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Equipment Discussions >> Electronically Assisted Astronomy

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jdbastro
sage


Reged: 08/18/07

Loc: W. Coast
Re: Nebula Pics thru Image Intensifier new [Re: dtripz]
      #5623727 - 01/15/13 01:04 AM

Quote:

Well done! I'd love to see some more if you have. Out of curiosity how do these compare with looking through the tube with your own eye, also what light pollution zone are you in?




My light pollution zone is a suburb of Los Angeles. So there's lots of sky glow. When viewing the intensifier with my eye, on the Flame, and HorseHead, only the faintest outlines are visible. On the Crab, again only the outline is visible - can't see any of the 'vein-like' structures.

If I view these nebulae from a much darker location like Mount Pinos, CA (altitude 8300 ft), the Flame and Horsehead appear at about 80-90% of the detail in these photos. The Crab, although showing brighter, still does not reveal the 'vein' structures.

I took pics of some other nebulae, but I need to see what I've got before I post more.

Also, I plan to shoot similar objects in some of my faster scopes (f7 and f5.6). Both of these scopes are faster but have smaller aperture than the Mewlon. BTW, the Mewlon 250 is f12 - pretty slow.

My ultimate objective is to shoot video with the G5 camera, however I need a faster lens on the camera or some other coupling with less light loss between the camera and intensifier output to make video work. I know someone else on CN has posted some impressive videos using an image intensifier.


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GlennLeDrew
Postmaster
*****

Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: Nebula Pics thru Image Intensifier new [Re: jdbastro]
      #5623769 - 01/15/13 02:20 AM

For extended objects like nebulae and galaxies, f/ratio controls image surface brightness and aperture controls image scale at given f/ratio.

A 3" f/6, a 6" f/6 and a 12" f/6 system will all produce equally bright images, because the f/ratio is the same. As far as extended objects are concerned, the only difference is image scale and hence the level of detail recorded. However, for stars, a larger aperture will record fainter ones.

An f/1.2 lens on your camera is plenty fast, and you'll be hard pressed to find anything faster. That's not the weak link. Strive for the very fastest light cone obtainable from the telescope, yet which is not too badly aberrated in the off-axis part of the image.


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jdbastro
sage


Reged: 08/18/07

Loc: W. Coast
Re: Nebula Pics thru Image Intensifier new [Re: jdbastro]
      #5625543 - 01/16/13 01:13 AM Attachment (20 downloads)

OK, here's a shot of M82 using an Astronmik CLS light pollution filter at 240 power (f24!) taken in about 1 second):

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Lightning
sage


Reged: 07/04/10

Loc: Canberra, Australia
Re: Nebula Pics thru Image Intensifier new [Re: jdbastro]
      #5627379 - 01/17/13 02:55 AM

Considering the F-ratio, that's an awesome pic!

Would you mind trying your lowest F-ratio and taking a number of short pics and stacking them with DSS? I'd really like to see just how smooth an image is possible.


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