Gast
Hi everyone,
Can any of you explain to me what’s so special about split exposure?
Various experts claim that you can use it (e.g. through heavy post-exposure) to create a curved or kinked gradation curve.
Since I’ve always assumed that the resulting gradient depends entirely on the ratio of the light quantities (integral, i.e. time times light intensity) of blue and green light, why is a (in this case blue) re-exposure any different from simply using a different filter???
Or, if that’s true, how do even gradients other than 00 and 5 come about in the first place? Can I even achieve even intermediate gradients with a blue/green light source?????
Thanks in advance for the clarification,
Martin :D
Urnes
Hi Martin,
I’m just having a bit of fun with gradation curves and green and blue light at the moment. I have an image that’s exposed pretty much perfectly at Level 3. The only thing is, the sky could do with a bit more exposure. However, that’s tricky because there are a few trees sticking up into the sky. So I’m giving the whole image a bit more exposure at Level 0. At level 0, the density initially increases in the bright areas (the sky), whilst nothing happens in the dark areas because they’re already dark. This saves me the trouble of laboriously masking the trees that extend into the sky. If I do notice an unwanted increase in the shadows, I simply reduce the exposure time slightly at level 3. There are, however, a few books that cover this topic more or less exhaustively. If you’d like the titles, just let me know.
Regards, Sven.
Gast
Got it!
I assume old Ansel (the positive one) isn't in there, is he?
Thanks in advance
Martin
Gast
gruebelgruebel, :D
Now you’ve got me confused. So I can’t just replace the two exposures with a SINGLE exposure using a filter with the appropriate average? (As would be possible, for example, with a colour mixing head... wouldn’t it?)
Regards, Claus
Urnes
Hi Martin,
No, that’s not in Adams’ *positive*. He worked with the zone system and therefore only used fixed-grade paper. You can find this in Andreas Weidner’s book *Workshop*.
As for split grades, I’ve found two books:
Workshop Monochrom by Worobiec/Spence, published by Augustusverlag
Split grades are covered in the introductory section over three or four pages. Otherwise, it’s a very good book on alternative printing and toning processes.
And:
Larry Bartlett’s Photographic Printing Workshop
(I believe the German title is *Workshop Schwarz-Weiss Fotografie*; I got the English edition quite cheaply at the time and only have a German copy for reference, from which the title isn’t clear)
It should also be published by Augustusverlag.
There are two pages on split-grade printing in it. However, it’s now more of a book on the topic of how to achieve a good print using post-exposure and so on; otherwise, it consists of quite a lot of sample images, which are then explained in terms of how they are processed, and split-grade printing is frequently mentioned there.
Hello Claus,
You can’t average the filter because you have different exposure times for each gradient, or you might only be working partially in one area or another. The company Heiland has developed a split-grade head where exposure is apparently only done at grade 5 and grade 0, and Mirko has always stated in his catalogue that pretty much anyone could produce fine art prints with it.
Regards, Sven.
Gast
Hi Sven,
I’ve got Worobiec/Spence, but there’s no answer to that question in there. I’ll have to have a look in Bartlett.
I don’t understand exactly what Claus is asking either. According to Mirko (www.splitgrade.de), two emulsions are cast onto VC paper: one blue-sensitive and hard, the other green-sensitive and soft. With a filter, I’m doing nothing other than altering the blue and green components. Since the density of the emulsion depends on the integral of the light (the image doesn’t become harder or softer with stopping down or extending the exposure time).
Either the paper behaves almost perfectly, in which case I should never be able to achieve a straight gradient except for very hard and very soft.
Or the intermediate colours (yellow) have an influence; in that case, I should only be able to achieve straight intermediate gradations with an opal bulb, but not with the split grade – with the split grade, almost all of them would have to be kinked. As I’ve ordered LEDs for Christmas – i.e. I want to build a very strict split light source – the question remains: will I ever get a straight 2 with it?
Let’s see what I can work out.
Regards
Martin
Let’s see where I can find some clarity.
Gast
Multigrade paper consists of emulsions that are sensitive to light of different wavelengths (i.e. different colours). It doesn’t matter whether these different wavelengths strike the paper simultaneously (as with Filter No. 3, for example) or in succession (as with split exposure using filters 0 and 5).
In this respect, without dodging and burning, there is no difference in the result between a single exposure with a medium gradient and a corresponding split exposure.
However:
- Of course, you can also set ‘uneven’ gradients with split exposure, such as 3.76 (though this is also possible with a colour head or Vario module).
- With single exposures using 0 and 5, you can selectively dodge/burn different areas and thus obtain an image that exhibits different gradients in different areas. You can, of course, also, for example, re-expose specific areas with grade 4 on an image that has been base-exposed with grade 2. However, this is then almost equivalent to split grades, only with fewer ‘pure’ wavelengths.
- Using only 0 and 5 can help with some subjects to work towards the final result in a more targeted way, because it is easier to see which areas need to be hard or soft in terms of exposure or blocked out.
Overall, split-grade (manual or Heiland) is therefore ‘just’ another, more systematic method of achieving a result that could also be attained by trial and error.
Regards, Jens
Gast
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I’ve always understood a curved or kinked gradation curve to mean something else:
By using filters – whether on a colour-mixing head, a condenser or an LED (which colour, exactly?) – I can select the gradation curves depending on the paper; some people call this ‘shifting’. With split-grade (base exposure once very soft + once very hard), this actually(!) amounts to the same thing. But some swear by exposing them one after the other; it’s said to give a more defined/better dynamic range. I saw this quite clearly when testing it – and the next day couldn’t tell the two prints apart. :blink:
But if ‘split-grade’ refers to re-exposing with a harder or softer gradient, you actually have a massive influence on the shape of the curve! If you imagine a textbook S-curve (in a normal print), you have a relatively flat shoulder in the highlights. But if, for example, you re-expose a dull cloudy sky more dramatically with two additional gradients, you increase the contrast precisely (and only in this part of the curve) in the otherwise flat shoulder. This cannot be achieved even with irregular filter values. Even a two-bath developer manipulation isn’t the same, even if it’s in the same direction.
That’s how I’ve explained it to myself. Perhaps it’s right.
My favourite book on the subject is “The Variable Contrast Printing Manual” by Steve Anchell. FOTOIMPEX also stocks his “Darkroom Cookbook”.
Anchell distinguishes between “Multiple-Filter Techniques” and “Split Printing”
