Efke IR sheet film

[eclarke]

Hi all,
How much focal adjustment are you using with a view camera for 4x5 Efke IR film through an 092 filter and what apertures are you using?..Thanks..Evan Clarke

 

[keithwms]

I am not familiar with the 092, I have been using a #87 so bear that in mind as you read this.

If you use an apo lens (e.g. an apo process lens) you won't need any focus adjustment at all. With other lenses, it varies, but what I do when in doubt is focus ~10% or so closer than my subject and then stop down one extra stop. But at close focus I'd be more cautious... or simply use one of my apo nikkors. They are shutterless, but hand shuttering is no big deal when the exposures are typically past a second anyway...

I think it is unfortunate that so many IR photographs are shot with lenses stopped way down simply because of concern about the focus correction. We (photographers) can do better... the apo lenses are really not that expensive!

 

[eclarke]

I am not familiar with the 092, I have been using a #87 so bear that in mind as you read this.

If you use an apo lens (e.g. an apo process lens) you won't need any focus adjustment at all. With other lenses, it varies, but what I do when in doubt is focus ~10% or so closer than my subject and then stop down one extra stop. But at close focus I'd be more cautious... or simply use one of my apo nikkors. They are shutterless, but hand shuttering is no big deal when the exposures are typically past a second anyway...

I think it is unfortunate that so many IR photographs are shot with lenses stopped way down simply because of concern about the focus correction. We (photographers) can do better... the apo lenses are really not that expensive!

Thanks, I actually am using a 210 Schneider APO Symmar L and made a focus adjustment which didn't work, now I know why and will make some more test sheets tonight..Evan

 

[keithwms]

Yep you probably don't need adjustment with that lens and these films are only sensitive to 850nm or so... so unless you use a really deep filter, you're probably fine.