Flats with a white laptop screen?

[M00NMonkey]

Hi all

I have been reading loads of articles on building a light box to take flat frames with. Seems fairly easy to do and will give it a go soon, but I was just wondering if a white T-shirt over the scope and a white image on a laptop screen up against or near the scope , would work?

Also, I have found conflicting info on whether the temperature, when the flats are taken, matters?? It does tend to lean towards "it does matter" and you need to take them at the same time as other subs, as well as being the same settings. It would also seem more logical to capture all the data at the same time, so I am guessing this is best?

Thanks

Jez

[Tinker1947]

You image in the dark, flat with a white t-shirt would require sun light, so i doubt the time and temperature matter to much. There was another thread some time back on this subject. A laptop with a white screen would working i guess depending on your tube diameter, this is my tablet with a flashlight app..

[Bizibilder]

A white screen will work - you may need the t shirt or a sheet of semi-transparent white acrylic sheet just to "blur" the light source. Temperature is not critical for flats but you must take them with exactly the same optical set-up as your lights ie no change in focus / orientation of the camera etc.

[M00NMonkey]

Thanks for the replies. I will give it a go with laptop/t shirt and see how it goes. Surely it will be better than not having flats at all until I get the light box sorted.

Roger, it was your light-box I was looking at building. just searching around looking for all the bits.

[johnrt]

I use my iMac screen with text editor open - just a white screen. I need to turn the brightness down a little on the screen but it works a treat. I don't use a t-shirt over the scope, I think at 900mm focal length a white monitor screen a couple of inches off the front of the ota will be pretty blurred already. Good advice above - make sure you focas point and camera orientation has not changed from when you took your lights.

[Bizibilder]

That LB works really well !! I just slew the scope to vertical and rest the LB on the dew shield. There is no real need for the variable supply to the box as the camera (DSLR) sets the exposure automatically if you set it to Av.

[Guest]

Hi,

I have read this thread with interest, i have not ventured into using flats yet, but have been considering it as i get a bit of vignetting from using a FR in my imaging set-up.

You say all settings should mimic the imaging ones, like, focus, camera angle, but do you have to have the same filters in place, iso and exposure times like you do with darks?, if not what should they be?

I am a beginner so bare with me.

Olly

[Guest]

Hi,

I have read this thread with interest, i have not ventured into using flats yet, but have been considering it as i get a bit of vignetting from using a FR in my imaging set-up.

You say all settings should mimic the imaging ones, like, focus, camera angle, but do you have to have the same filters in place, iso and exposure times like you do with darks?, if not what should they be?

I am a beginner so bare with me.

Olly

Also i guess the focal reducer needs to be in place as this is what causes the need for flats in the first place??

[Psychobilly]

I use a whitescreen on the netbook, laptop ot tablet when shooting with camera lenses and I don't bother with a diffuser either...

Peter...

[M00NMonkey]

OK, so i got a white screen set up and I will try both ways, with and without a diffuser (t-shirt ) and see what results I get. I basically exported a blank white png from gimp and set it as a slideshow to get it fullscreen. Obviously got the brightness buttons on mac to adjust the image, so should work well.

In the long run I will attempt to build Rogers lightbox, but the above will suffice for now.

Cheers

Jez

[stem1989]

t shirt and laptop screen worked for me last week.