Quote:
Originally Posted by Lester
Fantastic detail Trevor. Are you using a DMK camera, just interested in what FPS you can use with the IR filter? Thanks.
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Thanks Lester, yes I am using my DMK.
Lester, I have never imaged Mars prior to this apparition with the DMK, in all truth I have never really put much time into imaging Mars with anything. So for for this apparition I have imaged it on 5 different mornings and obviously this has involved a lot of experimentation.
The IR filter that I am using cuts back a lot on the light that passes it and I have tried various combinations of frame rate, exposure and gain. Based on the results with this image I think I am approaching the optimum setting for this target for my setup. For this image I used 30 fps and 1/30 sec exposure. The size of my aperture allowed this, a 16" primary collects a lot of photons.
Quote:
Originally Posted by multiweb
Hi Trevor, excuse my ignorance but planetary imaging is like black magic to me. Is this a 2" IR filter we're talking about? And you're unaffected by the seeing?
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Hi Marc, I use an Orion manual filter wheel that can take 5, 1 1/4" filters. I have it loaded with LRGB and IR filters all are Astronomik. There are many different IR filters. Visible light is 400 to 700 nm and there are various IR filters as we move past 700 nm into the infrared. The particular filter I use passes the electromagnetic spectrum from 807 nm onward. Of course the seeing is still relevant but not to the same extent.
I don't know if you are aware of the work of Andrea Ghez. Using the Keck's with adaptive optics and in the IR she was able to see through all of the considerable amount of gas and dust right to our galactic centre and image directly the high velocity stars in very close orbit around the super massive black hole candidate Sag A* that resides there. Just as professionals use IR to peer into dense regions so amateurs can utilize IR, especially when imaging objects close to the horizon to help alleviate the effects of the considerably larger airmass at low altitudes. IR is also beneficial for many other reasons for planetary imaging but I think I have probably rambled on to far already.
The image of Mars that is the subject of this post had other things going for it beside the IR filter. My Peltier cooler had been running from 2am through to 3am and by the time I started imaging at 3:30 the air currents generated by the cooling system had subsided and my mirror was at its optimum temperature. The collimation of my scope was as close to perfect as was humanly possible, adjusted with the scope in the same orientation that the images were captured. I cannot overstate the need for attention to detail when imaging at very high power.