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Astrophotography and Sketching >> DSLR & Digital Camera Astro Imaging & Processing

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Astro Boy
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Re: Agile DSLR Astrophoto Imaging & Processing new [Re: mmalik]
      #5363987 - 08/11/12 10:16 PM Attachment (31 downloads)

Chris nice images with your 24" I have a similar Dob and a camera adapter on the way for the Paracorr 2 on it will be good to see what the 5D II will do I hope I can get good tracking out of the Servo Cat.
I find the tracking on the mount is the limiting factor ( unguided ) 3mins on the AP600E , if I have to resort to autoguiding the camera noise is the limit which I thought was 10 min but will have to experiment.
Maybe if we call it Minimalist or Fast Track imaging would cover what we are trying to do.
As some have pointed out I have the advantage of dark skies down here , but like most things in life , Its what you do with what you've got .
Number one thing is to have Fun !
This shot M83 10min exposure and about 10min post processing.

Zane


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mmalik
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Re: Agile DSLR Astrophoto Imaging & Processing new [Re: Astro Boy]
      #5364226 - 08/12/12 02:10 AM

Quote:

Maybe if we call it Minimalist or Fast Track imaging would cover what we are trying to do.




Or we could include what you are suggesting into the definition.

Great looking image of M83; I presume it is single 10 min exposure?


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Starhawk
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Re: Agile DSLR Astrophoto Imaging & Processing new [Re: mmalik]
      #5364249 - 08/12/12 03:05 AM Attachment (25 downloads)

The DSLR has a little to do with this. But the big one is available optics to go to lower f/#s.

I took this photo with a Pentax K-5 (which doesn't have the aggressive IR filter Canon and Nikon are in love with), and a C11 using hyperstar.

The frames are 30 second subs, and you can see a lot of the dim hydrogen clouds are coming through. For this fall, I still want to go to longer exposures to get cleaner data on the really deep exposure portion.

Because of that, I have to disagree with part of the supposition of short exposures being a 90% solution. The longer exposures still have less fixed pattern noise, and the cameras really only reward low f/# imaging trains.

-Rich


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mmalik
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Re: Agile DSLR Astrophoto Imaging & Processing new [Re: Starhawk]
      #5364324 - 08/12/12 06:00 AM

Quote:

But the big one is available optics to go to lower f/#s.

...I have to disagree with part of the supposition of short exposures being a 90% solution. The longer exposures still have less fixed pattern noise, and the cameras really only reward low f/# imaging trains.




Welcome to the discussion Rich; I don't think anyone is suggesting short exposures (< 1min) per se if I understood you correctly; although folks with really large apertures (e.g., 24”) have tried sub-1min exposures and I think rightly so.

Partly the idea is to reduce overall integration time, regardless of individual exposures which are going to vary given the equipment and type of the object. So yes, longer exposures with shorter overall integration time are part of the ‘Agile’ equation just as shorter exposures with shorter overall integration time are.

Lower f# is a good point you mention; I'll let folks chime in on that.


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austin.grant
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Re: Agile DSLR Astrophoto Imaging & Processing new [Re: mmalik]
      #5364473 - 08/12/12 09:39 AM

Don't we already have an entire collection of threads based on this "style" of imaging? It's called Beginning and Intermediate Imaging.

What you are proposing fits that existing model precisely: short subs, low total integration times, minimal processing and a "natural" look.

Whatever the purpose of this thread, I think you should revise one of the opening statements. The idea that, "one is going to capture almost 95% of the features of most DOSs [sic] in about 30 min combined exposure" is simply absurd.


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Starhawk
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Re: Agile DSLR Astrophoto Imaging & Processing new [Re: austin.grant]
      #5364706 - 08/12/12 01:10 PM

The point is, the K-5 has the most sensitive detector (ISO 51200) thusfar deployed in a DSLR, and while the noise is quite low, it is still the signal you see in an image.

Where the DSLRs do well is high signal. I've been using something I invented called the brightness factor to compare setups:

Br=1000/(f/#)^2

So, here are a few to give an idea how it works. It puts the brightness of the image on the focal plane on a common footing where a brightness factor twice as big means the image really is twice as bright.

AP130 EDFGT, f/6.3:

Br=1000/6.3^2= 25.2

AP130 EDFGT with 0.75 reducer, f/4.725:

Br=1000/4.725^2= 44.8

Note, a magnitude change in brightness reached on the camera in a given interval requires a 2.512 improvement in the brightness ratio. So, the focal reducer isn't even giving 1 magnitude improvement as there was only a 1.78x improvement in image brightness.

Here's another:

C11, f/10:

Br=1000/10^2= 10

C11 with f/6.3 reducer, f/6.3

Br=1000/6.3^2= 25.2

Note, all identical focal ratios give identical image brightness. Also note the 2.52x improvement in the brightness ratio means this is getting a full magnitude in performance improvement. Compared to the AP130 EDFGT, this has less than half the field of view, though.

C11 with hyperstar, f/2:

Br=1000/4^2= 250

This is the configuration DSLR cameras made possible. The 25x in brightness improvement means an exposure gets close to 3.6 magnitudes of improvement over an f/10 image.

But this comes at a cost- the very low back focus leaves no room for filter wheels, and the fact it's in the middle of a glass plate means the camera has to be light. But the DSLR has built in filters and a compact light form factor, so this is possible.

As for other magic, going wheels up without a PC following the telescope around is awesome.

-Rich

Edited by Starhawk (08/12/12 02:58 PM)


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mmalik
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Re: Agile DSLR Astrophoto Imaging & Processing new [Re: Starhawk]
      #5365830 - 08/13/12 02:34 AM

Quote:

Where the DSLRs do well is high signal.

But this comes at a cost- the very low back focus.../-/...DSLR has built in filters and a compact light form factor, so this is possible.

...going wheels up without a PC following the telescope around is awesome.




You bring up some important points. And thanks for your brightness factor details; I presume the 'factor' is in support of the premise of this discussion?


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mmalik
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Re: Agile DSLR Astrophoto Imaging & Processing new [Re: austin.grant]
      #5365839 - 08/13/12 02:46 AM

Quote:

I think you should revise one of the opening statements.




You may have taken some of the statements out of the context; there was a follow up statement "Since imaging agility will vary given the scope/camera/sky conditions, the idea is to produce decent images in less time. That less time, for example, may be 10 min (combined) for 24” scope, 30 min (combined) for 10” scope, and may be 45 min (combined) for 5” scope, etc. Note: These times are just examples, not actual recommendations."

This is a discussion/work in progress, not a conclusion per se. I'll try summarizing along the way as evidence accumulates.


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mmalik
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Re: Agile DSLR Astrophoto Imaging & Processing new [Re: mmalik]
      #5365870 - 08/13/12 03:45 AM

Following are few samples of ~30 min integration with a 254mm APO and Canon 60Da of larger brighter objects:

Note: All images are cropped.

NGC 7635 - Bubble Nebula in Cassiopeia
M51, NGC 5194 - Whirlpool Galaxy


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mmalik
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Re: Agile DSLR Astrophoto Imaging & Processing new [Re: mmalik]
      #5365871 - 08/13/12 03:47 AM

Following are few samples of 45 min and 15 min integrations, respectively, with a 254mm APO and Canon 60Da of smaller dimmer objects:

Note: All images are cropped.

NGC 7048 (Planetary Nebula in Cygnus)
Minkowski 4-11 (Planetary Nebula in Scutum)


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Astro Boy
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Re: Agile DSLR Astrophoto Imaging & Processing new [Re: Astro Boy]
      #5368792 - 08/14/12 05:59 PM

I take it you didn't use any noise reduction software , the images show a lot of promise but a bit noisy for my taste .
The only way I can get images I'm happy with is using Topaze Denoise and Adjust , I find them both quick and easy to use .

Zane


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Eric Gage
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Re: Agile DSLR Astrophoto Imaging & Processing new [Re: Astro Boy]
      #5368903 - 08/14/12 07:15 PM

I just read the fine print...254mm APO? Wow! Congrats!

I think most imagers would notice an increase in agility with that kit under dark Aussie skies.


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mmalik
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Re: Agile DSLR Astrophoto Imaging & Processing new [Re: Astro Boy]
      #5369381 - 08/15/12 12:57 AM

Quote:

I take it you didn't use any noise reduction software , the images show a lot of promise but a bit noisy for my taste . The only way I can get images I'm happy with is using Topaze Denoise and Adjust , I find them both quick and easy to use.




I would agree, some smaller/dimmer ones are bit noisy; planning to redo those. Given short integrations, I have been using in-camera noise reduction.


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mmalik
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Re: Agile DSLR Astrophoto Imaging & Processing new [Re: Eric Gage]
      #5369386 - 08/15/12 01:01 AM

Quote:

I just read the fine print...254mm APO




Actually, those image samples are from a suburban/red zone; not a perfect spot but still worth the try.


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Starhawk
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Re: Agile DSLR Astrophoto Imaging & Processing new [Re: mmalik]
      #5369867 - 08/15/12 10:38 AM

Partly- the DSLR format isn't going to have an infinite horizon for sensitivity improvement. The quantum efficiency of the professional cameras is not going to appear in DSLRs without a technology breakthrough. Because of this, they really need fast optics (previous post tells how much energy you get on the detector versus f/# of the optical system).

The conventional photographers are the driving reason for the cameras, and their needs are driving development. The internal automated routines are often impossible to turn off. So, there is a lot of hidden effort with DSLRs to bypass behaviors which affect the data.

So, I kind of feel the DSLRs are operating in a niche. If they are going to completely supplant other cameras, they are have to grow in ways their main user base is not strongly interested in. For example, the up and coming application in the mainstream world is HD video. While it's nice to see Canon throwing a bone to the astrophotography crowd now and then, the cameras they are doing it with aren't even as sensitive as the 3rd party mods.

So, I like the sentiment of the OP, but it seems to rely on something we haven't seen, yet.

-Rich

Quote:

Quote:

Where the DSLRs do well is high signal.

But this comes at a cost- the very low back focus.../-/...DSLR has built in filters and a compact light form factor, so this is possible.

...going wheels up without a PC following the telescope around is awesome.




You bring up some important points. And thanks for your brightness factor details; I presume the 'factor' is in support of the premise of this discussion?




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mmalik
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Re: Agile DSLR Astrophoto Imaging & Processing new [Re: Starhawk]
      #5370559 - 08/15/12 06:56 PM

Quote:

Partly- the DSLR format isn't going to have an infinite horizon for sensitivity improvement. The quantum efficiency of the professional cameras is not going to appear in DSLRs without a technology breakthrough.




Understandable. That would mean CCD is in the same boat as well, correct (horizon for sensitivity improvement I mean)?


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mmalik
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Re: Agile DSLR Astrophoto Imaging & Processing new [Re: Starhawk]
      #5370571 - 08/15/12 07:06 PM

Quote:

So, I kind of feel the DSLRs are operating in a niche. If they are going to completely supplant other cameras, they are have to grow in ways their main user base is not strongly interested in. For example, the up and coming application in the mainstream world is HD video. While it's nice to see Canon throwing a bone to the astrophotography crowd now and then, the cameras they are doing it with aren't even as sensitive as the 3rd party mods.




Very well said; I have asked this before in other threads, what are your thoughts on, hypothetically speaking, Canon offering an 'a' version of 5D Mark III? I wonder if that would be any closer to 3rd party mods.

Other thought I have is why would Canon leave 60Da hanging in terms of sensitivity compared to mods? Why not go all the way and meet or beat the mods if you (Canon) are going to do it anyway? Daytime argument...I don't get it; I never use mine for daytime; if I did, there are better choices.


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mmalik
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Re: Agile DSLR Astrophoto Imaging & Processing new [Re: Aquatone]
      #5370577 - 08/15/12 07:12 PM

Quote:

Link...




I recall you did amazing single 15 min exposures through your 24"; wondering would you like to may be try stacking/combining a few samples of both, larger/brighter and smaller/dimmer DSOs to take the 'Agile' discussion further? I am thinking may be doing ~5 minutes of integrations for each object and posting results here? That's if you are up to it.


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Jerry Lodriguss
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Re: Agile DSLR Astrophoto Imaging & Processing new [Re: mmalik]
      #5370620 - 08/15/12 07:46 PM

I don't know if you would call this "agile" or not, but here's a shot of the Milky Way and Summer Triangle shot on a fixed tripod:

http://www.astropix.com/HTML/SHOW_DIG/Summer_Triangle_Fixed_Tripod.HTM

18 x 8 second exposures at ISO 6400 at f/2.8.

Jerry


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mmalik
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Re: Agile DSLR Astrophoto Imaging & Processing new [Re: Jerry Lodriguss]
      #5370841 - 08/15/12 10:46 PM

Quote:

18 x 8 second exposures at ISO 6400 at f/2.8




Definitely agile... 2.4min integration. Very nice wide FOV.


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