How do I take flats with a laptop screen?

[evilgeenius]

How do I take flats with a laptop screen?

I'm outside on my laptop so If someone could reply quickly that would be great :-) If not then I'll use the technique tomorrow.

I think maybe I should get some better thumb screws to hold my DSLR securlly into the telescope. It moves easily at the moment so its hard to keep in position during the transfer of telescope to house.

Cheers

Chris

[jgs001]

You could open notepad, maximise it and hold it over the objective. Stick your SLR in Av mode, grab a shot. Go back to manual and set those same exposure settings (well shutter speed) and shoot a load more. The other option is Al's virtual Lightbox. You really should have everything fully tight, not just for moving it about but for imaging too.

[swag72]

When I take my flats using the laptop (as John said above) I always over expose by +1/3rd of a stop. Seems to get better flats that way.

[SteveKinder]

You could open notepad, maximise it and hold it over the objective. Stick your SLR in Av mode, grab a shot. Go back to manual and set those same exposure settings (well shutter speed) and shoot a load more. The other option is Al's virtual Lightbox. You really should have everything fully tight, not just for moving it about but for imaging too.

Apologies if I am being thick here but I am just starting to try to include flats in my processing.

Why not just keep taking shots is Av mode? Why go to manual and use the same settings? Not the first time I have heard this and I don't get it. What am I missing?

Help much appreciated.

Steve,

[ianaiken]

Because inn AV mode the camera can change the exposure, which it did to me the other day, so your flats will nit be consistant. Take a **** in AV mode and assess the histogram. Figure out if you need to adjust the shot or not. Switch to manual and them fire away. Once you've done your set rotate the laptop 90 degrees and repeat with exactly the same exposure.

I'm currently in the dark indoors taking mine right now waiting for it to get darker.

[ianaiken]

Those stars in previous post meant shot it must have put an I instead of o. By changing exposure I mean shutter speed. AV means you set aperture and camera decides shutter. In manual you get to control both.

[evilgeenius]

Thanks everyone.

I have a big problem with the thumb screws. It seems impossible for me to screw the DSLR into position without it being able to move fairly easily. It's not completely loose, it's just that it doesn't take much to move it. Is it possible to get better thumb screws? mine seem really puny and are difficult to screw really tight.