Infrared Konica 750nm processing

Dear All,

Hi, I have a question about Infrared film. I was out in Wyoming filming with my Holga camera. I shot 4 rolls of 120mm film - Expired Infrared 750nm that I had stored in my fridge for several years. I shot on my plastic holga on Bulb setting with an approximate of 1 second in bright bright daylight in the open plains of wyoming. I used a 46mm IR NM filter that looks opaque black unless you point it to bright light. There was one roll that where I opened the back chamber to check and see if I had advanced the film properly (I sealed up the back of the camera to prevent light leaks so I could only guess whether I was on the right frame by advancing the frame 34 clicks). I placed the film back in an aluminum wrapper, but did not put it in a black bag. I made sure that when flying back to NYC that the film did not go through the x ray machine. *I read somewhere that 750 nm is actually not that senstive and will not fog if you do not put it in a black bag...

 

So I brought my film to a lab that processes black and white film. The lab has a dip and dunk machine and I explicitly said they must turn off any lights that emit infrared light. They said okay.

 

The rolls (I only have 2 / 4 processed so far) came back completely transparent, except for 1 roll that had a dark frame that seemed to suggest the moment when I opened the back chamber to see if the roll was finished. I cannot imagine that the roll was not exposed at all... or 2 rolls were completely fogged to be transparent.

*Sorry I am a bit confused as to whether the film roll of 120mm 750 konica nm infrared is negative or positive. I am inclined to believe that it is positive, which means if the film was exposed, the roll would turn black.

 

The clear rolls have the frame number and the edge dma8 (is that what you call it)? Which the lab claims is proof that they processed the film okay. So... It's all a bit of mystery to me - either -- the infrared filter was so dark that I should have had the holga camera set to bulb and exposed for more than 1 second in bright daylight ... or the lab did something wrong with processing (which means I might have a chance at saving the images if I sent it to another lab)... or the film got fogged when in transport traveling from wyoming to nyc. Still, why would 2 rolls not yield any images at all? I could have sworn my film was exposed in the bright sun of wyoming!

 

thanks so much

Lili

The usual IR filter is 720nm, but there are others.

 

As far as I know, the film you have is negative, so clear is unexposed, and black is exposed.

 

Between 720nm and 750nm isn't all that much, but it should be enough to get a non-clear negative.

 

But if you filter is 780nm, then clear is probably right.

Yeah, Konica 750 nm barely qualifies as an infrared film since its sensitivity barely goes beyond the red end of the spectrum. With the proper filter (and I think Glen is correct about the 720 nm filter) this film can produce impressive results without being as finicky to handle as the films that go deeper into the infrared spectrum.

From the situation described I would think there would be some images unless the camera is not functioning properly.

Thanks for all the response. So, is there any chance a cheap IR720 filter from Hong Kong (16usd vs 77usd for the hoya) could have been so opaque that no image would be visible / there would be a clear negative?)... Or is it more likely that the lab developed the infrared film incorrectly using a black and white dip and dunk method that was not appropriate to infrared film?

best

Lili

Is it a 720 filter, or something else?

 

The eye has enough sensitivity at 720nm that you should be able to see, though just barely, through one.

That is, really really really dark red.

 

I have a Chinese 720 filter that I have used on digital cameras, but so far not with film.

I can see enough in sunlight to point in the right direction, and exposure is possible hand held, though

not too easy. Between the rising edge of the filter, and the built-in IR block filter in the camera,

there is just enough to get pictures.

 

Since you see frame numbers, but no images, it sounds like there was no exposure, within the sensitivity of the film,

but that processing was correct.

 

Asking the lab about IR is good, as some processing machinery does use IR for film tracking.

The data sheet is here:

 

http://photo-element.ru/book/pseudo_ir/ir_films/KONICA_inf_750.pdf

 

note that it is not green sensitive, but is from about 680 to 800 nm.

 

Normal uses is with a red filter, which blocks the blue sensitive range, but allows the full IR range.

 

From that graph, I would expect a 720nm filter to work fine, but you might have something else.

 

Neewer 4 Pieces 52MM Infrared Filters IR720,IR760,IR850,IR950 with Pouch | eBay

 

is a kit with 720, 760, 850, and 950nm IR filters.

 

If you have one of the latter two, you won't see anything.

 

I suppose it is possibly mislabeled, though.

http://wwwuk.kodak.com/global/en/professional/support/techPubs/f13/f13.pdf

 

is the data sheet for the Kodak film discontinued 10 years ago.

 

You can see that it goes to about 900nm.

 

It also has the transmission data for some popular filters, such as the 87,

which is the one traditionally used with this film, and which blocks most

of the spectrum your film is sensitive to.

I have a roll of the Rollei film:

 

https://www.foto-r3.com/files/Rollei_Infrared400_ING.pdf

 

note that they claim 820nm, but that it falls pretty fast before that, so 750nm is probably

a better indication.

 

This is a panchromatic film, so green and full red sensitive.

 

I suspect more and more that you don't have a 720nm filter.

Dear All,

Thank you for all the advice. I went out and shot a roll of this film with an orange filter and without a filter and also with the infrared IR 720 filter. Based on the specs of the Konica film, I am beginning to suspect that the film cannot handle the IR 720 filter - it is far too opaque and if the film speed has an average asa 72, then - with the opaque black IR 720 filter, It's highly possible there would be no exposure. The last rolls that yielded images from a few years ago were when I shot with a red filter, not a specifically IR 720 filter. I'll keep you posted when I get the test roll back from the lab! - I just am interested to know what is the difference between using a cheap red filter on konica IR film vs using an IR 720 filter ?

Thanks, Lili

Kodak IR (non high speed) is blue plus IR. It is usual to use a red filter.

 

Kodak HIE is panchromatic plus IR. A red filter will allow red, which the film is sensitive to.

 

Konika 820 is blue plus IR, though it may go up into the red.

 

Human vision is commonly considered 400 to 700, but the tail is long.

 

With enough intensity, you can see somewhat past 700, even 740 or 750.

Hi All,

I got my film back from the lab - the test roll. I shot a few images without the filter at apx 4 sec bulb (holga shutter), a few shots with an orange filter and a few shots with the infrared IR 720 opaque filter. The strange results yield this - i get a faint image with the orange filter, but it's mostly clear with speckles of black. (from the sky surrounding tree folliage)... Most of the roll was clear! My question is this - I am getting very confused. If the roll of this Konica is clear, does this mean that I did not expose the film for long enough (4 seconds / some shots were double exposed and were still clear)... Or... That the images were exposed for too long! I got a very faint 'something' with an orange filter... this film is super expired (yes, I know I shouldn't but I do, the film is from 2000 but has been sitting in the fridge). I know the camera works with Black and White and Ektrachrome because the lab processed that... OR do you think their developing times on the infrared were set for too long.

I still have 2 rolls of infrared I have not processed and shot in Wyoming, and I am fearful if I do, it will be clear again . Furthermore, I would still like to continue to shoot infrared because I have this unsused film, and would prefer not to toss it. I just need to figure out if I should be giving 15 second exposures on a clear or cloudy day.... instead of 4 second exposures

 

Thanks so much

Lili

If I'm understanding, you shot some shots without filter but most of roll was clear? Without filter the Konica film should be able to produce images at normal shutter speeds. Without a filter this film is basically panchromatic plus extended red sensitivity and a little infrared sensitivity. Without a filter it's fast enough that a Holga would probably overexpose the film on a sunny day, especially since sunlight contains plenty of infrared in addition to visible light.

Yes, This much I understand. However, what I am confused about - because it is infrared, is -- when the roll comes out clear - does this mean the film was overexposed or underexposed? When it comes out black, does it mean it was not exposed or it was overexposed? Am I looking at a positive reversal roll after processing and development, or am I looking at a negative? Both make a huge difference in terms of how to read the whites(clear) and blacks.

thanks so much,

lili

Clear means underexposed for negative films.

 

Reversal processing of black and white films is possible, but rare. I don't know any lab that would do it a without specific request, and even then most won't do it.

 

If the frame numbering comes through, then processing is correct. Also, the edges (outside the actual image area) will be unexposed, so again you can test.

 

Otherwise, I am running out of suggestions. Maybe the shutter doesn't work?

Oh, also, old films tend to fog, so get darker, not lighter. (Lighter for reversal films.)

 

I suspect your film isn't so old. IR films are more sensitive, but this doesn't go so much father than other panchromatic films.

 

HIE you are supposed to keep refrigerated.