Infrared, R72 filter on SL2 and M3 (Ilford SFX)

[Emad Muzaffar]

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Hi,

I've recently been considering an R72 filter for use on my SL2 and M3.

Firstly, has anyone used an r72 on an SL2 body, how much of an exposure compensation is usually needed, and how do images turn out?

For the M3, I'm planning to use Ilford SFX film pushed 1 stop to 400 iso, and then with the 6 stop compensation for the filter. Is 6 stops advisable for an R72, and does any of that sound wrong or abnormal.

As far as lens selection goes, I'd be using my dual range because of filter thread sizes. I've heard a lot about the infrared focus shift causing problems. I assume that this would not cause issues on the SL2 because of live view. On the other hand, with the M3 I plan on shooting at f11 (tripod), hoping to eliminate any focusing problems. By any chance, does anyone know how much to shift the focus, and in what direction? Also, what should I do at infinity, would adjustment still be necessary?

-Emad

[Pyrogallol]

I use Rollei 400 Infrared film and find that 5 stops compensation for the red filter is about right, whatever filter I use from plain red that you can see through up to very dense black/red that you can hold up to the sun and only see a feint sun through.

I have not noticed any focus shift, though I do take notice of the “R” focus index on the older Leica lenses and usually turn the focus a bit closer to compensate. At f11 the depth of field should cover any small focus shift.

[jaapv]

Focus shift is dependent on the lens. The SL2 is quite difficult as the viewfinder will black out. 

[Elliot Harper]

If you want to do IR photography, you'd better make a full spectrum conversion. Simply adding a filter in front of the lens will not give you what you want.

Find an old mirrorless or even DSLR camera, get it done by Kolari or somewhere. It's much easier and simpler and cheaper.

[Emad Muzaffar]

On 6/26/2025 at 2:13 AM, Pyrogallol said:

I use Rollei 400 Infrared film and find that 5 stops compensation for the red filter is about right, whatever filter I use from plain red that you can see through up to very dense black/red that you can hold up to the sun and only see a feint sun through.

I have not noticed any focus shift, though I do take notice of the “R” focus index on the older Leica lenses and usually turn the focus a bit closer to compensate. At f11 the depth of field should cover any small focus shift.

My lens does not have an R on the focus index, which way would you usually turn the focus (closer or further)?

[Pyrogallol]

1 hour ago, Emad Muzaffar said:

My lens does not have an R on the focus index, which way would you usually turn the focus (closer or further)?

Focus a little closer. There are discussions on the internet about it https://www.35mmc.com/30/03/2023/focus-adjustment-and-other-considerations-when-shooting-infrared-by-tony-warren/#:~:text=The principal consideration when photographing,the exposure for optimum sharpness.

[jaapv]

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And focus bracket. 

[jaapv]

On a sidenote: you need to pay attention to the lens you are using; many modern lenses exhibit a hot spot ( extreme vignette) and are not very sharp in the IR range. The best ones I found during experiments years ago were the Summarit 50/1.5 and Hektor 135.