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Options for UV/IR cut filters

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#1 Andy Perrin

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Posted 26 September 2017 - 03:51

Fall is here in the northern hemisphere and I would like to use my full spectrum camera to take some good old visible light photos. What are the available options for UV/IR cut filters and do people have a favorite? Price is always a consideration.

Edited by Andy Perrin, 26 September 2017 - 03:51.


#2 JMC

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Posted 26 September 2017 - 05:45

Lens selection (and therefore filter diameter needed) will come in to this choice too. I've run a couple of different ones (B+W and Baader) through the UV Vis spectrometer to get the transmission spectra and they do look different (towards the bottom of page 2 of the thread below);

http://www.ultraviol...ts/page__st__20

The Baader gives a sharper cutoff, and covers a smaller range of wavelengths, while the B+W has a more gradual cutoff, but lets some IR and UV through. However the Baader is max 2" while the B+W comes in different sizes suitable for larger lenses. I picked all mine up second hand on a well known internet auction site for much less than the new prices. To be honest for general use (and with larger lenses) I find the B+Ws fine. I've not tried any of the really cheapy cheap ones as a comparison.

#3 A.S.

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Posted 26 September 2017 - 05:46

I have a Hoya UV/IR cut and very cheap chinese UV/IR cut filter. The cheap chinese filter is only usable with longer focal length with wide angle lenses there is a color different visible in edges and center of image. I have found this Hoya UV/IR cut filter in used condition on Ebay so this filter was also not too expensive an I can use it with the Olympus 17mm f/2.8 lens on full spectrum modified micro four third camera without problems.

#4 enricosavazzi

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Posted 26 September 2017 - 11:32

Astronomik makes three L filters with sharp shoulders at the UV and IR cut wavelengths. L-1 is the one with the broadest bandpass (includes a little UV and IR), L-3 the most restrictive (roughly 420-680 nm, so it cuts also a little VIS violet and VIS red). Not cheap, but usually less expensive than typical Baader filters.

Edit - these filters have a much sharper edge at the VIS-NIR border than built-in UV- and IR-cut filters used in digital cameras, so they do not emulate the latter filters and do not restore the original color rendering of a converted camera. The latter filters have very gradual VIS-NIR shoulders that cut significant amounts of VIS red.

Edited by enricosavazzi, 26 September 2017 - 11:39.

-- Enrico Savazzi

#5 OlDoinyo

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Posted 26 September 2017 - 13:31

I use the KolariVision "hot mirror" filter which is not a hot mirror at all but a piece of BG-type glass. Other filters based on similar glass might work more or less well. I do not recommend dichroic hot mirrors unless you only use telephoto lenses.

#6 Andy Perrin

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Posted 26 September 2017 - 14:16

Thanks all! It sounds like I have to choose between sharp cutoffs vs natural scene rendering so it may eventually boil down to having one of each type.

#7 UlfW

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Posted 26 September 2017 - 19:26

The filters in my Canon Eos 60D before modification was of both of absorbing blue-toned and dichroic types:

Attached Image: Canon EOS 60D Sensor Filter.jpg Attached Image: Canon EOS 60D Dust-shaker Window.jpg

The graph to the left show the transmission of the original bluish filter placed in front of the sensor. The graph to the right show the transmission of the dust shaker window.

If I understand the function of the blue sensor filter correctly, it is there to attenuate and balance the intensity of the red (and infrared) light to avoid saturating the red channel before the other channels.
The maximum sensitivity of the sensor is in that region.

I have tried several alternatives, for visual photography, both dichroic and BG-type of glass, but not combinations of both types.

I liked the result with a BG38, 2mm best, giving pictures with the most true colours in the red end. The transmission of BG38 is similar to the removed blue sensor filter.
There might be some influence from the UV- and IR-spectra left that the original shaker filter would have cut, but I have not seen any traces of it in my pictures yet.
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#8 Cadmium

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Posted 26 September 2017 - 20:07

I use Schott BG38, it is my favorite visual filter for my full spectrum Nikon cameras. Some use BG40. Some even use BG39 or S8612, but those look too blue for me.
Baader UV/IR-Cut filter looks too red.
More RED - Baader UV/IR-Cut - BG38 - BG40 - BG39/S8612 - More BLUE
Some stack the Baader UV/IR-Cut filter (or other such sharp cut) with BG40 or such, to round out the curve, I can see where this should perhaps make some curves a bit less red.
One could also stack BG40 (say) with GG400 or GG420. However, except with extreme cases I never see any UV in visual shots because the visual light is so overpowering.
I believe that one of the aforementioned "hot mirror" filters is Schott BG40 or some equivalent.

Edited by Cadmium, 26 September 2017 - 20:08.


#9 JCDowdy

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Posted 26 September 2017 - 21:53

This my be helpful: UV/IR-Block & IR-Block Filters on a Converted Camera

#10 Andy Perrin

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Posted 27 September 2017 - 04:45

Andrea

View PostJCDowdy, on 26 September 2017 - 21:53, said:

Yes, it is.

Andrea, what thickness were those glasses in the tests?

#11 Cadmium

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Posted 27 September 2017 - 15:57

I posted these here a year ago, but can't find the topic link.
So here are a few of the tests I posted back then.
Attached Image: D7200_all_S8612_BG39_BG40_BG39_BaaderUVIRcut_Auto_1280.jpg

This compares D610 stock camera with no filter to a D7000 UV/IR converted camera with a BG40 filter.
NOTE: No UV pattern difference between the D610 stock and the BG40/full spectrum.
Attached Image: D610_Stock_D7200_UVIR_BG40_1280.jpg

#12 Andy Perrin

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Posted 27 September 2017 - 20:09

Heh, well ALL of them are better than the 1.75mm S8612 I've been using lately. I just bought a Hoya UV/IR cut, but it may not be my endpoint. I'm also giving strong consideration to the Kolari. Cadmium, I looked for 2mm BG39 at 52mm diameter, but I couldn't find any from you? Are you out?

#13 Cadmium

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Posted 27 September 2017 - 20:28

There are some BG39 52mm x 2mm. It is hard to say how BG39 and S8612 look on other cameras, but I don't use those for visual myself. Different cameras will need different filters to work closer to stock.

#14 Andrea B.

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Posted 01 October 2017 - 17:44

Andrea, what thickness were those glasses in the tests? UV/IR-Block & IR-Block Filters on a Converted Camera

The Schott glass is all 2 mm thick.

The B+W filters are X mm thick.

(SigOther is looking for the calipers........)

Added:
The B+W 470 filter measures 2.3 mm thick. That's a bit strange?? Wouldn't you think it would be 2.5 mm??
B+W 039 = 2.0 mm.
B+W 038 = 1.9 mm. Also strange.
The calipers I'm using are old, so I don't know if that is why I'm getting unusual thicknesses in the B+W glass?? Or is there that much variation in 2.0 mm or 2.5 mm thick glass?

*****

I think the Kolari filter is just some BG glass?

The key point of the experiment was that you must pre-measure white balance in-camera* under any of these UV/IR-block filters that you use. Once you do that, then you'll have a better visible colour outcome. A UV/IR-block filter used without pre-measured white balance will not always give back your camera's original colours before conversion.

*Alternately, you can shoot a white/grey card under the UV/IR-block filter, white balance the card in your converter and apply the WB result to the other photos in the shoot.
Andrea G. Blum
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#15 Andy Perrin

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Posted 01 October 2017 - 19:07

My plan was to do what's in your asterisk there, in fact. I have the Hoya filter now, which is pretty similar to the Baader and other dichroic blockers.

http://www.hoyafilte...ilters/uvircut/