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Old 01-09-2009, 10:18 AM
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Idea for flats

I'm still learning,however I had an idea of doing flats with handy to use things. If I laser cut a 3mm med denisity white opaque piece of acrylic the same size as my laptop I could put it on the screen, put up a white image and put the refractor dew shield hard up to the laptop and click away.
Or am I on the wrong track?
I'm slowly getting some gear together, and as yet do not have a camera to test my idea.
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Old 01-09-2009, 11:04 AM
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David,

Have a look here:

http://www.iceinspace.com.au/forum/s...tual+light+box

Why bother with the acrylic?

Al.
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Old 01-09-2009, 11:06 AM
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I've read of people doing it before, eg http://www.flickr.com/groups/2519165...7614568400032/ but I have yet to take my own flats.

I imagine it'd be difficult to get even if you're just holding the laptop there, and white light is not good if it leaks at a dark site get-together.

[edit] I see Al has posted a link to one here on IIS. That's the one I was looking for but couldn't recall where I'd seen it.
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Old 02-09-2009, 05:24 PM
Hagar (Doug)
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I actually use an A3 size Electro luminous sheet stuck between a sheet of ply wood and a sheet of opaque white perspex. It is very portable, just sits on top of the scopes and runs off 12 Volts and works a treat.
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Old 02-09-2009, 06:09 PM
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I've tried using a laptop screen, and an LCD computer monitor, and a LCD TV for flats... They are not uniformly illuminated.. It might look it, but they are not... Every time i have taken flats using an LCD of any type there has been anomalies.. I've seen perfect flats taken with light boxes, and perfect flats taken with the electro-luminescent panels Doug mentioned.. but an LCD is not the best way of doing it... With an opaque diffuser on it it might be ok..
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Old 02-09-2009, 06:38 PM
Ian Robinson
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Hagar ,

Is this http://etrade.daegu.go.kr/co/itemban...061/Eflex.html the stuff you used ?

Where did you buy your light source sheet ?
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Old 02-09-2009, 06:50 PM
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Here is an unconventional lightbox design using luminous paint as the source.

The "lightbox" fits inside the telescope dust cover.
It works well for me.

http://users.westconnect.com.au/~sjastro/Tutorial/lightbox.html

Steven
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Old 02-09-2009, 07:58 PM
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mmmmm interesting.
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Old 02-09-2009, 08:21 PM
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Quote:
Originally Posted by AlexN View Post
I've tried using a laptop screen, and an LCD computer monitor, and a LCD TV for flats... They are not uniformly illuminated.. It might look it, but they are not... Every time i have taken flats using an LCD of any type there has been anomalies.. I've seen perfect flats taken with light boxes, and perfect flats taken with the electro-luminescent panels Doug mentioned.. but an LCD is not the best way of doing it... With an opaque diffuser on it it might be ok..
Thanks for pointing that out, Alex.

I haven't used my VLB as alight box, I just wrote the code... it's handy to know its not such a good idea.

Al.
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Old 03-09-2009, 06:22 AM
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what's wrong with a simple white t shirt stretched over the scope?
frank
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Old 03-09-2009, 06:39 AM
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Quote:
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what's wrong with a simple white t shirt stretched over the scope?
frank
Coz my flats would all have Pearl Jam tour dates all over them...
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Old 03-09-2009, 06:42 AM
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Quote:
Originally Posted by spearo View Post
what's wrong with a simple white t shirt stretched over the scope?
frank
Absolutely nothing wrong with this method.
I simply took a shot at cloudy sky through telescope (narrow field lens)....
For wide angle, I just placed the piece of white paper in front of the lens.
No batteries needed :-)
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Old 03-09-2009, 03:12 PM
Benny L (Ben)
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just go for sky flats.. not hard to do and you can do them before/after the imaging run if you pull an all nighter
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Old 03-09-2009, 04:07 PM
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Quote:
Originally Posted by Benny L View Post
just go for sky flats.. not hard to do and you can do them before/after the imaging run if you pull an all nighter
The problem with this technique is that it assumes you can actually get to your scope at twilight. Sadly with a family and the commitments re dinner, homework, school lunches etc I find it virtually impossible to use my scope before 9pm.
I have a piece of gyprock on the wall of my observatory that I aim the scope at. I then use a flash and aim it at the back of the observatory. This bounces around quite nicely giving me an evenly illuminated flat.
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Old 03-09-2009, 07:42 PM
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Quote:
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Coz my flats would all have Pearl Jam tour dates all over them...
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