T shirt flat

[brrttpaul]

Probably going to sound like the village idiot here but if you dont ask you wont find out. Has a T shirt flat got to be white?, there is a good reason  Im asking, I use a lot of lens cleaning cloths roughly about 12x9 and a lens cleaning cloth is a lot smotther and denser than a T shirt, trouble is most of my cloths are light grey so just messing about I put one on my telesope and put my luminence panel on top and using the flat wizard my exposures turn out at just under 2 secs which I think is right in the ball park, only fly in the ointment is the cloth is grey not white.  surely we just looking for a flat even illuminated image or should i get my coat lol??

[vlaiv]

It actually does not need to be, but it helps if color is relatively neutral (grey is).

Very strong primary color will effectively reduce light in rest of the spectrum and you'll get lower histogram for say blue and green then red if you use red cloth. This is in case you are using OSC camera of course.

Second problem is that it will impact color cast of the image if each flat channel is not normalized separately (something one should do anyway - and should be part of calibration software).

Other than that, I'd say - it does not matter much.

[brrttpaul]

thanks for the quick reply,  this is just a pale grey cloth (like a grey card for photography), I can understand if it was bright pink or orange , I will give it a go nothing ventured etcthanks for the reply