Im thinking of have a shot at a night time terrestial IR photo composed with the sky in the same shot. The 87 filter I have, as shown in the attachment, shows it neatly cuts Ha out, so I can only hope for some exposure from stars fields and galaxys, being broad band scources. Has anyone tried an astro pic with a IR filter?, Is there enough IR light from stars thru the atmosphere to register an image?. This filter is very dense, and results in greyscale only with a modded DSLR. Im also assuming IR radiation from plants and trees in total darkness would produce an image , I havent seen examples taken at night with it.
I did some testsa couple of years ago using an IR filter.
Suprising how much data i got in 90 seconds of exposure, as apposed to 5 minutes using normal vision spectrum.
The camera was a QHY-8, but a modded Canon 20D etc, was just as good. In fact, with the UVIR filter removed, and using a small exposure time, i actually got the glow of heat from a soldering iron running at 400 DegC. It was cool to see the iron glowing in white light.
Anyway, heres the images, and it really is cool to see things that just dont come up on a normal image.
OK, thats encauraging Theo, but I see some colour and neb there, which implies it passed Ha at 650nm odd, and well.........RGB, how is that possible with an IR filter, do you remember what the bandpass was?, or is it a blend?.
Holy cow, thanks Marc, thats awesome. I cant workout if that was from a space cam, but anyway, it seems some other filters were used above IR to be able to create a false colour image, tricky. They mention ionised Ha too, so that must be in the pic band width.
I take lots of images through a "I" photometry filter.
The passband is in this graph. http://www.astrovid.com/other_images...ilterchart.jpg
Using my ST10XME the exposures need to be about 50% longer than R to get equivalent levels in the image but they are much brighter than B or G exposures.
As for terrestrial imaging. I remember using IR film and it worked best with bright sunlight. Green things like trees reflected lots of IR but needed bright sunlight to do this. Images were very washed out if it was overcast.
I don't think that you would get much at night.
I take lots of images through a "I" photometry filter.
The passband is in this graph. http://www.astrovid.com/other_images...ilterchart.jpg
Using my ST10XME the exposures need to be about 50% longer than R to get equivalent levels in the image but they are much brighter than B or G exposures.
As for terrestrial imaging. I remember using IR film and it worked best with bright sunlight. Green things like trees reflected lots of IR but needed bright sunlight to do this. Images were very washed out if it was overcast.
I don't think that you would get much at night.
Thanks Terry. Pity about terrestial, but what you say makes sense. The I filter is above Ha, so I might give this filter a shot with the ST10, It would allow a different colour pallet with other NB filters.