We are now stuck with this stupid ISO system.
We are now stuck with this stupid ISO system.
You'll note that ASA speeds were determined on the basis of print results. The goal was to find the lowest exposure that would provide excellent results. This worked, and I agree with this methodology. Then, after WWII, faster films became available. The cameras of the time (mostly leaf shutters) were designed for slower films, and this forced users into using the smallest apertures, because maximum shutter speeds were not very high (1/300 was the usual top speed for most cameras of the period). When this is done, the exposure is proportionally greater than it would be with larger apertures. So, 1/50 @ f/16 is not equivalent to 1/400 @ f/5.6 with a leaf shutter. This is because the entire aperture is uncovered for a proportionally longer time when the aperture is small. Nonetheless, the powers that be decided to double the film speeds in 1960. This would mean that an exposure of 1/100 @ f/16 under the old speed would become 1/200 @f/16 with the new higher speed. But that is the wrong approach. The correct thing to do would be to inform photographers who have leaf shutter cameras to use higher shutter speeds when they are using small apertures.
This whole thing was ironic, because right then, cheap Japanese SLRs with focal plane shutters started flooding the market, which made the change unnecessary. We are now stuck with this stupid ISO system.
The speeds doubled in 1960 because the safety factor was removed. There were several reasons for this at the time, but they are less relevant now given the higher image structure performance of contemporary B&W films, so the solution is simple - cut the ISO speed in half. You don’t really give anything up doing that (unless you need a faster shutter speed), and at the same time it obviates the “need” to run the “personal EI” test. If you know a few things about this stuff you can simplify your exposure/development life and focus on printing/editing which is where the control is.
Andy, next time shoot your 400TX at EI 200, then develop it in D-76 1+1. Enjoy all the shadow luminosity you prefer and don't worry much about highlights burning out. See attached curve from fotoimport.no.
And what does one take away from that? What conclusions, if any, can be drawn from the examples?At the foot of this interesting discussion, it's worth remembering that it all began because of the differences in shadow detail in Andy's examples—shot in his camera and developed by him in his developer, one 400 film had more than the other!
And what does one take away from that? What conclusions, if any, can be drawn from the examples?
My take away is that in this case Tri-X had lower shadow speed than HP5+.
But "in this case" has lots of interesting variables like, this developer, this scene spectral content, this agitation scheme, and so forth.
Like you, I find Tri-X shadow speed to realistically be more like EI 200. But that's also how I expose HP5+, at least for conventional development and agitation methods. When I semistand or EMA process these films, use use ISO speed as my EI.
As always, @Andrew O'Neill provides interesting experiments for us all to observe...
I didn’t say I thought either Tri-X or HP5+ were anything other than ISO 400 films. I’ve never worked with HP5+ but I found Tri-X to be ISO 400. I don’t think the comparison in the video was valid but it’s time to move on.
I'm curious to hear why you think it was not valid.
But this 'stupid ISO system' in no way depends on particular shutter mechanics. So the whole story you told above (again) is pretty much moot. It's a bit like arguing how you dislike the shape of a round wheel because at some point horses pulled carriages. There's a historic relationship, but the argument as such is nonsensical.
Analytical definitions of ISO notwithstanding, I pretty much agree with you here so long as you also reduce development slightly - I typically start about 20% less than recommended for the film/developer/dilution/temp I am using.
Adding a full stop of exposure viz box ISO will give you better shadows, but it also runs the risk of overexposed highlights. For long SBRs, that means having some method of keeping highlights in check.
No, it isn't.
Your argument goes "people used leaf shutters and no light meters in 1960. Therefore, the ISO system is now broken"
@Augustus Caesar I've been playing around with Pan F in D-23 spiked with Sodium Hydroxide. I normally shoot this film at EI 25 in D-23 1+3. In the spiked version (D-23 1+10 + 0.2g Sodium Hydroxide), definitely a higher EI than 25 is needed (still working on it). If I shoot the film at EI 25 with the spiked version, it looks over exposed, with very ugly midtones. Film manufacturer's ISO's to me are only starting points. Kind of like when we take metre readings. That Zone V reading is merely a starting point (unless we are reading a gray card or literally place a reading on middle gray).
@chuckroast very nice definition!
There would seem to be some evidence from other videos on comparisons between HP5+ and Tr-X that the vast majority who shoot 2 identical scenes with 2 cameras at box speed seem to come to the same conclusion As far as I can recall I haven't seen any videos that reached different conclusionsMy take away is that in this case Tri-X had lower shadow speed than HP5+.
We have lengthy discussions on such matters and represent a much "broader church" in photography terms than the vast numbers of people who did take film photographs to record scenes using either HP5+ or Tri-X which were probably the most used films for the "man in the street".
pentaxuser
1. HP5+ has better shadow detail
2. Tri-X has brighter highlights
pentaxuser
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