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Slightly confused - did I mess up?

Ernst-Jan

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I just finished shooting my second roll of HR-50 and the first one that I partially shot with the Adox Snap-on "IR" filter.

The packaging of the filter says "2x". And since I am planning to develop HR-50 with Adox HR developer. If you want to use this developer at 20°C, the film should be exposed at iso 40.
Since the packaging of the filter said "2x" I set my external light meter to iso 10. So far, so good and quite logical would I say, as I am used to with other films/filters

But then I got confused when I took out the film - the canister said "for IR use combine with Adox IR 2x filter and expose to iso 25"
Is that than just one stop of light the filter takes? Why is it called "2x" then?

I hope the results still will be somewhat useable.

Schönes WE!
 

pentaxuser

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I think "2x" refers to factors and not stops. 2x or a factor of 2 = one stop or a halving of film speed which is why i think Adox says 25 which is one stop less than its film speed of 50

If I am right then as a development time of 20C needs a film speed of ISO 40 then a one stop reduction makes it an ISO of 20

A one stop reduction seems to be very small for an IR filter but if that is what Adox says its filter requires then presumably it has tested it and has got it right

I have never used HR 50 and know nothing of is IR filter so I have no meaningful opinion to give on either the film or its IR filter

pentaxuser
 

Donald Qualls

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The way I'm reading these combined items is: in IR wavelength, the film loses sensitivity and should be metered at EI 25; in addition, the filter has 2x density (which I'd equate more with Neutral Density numbers, meaning two full stops). End result, your EI would be 6 with the IR filter and the sensitivity reduction of the film.

I don't know where you'd get an IR filter with only two stops of light reduction, though. An ordinary red filter is 3 stops filter factor, and a deep red is 4 or 5 (depending on the film).

The filter supplied may be only a red, deep enough to get Wood effect on a film with sensitivity beyond 700 nm; if that's the case, it might only be 2 stops filter factor after rating the film at EI 25...
 
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Ernst-Jan

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pentaxuser said:
I think "2x" refers to factors and not stops. 2x or a factor of 2 = one stop or a halving of film speed which is why i think Adox says 25 which is one stop less than its film speed of 50
Click to expand...
I took the external measuring (set at iso 10) just to be sure, but meterings matched the values of the internal meter (still at iso 40). So I would say 2x is amount of stops it takes.
 
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Ernst-Jan

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Donald Qualls said:
I don't know where you'd get an IR filter with only two stops of light reduction, though. An ordinary red filter is 3 stops filter factor, and a deep red is 4 or 5 (depending on the film).
Click to expand...
At Fotoimpex, some gelatine filters they made with cibachrome technology if I remember correctly.
It's not a true IR filter though.
 

pentaxuser

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Thanks for the link Ballinderry-Michael. I now recall seeing this before. It looked to me then and still does that EI 12 was the best speed for an IR filter but that's just my preference. However it is interesting that a two stop reduction which is what Adox may mean when it says "2x" for its IR filter gives a figure of 12 and this seems to be the link's findings as well when it was an R72 that was used

So it would appear that HR 50 does require quite a different reduction in speed for IR shots than most films require when using an IR 72 filter

pentaxuser
 

Donald Qualls

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Ernst-Jan said:
It's not a true IR filter though.
Click to expand...

That's part of the equation -- it's more of a deep red, and combined with film sensitized to 720 or 750 nm, perhaps even at a higher level than its yellow/green/blue sensitivity, you might only need two stops reduction.

This likely also depends on what meter you use; a silicon cell is more sensitive to IR than, say, a selenium cell. If you want to regularly shoot Wood effect images with HR50, it would surely be sensible to make a test roll with your meter, your filter, and your development to determine your own EI.
 

pentaxuser

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Yes I always understood 2x to be a filter factor and this is one stop only However I have a feeling that a one stop reduction in film speed to 25 may not be enough to get you that "wispy " white look to green foliage that is usually associated with IR

I might be wrong about this but I do wonder if the Adox filter is not closer to a red 25 or 29 than to the likes of Hoya R72

I'd be tempted to try an R72 with HR 50 to see if this makes the scene more IR looking than the Adox filter does. That means dropping the speed to 12

pentaxuser
 

Andrew O'Neill

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I've been waiting for the sun to come out so I can play with this film and its IR sensitivity... There might be a an opportunity mid week...
 

250swb

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I've been using HR-50 for a few months now and I think the confusion may be because it shows its IR sensitive even with a mild red filter, so I'm assuming the Adox filter isn't a full on IR but simply 'red'. Hence the Adox filter factor. When I've used a 718nm filter it certainly improves the IR rendering although I prefer a simple red filter aesthetically. It is a very, very nice film to use whatever you do, no filter at all is also worthwhile.
 

Ivo Stunga

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Ernst-Jan said:
Is that than just one stop of light the filter takes? Why is it called "2x" then?
Click to expand...
Don't know why X is called Y, but with 720nm filter I have to give it 3-6 stops from normal reading, depending on lighting.

Your film and your preference will tell what's to be altered next time around.
 

ADOX Fotoimpex

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This is our product description:

Filter Type: Dark red / IR 600nm
Coating: None
Light infrared filter to get started with infrared photography. Ideal for the ADOX HR-50 or Ilford SFX film. The filter has only a double filterfactor, which means the exposure time must be doubled-or the aperture can be opened by one step.
Thus the ADOX HR-50 with 25 ASA can still be photographed from the hand.
Stronger infrared filters as we offer for example from Heliopan have filter factors of 4, 8, or 16 and can be placed almost without exception only with a tripod one. For this, they deliver more infrared effect.
Those who have met the fascinating infrared photography with the ADOX filter can then upgrade later.

--------------------------

I am sorry if this is confusing but when I wrote it I thought it was pretty clear

To answer the initial question: 2X means the film behind the filter needs 2 times the exposure.

I hope all is clear now.
 

JPD

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250swb said:
I've been using HR-50 for a few months now and I think the confusion may be because it shows its IR sensitive even with a mild red filter, so I'm assuming the Adox filter isn't a full on IR but simply 'red'.
Click to expand...
True, and Adox call the effect "pseudo IR". Simply Red is also a pop band that was popular in the 1980s, and they weren't infrared either. Maybe there is a connection.
 

250swb

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JPD said:
True, and Adox call the effect "pseudo IR". Simply Red is also a pop band that was popular in the 1980s, and they weren't infrared either. Maybe there is a connection.
Click to expand...

I didn't know it was 'pseudo IR', perhaps that's only if a pseudo photographer is using it? I am willing to believe the Adox datasheet for HR-50 which I quote

"ADOX HR-50 can be used as an Infrared film and responds extremely well to any sort of filtration (yellow, orange, red, blue, green). The new ADOX *SNAP-ON*- Gelatin Filters are a prefect match"

Now what I read from that is that it can specifically be used as an infrared film, but like other infrared films it can also be used as a normal film without an IR filter. The IR effect is obvious when using an IR filter or a red filter, so I why would they call it pseudo with a film clearly sensitive to the spectrum? Perhaps it falls short by a small margin of being a full-on IR film, or they simply want to sell more of it without pigeonholing it as a specialty film? I'm glad to report I can't see any connection with the pop band 'Simply Red', I couldn't do with any film making that dreadful whiney noise inside the camera.
 
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Ernst-Jan

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Now that I read everything (again) it is pretty clear indeed. I might have read it when I bought the filter but forgot it when I used it

If the filter is for beginners, maybe explaining it a bit more on the package/cardboard. Just a sentence like "Need 2x the amount of light - overexpose 1 stop" would be really benifical.

Anyhow, I won't forget now! Looking forward to to finally process the first roll and shoot the second one.
 

JPD

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The "pseudo IR" is what they called using the red Adox filter with the film, so it's just marketing, since they don't have a "true" IR filter in that line of filters. A darker red, if not the almost black ones, would be better.
Never been a Simply Red fan, but they were popular, so maybe they are pseudo good.
 

ADOX Fotoimpex

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It´s not about the filter. A true IR film is sensitive to 800nm and above. Our IR made by efke was sensitive to 815nm, Kodak HIE even 850. All currently available IR films are only "pseudo" IR. You can create a wood effect but not much more. Thus I would not call this a marketing gag- it´s rather the opposite- we try to stay correct and play it down. Given the fact that there are no better alternatives out we could pump the marketing much more in this direction
About the filter: We did not want to make a higher IR filter because the use is becoming clumsy and it narrows down the scope. Our filters are easy to use and competitively priced to promote the use of filters. We actually recomend to buy a more "proper" filter later if you liked the results
 

MattKing

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ADOX/Mirko.
I would suggest that there is a problem with definitions here.
"Pseudo" IR implies that the results from the film are essentially faked. However, when people use films like this for pictorial effect they are actually most interested in the Wood (not "wood") effect, not in the more scientific or technical recording of IR radiation. As much of the Wood effect is recorded by films with this more limited spectral sensitivity, there is really nothing "pseudo" about this film.
It is quite appropriate to instead refer to the film's sensitivity as being to the "near-IR" spectrum, and that is what other manufacturers like Harman/Ilford have chosen to do.
 

Ivo Stunga

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ADOX Fotoimpex said:
A true IR film is sensitive to 800nm and above. Our IR made by efke was sensitive to 815nm, Kodak HIE even 850. All currently available IR films are only "pseudo" IR. You can create a wood effect but not much more
Click to expand...
I guess it's better to avoid using term "pseudo" and opt for using NIR or Near Infrared which it is or approaches enough to be practically the thing.
To compare this in terms of color: indeed IR films of today provide just a slice of "green", doesn't cover all of it, but that doesn't degrade the slice of "green" achieved.
Even Kodak HIE fits into NIR slice of IR radiation and there's nothing "pseudo" about that


"NIR"
Near-infrared light (NIR) is infrared light closest to the range humans can see, with wavelengths from 0.75 to 1.4 micrometers.

What Is Near-Infrared Light? What Is It Used For? - Optics Mag

What exactly is near-infrared light? Why is it different from normal light? To answer this, we’ll go into the details and explain both the basics and the in-depth knowledge...
opticsmag.com

"Pseudo"
1) being apparently rather than actually as stated

Definition of PSEUDO

being apparently rather than actually as stated : sham, spurious… See the full definition
www.merriam-webster.com
2) Pseudo- is used to form adjectives and nouns that indicate that something is not the thing it is claimed to be.


Best/strongest IR effect with near-NIR (lol) films today are to be achieved with ~715nm IR filter that filters out all visual light and let's only that very limited slice of "green" to expose film.

Granted - there's not that big of a slice of that "green" available to film shooters today - films of yesterday offered way bigger slice of it, but it's still fun to work with what we got and the world looks plenty different even in this part of the EM spectrum so thanks for offering these films
 
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Ivo Stunga

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Hmm, wouldn't it be possible for Adox to take say HR-50 and to differentiate ir really by sensitizing it deeper into Infrared?

Could Adox make a "proper" IR film?
 

ADOX Fotoimpex

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Matt,

I think this has been historically developed. I did not come up with this nomenclatura and just started using it in product descriptions like everyone else did. HIE and efke IR were called "infrared", SFX and Aviphot 400 and his twins were called "pseudo infrared". I have no clue who invented the terminology. Now fastforewarded 20 years there is not much else and since also most people have left in the trade sector as well, things are up for a re-definition and I am happy to implement changes. My main point was that this was not intended to give the product something via marketing, that it actually does not have
So shall it be "near infrared" now.
We actually use the term "superpanchromatic" for this film in the general description. The "pseudo" is, if at all, used only with reference to IR photography.

Mirko
 

ADOX Fotoimpex

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Ivo Stunga said:
Hmm, wouldn't it be possible for Adox to take say HR-50 and to differentiate ir really by sensitizing it deeper into Infrared?

Could Adox make a "proper" IR film?
Click to expand...

Yes, this is still an old, but not canceled, project. 400 speed instead of 100 with efke´s true IR dye. The samples must be 12 years old now or even older. I am not sure if we can still buy the dye or if we have to sensitize it. In the second case prices and doability will have to be re-evaluated.
 
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