Infrared comparison, lab error or mine?

young_ghiaccio · Sep 26, 2019

Hi all,

I am a bit confused with the results of my latest infrared roll (SEE ATTACHMENT). I am shooting using a Mamiya 7 (65mm) and using Rollei IR400 with Hoya 72 filter.

I recently switched photo labs and the result on the left is from the new lab. The result on the right is from the old lab.

Both photos were exposed the same way, F4 at 1/60. This is how I shoot infrared and always get good results when it's a bright day with the sun on my back.

The only other difference is that the photo on the left was taken in September and the photo on the right was taken in early August.

Both days had bright blue skies, intense sun, and temperatures in the 80s-90s.

Thoughts?

John Koehrer · Sep 26, 2019

1st question I'd have is if there's an IR light source in the lab or over exposed in printer?

cramej · Sep 26, 2019

John Koehrer said:
1st question I'd have is if there's an IR light source in the lab or over exposed in printer?

Probably not since the "new lab film" isn't over exposed.

Looks like the white point was brought way down - probably auto-corrected in their scanner. The best way to compare exposures is to look at the negatives. Is the density similar? If yes, then probably the lab

young_ghiaccio · Sep 26, 2019

Thanks cramej, I just received the files today (wetransfer) and haven't reviewed the negatives -- that is a good piece of feedback though, hopefully that will resolve the issue.
It is quite upsetting!

young_ghiaccio · Sep 26, 2019

young_ghiaccio said:
Thanks cramej, I just received the files today (wetransfer) and haven't reviewed the negatives -- that is a good piece of feedback though, hopefully that will resolve the issue.
It is quite upsetting!

I mentioned the white point adjustment -- they said the negs were underexposed -- which doesn't make sense bc I just shot a roll a month ago with the same conditions/settings.

Two things:

1) Would a hot and bright late-September light be different than a hot and bright early-August light in terms of infrared?

2) If the film was not used for 6-8 months and not refrigerated, could have that impacted the IR sensitivity? (it was at room temperature in a cabinet)

TIA

MattKing · Sep 26, 2019

young_ghiaccio said:
1) Would a hot and bright late-September light be different than a hot and bright early-August light in terms of infrared?

Very likely!
Equally important, the IR reflectivity of the foliage can and will change in the same period of time.
Scanning throws in a whole bunch of additional variables - it is difficult for either the built in algorythms in the scanning software or the scanner operator to know what the "normal" result should be when the negative is an IR sensitive film.
If you are dealing with a local lab, take both films and scans in to them and show them what you want.

Pentode · Sep 26, 2019

The difference between early August and late September might be noticeable on IR film, as might a difference in time of day. Neither, IMO, would make as big a difference as we're seeing here.

Just curious: do both labs use the same chemistry? I suspect the only way you'll know for sure what's going on would be to shoot two rolls on the same day and bring one roll to the old lab and one to the new. At least then you'll have some sort of baseline to work from. IR is peculiar stuff and it may just be that lab #2 isn't used to working with it.

Paul Manuell · Sep 27, 2019

Out of curiosity, why did you use a different lab in the first place when the original one did such a good job?

pentaxuser · Sep 27, 2019

I wonder if the new lab realised that this was IR film anyway or as has been hinted at, thought this was a way over-exposed normal negative and attempted to produce as near as a possible a "normal" print.

It might help of you can take a digital picture of the September negative so we can see. As others have said I doubt as well if a bright sunny day in September varies enough from August to effectively destroy any semblance to IR

pentaxuser

msage · Sep 27, 2019

It is hard to tell without seeing the negatives and knowing the developer, time and so on but it looks both under developed & under exposed (the kiss of death in photography!). The shadows are empty and the highlights are flat. I always bracket when shooting IR, what my hand held meter says, +1 stop from that and usually a third shot at +2 stop from the meter reading. Have not had a problem for a long time following this guideline. In IR photography the meter reading is only a guess and what worked last week is only a starting point!

Bill Burk · Sep 27, 2019

I think you simply have two different buildings, two different times of year.

One of the uses of infrared film is to see how healthy the vegetation is.

I poked around and found a random statement to confirm what I thought... "Healthy plants reflect much more NIR than unhealthy or stressed plants"

The later season plants are not reflecting significant infrared. They are not as healthy.

Your pictures are fine. Infrared is doing its job.

jtk · Sep 28, 2019

Why use a lab?

pentaxuser · Sep 28, 2019

Bill Burk said:
Your pictures are fine. Infrared is doing its job.

Be nice to see shots of the two negatives however to get confirmation. That is one heck of a difference in one month especially as the period would seem to still largely qualify as summer- early autumn being early August to mid September

pentaxuser

cowanw · Sep 28, 2019

Looking at the signs on the telephone pole in the left hand picture. Do street signs give off IR to such a degree? I didn't think reflected sunlight was IR.

Sirius Glass · Sep 28, 2019

cowanw said:
Looking at the signs on the telephone pole in the left hand picture. Do street signs give off IR to such a degree? I didn't think reflected sunlight was IR.

Reflected sunlight off metal, call specular reflection does reflect infrared light equally proportionate for the visible light. infrared light and its phenomenology is one of my expertises dating back to the early 1970s.

mshchem · Sep 28, 2019

jtk said:
Why use a lab?

Exactly.

winger · Sep 28, 2019

If the left one is their scan, then I'd reserve judgement until you look at the negatives. If you have the capacity to do your owns scans, then I'd definitely do that once you have the negative. And why did you switch labs? Also, why not do it yourself?

And, yes, as has been said, August and September can have different light.

Bill Burk · Oct 1, 2019

pentaxuser said:
Be nice to see shots of the two negatives however to get confirmation. That is one heck of a difference in one month especially as the period would seem to still largely qualify as summer- early autumn being early August to mid September

pentaxuser

Yes it would be nice to see a side by side picture of the negatives. young_ghiaccio, this is when it is perfectly fine to take a “terrible” cell phone picture of the negatives to show.

pentaxuser, did you notice the building isn’t the same one, light poles in one picture aren’t in the other. Not the same tree.

pentaxuser · Oct 1, 2019

Bill Burk said:
Yes it would be nice to see a side by side picture of the negatives. young_ghiaccio, this is when it is perfectly fine to take a “terrible” cell phone picture of the negatives to show.

pentaxuser, did you notice the building isn’t the same one, light poles in one picture aren’t in the other. Not the same tree.

You are quite right, Bill The building looks quite alike on both pics at first glance but not if you really look which I didn't. I think I thought it was the same scene simply a few weeks apart for accurate comparison purposes. As it is not then what may be relevant is the kind of vegetation in terms of how different it is ( deciduous v evergreen ) and /or the time gap in the vegetation's sensitivity to IR.

Until we see pics of the negatives we are trying to solve the Marie Celeste mystery

pentaxuser

Sirius Glass · Oct 1, 2019

pentaxuser said:
You are quite right, Bill The building looks quite alike on both pics at first glance but not if you really look which I didn't. I think I thought it was the same scene simply a few weeks apart for accurate comparison purposes. As it is not then what may be relevant is the kind of vegetation in terms of how different it is ( deciduous v evergreen ) and /or the time gap in the vegetation's sensitivity to IR.

Until we see pics of the negatives we are trying to solve the Marie Celeste mystery

pentaxuser

Good call, it is not the same building unless someone cut down the light pole.

pentaxuser · Oct 2, 2019

In the meantime what has happened to the Captain of the Marie Celeste? We need his input to solve this mystery

pentaxuser

Infrared comparison, lab error or mine?

young_ghiaccio

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