How to shoot Ilford SFX 200 the most effectively?

Patrick Robert James · Feb 25, 2023

Helge said:
There is a misunderstanding that near infrared is not true infrared.
It absolutely is.
Anything over 700 nm is well and truly infrared.
IR is just such a large band up to microwaves, that it has to be split up into near, medium and far IR.
Wood effect starts right around 700 and Rayleigh effect has planed off about as much as it will there too.

I quoteth Ilford, who knows more than you-

"It has extended red sensitivity (up to 740nm)"

Go ahead and slap that 87 filter on there skippy and see how long your exposures get....

john_s · Feb 26, 2023

Patrick Robert James said:
I quoteth Ilford,

Incorrect use of the -eth verb ending.

Helge · Feb 26, 2023

Patrick Robert James said:
I quoteth Ilford, who knows more than you-

"It has extended red sensitivity (up to 740nm)"

Go ahead and slap that 87 filter on there skippy and see how long your exposures get....

Red sensitivity can include IR.

There is some of advantages to these type of IR film.
- They are not very particular about loading and unloading.
- You are not forced to pure IR for a whole roll. You can scale the effect however you like.
- You don’t need focus correction.
- They are not affected by SLRs with IR sprocket counters.

That said, something like the Konica IR film would be very welcome.
A film with a hole in the response where green and red would normally be. And then proper extension to 780 or so.
Still a slow film. But I guess that is the nature of the beast, unless it’s HIE that uses every trick in the book and compromises in a lot of places.
Speed of Konica IR was not faster than current emulsions. And was only about 32 filterless.

Perry Way · Feb 26, 2023

Hey guys, I'm kind of surprised to see this here since I've only been back here after a decade of hiatus only to find the same misery taking over here as is on social media.

This was my thread and now a few people have bombed it with sour attitudes and verve.

Please people, I just paid for this site again after years. Do I have to ask for a refund already?

Try to be human with one another and stop measuring your dicks please.

Helge · Feb 26, 2023

Perry Way said:
Hey guys, I'm kind of surprised to see this here since I've only been back here after a decade of hiatus only to find the same misery taking over here as is on social media.

This was my thread and now a few people have bombed it with sour attitudes and verve.

Please people, I just paid for this site again after years. Do I have to ask for a refund already?

Try to be human with one another and stop measuring your dicks please.

What exactly are you referring to?

Perry Way · Feb 26, 2023

Helge said:
What exactly are you referring to?

I'm not here to confront. Only to say that social media has ruined it for me over the past I dunno... n number of years. And I see the same things happening here on many posts and then on this thread there is some of that. We're here out of a love of photography and light and expression. Not the need to be right at the cost of others sensibilities, right?

Helge · Feb 26, 2023

Perry Way said:
I'm not here to confront. Only to say that social media has ruined it for me over the past I dunno... n number of years. And I see the same things happening here on many posts and then on this thread there is some of that. We're here out of a love of photography and light and expression. Not the need to be right at the cost of others sensibilities, right?

What? You need to be super specific otherwise it’s just handwaving accusations.
There is very little idle bickering here compared to other places.
It’s seems to me you are contributing meta bickering now.

MattKing · Feb 26, 2023

WOA folks.
On topic differences of opinion are not uncommon, and we don't moderate them unless they become uncivil.
While "Go ahead and slap that 87 filter on there skippy and see how long your exposures get...." is more flippant than might be ideal, the latter half of "Try to be human with one another and stop measuring your dicks please." isn't acceptable, both for word choice and for attempting to act as a moderator.
It is, however, always okay to post suggesting that the thread get back on topic. I wouldn't say though that a minor digression into comparing SFX with other IR films is a total digression - more the sort of wandering that sometimes helps, and sometimes doesn't.
If you think a post or posts should be moderated, don't respond to the issue in the thread - Report the post(s) using the report function.

Patrick Robert James · Feb 26, 2023

I should have slapped a smilie on the end of my post. Oh well. Here is one after the fact.

Helge · Feb 26, 2023

Patrick Robert James said:
I should have slapped a smilie on the end of my post. Oh well. Here is one after the fact.

I tought it implicit. Skippy, is that a ref to the kangaroo?

Patrick Robert James · Feb 26, 2023

Helge said:
I tought it implicit. Skippy, is that a ref to the kangaroo?

Nah, it is just a colloquial sort of a mild nickname for someone. Maybe it comes from skip ahead or over. It kind of has that sort of meaning. I'd for example say to my nephew if he was going to run out of the house without shoes on. Something like "whoah, slow your roll there skippy!" In other words, don't get ahead of yourself. Hope that makes sense.

Sirius Glass · Feb 26, 2023

Patrick Robert James said:
Nah, it is just a colloquial sort of a mild nickname for someone. Maybe it comes from skip ahead or over. It kind of has that sort of meaning. I'd for example say to my nephew if he was going to run out of the house without shoes on. Something like "whoah, slow your roll there skippy!" In other words, don't get ahead of yourself. Hope that makes sense.

Colloquial where? You do not show your location so there is no context for anyone but yourself.

Perry Way · Feb 27, 2023

Thank you everyone for your contributions. The funny thing is I think I'm still lost, but now more educated So the next step is to stop yappin' and start experimenting! Red25 to start, and if I want heavier effects, experiment with 72 or 89? I think the consensus is not 89 unless using actual infrared film not just infrared sensitive. The limit being 72 for that, and at the expense of a very long exposure time. Kinda sounds impossible unless I'm in a terrarium without a fan!

pentaxuser · Feb 27, 2023

Perry Way said:
Thank you everyone for your contributions. The funny thing is I think I'm still lost, but now more educated So the next step is to stop yappin' and start experimenting! Red25 to start, and if I want heavier effects, experiment with 72 or 89? I think the consensus is not 89 unless using actual infrared film not just infrared sensitive. The limit being 72 for that, and at the expense of a very long exposure time. Kinda sounds impossible unless I'm in a terrarium without a fan!

Sounds like a good idea, Perry and you might try retina restoration's idea of overexposing with a red 25 to see what difference that makes to the IR effect

Let us know how you get on and the best of luck

pentaxuser

Perry Way · Feb 27, 2023

pentaxuser said:
Sounds like a good idea, Perry and you might try retina restoration's idea of overexposing with a red 25 to see what difference that makes to the IR effect

Let us know how you get on and the best of luck

pentaxuser

Most assuredly I will definitely report back. This is going to be fun. My RSS 6x9 was delivered today but... I have to wait for that filter.

Perry Way · Feb 28, 2023

Maris said:
I shoot Ilford SFX 200 behind a #25 red filter at E.I. = 25 and at E.I. = 6 behind a IR720 filter.
The reciprocity failure correction number given by Ilford is 1.43. This means for measured exposure times more than a couple of seconds
take that measured exposure time to the power 1.43 to get the corrected time.
Good luck.

I made this table with their reciprocity numbers for this specific camera RSS 6x9 (f137). I'm just not sure where the failure begins. That is not on any datasheet. I had that information in the past when I sold my Zero I gave it to the buyer. So your guess is as good as mine as to exactly what point reciprocity failure occurs. I believe this would be around 1-2 seconds, more towards 2 seconds being the failure point where meter no longer provides the right exposure time. I also posted this in the Pinhole forum in case anyone else can use it.

Also you can see easily that SFX is the worst film to work with for long exposures. That factor is worse than Delta 400 which I have always called out in the past. So If I play with SFX and pinhole, I'm going to be waiting a long long long long time to bracket my shots

retina_restoration · Feb 28, 2023

Perry,
Get yourself a copy of Pinhole Assist for iPhone. It calculates reciprocity on the fly for most known films, SFX included. Just plug in the film type, aperture value and meter away, and it gives you the exposure time. Couldn't be simpler.

Perry Way · Feb 28, 2023

retina_restoration said:
Perry,
Get yourself a copy of Pinhole Assist for iPhone. It calculates reciprocity on the fly for most known films, SFX included. Just plug in the film type, aperture value and meter away, and it gives you the exposure time. Couldn't be simpler.

Yeah that app is not available for my phone. Looked for it. I have other apps but none work in reciprocity nor even mention film names

MattKing · Feb 28, 2023

It is important to remember that (low intensity) reciprocity failure has nothing to do with the times being long. It is instead related to how low the light intensity is at the film plane.
If you are exposing for IR, the intensity of that light is far, far lower than the intensity of the visible light that it is mixed with. In fact, the correlation between metered visible light intensity and the amount of IR present is actually quite unreliable.

Perry Way · Feb 28, 2023

MattKing said:
It is important to remember that (low intensity) reciprocity failure has nothing to do with the times being long. It is instead related to how low the light intensity is at the film plane.
If you are exposing for IR, the intensity of that light is far, far lower than the intensity of the visible light that it is mixed with. In fact, the correlation between metered visible light intensity and the amount of IR present is actually quite unreliable.

Yes, I understand that. I think that is what Retina_Restorer was trying to say earlier, when he referred to "overexposure". That even when you calculate things you should also throw in more exposure time. What would be interesting to know is like some kind of range of ratios to work with, for instance, when it's a bright sunny day with no clouds, IR is much higher than on days when it's overcast, by far. Even when measuring for ambient light levels (visible light), the overcast day will be much harder to calculate, the time will be much longer because IR is lower on overcast days. It would be great if there was some kind of tool perhaps that actually measures IR radiation on that particular day and give you a factor you could then add to this reciprocity adjusted exposure time. Am I making sense? Maybe it's my methodical programming mind but I think there has to be a way to quantify the IR for the particular day.

pentaxuser · Feb 28, 2023

MattKing said:
It is important to remember that (low intensity) reciprocity failure has nothing to do with the times being long. It is instead related to how low the light intensity is at the film plane.
If you are exposing for IR, the intensity of that light is far, far lower than the intensity of the visible light that it is mixed with. In fact, the correlation between metered visible light intensity and the amount of IR present is actually quite unreliable.

So, if I may ask, what information is available to someone who has the problem Perry way has described?

pentaxuser

MattKing · Feb 28, 2023

And the answer will be affected by things like season, latitude and, for all I know, humidity.

Perry Way · Feb 28, 2023

retina_restoration said:
You're setting yourself up for some frustration. Its not that complicated - it just requires some trial and error and experimentation. I think you'll find you can simply "expose for X minutes when its overcast" and you'll get usable negatives 95% of the time - you just need to run a test roll and make notes about what you did, and figure it out from there. As others have stated, measuring IR is very difficult and trying to take readings is likely to mislead you.

I'm an AmeriCAN This 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

Perry Way · Feb 28, 2023

MattKing said:
And the answer will be affected by things like season, latitude and, for all I know, humidity.

Yes, but you know Matt, this afternoon I had this brainstorm. I'm looking into the possibility of finding and using an IR photo detector and then go do my experimentation, document exposure times and document the IR reading for that location. This could develop into something very useful in the future, and eliminate wasting so much silver in our expensive films.

Sirius Glass · Feb 28, 2023

MattKing said:
And the answer will be affected by things like season, latitude and, for all I know, humidity.

Water vapor does attenuate infrared.

How to shoot Ilford SFX 200 the most effectively?

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