Red gradient of filters to simulate Aerochrome

[Ninjin]

It is gradient of filters to simulate Kodak IR Aerochrome.

(I did some grading-test to see the red palette.)

 

First photo:

Some comparative testing of Lee 729 vs СЗС20+ЖЗС5 stack.

Used filters:

Lee 729 (Scuba Blue Gel) to 1mm.

СЗС20+ЖЗС5 (Eka's made stack) - 2mm each glass.

 

+IR block:

KG3 2mm. (Thank you, Cadmium!!)

KG1 2mm.

СЗС24 3mm.

СЗС25 3mm.

СЗС26 3mm.

СЗС27 3mm.

 

The test was done on a diffraction grating (1000 lines) in complete darkness.

Light - one 60w incandescent lamp.

 

Top row - visible light (S8612 1 mm),

bottom row - for comparison, (Tiffen 12, after changing channels as for traditional Aerochrome processing).

So in this photo:

test comparison of Lee 729 filter + different 'weak' IR block, vs

the stack СЗС20+ЖЗС5, also + different 'weak' block.

 

This result was obtained - directly from the camera, without replacing the channels.

White balance - auto, then in NX_D, on a white background.

I used a Nikon 7100 camera and a Kuribayashi 35, lens.

I think - this result can be obtained stably, for all these filters.

 

 

Only Lee 729 alone and Lee 729 in combination with IR block.

The top row is visible light (S8612 1 mm), the bottom row is for comparison (Tiffen 12 after changing channels).

 

 

(СЗС20+ ЖЗС5), one, and in combination with IR block:

 

Top row - visible light (S8612 1 mm),

bottom row - for comparison - (Tiffen 12 after changing channels).

 

I'm not sure, if KG3 presses stronger (?) than СЗС 24. But probably, yes.

 

[dabateman]

Wow very cool.

I really like this way of presenting data. Not only informative, but very nice to look at.

The C3C25 filter addition is interesting as you getting a light bleeding effect. I would expect an oranger image with that one. Or magenta, I may have my mind backwards.

More green was magenta, more blue is orange. That may be correct.

[Cadmium]

Indeed, very impressive and well done!

KG3 attenuates higher IR slightly more than KG1.

C3C24 looks like it is closer to KG1, maybe, hard for me to tell.

Top comparison shows the range of visual red suppression.

You do these amazingly!

[Ninjin]

Dabateman, thank you! I still can not make a conclusion about the red. Now I just see what happens.

But this result is stable, can be repeated. I did several times - all the same.

 

Cadmium, thank you very much!!

Yes, here is the result for KG3 vs KG1 only:

 

[Cadmium]

OK, thanks, now I see some more IR cut-off with the KG3 than the KG1, indeed, that makes sense now. Thank you.

I can see the difference with them next to each other like that.

You do these so well! Very impressive.

[Ninjin]

I would like to show some more tests, for the IR-'red' part.

Sure, such a test is not an exact measurement, but I do it just to have a visual representation.

 

This is my collection of IR-block filters.

For S8612, I indicated the thickness, all other - 2 mm thickness.

 

First row - no filter.

I drew a few numbers on the background, in pencil.

Then I set the grading - so that the visible part (S8612_1.5 mm) ends at about "1".

 

The test shows what the 'IR red part' looks like for all of these filters.

Most of them are antique, they are not used today or are rarely used. I noted modern filters with gray color.

 

The conditions are the same: Diffraction grating of 1000 lines, one 60W incandescent lamp. White cotton paper with printed markings for the background + few numbers.

 

[Ninjin]

Two more examples:

 

Tiffen 12 is one, and Tiffen 12 + IR block KG1, KG3.

 

 

OC12, one, and with KG1, KG3.

(The combination OC12 filter + IR block, was earlier shown on the forum by member Eка, for the landscape).

 

 

Cadmium, OC12 looks like to OG530, right?

 

The top row is visible, all others with replacement channels for Aerochrome style (all the same, identically).

The gradient shows how 'yellow' - brighter, and 'red' changes slightly.

 

Tiffen gets a lot of 'purple' before 'blue', though. What this 'purple' looks like on the landscape, I have not tested yet..

[Cadmium]

Once again, these are well done, they look good!

What about "orange", you asked me?

 

Thanks for posting these!

[Ninjin]

I mean, if an 'orange' filter like OG530 probably identical to OC12.

In combination with a weak IR block, like KG1, OG530 also may have advantage with regard to 'yellow'.

I don’t remember if I saw any example how it works with the KG1 + OG530. But the same, I guess. Or very close.

[Cadmium]

I have never tried, and I don't think I have ever seen any examples of #12 + KG, but it sounds interesting.

[ulf]

Ninjin, I must compliment you for the well performed experiments.

The result are very illustrative and excellent for comparisons of different filter combinations.

 

I mean, if an 'orange' filter like OG530 probably identical to OC12.

In combination with a weak IR block, like KG1, OG530 also may have advantage with regard to 'yellow'.

I don’t remember if I saw any example how it works with the KG1 + OG530. But the same, I guess. Or very close.

 

I think this is a good idea. This is a way to get closer to the film Aerochrome with digital simulation by channel swopping etc. like with the Tiffen12 PS action.

If I remember correctly the film was less sensitive to the upper IR-light than our modern image sensors.