That's my finding exactly - the extended red being so close to visible that no practical compensation is necessary.Focus correction is not necessary with current IR films
Or wash off that layer and glue white sticker to the pressure plate to emulate the effect pretty closely. This neatly increases the practical speed too due to missing AH layer + reflections/scattering from the now white film pressure plate. Up to about a stop or two. Goes best with soft/underperforming lenses to further the bloom/dreamy effect.All we need is an ortho film with IR dyes and no AH layer.
Still would not get the hole in the response that allows use of red or even yellow filters for Woods, Rayleigh, haze penetration and contrasty shade.That's my finding exactly - the extended red being so close to visible that no practical compensation is necessary.
Or wash off that layer and glue white sticker to the pressure plate to emulate the effect pretty closely. This neatly increases the practical speed too due to missing AH layer + reflections/scattering from the now white film pressure plate. Up to about a stop or two. Goes best with soft/underperforming lenses to further the bloom/dreamy effect.
Well, I shot/developed/partially scanned a few rolls of 120 with my 4x5 and 6x9 back, and I’m consistently getting good results at 50 or 25 iso when overcast, and 100 or 50 in sun. My shutter speeds are accurate, so unless my Sekonic light meter is off, I’m sticking with those ratings.
I’ll try to post some examples soon.
Well, I shot/developed/partially scanned a few rolls of 120 with my 4x5 and 6x9 back, and I’m consistently getting good results at 50 or 25 iso when overcast, and 100 or 50 in sun. My shutter speeds are accurate, so unless my Sekonic light meter is off, I’m sticking with those ratings.
I’ll try to post some examples soon.
3 pages of this thread and it hasn't been resolved whether the OP's iso 50 is metering through the filter, or without a filter.
If the film is nominally ISO 200, and you take a reading without filter and compensate by 5 stops for R72, that's ISO 6. But if you set ISO 6 on the camera meter and meter through the filter, now you're going to overexpose by however much the filter cuts light to the meter (depends on the meter, could easily be 3 stops).
Yes, I’m exposing through an r72 filter. So I am metering at, say, iso 50 and that is already taking the filter into account. Of course, I could meter at the film’s speed of 400 and apply a filter factor of 3 stops to arrive at the same exposure.So what would you ask him to establish whether he is metering though the filter, in his case an R72? His #54 and all his previous replies suggest to me that he gets to EI 50 from what he regards as the speed of Rollei 400 i.e. 400 so EI 50 from that equals 3 stops and that is what he applies for the R72. Yes it is remarkably high by consensus standards
However on the general subject of trying to be sure we know exactly what any person means I do agree that we often "tell" (usually what we do and works for us) rather than ask more questions. Sometimes we even get sidetracked into having conversations with each other instead of the OP
I also agree that being persistent in being absolutely sure we know what someone is telling us is actually what he is telling us can be difficult and can seem to some to be rude so isn't done as thoroughly as it should be but unless we do this it can be a disservice to the OP
pentaxuser
Yes, I’m exposing through an r72 filter. So I am metering at, say, iso 50 and that is already taking the filter into account. Of course, I could meter at the film’s speed of 400 and apply a filter factor of 3 stops to arrive at the same exposure.
I’m not finding it necessary to apply more than a four stop filter factor - or set my meter for iso 25. And that’s primarily on cloudy days. I realize this seems unusual, and I’m not sure how to explain the discrepancy. But when I metered at iso 6/6 stops I was massively overexposing the film.
Ok I start at ISO 400 and adjust 5 f/stops, and you start at ISO 50 and make 3 f/stops
400 to 200 1 f/stop200 to 100 2 f/stops100 to 50 3 f/stops50 to 25 4 f/stops25 to 12.5 5 f/stopsVersus50 to 25 1 f/stop25 to 12.5 2 f/stops12.5 to 6.25 2 f/stops
So we are 1 f/stop apart and using a filter factor of 4 would be "massively overexposing the film."
No, I’m also starting at 400, but then applying only three stops to reach 50. I’m not exposing at three stops over 50.
I’ve been using a Sekonic l-478dr that I picked up used. I haven’t calibrated it, but I’ve had good results when using it with other (visible wavelength) films so I’m assuming it’s fairly accurate. The other variable is that lately I’m using a 5 degree spot attachment - I’ve been trying to read off objects that should fall in the middle of the gray scale. Obviously that’s a little tricky with infrared, but my results have been fairly consistent. And on a totally overcast day, a lot of the scene falls in the middle.
I have not used my Pentax Digital Spot Meter [1 degree] for infrared photographs. I am using a general reading without the sky in the field of view of the sensor.
My experience exactly with Hoya RG715 / Digital King IR72 + current NIR sensitive films + BW reversal + OM-1n built-in meter:I’m not finding it necessary to apply more than a four stop filter factor
Yes, I’m exposing through an r72 filter. So I am metering at, say, iso 50 and that is already taking the filter into account. Of course, I could meter at the film’s speed of 400 and apply a filter factor of 3 stops to arrive at the same exposure.
I’m not finding it necessary to apply more than a four stop filter factor - or set my meter for iso 25. And that’s primarily on cloudy days. I realize this seems unusual, and I’m not sure how to explain the discrepancy. But when I metered at iso 6/6 stops I was massively overexposing the film.
Sorry, in order to understand this a little more information is needed. When you say you are "taking the filter into account," what literally are you doing? For example some possibilities:
Example 1. TTL metering through the filter: I am setting the camera's iso at 50, putting an R72 filter on the lens, and exposing at whatever the camera's meter says to do.
Example 2: TTL metering w/o filter: I set the camera at iso 50, meter without the filter, set the exposure, then screw the filter on the lens and shoot.
Example 3. Filter factor: I am setting my separate light meter (like your Sekonic) at iso 50, metering without the filter, and then applying a 3 stop filter factor when transferring the exposure from meter to camera.
Example 4. No filter factor: I am setting my light meter at iso 50, metering without the filter, and transferring the exposure directly to camera w/o filter factor. (That's what I think you said above, but just trying to be sure.)
Example 5. Non-TTL metering with filter: I'm holding the filter in front of the light meter to take the reading before putting the filter on the lens, etc.
This may be belaboring the subject, but these examples wind up with different effective ISOs, and you have both a TTL and a non-TTL meter, so it's hard to know exactly how your process might be the same or different as other users. As far as I know, the usual ISO 6 advice builds the filter factor in for non-TTL metering (like example 4, but setting the non-TTL meter at ISO 6).
Then I'd be surprised if you don't have underexposed film on your hands. By 2 stops at least. Can you provide examples?
I know from my experience/processing that "filter factor" of 6 will yield overexposed slides, but doing absolutely no "filter factor" - underexposed. So based on my preferences and observations, I'm somewhere in the middle of consensus: in my experience and processing I know that I need "filter factor" of 2-3 stops in sunlight and 4-5 in shade/overcast + a tad more for shooting IR in premises.
I would be curious to see your shot in direct sunlight. I find 5 stops (equivalent of ISO 12) works well for me, similar to Sirius. I meter reflected whole scene or incident, ISO 12 then transfer to the camera with IR72.You’ve got it with your example #4. I’m shooting 4x5 film or 120 film in a 6x9 back on the view camera, so there’s no internal meter. Hence the external Sekonic handheld meter, set to iso 50, or even 100 in bright sun. The exposure that yields is transferred directly to the camera with no additional filter factor applied.
Then I'd be surprised if you don't have underexposed film on your hands. By 2 stops at least. Can you provide examples?
I know from my experience/processing that "filter factor" of 6 will yield overexposed slides, but doing absolutely no "filter factor" - underexposed. So based on my preferences and observations, I'm somewhere in the middle of consensus: in my experience and processing I know that I need "filter factor" of 2-3 stops in sunlight and 4-5 in shade/overcast + a tad more for shooting IR in premises.
Please do so and provide the pic of the negative if possible, please.
Some examples from my exposures:
Māras dīķis by Ivo Stunga, on Flickr
4 stops in cloudy sunlight resulted in slight overexposure, reduced it in Lightroom
Pareidolia | Kodama by Ivo Stunga, on Flickr
IR close-up, 4 stops in shade
URBEX LV : Infrared by Ivo Stunga, on Flickr
IR in premises, 5 stops
yeah, a wider average of the scene would probably be better, but my meter is either spot or incident, so I’ve just been trying to judiciously use the spot function.
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?