A joyful use of color filters in AF (IR) photography

alex ph · Joined: 16 Mar 2013 Posts: 1710

I've taken Panasonic Lumix TZ7, a compact digital camera from the late 2000s which is pretty nice on its own, and I transformed it to a "full-spectrum" camera with a simple detachment of a "hot-mirror" filter covering its sensor. Now the camera captures plenty of "extra" waves which give to daytime images a hard magenta tint. But this also pushes the camera to the well recognized IR performance, with mutated leaf and skin colours. That is pretty much of fun. I do not have a 720nm filter in my box, so used color filters, just putting them handheld in front of the Lumix lens. This is even more fun.

Compact digital zooms do not often have a filter thread on the lens, which is the case of my Lumix. What I am interested in, do you use or know any solution to attach a thin colour film on the front of the lens? I mean, I can easily cut a circle of a colour film and try that myself. What could be the source of thin film of different colours? And does it exist a film-thin 720nm material (not a classic glass filter) to use for a full-pfledged IR shooting?

Here are some samples from my first experiments

#1 With a blue glass filter held in front of the camera, light exposure and contrast tweaks

#2 With a green glass filter held in front of the camera, light exposure and contrast tweaks

#3 Orange or maybe blue or green filter, I haven't noted

#4 Bare "full-spectrum" shot, with WB corrected + light exposure and contrast tweaks

#5 Same in macro, just to see if it is possible to go "normal' with such a camera

#6 Red filter held in front, bw converted, contrast boosted

#7 BW conversion after a blue filter used

So, my question now is how to avoid holding large glass filters in front of the camera and just put a thin film layer directly on the lens which is regularly moving when zoomed and folding when the camera is switched off.

alex ph · Joined: 16 Mar 2013 Posts: 1710

And another one, with the orange filter, leaving interestingly pretty much of magenta in the folliage colouring

Vintage_Photographer · Joined: 10 Jun 2024 Posts: 113

My old vintage 1960 Voigtländer Vitomatic range finder has no threads but Voigtländer overcame this with push on filters.

Theoretically you could knock something up using a 3d printer to take Cokin filter holders and filters.
Filter in place:

Filter detached:

If you make it in TPU it should be soft enough not to damage anything.

DConvert · Joined: 12 Jun 2010 Posts: 936 Location: Essex UK

I've played with loads of colour filters on both my full spectrum cameras.
All the red filters I've tried work well though the #25 remains my favorite, most yellow & orange filters are also long pass designs, that just add a little more visual light to the IR.
Blue filters are more variable, but darker types can be effective. The #47 tends to give goldie type results (blue skies & yellow foliage), I've also had interesting results from some technical glasses such as BG3 & U330 that transmit UV, a little blue & IR. I've only got these two as 25mm bare filters so I'm rather limited on the lenses I can tried them on (this makes a BIG difference when UV is included)
I've found green filters to be very variable, with 3 different #58 filters giving very different results to each other one transmits loads of IR, one hardly any and the third half way between the first two. One of these works well on my Foveon camera (which is IR sensitive with the dust filter removed (very simple on the SD14)

If your after a cheap filter for IR only, crossed polarisers can come close (the first needs to be a linear type), many ND filters will also transmit IR, so darker types give an IR look. Unexposed but processed B&W negative is also an option...

Examples of many of my IR shots can be found in a IR dedicated flickr album here https://flic.kr/s/aHsjsHz7nC (rather than clutter your thread with my images)

alex ph · Joined: 16 Mar 2013 Posts: 1710

alex ph · Joined: 16 Mar 2013 Posts: 1710

I've found an interesting solution for the issue of the non-changeable IR filter stuck to the lens' front. I discovered the existence of variable IR-filters from China. So I've got a 37mm one which I stuck to the front of the Lumix. Now it looks like that and, following the specification, the IR capacity of the filter varies from 550nm to 750nm which is a nice range indeed.

Now I have a difficulty to use simple colour filters which was a fun, but I've got access to a more "classic" IR photography with "many-in-one" solution. Here are some samples in residual colour of various transmission degrees coming from this setup, as well as simple BW conversions of the shots.

At the widest angle the thick revolving filter vignettes quite visibly, adding some more vintage character to the shots. Once the lens is slightly zoomed, the field of view gets normal.

#1

#2

#3

#4

#5

#6

#7

#8

DConvert · Joined: 12 Jun 2010 Posts: 936 Location: Essex UK

alex ph · Joined: 16 Mar 2013 Posts: 1710

Thank you so much for your precise explanation and hints! Now I get better how the variable ID filter works. And I definitely should try a variable ND with the Lumix mod. I just need to figure out how to change the filter stuck quite solidly with the sticky ribbon to the front lens, as the zoom mechanics of P&S cameras is rather tender.

And yes, I feel you are right saying variable filter adds ghosting. At least with the cheap one I've got it's clearly visible.

By the way, I looked again at your IR shots following the link. Found again many great ones. And this time I was especially impressed with your shots of old trees. Congrats!

DConvert · Joined: 12 Jun 2010 Posts: 936 Location: Essex UK

alex ph · Joined: 16 Mar 2013 Posts: 1710

You are definitely right when suggesting the use an intermediary ring. It must be a step-up one, as long as a 37mm thick filter vignettes at the widest zoom setting of this Lumix. Something like a 37mm->42mm step-up ring and then a 42mm variable ND or IR filter. I'll see at which point this additional setup squeezes into the budget of my curiosity game.

philslizzy · Joined: 07 Aug 2012 Posts: 4751 Location: Cheshire, England

I made one for my Canon compact, however you can buy Cokin filter holders for compact cameras, I think this would do the job for you. I searched 'Cokin filter holder for compact camera'

alex ph · Joined: 16 Mar 2013 Posts: 1710

Thank you, that looks like an ingenious solution. Even though quite bulky too. This way a pocket compact camera stops entering back your pocket.

Does your setup look the same or more compact? How do you find it operating in practice?

alex ph · Joined: 16 Mar 2013 Posts: 1710

Meanwhile I continue to experiment with PP settings trying to reach some "classic" IR unreal effects.

A couple of shots with swapped colour channels. All online tutorials say one needs to swap red and blue channels only. What I see is that if one touches green channel too, the shot may become more expressive. Or may not.

#1 With tweaks in green channel

#2 Just red channel swapped

#3 The bare shot via IR filter

#4 Just another bare one, with contrast boost

#5 For curiosity, a shot from IR-ed Canon Powershot (produced several years later than the Lumix), with a ND filter on

I must say, I see more positively IQ of the mid-late 2000s compact cameras other than from their younger relatives coming from the same makers. Canon gives a good illustration here. Earlier P&S shots look more interesting, with good detail and contrast in a right way. And I do not quite understand why the later models which are optimized pixelwise look less interesting and less jucy.