I just tried IR chrome effect

[lukaszgryglicki]

Hi, this is my first attempt at the IR chrome effect. Fuji 50R full-spectrum, Kolari IR-Chrome filter.

 

Those more orange are sooc (WB on the building wall) while the one with more red vegetation is very easily extracted from the RAF file with just 3 parameters modification: more color saturation, a bit of hue shift, and then WB on the building wall.

 

 

[lukaszgryglicki]

BTW: did somebody from this forum have a transmission spectrum for Kolari IR chrome? They don't publish it, they make a big secret from this - their email answer was that transmission is classified. But maybe somebody just did spectrometer test of it and can publish?

 

[Fandyus]

15 minutes ago, lukaszgryglicki said:

BTW: did somebody from this forum have a transmission spectrum for Kolari IR chrome? They don't publish it, they make a big secret from this - their email answer was that transmission is classified. But maybe somebody just did spectrometer test of it and can publish?

 

It most likely passes around 720nm, suppresses red and passes green and blue well, blocks any deeper IR. That results in blue and green photocells to work as intended and the red ones pick up near IR only.

[ulf]

It is rather silly to say that the transmission is classified when they sell the filter as the filter is carrying the transmission!

 

Anyone with access to a filter and a spectrometer could make it un-classified.  ;-)

 

I would never dream of buying that filter but would love to reveal the transmission here if anyone would loan me a filter. 

I think Fandyous guess is reasonably correct.

 

At least they cut most of the upper NIR.

That is proven by that there are no fringing effects in the pictures from longer wavelengths.

[lukaszgryglicki]

You mean you want me to send you my filter for measurement?

 

[ulf]

I was not pointing directly at you Lukasz, but yes if you would dare risking sending the filter and can be without it a few weeks it would be an interesting exercise.

Please do not feel forced to do it.

Maybe you are curious about the transmission too?

We could see it as a joint effort to widen our knowledge and share that "Classified" information with everyone.

 

Naturally I would cover the return shipment costs.

Shipping losses are rather rare, I think, within the EU.

[lukaszgryglicki]

OK I will send it for you, but not now, maybe some few weeks from now, I of course wonder its transmission and we will publish it then, I saw many people here struggle with IR chrome effect, having a transmission specctra of this filter would help a lot.

 

[ulf]

[Christoph]

Look at the transmission curves of GRB3 and Peacock Blue (Lee) and you'll get a good impression of what IR Chrome is. It's identical in my opinion.

[lukaszgryglicki]

OK I saw GRB3 transmission but also that filter's photo - so Kolari IR Chrome has a different color (more blue) and looks more dense - so at least in visible spectrum they are different.

Same with Peacock Blue (Lee) - looks a bit less dense and more green than Kolari IR Chrome.

But at least I have some approx.

Thanks.

 

 

[Christoph]

Some while ago I made a comparison between IR Chrome and GRB3+Peacock Blue.... the resulting images are very similar: Make your own IR Chrome | Hidden Realms

[Fedia]

4 hours ago, lukaszgryglicki said:

Kolari IR Chrome has a different color (more blue) and looks more dense - so at least in visible spectrum they are different.

Same with Peacock Blue (Lee) - looks a bit less dense and more green than Kolari IR Chrome.

You are right, Lukas. The peacock blue gel and the IRchrome don't look the same to the eye so they have to have a different transmition curve, at least in the visible.

I tried a few other blue-green gels and it appears that in combination to the GRB3 they all produce the Ir chrome effect. I suppose christoph tried a lot of these and concluded that peacock blue was the best at it.

 

It's intresting because in theory christoph's combo could be more efficient thant the real thing. It passes more green so the gain in the green channel doesn't have to be raised as much as with a bluer filter in the white balance, which diminishes the risk of ending up with orange tones.

I think the orange tones in your picture is due to Ir getting in the green channel and not to the actual green reflected by the plants.

 

Also with peackock blue the transmission of the red falls down to 0% which turn the red channel into a great recipient for IR. I never saw an Irchrome for real, but from the pictures it doesn't look so agressively anti-red as peacock blue.

 

I suppose there was some constraints in the making of the Irchrome to make it from optical glass and an actual product. So  maybe the bluer coloration of the Irchrome is a compromise on the ideal filter. I remember Yann Phillipe saying somewhere that you could achieve the Irchrome effect from gels but that you couldn't using only glass.

[Ming]

@lukaszgryglicki, @ulf, May I cut in line?  I can send Kolari IR Chrome Lite to Ulf right away.  It is the magnetic clip-in kind, thin and rectangular.  I don't plan on using it for the next few months.

 

[ulf]

@Ming, I am afraid it is not a good idea that you send your filter to me.

It will be complicated as we have customs barriers between the US and EU, that add more costs, processing and risks of losses.

There has been losses and problems a few to customs handling.

 

I prefer to borrow a Chrome filter from someone within the EU.

I do not think we would gain any time by measuring your filter  instead of the one Lukasz will send to me.

 

 

[lukaszgryglicki]

Yeah, customs can be a problem - BTW: my IR chrome arrived from the US and there were no customs... :p

 

[Lou Jost]

I have the Kolari filter and I can make a photo of the spectrum easily with my FS Sony A7R, next time we have a sunny day. I like this filter very much. I only wish that Sony cameras gave deep reds rather than yellow-orange for IR.

[lukaszgryglicki]

Thanks, please do.

 

[FL_96]

Hello, 

 

It seems someone did a partial transmittance plot of the filter here :

https://www.pentaxians.de/40456504nx51499/tipps-und-tricks-f41/tutorial-digitale-infrarotfotografie-mit-pentax-t15268-s110.html

 

[Lou Jost]

Here's my spectrum through the IR Chrome filter (bottom) and unfiltered (top) on a Sony A7R full-spectrum camera.

 

[Edit: Deleted all-black image.}

 

Hmm, that's curious, wonder why it is black? Answer: Image too large, the site does not resize photos to fit the space..

 

[Lou Jost]

Try a smaller version. Counter-intuitively the filter cuts out quite a lot of IR.

[ulf]

3 hours ago, Lou Jost said:

Try a smaller version. Counter-intuitively the filter cuts out quite a lot of IR.

That is as expected as several reviews report that there are no typical IR-fringing effects with the filter.

Here is one: https://www.edwardnoble.com/irchrome

As there are no or very little left of the hot spot problem too, my conclusion is that the IR-chrome filter is mainly a VIS-filter that use a tiny bit of IR for hue adjustment

It will be interesting to eventually reveal the "classified" transmission.

[Lou Jost]

3 hours ago, ulf said:

That is as expected as several reviews report that there are no typical IR-fringing effects with the filter.

Here is one: https://www.edwardnoble.com/irchrome

As there are no or very little left of the hot spot problem too, my conclusion is that the IR-chrome filter is mainly a VIS-filter that use a tiny bit of IR for hue adjustment

It will be interesting to eventually reveal the "classified" transmission.

[Lou Jost]

I think we have to look at the relative transmissions of different colors. The infrared transmission, though much lower than the unfiltered IR transmission, is still about as large as the vis red transmission. I have used it a lot since it first came out a couple of years ago, and there is no doubt that it really does present strong infrared reflectors as orange-red; it is not a faux-IR effect.

[ulf]

I am not saying that it is a faux-IR effect, only that they use very little of the actual IR band to create the effect.

 

If you stack a few different long-pass filters like 690nm, 720nm, 760nm and 800nm with the chrome filter and compare the difference in exposure times, to the time you get with the time from filter only, you'll get a hint of the amount of IR light that actually is used in the process. 

 

Partly that might be a good thing when emulating the film as I do not think the film was sensitive to the longer wavelengths of NIR like a silicon based sensor. 

[ulf]

What I miss from the IR Chrome is the darker sky, red tones turning yellow and the strange skin tones that are typical for Aerochrome too, beside the red foliage