Using my TV to make Flats

[Earl]

I have a 40" Bravia hooked up to my HTPC it runs all my tv etc...

As I can set the desktop to white can I use this to make my Flats as the light should be pretty uniform in the area I point the scope at.

there is no need to worry about focus is there? as there is nothing to focus on?

[jgs001]

That's a large scale version of how I shoot my flats. I use Al's Virtual Lightbox and hold the lappy screen over the muzzle of the scope...

[Ant]

Not sure if you an use a TV or not - but you must not alter the focus at all - or the orientation of the camera to scope, or adjust remove turn filters )or filter wheels...

Flats MUST be taken with ALL the optics in exactly the same position as when used to take the image.

Cheers

Ant

[Earl]

ah cool, the more i ask the clearer the picture becomes... bad pun totaly intended

[RobH]

It'll work fine...quite a few use laptops set to white to shoot flats.

Thinking about it, you could also use different colours with different filters to cut down your flat exposure time....I'm thinking narrowband filters here.

Maybe I could use this as an excuse to stick a big flatscreen telly in the obsy

Rob

[Psychobilly]

It'll work fine...quite a few use laptops set to white to shoot flats.

Thinking about it, you could also use different colours with different filters to cut down your flat exposure time....I'm thinking narrowband filters here.

Maybe I could use this as an excuse to stick a big flatscreen telly in the obsy

Rob

Hmmm....

Not to sure about that... the need to change the display colour for "narrowband" filters that is...

Nowt wrong with the indes for a big telly in the obs though

Peter...

[ollypenrice]

[quote=RobH;

Maybe I could use this as an excuse to stick a big flatscreen telly in the obsy

Rob

You're not there to enjoy yourself!!

Olly

[RobH]

Hmmm....

Not to sure about that... the need to change the display colour for "narrowband" filters that is...

Nowt wrong with the indes for a big telly in the obs though

Peter...

It should work fine Peter.

It doesn't matter what colour you use as flats are applied as monochrome images.

What got me thinking about it is the fact that with my EL panel, the light is predominantly blue. This makes my Ha flat exposures quite long in comparison to anything green or blue.

If I tuned the lightsource so it was as close to the band allowed through by the filter, this would cut down my exposure time.

This could also work the other way if you needed to increase exposure time, for example with the new 8300 full frame sensor cameras, where there's a mechanical shutter which has a minimum exposure time.

Just brainstorming the idea really

[Psychobilly]

You have a pm

Peter..

[Earl]

Are Flats effected by temperature?

[Earl]

That's a large scale version of how I shoot my flats. I use Al's Virtual Lightbox and hold the lappy screen over the muzzle of the scope...

Al raises an interesting point where i found the link that he had heared that not all screens give a uniform flat image.

I know that this is the major issue with TV's with Blacks, but is this going to effect Flats?

[jgs001]

Only one way to find out

[RobH]

Are Flats effected by temperature?

Theoretically yes, but in practice I find it doesn't matter.

You have to balance the theory with the fact that you're trying to image and don't want to be shooting new flats every time the temperature changes by a couple of degrees.

I know I should really shoot thm at the end of a session, but as my scope/camera comnbination stays the same for weeks on end, I tend to use the same flats for quite a long time.

Rob

[Earl]

sigh over two years later and i still cant get these Flats right..........

[Catanonia]

I use an old 17inch LCD flat monitor and a white teashirt over the scope. Works fine. The teashirt difuses the light and dims it too.

I point the scope vertical. Lay the teashirt over and balance the screen over the top. The LCD is plugged into a laptop with notepad full screen. Be careful with the balancing and ensure your mount is truely locked. Works fine on a heafty 8inch newt.

For the WO66 I used a iPad II with a full screen white picture.