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Equipment Discussions >> Electronically Assisted Astronomy

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Moromete
professor emeritus


Reged: 02/15/12

Loc: Romania
Re: Video integration time equivalent to eye? new [Re: highfnum]
      #5802247 - 04/16/13 10:05 AM

I did a test last night with a Canon 550D + Canon 50mm F/1.8 lens. The 550D showed the same image brightness and detail like my eye saw when it was set up at ISO 3200 and 1/50 shutter speed.

I think human eye is very efficient or current sensor technology is not so sensitive yet, as we would like it to be for real live viewing of DSOs (at ~1s exposure duration).
Just image how powerful our eyes could be if they were capable for long exposures like CCD astro cameras.


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GlennLeDrew
Postmaster
*****

Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: Video integration time equivalent to eye? [Re: Moromete]
      #5803471 - 04/16/13 08:16 PM

Moromete,
Your test, at only 1/50 second (!), most certainly could not record such a faint phenomenon as the Gegenschein. Which the dark adapted eye does see at a dark site.

I point this out because the result of the test depends sensitively on the subject. A very brief exposure can reveal all the naked eye stars from a light polluted locale, a longer exposure will be required to capture all the naked eye stars at a dark site, a yet longer exposure is needed to equally well represent the brightest nebulae, a still longer exposure is required for the fainter nebulae, and the longest exposures are required to capture the very lowest surface brightness stuff.

It's a continuum. And so the object type and conditions are very important variables to consider.

The eye's huge dynamic range, and its ability to dark adapt, make it impossible to derive just one global equivalence between eye and camera. One has to specify, pretty narrowly, the conditions. Depart much from these, and a new equivalence results.


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Puck Ja
scholastic sledgehammer
*****

Reged: 11/21/12

Loc: OK, USA
Re: Video integration time equivalent to eye? new [Re: nytecam]
      #5842342 - 05/05/13 08:03 PM

Quote:

Thanks for your interest. Which of my four pics posted does M51 seem like in your EP?




I realized that I have never answer this question. Compare to Nytecam's photo, two nights before clouds came in I had quick peek through my XT8 when M51 was close to zenith. Still, through my eyepiece, the M51 and its companion were just two cloudy disks without much hint of arms. So it was equivalent and slightly less detailed than the 1-sec integration from Nytecam's 12" and Lodestar. However, that was with a NOT-dark-adapted eye sine I was working with my newly acquired Lodestar. The light from computer really destroyed my dark adaptation.

The good thing now with my XT8 on Atlas, I can get 1-min exposure with good detailed arms structure from M51.

But I made some mistake during saving the image to TIF so I ended up with no picture to show. And the clouds came.


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nytecam
Postmaster


Reged: 08/20/05

Loc: London UK
Re: Video integration time equivalent to eye? new [Re: Puck Ja]
      #5842890 - 05/06/13 02:58 AM Attachment (6 downloads)

Quote:

Quote:

Thanks for your interest. Which of my four pics posted does M51 seem like in your EP?


I realized that I have never answer this question. Compare to Nytecam's photo, two nights before clouds came in I had quick peek through my XT8 when M51 was close to zenith. Still, through my eyepiece, the M51 and its companion were just two cloudy disks without much hint of arms. So it was equivalent and slightly less detailed than the 1-sec integration from Nytecam's 12" and Lodestar. However, that was with a NOT-dark-adapted eye sine I was working with my newly acquired Lodestar. The light from computer really destroyed my dark adaptation. The good thing now with my XT8 on Atlas, I can get 1-min exposure with good detailed arms structure from M51. But I made some mistake during saving the image to TIF so I ended up with no picture to show. And the clouds came.


Good to hear of your pogress and getting to see on your screen more than possible by eye alone. It's now nearly two decades that I've been doing "electronic assist" deepsky viewing via various CCD cams with the bonus of colour, a record to show others and something to work on on cloudy nights. The only time visual matched my cam was M13 via 16" Dob at a darksite - faint fuzzies forget it - it's cam everytime in the comfort of my LP backyard. Here's some DSOs in CVn from the other night



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