Hot mirror filter for far red / IR reduction - Do GH1 need them?

[Martti Ekstrand]

Hi,

there's are some CMOS cameras that have a problem with "the far reds" (near infrared) contaminating the image when using NDs in daylight. Tiffen has made screw-in versions of these for still cameras. Does anybody know if these have an effect on GH1? I'd test myself but these filters aren't available in Sweden currently. Here's an article about it regarding the Sony EX1 / EX3 cameras.
http://provideocoalition.com/index.php/aadams/story/the_last_far_red_filter_youll_ever_need/P0/

And here are the Tiffen filters at B&H Photo Video

http://www.bhphotovideo.com/bnh/controller/home?O=search&A=search&Q=&ci=0&sb=bs%2Cupper%28ds%29&sq=asc&sortDrop=Brand%3A+A+to+Z&ac=&bsi=363&bhs=t&ci=162&shs=&at=Type_Hot+Mirror

[Mike@AF]

Good question. I'd like to know the answer to this as well.

[Kholi]

I dunno but I'm gonna get one or a combo if they have it regardless. Rather be safe than sorry.

[Martti Ekstrand]

I would too but nobody seems to be selling them this side of the pond so please tell what you think. Testing them should be easy, just hold them halfway over the lens :)

[brownpaperbagproductions]

This guy says "Use an IR/ND combination filtration rather than just ND whenever possible."

http://www.hotrodcameras.com/2009/06/06/17-tips-for-shooting-with-the-panasonic-lumix-dmc-gh1/

[menace3000]

opposite question: anybody tried IR Filming with the Gh1?
How do I modify if need to?
thx

[Martti Ekstrand]

Bump! Anybody has more info on this? I've seen Illya's off-hand remarks but no comparison images or which type of hot mirror works with GH1. As they come in various flavours I'd appreciate some more in-depth comments.

[Martti Ekstrand]

Bump again! Is there really nobody with access to IR-cut / Hot Mirror filters that has tried it with GH1?

[Tameside]

will give it a try on my 45-200 zoom and report back in next few days. Shoot near foliage-trees? yes, anywhere else you want to see its effect?

[Martti Ekstrand]

A good way of testing this is assorted black fabrics in daylight with 4 or more stops of ND filter on compared with stepping down aperture (or shutter) equally. Then perhaps also under tungstens like a couple of Redheads. You can look at the article I linked to in my first post and this one for ideas.

http://www.hdwarrior.co.uk/2009/09/21/tiffen-t1-filter-test/

Much appreciated!

[Tameside]

Shooting indoor at laptop cases, black straps etc there is no perceptiable IR leakage IMO, ie the strange purple effect that used to happen on Nikon's etc. For info I thought the IR leakage was a ccd problem not cmos.

IMO, hot mirror has no effect, but will do some more tests.

[Martti Ekstrand]

Thanks for the report sofar. The IR contamination is indeed a problem even with several video CMOS cameras like the EX1 / EX3 ones mentioned in the article in my first post.

[mwabrisa]

I don't have specific knowledge about the effects of various hotmirror filters on GH1, but I do know that there are significant differences between various filters in how effectively they filter IR/UV and visible light. Some are very good, some are not. My suggestion would be to acquire a copy of the spectrograph for any filter before you purchase it. That way you'll know what it's actually going to do.

For an example of a custom hotmirror spectrograph click here (http://zcrcoatings.com/heat-control/hh-vis-1600-hot-mirror/).

If there is not a commercial hotmirror filter available to you where you live, I'm sure one can be custom made.

[thisisapocalypse]

I'm using the Tiffen T1 IR cut filter as recommended by the guys at Hot Rod Cameras and I can say that it does indeed help in creating a cleaner image since it cuts the red channel a bit and blacks look much more like black with it.

[Martti Ekstrand]

OK - good to know. Thanks for the info! Do you have any test image with and without?