Um, the difference between a 400 ISO and 1600 ISO film is how much shadow detail is available.
Compared to what?Yes, you are correct.
But what i mean is that the contrast obtained when pushing HP5 is still reasonable. A "normal contrast" film, pushed 2 stops, would have a very noticeable "high contrast" look.
Pushing does not significantly change the speed of a film, maybe a 1/3 stop or so is realistic; so 800 not 1250. Beyond that the question is all about how much shadow detail you can do without.Another thing to bear in mind is that a PQ or Phenidone-Ascorbate developer can bump the shadow speed by 2/3 stop as a matter of course - thus if it's raising the effective speed of a 400 speed film to 650, a 1 stop push would nominally suggest an EI of 1250 or thereabouts - probably hard to tell apart from 1600 for most people. Consider too that Ilford's 'normal' contrast index of 0.62 is regarded as a 'push' by Kodak's standards and you can see how easy it is for people to obfuscate and claim wildly...
Pushing does not significantly change the speed of a film, maybe a 1/3 stop or so is realistic; so 800 not 1250. Beyond that the question is all about how much shadow detail you can do without.
AFAIK, film makers now have some leeway when measuring ISO speed, so rest assured that they measure their box speed with the fastest speed reaching developer they can get their hands on. Therefore I would not expect ISO 1600+ from Delta 3200 in DD-X or Crawley's FX-11, but rather ISO 800 from Delta 3200 in D-76.Another thing to bear in mind is that a PQ or Phenidone-Ascorbate developer can bump the shadow speed by 2/3 stop as a matter of course - thus if it's raising the effective speed of a 400 speed film to 650, a 1 stop push would nominally suggest an EI of 1250 or thereabouts - probably hard to tell apart from 1600 for most people. Consider too that Ilford's 'normal' contrast index of 0.62 is regarded as a 'push' by Kodak's standards and you can see how easy it is for people to obfuscate and claim wildly...
AFAIK, film makers now have some leeway when measuring ISO speed, so rest assured that they measure their box speed with the fastest speed reaching developer they can get their hands on. Therefore I would not expect ISO 1600+ from Delta 3200 in DD-X or Crawley's FX-11, but rather ISO 800 from Delta 3200 in D-76.
The big difference between Delta 3200 and HP5+ (apart from ISO speed) seems to be their toe shape. Delta 3200 has a pronounced, sharp toe, and pushing gains contrast but no shadow detail. HP5+ appears to have a long toe, which responds well to pushing.
P.1 of the Delta 3200 tech document clearly states an ISO of 1000 in ID-11 - which is what all of Ilford's tech documents specify as being used to test for ISO film speed. However, from a little looking at the other data in that document it becomes clear that the design G-bar/ CI for this speed was lower than Ilford's usual 0.62 G-bar - the G-bar at which they suggest you'll get a usable EI 3200.
Compared to what?
Were both films developed to the same measured contrast index?
Were the same subjects compared?
What adjustments were made when printing?
Not really - HP5+ under test conditions at 0.62 CI should hit the ISO standard for 400 speed & its longer toe will help compensate to an extent for underexposure.Thank you very much!! This is what I was trying to say. As i understood it, there are films that are designed with a lower contrast at their base ISO, and those are the films that are intended for push processing (or that push really well). Delta 3200 is such a film, and I say that HP5+ is such a film as well (i've read somewhere a feature on when HP5+ was introduced, that the Ilford representative mentioned that one of the design goals was better push-processed results)
Compared to what?
Were both films developed to the same measured contrast index?
Were the same subjects compared?
What adjustments were made when printing?
HP5 is a normal film, it responds to pushing very much like Acros would. They both have long straight lines. CI 62 on either will produce similar print contrast. Not exact but pushing either creates a snappier contrast rate.See above. Compared to a "normal" film.
There are different approaches to pushing. There are zone system disciples, who use it for contrast control. If only the straight line part of the H&D curve is used in printing, then yes, HP5+ and Acros behave the same. Delta 3200, on the other side, has a pronounced shoulder, which becomes even more pronounced with pushing.HP5 is a normal film, it responds to pushing very much like Acros would. They both have long straight lines. CI 62 on either will produce similar print contrast. Not exact but pushing either creates a snappier contrast rate
I agree that there is a pronounced shoulder, but so what? The whole curve doesn't get printed.There are different approaches to pushing. There are zone system disciples, who use it for contrast control. If only the straight line part of the H&D curve is used in printing, then yes, HP5+ and Acros behave the same. Delta 3200, on the other side, has a pronounced shoulder, which becomes even more pronounced with pushing.
Then there are folks who use pushing to increase effective film speed, which in their case means: reduce the amount of light needed to create discernible image matter. These folks care mostly about the toe part of the H&D curve, and how it can be affected by pushing. For these folks Acros is similar to Delta 3200, but very different from HP5+. Unlike Acros and Delta 3200, HP5+ has a long toe, and increasing toe contrast by pushing extends usable EI, assuming overall contrast is controlled by other means (dodging&burning, hybrid techniques).
+1Well said, Matt.
However, i differ with you in HP5. My opinion is that HP5 is also a rather lowish contrast film, that's why it pushes so well at 1600. I have some shots made with HP5 pushed to 1600 (using Microphen) that look so good, you'd think HP5 was actually a ISO 1600 film. Of course, still there is less shadow detail, but contrast is not exaggerated.
Again, where did you meter? If you metered in the shadow regions, or used average metering on a mostly dark subject with few highlights, then we should not be surprised that HP5+ at EI 1600 looks good, whereas Delta 3200 with its soft shoulder will also look good. If you (in theory) redid these shots with increasingly reduced exposure, then HP5+ @ EI 1600 would suffer from poorly defined shadows long before Delta 3200 shot at EI 1600, the HP5+ version would, of course, be finer grained than the Delta 3200 (assuming same negative contrast is reached).
I wonder if there's another option?
In my experience tmax 400 is (my best film) for pushing.
This is tmax400 shot at 3200 and developed as 5000 in microphen; 1+0 12min 1min/agit @20C
Have a look in good resolution at flickr, and notice the shadows
267 m645 11 by Johan, on Flickr
that will give you plenty of shadow detail but very flat midtowns and a very soft negative; not to my liking; lost all the punch.Try a bit of pre-exposure to lift the shadows and develop less to reign in the highlights.
Not too much of either - find the happy medium.
Well, that's what old Ansel said !
JP
Hi howardpan,
thanks for the quick and informative update. Am I correct to assume, that 'set it as Zone III' means set exposure dial to 2 stops underexpose, which means the shadow regions was exposed as EI 6400 (= EI 1600 minus two stops, and you said it was HP5+ @EI1600)? Or did you expose the shadow regions as EI 1600 ?
And about the dragon in the 0004 image: that's black subject matter measured with incident light metering, then printed to give 15-30% gray in the print, which makes the image much brighter (compared to an 18% gray card) than it was. This EI 1600 measurement would have easily been EI 6400 with a spot meter set to the same regions.
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