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  #21  
Old 19-11-2013, 10:07 PM
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Cost and field size do matter! I can have a 35mm diagonal for $2,000 (modified Canon 6D) or about a 4th of that for $4500 (QSI 583). Then I've got to add the cost of filters.

For now I'll be sticking with DSLR cause the alternative is that I'll never be able to afford a decent car, let alone kids. I think that's a fairly powerful argument.

Cheers,
Cam
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  #22  
Old 19-11-2013, 10:19 PM
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Originally Posted by LightningNZ View Post
Cost and field size do matter! I can have a 35mm diagonal for $2,000 (modified Canon 6D) or about a 4th of that for $4500 (QSI 583). Then I've got to add the cost of filters.

For now I'll be sticking with DSLR cause the alternative is that I'll never be able to afford a decent car, let alone kids. I think that's a fairly powerful argument.

Cheers,
Cam
If you see Scotts images - down the page -
he does so well with a DSLR but he uses an ONAG for guiding
& he takes mega data - usually 100 subframes - sometimes 300 subframes!
He's also a wizard at processing & even has his own video tutorials.

Could you pick up a 2nd hand CCD camera on Astromart for half price?
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  #23  
Old 19-11-2013, 10:23 PM
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Hi Raymo. The meaning of the ISO speed rating of a camera is largely up to it's maker and it can be defined in a number of ways, so there is no reliable way to directly relate ISO to CCD capability.

If you haven't already done it, maybe choose a bright astro object from the book and take some images of it yourself at different exposures with your DSLR system. Compare your results with the book image and then you will have at least a rough idea of how an exposure time given in the book relates to your requirements.

As others have pointed out, a cooled CCD will give better results (in a shorter time too) than a DSLR. If you decide to go that way, a cooled colour camera may be a good place to start, rather than jump straight in the deep end of a mono camera + filter wheel and heavy duty processing. And of course you will need a fairly good tracking mount whatever you do, but I guess that you probably have that already.

Last edited by Shiraz; 20-11-2013 at 07:09 AM.
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  #24  
Old 19-11-2013, 10:47 PM
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The gulf is wide between a good mono astro CCD and DSLR but so is the price tag.
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  #25  
Old 20-11-2013, 12:21 AM
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Quote:
Originally Posted by raymo View Post
Thanks again Allan. At my age I am finding digital imaging/processing
a steep learning curve, and as I am producing what I consider very promising single exposure results, I'm thinking of sticking with that.
I'm pushing 80 and don't want to spend large chunks of my remaining
years sitting at a computer.
raymo
Raymo, don't give up

Check these Deep Sky images out below .... and all taken with a DSLR!

Both guys were Astronomy Photographer of the Year 2013 finalists (top 5) in the Deep Space category, beating out imaging luminaries of the likes of Rob Gendler and Martin Pugh who use much more sophisticated equipment on both sides of the globe. Most of their images are better than most CCD images of the same subjects.

...so it can be done, it is all in the capturing and processing, a good scope helps too

Canon 1000D: http://www.pampaskies.com/gallery3/Deep-Space-Objects

Canon 5DMkII (& 30D): http://www.astroeder.com/deepsky/deepsky.htm

Good luck, you are never too old to learn

Mike
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  #26  
Old 20-11-2013, 06:34 AM
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[QUOTE=Shiraz;1035056]Hi Raymo. The meaning of the ISO speed rating of a camera is largely up to it's maker and it can be defined in a number of ways, so there is no reliable way to directly relate ISO to CCD capability.

If you want to get some idea of how to relate your DSLR system exposure times to the ones used in the book, maybe choose a bright astro object from the book and take some images of it yourself. Use ISO400 and try about half an hour of 4 minute subs to start with. You are going to have to do stacking of the multiple subs and a histogram stretch to get anything useful. When you have an image, you will be able to see how much different it is from the published one of the same object and be able to increase the total imaging time to get a closer representation. Then you will have at least a crude idea of how an exposure time given in the book relates to your requirements.


Whilst it is true ISO (International Standards Organisation) is able to be measured several ways by the camera makers ISO images are heavily compared at sites like DP review. If they are too different the camera maker gets a lot of criticism. So I think they tend to be closer than that in practice. Certainly Nikon and Canon ISO's would be pretty reliable. Certainly Fuji fudges it a bit where ISO6400 is really only about ISO4800 or less. Sony's seems accurate.

Greg.
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  #27  
Old 20-11-2013, 06:42 AM
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That was an unfair comparison between DSLR and Hubble.
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  #28  
Old 20-11-2013, 07:37 AM
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Originally Posted by strongmanmike View Post
Raymo, don't give up

Check these Deep Sky images out below .... and all taken with a DSLR!

Both guys were Astronomy Photographer of the Year 2013 finalists (top 5) in the Deep Space category, beating out imaging luminaries of the likes of Rob Gendler and Martin Pugh who use much more sophisticated equipment on both sides of the globe. Most of their images are better than most CCD images of the same subjects.

...so it can be done, it is all in the capturing and processing, a good scope helps too

Canon 1000D: http://www.pampaskies.com/gallery3/Deep-Space-Objects

Canon 5DMkII (& 30D): http://www.astroeder.com/deepsky/deepsky.htm

Good luck, you are never too old to learn

Mike
Dear Mike,
this image:
http://www.pampaskies.com/gallery3/D...s/Cent_A_rural

says " Camera: Canon 1000D (modded and peltier cooled) "

this image:
http://www.astroeder.com/m81-82_flux_eder_en.html
Modified camera
exposure time 309 x 5 min(24 hours 45 min total) @ ISO 1600


These are not standard DSLR cameras & in one case the huge amount of data is ridiculous.
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  #29  
Old 20-11-2013, 09:54 AM
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These are not standard DSLR cameras & in one case the huge amount of data is ridiculous.
Oh I agree, one was modified with a new filter and the other cooled sure but still...pretty good images huh? In my opinion Ivans M81/82 + Galactic Cirrus shot is just about the best I have seen of this scene from either CCD or DSLR and in my opinion was the best image of the 5 finalists in the Deep Space category

Hey I use a CCD and do LRGB too too remember but if I thought I could do this sort of work by just changing the filter in my DSLR...well...? no more missing colour frames due to cloud etc ...it often comes down to what we are used to as well..besides 24hrs+ of data is being touted as all the go these days even with CCD

Mike
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  #30  
Old 20-11-2013, 09:58 AM
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I have found that it is indeed possible to get some decent results with a DSLR, however (in my experience at least) *lots* of subs and long integration times are needed to bring noise under control.

Taken throughout 2013 with a modded DSLR (filter mod only, so no cooling) and dark rural skies

NGC5128: http://www.astrobin.com/38483/
NGC5128 (as above but with extreme stretch): http://www.astrobin.com/38484/
NGC6744: http://www.astrobin.com/44546/
M83: http://www.astrobin.com/38648/
NGC6559: http://www.astrobin.com/48900/B/
NGC4038: http://www.astrobin.com/40910/B/
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  #31  
Old 20-11-2013, 10:08 AM
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I have found that it is indeed possible to get some decent results with a DSLR, however (in my experience at least) *lots* of subs and long integration times are needed to bring noise under control.

Taken throughout 2013 with a modded DSLR (filter mod only, so no cooling) and dark rural skies

NGC5128: http://www.astrobin.com/38483/
NGC5128 (as above but with extreme stretch): http://www.astrobin.com/38484/
NGC6744: http://www.astrobin.com/44546/
M83: http://www.astrobin.com/38648/
NGC6559: http://www.astrobin.com/48900/B/
NGC4038: http://www.astrobin.com/40910/B/
Yes some good examples there too Richard

Of course if we were to actually quantitatively compare a cooled CCD to a unmodded DSLR the sensitivity figures would come out well in favour of the Cooled CCD...but for Raymos sake, it is clear that incredible deep sky DSLR images are indeed possible

Mike
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  #32  
Old 20-11-2013, 10:22 AM
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Oh I agree, one was modified with a new filter and the other cooled sure but still...pretty good images huh? In my opinion Ivans M81/82 + Galactic Cirrus shot is just about the best I have seen of this scene from either CCD or DSLR and in my opinion was the best image of the 5 finalists in the Deep Space category

Hey I use a CCD and do LRGB too too remember but if I thought I could do this sort of work by just changing the filter in my DSLR...well...? no more missing colour frames due to cloud etc ...it often comes down to what we are used to as well..besides 24hrs+ of data is being touted as all the go these days even with CCD

Mike

True - but in my opinion it's all about location.
I wish we had a location like the Atacama desert in Chile
which is at high altitude & low humidity.
A DSLR up there would beat any CCD from an Australian site.
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  #33  
Old 20-11-2013, 10:36 AM
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I wish we had a location like the Atacama desert in Chile
Yeeesss, I keep hinting at a move to Chile... but the wife doesn't seem to see it from my perspective
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  #34  
Old 20-11-2013, 10:38 AM
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Yeeesss, I keep hinting at a move to Chile... but the wife doesn't seem to see it from my perspective

Very funny - I think you'd find it a bit cold there.

How about a remote robotic site up there?
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  #35  
Old 20-11-2013, 10:50 AM
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Very funny - I think you'd find it a bit cold there.
I'd cope

Anyway let's not high jack this thread with our dreams
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  #36  
Old 20-11-2013, 11:16 AM
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I don't think there is any doubt the Mono CCDs in cameras designed specifically for astrophotography have the potential to deliver better images than DSLRs over the full range of targets.

That said great results can be achieved using DSLRs within a certain range of targets.

This not an inexpensive hobby so for someone starting out saving some dollars by using a decent DSLR that they might already possess to begin imaging and building their skills in my view is a very viable option.

DSLRs are easier to operate. You don't even need a computer to drive them (though it is better to use one). They have their own power source and they obviously can be used for other forms of photgraphy as well. They are well suited to using lenses for wide field photography. They also generally offer more megapixels than CCDs, sometimes a significant amount more.

Where the CCDs have the real advantage in my view is their sensitivity to certain wavelengths of light such as Ha. For some targets this makes no difference and others it appears to make a huge difference.

The other major advantage is the ability to image in narrow band, allowing one to image from light polluted areas.

I don't have noise issues with my DSLR. I do use darks in my processing. No doubt it is noiser than a top of the line supercooled CCD camera but the noise it does generate does not seem to be materially effecting the quality of my images. Perhaps this will become more of an issue when I move onto imaging fainter targets but at this stage it hasn't been an issue for me.

While not specialised for astrophotography subjects the sensors in DSLRs have probably had 10 times the research dollars put into them than most fo the CCD sensors going around, many of which seem pretty long in the tooth to me.

So I guess I am saying don't write off DLSRs as "why would you bother"
They are a viable alternative for many targets and do have certain advantages.

For people starting off they can be a good value for money way to get into astrophotography.

For myself I use a Nikon D4 DSLR which I owned before I took up AP as a hobby so for me it was worth using it and building my skills generally. One day I will probably move to a CCD camera for the advantages I mentioned above but for now it is doing the job fine and I am pleased with the images I am creating as a newbie.
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  #37  
Old 20-11-2013, 12:02 PM
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I'd cope

Anyway let's not high jack this thread with our dreams

Come on Mike - dreams are free and if you'd win Powerball one day?
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  #38  
Old 20-11-2013, 01:02 PM
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Thank you all SO much for your responses, opinions, information, and links. I'm blown away by the quantity. I'll have to print it all so I can peruse it at my leisure. Incidentally,Mike said that an image of
M81 taken with a DSLR was the best he had seen of that object; well
the best M31 I have ever seen was taken a long time ago, on film, by
Daphne and Tony Hallas. I have yet to see an amateur digital version
to equal it. Thanks once again for your encouragement.
raymo
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  #39  
Old 20-11-2013, 01:38 PM
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I remember the images of Daphne and Tony Hallas.They used to feature a lot in the old Astronomy magazine I used to get in the 80's.

Even then the best film photographers used non standard equipment, as in hypered film and cooled cameras. It seems as though every photographic medium through time likes it cold.
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  #40  
Old 20-11-2013, 01:52 PM
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Yeeesss, I keep hinting at a move to Chile... but the wife doesn't seem to see it from my perspective
Just tell her she'd be hot stuff if you move there....."chile"
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