Setting custom WB via grey card

[MargaretR]

So I'm trying to set a custom (one touch) WB using a grey card, and the EM-10 is having none of it.

This is my newly-IR-converted EM-10, with which I'm now experimenting. Apparently for this particular IR filter, WB on a grey card is recommended, but I can't get the camera to 'take' it. All I get is the "X WB no good" message.

The card was in bright sunlight; I've tried over-exposing by 1, 2, 3, 4 and 5 stops (the maximum, it seems); I've upped the ISO; I have the aperture wide open at f2.8. Still, it doesn't want to know.

I've successfully done the WB on a white card, and on green grass, so the system does work ... just not with grey.

Any suggestions, anyone?

Or am I doomed to have to carry and include a grey card in every shot I ever take?

[Ricoh]

Re: Setting custom WB via grey card

At what wavelength range does the converted camera operate?
I suspect it's what's termed 'near IR'. IR is sensitive to temperature, isn't it?

[MargaretR]

Re: Setting custom WB via grey card

It's a 590nm filter. Other than obviously not being 'visible light' I have no idea how that impacts anything in terms of settings.

[Graham_of_Rainham]

Re: Setting custom WB via grey card

There are several Inks & Dyes that absorb near IR while appearing to produce the required colour in "daylight".

They are used a lot in ID cards where scanners can see hidden patterns using IR light.

You may have a grey card that absorbs IR making it look black to the sensor

http://www.hwsands.com/category/26.aspx

[Graham_of_Rainham]

Re: Setting custom WB via grey card

You could always ask about something like these as they are plastic.

http://www.7dayshop.com/products/7da...gc-b-7DSMQDG-B

[MargaretR]

Re: Setting custom WB via grey card

You could always ask about something like these as they are plastic.

http://www.7dayshop.com/products/7da...gc-b-7DSMQDG-B

Thanks Graham. I was looking at something similar

[Graham_of_Rainham]

Re: Setting custom WB via grey card

This looked "interesting" and may be of some use.

http://www.davidclapp.co.uk/blog/vie...s-in-lightroom

[stoates]

Re: Setting custom WB via grey card

Hi Margaret. To set custom WB on my E-5 I have to use a white target, not a grey card. If it doesn't find white I get a fail message that may be similar to yours. I know you have tried using a white source, did you test the custom WB with your filter afterwards to see how it looked? I find that regardless of using a custom WB with my 8 stop ND I still require further manipulation in LR to correct the colour.

[Invicta]

Re: Setting custom WB via grey card

On my IR converted camera I use an area of green grass to set the custom white balance.

Then I use Olympus Viewer software for the initial conversion as, unlike Lightroom, Olympus Viewer can read the custom white balance setting.

[MargaretR]

Re: Setting custom WB via grey card

Hi Margaret. To set custom WB on my E-5 I have to use a white target, not a grey card. If it doesn't find white I get a fail message that may be similar to yours. I know you have tried using a white source, did you test the custom WB with your filter afterwards to see how it looked? I find that regardless of using a custom WB with my 8 stop ND I still require further manipulation in LR to correct the colour.

Yes, neither the white WB nor the green WB is giving me what I think it should look like, at least according to the sample images from this filter on the conversion company website. I did anticipate further work in LR, and/or even a custom DNG profile, but I do want to try and get the WB as good as possible to start from, and I just feel I'm not there yet. Further messing about to be tried yet..

[MargaretR]

Re: Setting custom WB via grey card

On my IR converted camera I use an area of green grass to set the custom white balance.

Then I use Olympus Viewer software for the initial conversion as, unlike Lightroom, Olympus Viewer can read the custom white balance setting.