"T-Shirt" flats...

[SteveL]

Who here creates flats using the "T-Shirt" method? If so, what do you use to give it an even illumination?

[daz]

Steve

I have seen people pointing at the dusk sky using the t-shirt - it's what I'm planning on doing when I get there!!

[coatesg]

Who here creates flats using the "T-Shirt" method? If so, what do you use to give it an even illumination?

Yup - I do - anything that's fairly evenly illuminated. The sky at dawn/dusk/when overcast is a good one. Otherwise a patch of grass, monitor screen with a blank white display, or wall/net curtain are all things that appear to work OK. Just make sure there is no direct light or bright light source hitting the t-shirt.

Cheers

[Astroman]

As long as the flat is uniformly lit across the field it should be fine for "pretty pictures". For photometric consideration, it must be uniform in wavelength, too. Some paints reflect more in the blue than the red end of the spectrum, throwing off any photometric processing. A t-shirt that's been bleached may do the same. This is probably neither here nor there, but it may come into play when you process red images. Just a heads up to keep in mind if your results aren't what you expect.