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Lee 729 IR - West Green House garden

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#1 JMC

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Posted 01 September 2019 - 19:29

Took the Lee 729 filter out today to try and get some red/blue IR shots. I had my multispectral EOS 5DSR and 17-40mm lens, with a small square of Lee 729 in the filter holder at the back. Custom white balance, but stupidly I did not select the Picture Style I had developed for the 'Faux Aerochrome IR' look. So this one isn't quite completely out of the camera. All I did was tweak the hue slightly, and then alter saturation and contrast (which would have been done in the custom Picture Style I created for the camera). Oh and I got rid of some flare as well.

Attached Image: 1R4A9758_smaller still.jpg

Edited by JMC, 01 September 2019 - 19:30.

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#2 Andy Perrin

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Posted 01 September 2019 - 20:00

Well that is certainly striking!

#3 Cadmium

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Posted 01 September 2019 - 21:38

Looks pretty cool to me! Did you stack that with any KG3?

#4 dabateman

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Posted 01 September 2019 - 21:50

That looks like a straight up 729 filter to me.
Cool image. I actually really like the clouds.


#5 JMC

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Posted 01 September 2019 - 21:56

Thanks all. No, no additional filter. Just Lee 729.
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#6 Cadmium

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Posted 02 September 2019 - 02:05

A KG3 will 'clean it up' a bit, make grays less red, clouds less colored...
Running that pic there through Photoshop auto levels does it slightly for me, but KG3 will do it better and from the start.
Looks very nice though.
David Twede did it both ways and shows them here:
https://next-eyes.bl...tal-ir.html?m=1

Notice his first set of 729 shots, the sky is darker blue, then the second set using 729 + KG3, the sky is lighter blue, then compare whites, grays, etc....

Edited by Cadmium, 02 September 2019 - 02:05.


#7 Timber

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Posted 02 September 2019 - 12:28

if KG3 is too expensive then you can give a try with Hoya 80C as well. I am kinda happy with the results it gives on my Sony A7II

#8 Cadmium

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Posted 02 September 2019 - 22:14

We are only using KG3 to reduce the higher IR, without removing the lower range IR that 729 transmits. KG3 is not used to reduce anything except higher IR. 729 suppresses red on its own.
I don't know what the Hoya 80C transmission plot looks like beyond 750nm, which is the important transmission range for using KG3 at all.
If anyone has an extended IR range plot for Hoya 80C, please post it. Without cutting the higher IR, there is no reason to use anything except the 729 alone.

Schott KG3 compared to Hoya 80C.
Attached Image: Lee_Scuba_Blue_729_KG3_2mm_80C.jpg

Here is the KG3 beyond 800nm
Attached Image: Schott_All_KG_and_KG1_2mm_x_KG3_2mm_Stacked.jpg

Edited by Cadmium, 03 September 2019 - 05:06.


#9 dabateman

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Posted 03 September 2019 - 01:25

I think Timber and Cadmium are forgetting that Jonathan has the 729 filter in a back of the lens gel holder. No way to add a IR cutter. So doesn't really matter.

Olympus cameras also have a color creator adjustment in camera. I will have to see if this works when I slide a 729 gel behind my Panasonic 7-14mm. Same issue, no room for anything but a single gel.

Oh, stock Panasonic 7-14mm don't have a gel holder. But you can get a replacement part for the 8mm fisheye and switch it on the 7-14mm to get a gel holder. Will fit 22mm square filters.

#10 UlfW

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Posted 03 September 2019 - 04:32

Putty-mounting a smaller filter against the gel filter holder, with the Lee filter in place might be possible, if there is enough space margin to the mirror (EOS DSLR)
A thinner KG5 should work better for that. KG5, 1mm ≈ KG3, 2mm

Correction: KG5, 1.5mm ≈ KG3, 2mm

Edited by UlfW, 03 September 2019 - 10:12.

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#11 Cadmium

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Posted 03 September 2019 - 05:56

As I said, the only point of stacking the KG3 with the 729 is to reduce upper IR which has more of a tendency to 'pollute' the other two Bayer channels (green and blue) with IR.
We have suppressed visual red from the Bayer red channel using the 729, because we want the Bayer red channel to be used for only IR.
We want the green and blue Bayer channels to be used for visual green and blue only, or as close to 'only' as we can get.
Below I have superimposed a typical Bayer color channel graph over the other graphs, this will show how the Bayer red channel is more sensitive to IR in the 700-800nm range than the Bayer green and blue channels are.
At about 800nm to 850nm the Bayer color channels all become more equally sensitive to IR.
The 729 + KG3 stack has a peak IR sensitivity in the same range that the Bayer red channel is most sensitive.
How much this works in our favor, I can't really say, I only know the difference in photos I have compared.
The point being, stacking KG3 works to concentrate more IR into the red Bayer channel and less IR into the blue and green Bayer channels.
David Twede has shown examples both ways, with and without KG3 (like Jonathan's, without KG3), I am just explaining the reason for the addition.

Attached Image: Lee_Scuba_Blue_729_KG3_80C_Bayer.jpg

#12 Andy Perrin

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Posted 03 September 2019 - 05:58

Now I'm curious what that DB850 would do if stacked with Lee 729. It cuts all the upper lower IR and passes visible perfectly.

Edited by Andy Perrin, 03 September 2019 - 06:08.


#13 Cadmium

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Posted 03 September 2019 - 06:02

Andy, DB850 specifically suppresses the 700-800nm range, so it would probably make green and blue colors more polluted with higher IR, and the red would be less red. Try it. :-)
https://www.rmaelect...product_id=2535

Edited by Cadmium, 03 September 2019 - 06:03.


#14 Andy Perrin

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Posted 03 September 2019 - 06:06

Haven't got any Lee 729! I suppose I could get some? I think I misunderstood your comment, though. When you said "upper" for some reason I was thinking you meant the 700-800 range, but I guess that's "lower."

Edited by Andy Perrin, 03 September 2019 - 06:11.


#15 Cadmium

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Posted 03 September 2019 - 06:46

Yes, when I say upper IR I mean basically about 800nm there the Bayer channels become more even with each other.
Keep in mind we really don't know exactly what the 729 transmits about 800, I was hoping Jonathan would scan his and post it sometime,
but if we follow the trend of the 729 at 800nm it looks like it doesn't transmit much above 800nm. Would be interesting to know though.
(that crossed out part is wrong)

Edited by Cadmium, 03 September 2019 - 11:04.


#16 dabateman

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Posted 03 September 2019 - 07:05

Actually based on the Lee plot for 729, I bet it shoots straight up. Most Lee filters don't block any IR. I think the material used for the 729 is the same. So I would expect 50% at 850nm and near 100% just after 900nm.

Cadmium, Jonathan doesn't have a IR capable spectrometer. Only Ulf here does that I know. I maybe wrong, but I am fairly certain Jonathan's cuts off at 800nm.

Hopefully, Ulf scans his. I thought he was getting a sample pack a couple of months ago.

#17 Andy Perrin

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Posted 03 September 2019 - 07:12

Could you simply stack the Lee with some long pass that starts at 800nm and see how much gets through? Or, you know, Sparticle it?

#18 dabateman

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Posted 03 September 2019 - 07:26

Not a bad idea. Cadmium if you stack a 830nm Lp with the 729, I bet you would not see any difference in the exposure settings compared to just the Lp830nm filter.

Ulf ordered his in March and should have gotten it in April. Just read through the old thread. But haven't seen any thing from him. I wonder if he got it.

#19 Cadmium

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Posted 03 September 2019 - 07:43

I am not going to do that, but you could.
Not sure if I sent any 729 to Ulf or not. Maybe just the PTFE, can't remember.

Edited by Cadmium, 03 September 2019 - 08:06.


#20 UlfW

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Posted 03 September 2019 - 09:17

View PostCadmium, on 03 September 2019 - 07:43, said:

I am not going to do that, but you could.
Not sure if I sent any 729 to Ulf or not. Maybe just the PTFE, can't remember.
You did, a tiny bit, but without any comment of why. I forgot to ask.
I had already bought 100x more 729, that is less wrinkled and could be used for photo.

Have not had time for that too. I have too many balls in the air. :smile:

I'll try to get some time over to configure the optical bench for filter transmission measurements again and measure the Lee 729.
I hope to get some meaningful spectra from the Tiffen Haze 2A too. It arrived a few weeks ago
Ulf Wilhelmson
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