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Thread: TriX vs HP5+

  1. #21
    Steve Smith's Avatar
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    Quote Originally Posted by Lionel1972 View Post
    but in this case shouldn't we also apply these time steps with our cameras?
    We do.

    Each stop of aperture lets in half as much or twice as much light. Each stop of shutter speed opens for half or twice as long.

    The confusion arises when we use the same numbers on the aperture ring for our exposure times. The aperture f stop is derived from the diameter of the aperture opening whereas the actual area of the opening is proportional to the square of the aperture (a = pi x r squared).

    Apertures are marked up in f stop figures, each one being the square root of two times the last one. e.g. 2, 2.8, 4, 5.6, 8, etc.

    If we use the same numbers applied to exposure then we get half stop increments. If we use alternate numbers, they are full stops.

    I think it's easier to avoid confusion and use 10, 20, 40, etc, as you are doing.

    If you then find that the exposure you want is e.g. somewhere between 30 and 40 seconds then you can do a new test strip just between these values. With a bit more experience, you can judge where it is going to end up. e.g. if it's closer to 30 than 40 and just needs to be slightly darker, you might judge that 33 is enough and then you can be brave and do a whole print or just try an offcut of paper for that time.


    Steve.
    "People who say things won't work are a dime a dozen. People who figure out how to make things work are worth a fortune" - Dave Rat.

  2. #22
    Lionel1972's Avatar
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    I was talking about using the same time steps numbers as apperture numbers which some people do with paper exposures of test strips (i.e. 2.8, 5.6, 11, 22 are not accurate doubling steps whereas 1/25, 1/50, 1/100 are strict one stop steps in time). Of course 2, 4, 5.6, 8, 11, etc... are accurate F numbers for doubling the amount of light with fixed exposure time. I was wondering about the time steps, nor apperture steps in camera.

  3. #23
    Steve Smith's Avatar
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    Older cameras have 1/25, 1/50, 1/100 and 1/200 but they also tend to have 1/10 which is obviously not half of 1/25 and if they go faster than 1/200 then 1/300 is often the next speed or they sometimes jump from 1/100 to a top speed of 1/250

    http://www.kl-riess.dk/compur.01.jpg


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  4. #24
    Lionel1972's Avatar
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    Yes you're right, it doesn"t seem that accurate doubling of time steps is very critical. So I don't think using 2.8, 5.6, 11, 22 for printing test strips has a real advange over strick doubling steps like 10, 20, 40. I tend to think it's more complicated and less accurate.

  5. #25
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    A little word about this subject. I haved used both of them and both can give more or less contrast or grain, depending of the recipe used. Maybe trix can be more pushable than the hp5. On the other hand, I prefer the no-curly hp5 film and its transparent base, while the trix is curly and has a purple base (anti-halo) that cannot be entirely removed even with a pre-wash.
    It's only me.

  6. #26
    polyglot's Avatar
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    Quote Originally Posted by Lionel1972 View Post
    Yes you're right, it doesn"t seem that accurate doubling of time steps is very critical. So I don't think using 2.8, 5.6, 11, 22 for printing test strips has a real advange over strick doubling steps like 10, 20, 40. I tend to think it's more complicated and less accurate.
    Negative exposure at least can be pretty sloppy, so earlier cameras could happily get away with pretty coarse speed spacings. Especially when you consider that mechanical shutters can be off by quite a significant margin. However if you look at a modern(ish) electronic camera like my RZ, the shutter speeds are 8, 4, 2, 1, 1/2, 1/4, 1/8, 1/15, 1/30, 1/60, 1/125, 1/250, 1/400. Those values are nominal I suspect because no one really wants to see 1/32, 1/64, 1/128 and 1/256 on their dial; other than that the values are pretty much exactly powers of two. 1/400 is the odd duck just because the shutter physically can't do 1/500.

    In terms of printing, there's absolutely no benefit to using the 2.8, 5.6, 11 sequence over the 2, 4, 8 sequence - both are spaced by factors of two (whole stops). I was suggesting you use 2.8, 4, 5.6, 8, 11, etc, which gives you half-stop steps. In my experience, half-stop steps are a good way to do a test strip at moderate (grade 2 or 3) contrasts. 8 steps of half stop covers a LOT of exposure range (e.g. 4s to 45s) to get you in the ballpark even with an uncertain negative. Once you get more confident, you'll find yourself doing 4-step strips at 1/4 stop intervals.

    There is nothing special about the sequences I've illustrated, they're just (IMHO) the easiest ones because they're powers of two. You could just as reasonably use 5, 7, 10, 14, 20, 28, 40: still separated by a factor of sqrt(2) and therefore at half-stop spacing. You'll look at your strip, maybe you like one exposure, maybe want to go somewhere between two steps for a bit better rendition of subtle highlights. If so, you can so a second test-strip spanning the gap between two previous exposures. Say you like the look of the 11s and 16s exposures. You might want to try 1/8 stop steps: 11.3, 12.3, 13.5, 14.7, 16s. Yes, that's getting into finicky times but once you start doing fine prints at higher grades, you'll find that you need to be that finicky to ride the balance on highlights. With such fine exposure spacings though, there is very little benefit to doing exact logarithmic timing unless you're using an f/stop timer; you might as well use 11.5, 12.6, 13.7, 14.8, 15.9 or whatever.

  7. #27
    Steve Smith's Avatar
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    Quote Originally Posted by Lionel1972 View Post
    I don't think using 2.8, 5.6, 11, 22 for printing test strips has a real advange over strick doubling steps like 10, 20, 40.
    There is no advantage as what you are doing is perfectly correct as far as f stop printing method is concerned. You are doubling the time for each step.

    The traditional method of doing test strips is to increase by a fixed amount, usually 10 seconds, so the sequence would be 10, 20, 30, 40, 50, 60. In that case the difference between the first two exposures is 100% whereas the difference between the last two exposures is only 20%.

    The further you go up just adding 10 seconds at a time, the less the difference compared to the previous exposure.

    Quote Originally Posted by Photo-gear View Post
    A little word about this subject. I haved used both of them and both can give more or less contrast or grain, depending of the recipe used.
    Oh yes. This thread was about comparing Tri X with HP5+!


    Steve.
    Last edited by Steve Smith; 07-23-2012 at 08:58 AM. Click to view previous post history.
    "People who say things won't work are a dime a dozen. People who figure out how to make things work are worth a fortune" - Dave Rat.

  8. #28
    Thomas Bertilsson's Avatar
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    As many have said before, you need to get the film developed to the same contrast as your Tri-X film before you can start comparing them.

    The reason for this is that you cannot identify differences in tonality between the two films until your highlight and shadow points are in the same place. While films have an inherent level of contrast, how you develop your film determines what contrast your final negative will have (because the final result is more a function of how long you develop the film, developer dilution, agitation, and temperature). This is why coming up with developing times that work for your paper and paper developer is so utterly important. This takes observation in the area of contrast levels of the light you're photographing in, how to expose your film based on that, and finally how to process the film to compensate for BOTH. And never lose sight of the fact that you develop film to make sure the recorded tone scale fits the paper - that is how it's intended to work, not the other way around, (which is commonly seen), where printers try to wrestle the paper around the qualities of the negative.

    -------------------------------------

    Now, about developer - I use replenished Xtol, and up until I tried HP5+ in earnest (about 20 rolls), I was under the impression I could make every film work in that developer. But I discovered that I don't like how the grain looks using Xtol, replenished or not. But I bought a bottle of Ilfotec DD-X, and all of a sudden I had negatives I liked again. Go figure.

    ------------------------------------------------------------------

    About f-stop printing. It is confusing to think of it in terms of f-stops. I prefer to think of it as doubling your exposure every time you expose a new area of your test strip. 2s, 4s, 8s, 16s, 32s, and longer if you like really dense negatives (I like really dense negatives).
    The benefit is that in the lightest and darkest stripes of your test strip, you see things you wouldn't have come near with your regular approach. Highlights that sparkle, and really deep black shadows you otherwise would not have noticed - it makes you see a wider spectrum of versions of the same negative.

    The recommendation is - try harder and you will find that HP5+ and Tri-X are a lot more similar than they are different.
    "Often moments come looking for us". - Robert Frank

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  9. #29
    ChristopherCoy's Avatar
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    Quote Originally Posted by Photo-gear View Post
    On the other hand, I prefer the no-curly hp5 film and its transparent base, while the trix is curly and has a purple base (anti-halo) that cannot be entirely removed even with a pre-wash.
    It's only me.

    It's supposed to be clear? Cause my two rolls arent clear... By any stretch of the imagination.

  10. #30
    Jim Noel's Avatar
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    HP5+ is faster and sharper. Your more dense negatives are the result of it being faster than Tri-X. A set of good tests will show it to be 2/3 to 1 stop faster than Tri-X dependent on choice of developer and processing method.
    [FONT=Comic Sans MS]Films NOT Dead - Just getting fixed![/FONT]

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