different than what we see here on Photrio.
Even though at least two of the moderators here at least drop in there from time to time.

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Again, if it is the forum I think it is, then it has 912 registered members, the majority of whom seem to be relatively close to each other geographically.
Photrio is spread all around the world and has just under 99,000 registered members.
The other forum seems to be a great and friendly place, where most things happen in the same time zone, at a relatively measured rate. When someone does post there with a question, the response does seem rather neighbourly
In Contrast, you should see what my "Alert" queue looks like sometimes when I sign in in the morning!
The world is a better place when there is variety.