I guess a "primary blue" filter (Wratten #47B) should give basically the effect of a blue-sensitive-only film. To get faux-orthochromatic, you'd need more of a "minus red", which apparently is Wratten #44A.Quote:
Originally Posted by jnanian
-NT
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I guess a "primary blue" filter (Wratten #47B) should give basically the effect of a blue-sensitive-only film. To get faux-orthochromatic, you'd need more of a "minus red", which apparently is Wratten #44A.Quote:
Originally Posted by jnanian
-NT
A colour temperature correction filter, used for tungsten light with daylight film (80A), will work too.
It's something many people may already have.
But you are still wrong :(. Blue filter on pan film naturally passes only blue, and thus "emulates" blue-only sensitive film, not an ortho film. Ortho film is sensitive to wavelengths from blue to green, so to emulate it with pan film, you need a filter that passes wavelengths from blue to green, and stops (absorbs) wavelengths from yellow to red -- that is a cyan filter.Quote:
Originally Posted by Michael R 1974
Blue filter would give a much more dramatic visual effect on BW image, especially with skin tones. It's definitely not "ortho" look, but more drastic. For ortho look, just go with cyan. You also lose less speed that with blue.
i realized early on into this thread that i was saying "ortho" when i meant something different ..
i meant blue sensitive ( only!) orthochromatic ( not sensitized with dye ) film, like pre-1870s plates ... the baseline .
at present i am shooting paper negatives, a lot of them, and i was wondering if there was a
film equivalent to my paper negatives ... some of the papers i shoot are vc, and some are graded..
i also do some UV exposures, ... so in the end maybe just a bluish ( i will have to experiment, dark , light, greenish/cyanish )
and filter might works best.
as chemical photography marches forward, it seems that we are going backwards at the same time ..
i kind of hope that down the road there is a manufacturer of just plain old blue sensitive ortho film / plates
instead of pan film. i know it is inferior, and difficult to harness the contrast, and "deal with" because
of its slowness ( dyes increase the speed ) but it would be kind of nice to see a drastic change.
instead of chemical photography trying to keep up all the BS that the digi folks want us to worry about,
( we've already lost color image making to the computer ) i'd like to hunker down
and get back to the roots of photography. i know i am probably a minority,
but images from that early time period seem to be much more interesting than
things made in the last 100 years ...
thanks again for all your help, suggestions and information / education ..
john
Quote:
Originally Posted by jnanian
So I think my original guess regarding the general look you were after was on the right track. I'd then say a tricolor blue (wratten 47 or 47B) would simulate the effect well as it "cuts" pretty much everything but blue. You'll get those characteristic bleak-white skies, accentuated atmospheric haze and open shadows under daylight. The 47B is darker than the 47 but might be overkill and not add much other than lengthening exposure time.
On the other hand if you are also currently using VC paper for negatives, sensitivity is to blue and green so I guess you'd need more of a blue-green filter (wratten 44A is the only one I can think of). There is also a 44 which is similar to the 44A in the visible spectrum but is designed to also absorb UV light, so that's obviously no good if you're doing UV exposures.
I just realized I basically repeated what ntenny said. Sorry for the duplication.
Not really. These high pass filters have a rather soft transition as opposed to low pass filters (IR, red, orange, yellow). So there is some green and even red passing though.Quote:
Originally Posted by hrst
See curve "Blau 38":
http://www.heliopan.de/images/produk...ugruengelb.gif
These are not the tricolor cutting filters though.
Well yes, the filter you show is not "blue", but more likely "light cyan-blue". It is probably meant for coloring tungsten light sources to give an impression of "blue" compared to unfiltered light. The reason why it passes so much green and even red is to increase light output level for tungsten light sources that are low in blue wavelengths. In fact, that curve is quite close to 80A color temperature conversion filter! No, it's probably more close to 80B or even 80C. There's so much red passed.Quote:
Originally Posted by ath
There are also real blue filters available, and when I speak about blue filter, I really mean blue filter.
No, this filter is advertized as blue filter for b&w and not as correction filter. This is from Heliopan using Schott glass. Older B&W filter catalogs show similar curves for the blue filter.Quote:
Originally Posted by hrst
I found much narrower response for wratten gel filters but even these went up to 500nm. IDK if these are available as glass filters.