I'm an AmeriCANThis intrigues me, this idea. I have had other silly ideas and as a result created an unencryptable file/data transfering system that is totally secure. I just haven't sold it yet. But if I stay in programming much longer I will. It's already to go past Alpha, and now sorta Beta except for user interface. Someone told me Perry leave it alone, you'll wrack your brain, more misery, don't do it, just rely on the same algorithms that the NSA invented
Anyway, I am looking into Infrared detectors. Photo-detectors is the broad name applied. Now this is stuff I can't do personally but I know engineers that would be able to take the detector and measure the radiant IR wherever you point it. Then based on that reading come up with a method for applying that raw data against some experimentation in order to develop an IR-reciprocity-index. Make sense? Doesn't take much energy to do my research. This place here looks interesting, but I'm only a software engineer, I don't understand these measurements to know if any one of their detectors could be used for this purpose.
Infrared Detector Manufacturer
I’d be interested in a real IR meter too. As said, it shouldn’t be very difficult to take apart a silicon diode meter and remove the IR attenuation filter and insert a band pass filter.
Not super easy either though.
Problem is, just normal metering and using experience on top works well enough most of the time to make a dedicated meter stay a dream.
perhaps one day we can whip out an IR light meter and set our cameras and know we're going to be darn near close and well within the respectable film latitude as some films are better suited than others.
The interesting question is, for pictorial photography, will you actually need a spot meter?
I'm struggling with the concept of over exposing making the highlights more highlight in the greenery. How does that work?
For the making of actual photographs, on film - no, you don't need a precision IR measuring instrument. That's overkill.
Turns out there's a meter already made. Making use of it for IR film photography will require some education though as it's a scientific instrument.
LaserCheck (RoHS)
Handheld low power meter, silicon photodiode, measure to 1W with switchable attenuator, spectral compensation.coherentinc.my.site.com
I discovered this because of a period of my career I consulted for a video surveillance company building surveillance systems for them and IR lighting is really involved in that industry, so I started poking around on search engines and found this article. It's intended for videography, not photography, and they have sensors that are more capable of measuring IR than say Ilford SFX which is why they can get footage even in pitch black.
How to Measure IR Illumination
Using IR for night time surveillance is a popular choice. The added non visible light can improve image quality when ambient street or visible lighting...ipvm.com
I've got a number of things I need to do before I get to this IR pinhole project, so I did the investigation to this point and putting it on the shelf so I can attend to some plans for my section hike later this month. I do intend on returning and doing more research and I'll just keep providing any more information that I gather along the way. If anyone else decides to add to this, please feel free. Those of us who are motivated to come up with a more or less reliable system of predicting the behavior of any specific scene using instruments can make this whole concept less of a mystery and more of a system or procedure, much like most photographers just whip out a light meter to set their cameras, perhaps one day we can whip out an IR light meter and set our cameras and know we're going to be darn near close and well within the respectable film latitude as some films are better suited than others.
I’d be interested in a real IR meter too. As said, it shouldn’t be very difficult to take apart a silicon diode meter and remove the IR attenuation filter and insert a band pass filter.
Not super easy either though.
Problem is, just normal metering and using experience on top works well enough most of the time to make a dedicated meter stay a dream.
I have had good success with internal and external reflectance meters for HIE and Rollei IR 400, both at ISO 400 and then adjusted for the red filter used.
Some situations can surprise. A forrest for example can be a lot more IR dense than you’d expect with the shade. Maybe because the foliage reflects IR. A field of grass can be very hard to judge.
Human subjects vary a lot, depending on a number of factors.
Because IR is inherently contrasty and IR film is often contrasty on top is easy to miss exposure completely in these situations.
Seems it’s an instrument meant for measuring laser power. I’d be very surprised if it worked for IR photography.
One strategy I’ve employed when I have time, is to photograph the scene with a phone through the relevant filter and measure with a light meter app afterwards.
Not perfect, but results in a visible assessment of the scene that isn’t too far off from then actual film photo.
The EXIF data isn’t much use.
View attachment 331036
I have had good success with internal and external reflectance meters for HIE and Rollei IR 400, both at ISO 400 and then adjusted for the red filter used.
Sure, me too. You need to meter.
But the discrepancy between shade and direct sun is unpredictable and doesn’t go with what the meter was made for.
A colour meter might be a good alternative to a real IR meter.
If the light is warm there is a likelyhood that it will contain IR. Foliage is still a problem through because the Woods effect onset quite abruptly at 700nm.
I had good results by letting an N/F80 meter through an R72. Even AF works, although it’s slow and wonky.
I am looking for the Wood Effect, not using the Zone System to get every bit of shadow detail possible. I use Red23, Red25, R3d29 and 720 filters.
You’ll get a hint of Woods with R29, but only full effect with R72.
Again even if you refuse it, visible light polarizers do actually work with the lower NIR,
and they work wonderfully for: Blackening the sky out completely, bringing reflections down on water, metal and finally to tone down Woods effect.
Polarizers could be used, but why use a tool which is not as effective. One could also use a lens cap, but then there would not be any Woods Effect.
Not as effective? It’s works as it does on visible spectrum.
Simple as that.
I’m interested in experimenting with Ilford SFX 120 in my Fuji GF670 rangefinder. Am I correct in assuming that I can focus as normal if using without filters but if I use an IR filter, the focus point will change? What about a red or orange filter?
How do I go about accurate focussing, as there is no infra red marking on the lens? I know I’ll more than likely be using smaller apertures anyway, so probably not important? Should I just use f22 and focus at infinity?
Also, if I’m using a red filter which needs an additional 3 stops exposure, I can just set the meter to ISO 25 And develop normally?
I’m interested in experimenting with Ilford SFX 120 in my Fuji GF670 rangefinder. Am I correct in assuming that I can focus as normal if using without filters but if I use an IR filter, the focus point will change? What about a red or orange filter?
How do I go about accurate focussing, as there is no infra red marking on the lens? I know I’ll more than likely be using smaller apertures anyway, so probably not important? Should I just use f22 and focus at infinity?
Also, if I’m using a red filter which needs an additional 3 stops exposure, I can just set the meter to ISO 25 And develop normally?
As Sirius says, the film isn't sensitive to light that is far enough into infra-red to make it necessary to adjust the focus.
A red filter will give you a sort of "infra-red look". A 720nm filter will give you much more Wood Effect, while requiring much more exposure in order to compensate for the almost opaque filter.
When you take most of the visual spectrum light away with the 720nm filter, the contrast and Subject Luminance Range is changed a fair bit. Normal development tends to work best for me, but I tend to use this film in high overcast conditions - not bright sun.
This post may be useful for you:
https://www.photrio.com/forum/threads/choices-for-ir-film.174757/#post-2273526
Thank you for the info. Would the same apply to Rollei Infrared 400 (except the ISO rating). Just seen the price of Ilford SFX in the UK and it’s nearly twice the price of Rollei Infrared. Think I might try the Rollei first to experiment.
I prefer IR400, but it’s not 400. Closer to 160 probably. But the rating with a 720 filter is about the same. IE 10. Plenty fast for handheld in full sun.
It’s contrastier and finer grained than SFX.
Use a 40.5mm filter in the hood.
This is probably good: https://www.ebay.com/itm/4038950455...De7EmQ6S-q&var=&widget_ver=artemis&media=COPY
Never had problems with Chinese IR filters.
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