Digital Imaging - Flats and Darks Explained!

[BerrieK]

Alas I feel that your local supplier is incorrect. I believe you can get tungsten or xenon ultra white halogens. Maybe try an auto shop - they are sometimes available for car headlights (depending on what fitting you need). They are also sometimes use din shops to really bring the true colours out in displays.

[Octane (Humayun)]

Trevor,

Do you really need halogen bulbs?

I used high bright LEDs in my lightbox and they work a treat. I bought them from JayCar.

Regards,
Humayun

[Quark (Trevor)]

Originally Posted by Octane

Trevor,

Do you really need halogen bulbs?

I used high bright LEDs in my lightbox and they work a treat. I bought them from JayCar.

Regards,
Humayun

Thanks H,

Looking through this thread the only mention I recall of LEDs was that they may create a problem with one shot CCD's using various filters. I will only be using my 450D. I have used bright LEDs in the past to make an all round white anchor light for my boat. They were very bright, definitely white and consumed very frugal amounts of power.

It is most reassuring to know that you use LEDs, I really admire your work and have the greatest respect for your opinions on astro imaging.
I will now confidently go ahead and use LEDs.

Regards
Trevor

[gregbradley]

My understanding of bias frames is that you subtract them from your flats and then you do not need to use them again.

Also its best to use simple average for your flats and sigma reject for combining darks.

Greg.

[KenGee (Kenith Gee)]

I was looking to use a white shirt over my telescope when using my newEL flat pannel light. But I don't own a white shirt. I did have a ceap canvas pannel from a art and craft shop that I had been using for my flats. I tried it out today it works well.

[RobF (Rob)]

Originally Posted by Quark

Hi Eddie,

Have read your most excellent article and am in throws of building a light box, as per your basic design.

Can you provide any more info on the bulbs that you use. My local supplier assures me there is no such animal as an ultra white halogen globe, that halogen globes provide warm light ie: a yellowish light.

Any clarification would be greatly appreciated.
The box I am building is for a 16" scope so the diffuser will be quite large.

Regards
Trevor

Don't know what the experts'll say Trevor, but I use these from Jaycar, as per the ASIGN design, and get pretty similar flats to Paul (albeit with much longer exposures - about 0.5sec). They have small and "large" lamps with pre attached wires, so soldering up a bit easier - large ones a nice size for me.

I had an old 17" dead LCD screen I pilfered for diffuser screens that seems to work nice too (saved hunting in specialised lighting stores)