Ilford SFX 200 'Near Infrared'

[robertojoven]

I bought a roll of this to use on an abandoned nazi commune up in the hills of LA and had a few questions...

1. I have a red filter for my LF lenses (Hoya 25A) but it is too large for my standard 35mm primes. Will holding it over the lens work well enough or will the focus be skewed?
2. I know that some lenses have an infrared 'setting' on the focusing wheel on the lens to indicate the proper focus. Mine does not. How do I go about achieving correct focus?
3. Should I use TTL metering or my incident meter? What exposure compensation is needed?

 

[compur]

You can attach the filter with a step-up ring. They are inexpensive
and available at Freestyle (on Sunset in Hollywood), or on eBay, etc.

I wouldn't worry about focusing with SFX 200. Just focus normally.

Here is the data sheet on SFX:
http://www.ilfordphoto.com/Webfiles/2007651134552223.pdf

 

[robertojoven]

You can attach the filter with a step-up ring. They are inexpensive
and available at Freestyle (on Sunset in Hollywood), or on eBay, etc.

I wouldn't worry about focusing with SFX 200. Just focus normally.

Here is the data sheet on SFX:
http://www.ilfordphoto.com/Webfiles/2007651134552223.pdf

Step-up ring it is.

I read the data sheet already but the extent of their exposure recommendations is trial and error. I have no problem bracketing but I was curious if anyone had some experience with this film and could offer more concrete advice. Also, I won't be using a real IR filter but a 25a instead.

 

[Hamtastic]

1. It won't necessarily mess with focus, but if you jiggle the camera because you're bumping it or can't hold steady that's a problem. I'd use a tiny bit of duct tape or something. Or there are step up rings available.

2. Lots of DOF? Actually I don't think you'll have much to worry about. SX-200 still exposes mostly in the visible light portion of the spectrum, and the #25 filter only blocks the blue end of the visible light spectrum. You are still going to get a lot of visible light exposure. To get much IR effect you are going to need a filter that blocks up to 700ish nm, but not much more than that.

3. TTL automatically deals with the filter factor. If you use an incident meter remember to adjust for the filter factor.

 

[robertojoven]

1. It won't necessarily mess with focus, but if you jiggle the camera because you're bumping it or can't hold steady that's a problem. I'd use a tiny bit of duct tape or something. Or there are step up rings available.

2. Lots of DOF? Actually I don't think you'll have much to worry about. SX-200 still exposes mostly in the visible light portion of the spectrum, and the #25 filter only blocks the blue end of the visible light spectrum. You are still going to get a lot of visible light exposure. To get much IR effect you are going to need a filter that blocks up to 700ish nm, but not much more than that.

3. TTL automatically deals with the filter factor. If you use an incident meter remember to adjust for the filter factor.

Sounds like I'm going to just do a roll of Pan F 50 then.

What would be a good IR filter? I've seen a few variations...

 

[Hamtastic]

What would be a good IR filter?

If you want a strong IR effect you need IR film that's sensitive to wavelengths of 750nm and more (invisible IR). To block all visible light you need to have a filter that blocks at least everything under 700nm. The #25 blocks 580ish nm and lower. A #87C blocks 790ish nm and below. If the SX-200 maxes out lower than 750nm then it would be like putting the lens cap on. You need more IR sensitive film for filters that strong.

 

[robertojoven]

What would be a good IR filter?

If you want a strong IR effect you need IR film that's sensitive to wavelengths of 750nm and more (invisible IR). To block all visible light you need to have a filter that blocks at least everything under 700nm. The #25 blocks 580ish nm and lower. A #87C blocks 790ish nm and below. If the SX-200 maxes out lower than 750nm then it would be like putting the lens cap on. You need more IR sensitive film for filters that strong.

Going off of your information, would it be ideal to get a filter that blocks everything right above the visible spectrum of 700nm? Assuming that 700nm is the limit of the visible spectrum, what effect would be produced by putting a IR filter that blocks out, say, 800nm?


I guess what I was curious about was this:
If you have a filter that blocks out all visible light and only lets infrared in, is this ideal or would you desire some amount of visible light? Or, what about having a filter that not only blocks out all visible light, but also some infrared?

 

[compur]

SFX 200 has only a mild infrared effect (and only when using some filters).
Treat it as a normal ISO 200 B&W film. That is, set your ISO for 200 and use
TTL metering with any filter you wish to use. Ilford recommends a deep red
(#29) filter which Is how I have used it and the IR effect is mild. As far as
I know Ilford does not recommend using an actual IR filter (one that blocks
all but IR). Using the film with no filter or with, say, a yellow, filter produces
no particular IR effect -- it's like most any ISO 200 B&W film.

 

[Hamtastic]

...would it be ideal to get a filter that blocks everything right above the visible spectrum of 700nm? Assuming that 700nm is the limit of the visible spectrum, what effect would be produced by putting a IR filter that blocks out, say, 800nm?

What is "ideal" depends on your vision, taste, opinion, etc...

The more visible light you block the more pronounced the IR look will be. IR reflects off objects differently than visible light. For instance green leaves turn gray tone with visible light BW. But leaves reflect a lot of IR so they will expose much brighter in an IR exposure.

 

[Garbz]

Going off of your information, would it be ideal to get a filter that blocks everything right above the visible spectrum of 700nm? Assuming that 700nm is the limit of the visible spectrum, what effect would be produced by putting a IR filter that blocks out, say, 800nm?

I guess what I was curious about was this:
If you have a filter that blocks out all visible light and only lets infrared in, is this ideal or would you desire some amount of visible light? Or, what about having a filter that not only blocks out all visible light, but also some infrared?

The cutoff depends on the taste as mentioned above, but there are also practical limitations. The more of the spectrum you cut out the more various things stop reflecting. At 800nm cutoff you're really going to get some strange effects. At 720nm you get incredible contrast and glowing plants, but a still recognisable image. At 580nm or bright red like the 25A you end up with a contrasty image but not much of an IR effect.

Personally I shoot with a Hoya SHMC R72 (720nm cutoff) filter, and these days AGFA 820 IR film without an antihalnation backing. That produces images like http://farm4.static.flickr.com/3550/3383999038_b83345b6bf.jpg and http://farm4.static.flickr.com/3556/3383184239_251acbdd42.jpg, the glow being due to the lack of antihalnation layer on the film. With this film you for instance start running into problems when using an 800nm cutoff as the film is only sensitive to 820nm. So if I wanted an even more extreme IR effect my shutter speed would start ranging around the seconds rather than fractions of a second.


Also what people have said here so far regarding your focusing and how you deal with the filter will not be the same for a filter which cuts all the visible IR so let me answer your original questions from the perspective of a true IR filter:

2. Autofocus still works on the IR spectrum. If you use AF then there's no adjustment to be made. If you're manually focusing and you don't have an IR adjust then you're snookered. A best guess is in order. It's not much of a twist though the focus doesn't change much. The easiest way to deal with it may just be to shoot with a small aperture to increase your depth of field. But in reality each lens acts differently so it's hard to say how you would compensate your focusing with an IR filter except that nearly in every case it's a near focus adjustment so turn away from infinity.

3. The filter information is available in the datasheet. http://www.ilfordphoto.com/Webfiles/2007651134552223.pdf and well worth the read. Basically the way you read it a filter like the Hoya R72 would similar to a Wratten 89B. This has a filter factor of 4. How I use this:
i) Setup and compose the shot, focus and whatnot.
ii) Take note of camera settings, flick to manual and increase my shutter speed 4 stops.
iii) Mount IR filter
iv) With AF lens I then autofocus, with manual focus lens I then adjust the IR focus compensation.
v) Bracket 3 shots. I have had lots of luck with +/-1.5EV over 3 frames.

 

[zigomat]

So glad I found this thread, very useful.
I am trying out sfx 200 with the hoya R72, for the first time tomorrow, it'll be interesting to see what the results turn out like.

With regards to focus, does anyone know if...
My nikkor lens (28mm f/3.5) has a little red dot about 1cm to the left of the black focus line. There is no 'R', but I am guessing this is the infra red compensation?
Do you still need to adjust it that far if you are doing landscapes, or using a small aperture?

 

[seekinglight]

Here's a good link: APOGEE PHOTO MAGAZINE: Focusing When Using Infrared Film by Michael Fulks
For Ilford STX (not TRUE IR)
Things to consider are:
The red filters #25, #29, or Ilford STX will at least slow down or likely defeat your autofocus. (Ever try using autofocus in dim light? These filters can drop you 4 stops or more. If you have a 2.8 max aperture lens the filter would make it as dark as an 11 max aperture. Most autofocus won't work at that aperture.)
This means manual focus with filter on (tripod is a good idea), or autofocus with filter off -still need tripod to keep camera in same spot.
Filter references for these filters sometimes suggest compensating for the TTL exposure by +1 -so don't rely too much on your cameras light meter. (bracket)
How much to adjust your manual focus for this film is affected by your lens, and if it is a zoom lens the focal length. My lens has red marks for 70 and 100mm.
Notice form the Ilford specs this film isn't way into the infra red, but just into the 700's. That means the red mark on your camera lens is probably too much compensation. Hence the need for bracketing and taking good notes.
One recommendation was to plan on making mistakes on the first roll. So experiment around the house or yard with the first roll with bracketed focus and good notes. You'll need to test using the same lens you want to do your eventual IR money shoot with (or at least the same focal length) and shoot at max aperture opening to best judge the focus.

 

[timor]

Here's a good link

Two years to late.
But since it was resurrected: anyone has any experience with SFX200 and Cokin 007 ?