lonesome_dave Posted November 27, 2023 Share Posted November 27, 2023 After spending a year or so experimenting with IR photography I obtained a Tiffen 18A filter for UV photography. It had a similar pass spectrum to the modern day ZWB1 filter with maybe a later cut-on above 300nm. They both have a good UV-A passband but also an IR passband that extends into the deep red. I decided to use a non-panchromatic film (little or no red sensitivity) that was just sensitive to blue & green to get a 'pure' UV image. I had a roll of Kodak SO-410 film which was used for photomicrography and imaging phosphor screens like oscilloscopes and radar screens that were blue or green. I did several VIS/UV comparison shots on an old Agfa rangefinder camera to see what the differences were. To keep the bandwidths about the same I used a #47 blue filter for the VIS photos. Unfortunately I was unable to locate the matching UV & VIS negatives for most of them. Here is one set from my photo album (remember those?) that I can't find the negs for. Left pic is with the #47 blue filter and right pic is with the 18A. These show a mountain about 2 miles away that gets very hazy in the UV pic. Apparently evidence of the extra Rayleigh scattering of UV. The only set of matching VIS and UV negs I could find are the recent scans I just made below. First one is blue VIS and second one is UV-A. If you download these last two pics you can do a 'blink' test and see the different haze effect between Blue and UV-A more clearly. Aside from a few indoor tests with spectrum tubes shortly afterwards I lost interest in UV photography. Compared to the general darkening and increased haze in UV, IR photography offered haze penetration and a magical brightened rendition of vegetation. The adventure of color IR film was also a huge attraction. Only in recent years did I get interested in UV photography again thanks largely to this site and the many contributors here. Link to comment
colinbm Posted November 27, 2023 Share Posted November 27, 2023 It is the opposite for landscape & macro photography in UV & IR. As you can see in your landscape photos in IR. But in UV macro the UV is much sharper them macro IR. Link to comment
dabateman Posted November 28, 2023 Share Posted November 28, 2023 Very interesting. Too bad you didn't have a patch of dandelions there. It might have sparked your interest in floral signatures. Link to comment
lonesome_dave Posted November 30, 2023 Author Share Posted November 30, 2023 Yes I agree UV Photography is best done at macro and micro ranges. Not the best for landscapes. But you could lean into the haze effect like I did HERE with a false-color UV rendition earlier this year. Link to comment
DKoch Posted December 3, 2023 Share Posted December 3, 2023 i must dig up an old UV photo or two when I'm back in the city... they are B&W polaroids! Type 667 , ( ISO 3200).From the 80s I just simply put my 3"x 3" Kodak 18A glass filter in front of my manual polaroid camera ( a Polaroid/Mamiya). Didn't seem to need any focus compensation and exposure was a wild guess! Photochemical monochrome UV was so easy compared to digital.. An odd thing I ran into once: my confidence in UV imaging with the 18A filter made me once try it on a music video we were filming with Kodak Plus X B&W negative film. It was a sunny day with blue sky and we had the camera locked off . We first shot with a 29 deep red filter and polarizer yielding very dark blue skies and great distant haze penetration.Then we switched to the 18A UV filter and shot some more...the idea was we could cut or dissolve between the wildly different renditions of the same scene unfortunately, in the dailies we found that the UV version was completely out of focus! Not soft, completely uselessly out of focus. We were shooting in 16mm motion picture , so the focal lengths we use are quite short; the lenses was a Zeiss 10-100mm f2 and we were at 10mm and wide open at f2 or 2.8... I suspect that the short focal length was the culprit.a 10mm lens may have enormous depth of field in the subject, but very shallow "depth of focus" at the film/sensor plane... clearly the UV correction was horrendous in that very complex zoom lens. Obviously all that glass and the coatings were attenuating most of the UV; we were shooting a ISO 64 film in full sun at f2!!! Link to comment
DKoch Posted December 4, 2023 Share Posted December 4, 2023 here's a sketchy old scan from a Polaroid from around 1991...Polaroid type 667 with Kodak 18A filter... you can really see how the whites of the eyes stayed really bright but the skin tone darkened a lot Link to comment
lukaszgryglicki Posted December 4, 2023 Share Posted December 4, 2023 WOW - looking good! Link to comment
lonesome_dave Posted December 4, 2023 Author Share Posted December 4, 2023 Great image DKoch. Like most high-speed films Polaroid 667 did have extended red sensitivity but I don't see any evidence of IR contamination from the 18A IR passband in your photo. Below is the spectral response curve pulled from the Polaroid 667 data sheet. There is a nice bump right in the UV-A. Link to comment
DKoch Posted December 5, 2023 Share Posted December 5, 2023 On 12/4/2023 at 1:15 PM, lonesome_dave said: Great image DKoch. Like most high-speed films Polaroid 667 did have extended red sensitivity but I don't see any evidence of IR contamination from the 18A IR passband in your photo. Below is the spectral response curve pulled from the Polaroid 667 data sheet. There is a nice bump right in the UV-A. yes, it looks like the centre of the generally bad IR leakage for the 18A peaks around 740nm, so this film is quite blind to it. I remember back in the day, I was aware of the IR leak in this filter, but it just seemed unimportant as our films couldn't see it... I shot a lot of Kodak B&W IR film in 35mm motion picture back in the 90s. I would sometimes use an IR cutoff filter to convert this strange film stock into a Panchromatic stock; we wanted normal tonal rendition (especially of skin tone) but loved the weird heavy halation in overexposed areas due to the lack of an anti-halation backing. I think that a few of the qualities that people would attribute to the IR with this stock were actually structural in nature and not actually due to the IR light. Link to comment
lonesome_dave Posted December 6, 2023 Author Share Posted December 6, 2023 You're right about that halo effect in bright areas being a signature of HIE. Several folks on this board have commented about that with regard to digital IR compared to that film. My post of Konica 750 images HERE shows how dull that film looked in comparison as well. Link to comment
DKoch Posted December 12, 2023 Share Posted December 12, 2023 On 12/5/2023 at 7:01 PM, lonesome_dave said: You're right about that halo effect in bright areas being a signature of HIE. Several folks on this board have commented about that with regard to digital IR compared to that film. My post of Konica 750 images HERE shows how dull that film looked in comparison as well. it was very weird: the film stock overall was 50% thinner than ordinary B&W films.It was on an indestructible Estar base. I remember numerous times shooting high speed ( 120 frames /sec) with the IR film and we always had a hand on the camera's run switch; if there was a film jam, the IR film base was so strong , the camera could be damaged before the film would break! Apparently the emulsion was laid on pretty thick and of course the lack of an annihilation backing caused massive glow in overexposed areas. when properly filtered to aa purely orthochromatic spectral response (UV-green), the films photographic look was excellent for replicating really old photographic processes! Link to comment
lonesome_dave Posted December 13, 2023 Author Share Posted December 13, 2023 That's really interesting. It never occurred to me to try using HIE outside of the infrared band. My main memory of that film is how much trouble it was to handle for processing & printing. It was so thin it curled up like crazy when trying to load it onto a developing reel (in total darkness). Getting it flat enough for sharp prints usually involved a glass sandwich. The HIE film strips I have today are still curled after flat storage for decades. Link to comment
photoni Posted December 13, 2023 Share Posted December 13, 2023 . There has recently been a new orthochromatic photographic film... Foma Ortho 400 in 120 format (6x6 cm etc.) it is much more sensitive than the Agfa 25 and Ilford 80 iso. as always the characteristic curves are not very accurate before 400 nm. The strange thing is that all normal and infrared films seem... equally sensitive to UV. Some time ago I also tried a Rollei infrared, it works well with the Hoya R72 filter (>720 nm) and also well with UV filters . Below I have placed a table obtained from the PDFs of the individual films . Link to comment
DKoch Posted December 13, 2023 Share Posted December 13, 2023 8 hours ago, photoni said: . There has recently been a new orthochromatic photographic film... Foma Ortho 400 in 120 format (6x6 cm etc.) it is much more sensitive than the Agfa 25 and Ilford 80 iso. as always the characteristic curves are not very accurate before 400 nm. The strange thing is that all normal and infrared films seem... equally sensitive to UV. Some time ago I also tried a Rollei infrared, it works well with the Hoya R72 filter (>720 nm) and also well with UV filters . Below I have placed a table obtained from the PDFs of the individual films . wow, these "IR" films don't reach out very far compared to Kodak IR! I think we filtered the Kodak film with the Kodak gelatine 87 series...right out to around 900nm and got exposures. Link to comment
photoni Posted December 13, 2023 Share Posted December 13, 2023 2 hours ago, DKoch said: wow, these "IR" films don't reach out very far compared to Kodak IR! I think we filtered the Kodak film with the Kodak gelatine 87 series...right out to around 900nm and got exposures. I have gelatin filters 75x75 mm (Wratten 87 ~ 740 nm) and one (87c ~ 790 nm) if I remember correctly... the first one works well with the Rollei IR, it is very similar to Hoya R72, the second 87c doesn't. Today there are no black and white films with the sensitivity (and ghosts) of the Kodak IR :) . Link to comment
lonesome_dave Posted December 14, 2023 Author Share Posted December 14, 2023 Spectral sensitivity of Kodak High Speed Infrared (HIE). Link to comment
Andrea B. Posted December 15, 2023 Share Posted December 15, 2023 I have added a Film tag to this discussion. So much knowledge is being lost with the decline of film usage. I hope it is all being documented in an IR or UV Film History somewhere! Link to comment
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