Free Shipping on ALL Products
camera reviewsbest cameraslens reviewsphotography tipscamera forumvideo toursphotography bookssupport me
It is currently Wed Apr 16, 2014 4:37 pm

All times are UTC




Post new topic Reply to topic  [ 26 posts ]  Go to page 1, 2  Next
Author Message
PostPosted: Sat Jun 02, 2012 10:58 am 
Offline
User avatar

Joined: Sun May 25, 2008 12:48 pm
Posts: 7997
Location: UK
As hinted at in the "what are you thinking" thread, I'm currently considering advancing my CCD purchase a bit. As always, it's one justification leading to another... basically I still plan on going to a guided setup later in the year. That means I need a guide cam. But if I get the right guide cam, I can also use that for planetary/solar/lunar imaging too. And I could make use of that sooner rather than later.

So what's on my feature shopping list?
1: it has to be great as a guide cam. This is a must.
1a: to be the above, it will be a mono sensor.
2: it should be usable as a planetary imaging camera.
2a: capable of fast-ish frame rates. I don't know how fast is fast enough.
2b: pixel density should be on the higher end
2c: given the optics I have or will have, it would help to be a relatively big sensor. Note big in this sense will still be tiny in photographic terms.
2d: b+c implies a relatively high pixel count. Note high in this sense will still be tiny in photographic terms.

After a quick search, two models have caught my eye.
Starlight Xpress Superstar Autoguider
The Imaging Source DMK 41AU02.AS

Both use a Sony ICX205AL CCD sensor and are priced similarly. It looks like the Superstar is a relatively new release so there isn't so much on it out there, whereas the DMK41 is a bit more established. While both share the same sensor, the Superstar lists a higher output resolution, so perhaps the DMK41 crops a bit? Maybe it's a video thing. The DMK41 specifies an 8-bit dynamic range which sounds limiting to me. The Superstar is a bit more vague saying it has 16 bit data output. Of course there's no guarantee those extra 8 bits provide any more meaningful data.

For comparison, the Atik 314E also uses the same CCD but in a package designed for imaging. They have a 16 bit output but the framerate is incredibly low. Not important if the exposures are measured in minutes. Not so good if you want a lot of images fast. But this is a good example even if you have the same sensor, you can optimise the electronics around it for different conflicting needs.

Going back to the DMK41. At 1280x960 15fps and assumed 8 bit per pixel, that's just under 18MB/s uncompressed datarate. For comparison, USB2 has a maximum bandwidth of 60MB/s so we're comfortably under that. We can even afford to double that to 16 bits per pixel, assuming the USB protocol overhead doesn't eat into the maximum too much.

The Superstar's listed resolution is 1392x1040 and states 0.6s for a full resolution download over USB2. I think we can forget about framerates there.

So having gone through that, I guess the DMK41 is the choice if I want to attempt planetary imaging. Unless there's other models I've overlooked which might be even better.

_________________
Canon DSLRs: 7D, 5D2, 1D, 600D, 450D full spectrum, 300D IR mod
Lenses: EF 35/2, 50/1.8, 85/1.8, 135/2+SF, 28-80 V, 70-300L, 100-400L, TS-E 24/3.5L, MP-E 65, EF-S 15-85 IS
3rd party: Zeiss 2/50 makro, Samyang 8mm fisheye, Sigma 150 macro, 120-300 f/2.8 OS, Celestron 1325/13
Tinies: Sony HX9V.


Top
 Profile  
 
PostPosted: Sat Jun 02, 2012 12:19 pm 
Offline
Moderator
User avatar

Joined: Sat Sep 30, 2006 4:30 pm
Posts: 9784
Location: UK
Hi popo,

Given you don't have a low noise astro-CCD (yet) I'd say the question is can you live with the poor frame rate (not much better than 1 fps) from the Superstar for planetary "lucky" imaging and is that poor frame rate a compromise worth paying for a relatively low pixel count and pixels which at 4.65μm aren't, I think, that much smaller than those on your 450D. I'm already running very late today so forgive me for not checking but doesn't your 600D offer a zoomed in video mode with each sensor pixel delivering a video pixel? If so I'd say use the 600D for planetary video imaging (is it sensitive enough???) which releases your astro-CCD choice towards something more suited for deep sky. Sorry, must rush... :oops:

Bob.

_________________
OM-D E-M1 + ED 12-40mm f/2.8, H-F007014E, M.ZUIKO DIGITAL 45mm 1:1.8, M.ZUIKO DIGITAL ED 75mm 1:1.8, L-RS014150E.
OM-D E-M5, H-PS14042E, Gitzo GT1541T, Arca-Swiss Z1 DP ball-head.
Astrophotography: TEC 140 'scope, FLI ML16803 camera, ASA DDM60 Pro mount.


Top
 Profile  
 
PostPosted: Sat Jun 02, 2012 12:47 pm 
Offline
User avatar

Joined: Sun May 25, 2008 12:48 pm
Posts: 7997
Location: UK
Rush away Bob! These things aren't happening overnight. For when you get back...

The pixel pitch of the 450D and 600D are either side at 5.2 and 4.2um respectively. But you have that pesky bayer array on top which destroys the resolution potential and sensitivity for narrowband imaging. Plus you also have the video compression artefacts which kill what little is left of the detail, and the unfriendly mov container format that Canon use which requires transcoding before all the useful software will touch it.

I'm looking at the 15fps model as 1st choice, not the one with a 0.6s cycle. That should give a decent number of frames in a short time, even if not as much as, say, a smaller 60fps model could.

As a rough timeline for my planned astro upgrades, I think I'm going something like:
Today: CaK filter (more later)
July: Guide/Planetary cam, possibly budget refractor 80-120mm multi-function as guidescope and CaK solarscope.
Sept or later: HEQ6
Late 2013: big sensor cooled CCD - there are other more interesting things on my shopping list before this. And they're not cheap either...

_________________
Canon DSLRs: 7D, 5D2, 1D, 600D, 450D full spectrum, 300D IR mod
Lenses: EF 35/2, 50/1.8, 85/1.8, 135/2+SF, 28-80 V, 70-300L, 100-400L, TS-E 24/3.5L, MP-E 65, EF-S 15-85 IS
3rd party: Zeiss 2/50 makro, Samyang 8mm fisheye, Sigma 150 macro, 120-300 f/2.8 OS, Celestron 1325/13
Tinies: Sony HX9V.


Top
 Profile  
 
PostPosted: Wed Jun 06, 2012 4:53 pm 
Offline

Joined: Thu Jul 31, 2008 4:31 am
Posts: 291
DMK doesn't have a guide port so it could only blue used as a planetary cam.

_________________
Canon T2i (550D)- Tamron 17-50 F2.8 Non-VC, Sigma 70-200mm F2.8 EX DG OS HSM, Canon EF-S 55-250mm F4.5-F5.6
http://www.astronomyphotography.com


Top
 Profile  
 
PostPosted: Wed Jun 06, 2012 5:48 pm 
Offline
User avatar

Joined: Sun May 25, 2008 12:48 pm
Posts: 7997
Location: UK
Good point, but I don't think it important in my case. I'm planning on controlling the mount from PC anyway so don't need any built in guide port.

I'm planning on going something like the EQMOD setup option 2 shown at http://stargazerslounge.com/topic/88227 ... otography/

As a small side effect though, I was wondering if it is possible to guide for the sun with my existing alt-az Celestron mount (ignoring rotation effects). Do people guide for the sun at all??? I'm still wondering if it is possible to guide and image from the same sensor at the same time.

_________________
Canon DSLRs: 7D, 5D2, 1D, 600D, 450D full spectrum, 300D IR mod
Lenses: EF 35/2, 50/1.8, 85/1.8, 135/2+SF, 28-80 V, 70-300L, 100-400L, TS-E 24/3.5L, MP-E 65, EF-S 15-85 IS
3rd party: Zeiss 2/50 makro, Samyang 8mm fisheye, Sigma 150 macro, 120-300 f/2.8 OS, Celestron 1325/13
Tinies: Sony HX9V.


Top
 Profile  
 
PostPosted: Wed Jun 06, 2012 5:58 pm 
Offline

Joined: Thu Jul 31, 2008 4:31 am
Posts: 291
Yes I guide for the sun. I can take longer capture without the Sun moving out of the FOV. Alt-at or eq won't matter as you will splitt the frame anyway.

I like the guide port because it's practical to have and you can control both with stark software.

_________________
Canon T2i (550D)- Tamron 17-50 F2.8 Non-VC, Sigma 70-200mm F2.8 EX DG OS HSM, Canon EF-S 55-250mm F4.5-F5.6
http://www.astronomyphotography.com


Top
 Profile  
 
PostPosted: Wed Jun 06, 2012 8:38 pm 
Offline
User avatar

Joined: Sun May 25, 2008 12:48 pm
Posts: 7997
Location: UK
What guider and software do you use? I haven't made final decisions on anything yet...

_________________
Canon DSLRs: 7D, 5D2, 1D, 600D, 450D full spectrum, 300D IR mod
Lenses: EF 35/2, 50/1.8, 85/1.8, 135/2+SF, 28-80 V, 70-300L, 100-400L, TS-E 24/3.5L, MP-E 65, EF-S 15-85 IS
3rd party: Zeiss 2/50 makro, Samyang 8mm fisheye, Sigma 150 macro, 120-300 f/2.8 OS, Celestron 1325/13
Tinies: Sony HX9V.


Top
 Profile  
 
PostPosted: Wed Jun 06, 2012 9:08 pm 
Offline

Joined: Thu Jul 31, 2008 4:31 am
Posts: 291
I used PHD Guiding. Its free and very good.

_________________
Canon T2i (550D)- Tamron 17-50 F2.8 Non-VC, Sigma 70-200mm F2.8 EX DG OS HSM, Canon EF-S 55-250mm F4.5-F5.6
http://www.astronomyphotography.com


Top
 Profile  
 
PostPosted: Wed Jun 06, 2012 9:56 pm 
Offline
User avatar

Joined: Sun May 25, 2008 12:48 pm
Posts: 7997
Location: UK
PHD was pretty much a given anyway (see earlier link), although I haven't checked to see if it works on things other than stars.

And what guide cam did you go for?

_________________
Canon DSLRs: 7D, 5D2, 1D, 600D, 450D full spectrum, 300D IR mod
Lenses: EF 35/2, 50/1.8, 85/1.8, 135/2+SF, 28-80 V, 70-300L, 100-400L, TS-E 24/3.5L, MP-E 65, EF-S 15-85 IS
3rd party: Zeiss 2/50 makro, Samyang 8mm fisheye, Sigma 150 macro, 120-300 f/2.8 OS, Celestron 1325/13
Tinies: Sony HX9V.


Top
 Profile  
 
PostPosted: Wed Jun 06, 2012 10:04 pm 
Offline

Joined: Thu Jul 31, 2008 4:31 am
Posts: 291
I have the Orion Auto-guider.

_________________
Canon T2i (550D)- Tamron 17-50 F2.8 Non-VC, Sigma 70-200mm F2.8 EX DG OS HSM, Canon EF-S 55-250mm F4.5-F5.6
http://www.astronomyphotography.com


Top
 Profile  
 
PostPosted: Wed Jun 06, 2012 10:34 pm 
Offline
User avatar

Joined: Sun May 25, 2008 12:48 pm
Posts: 7997
Location: UK
I was nearly going to say I had also previously considered the QHY5 too, but then on closer look noticed Orion do more than one model...

I still don't see anything that looks more convincing at the price than the DMK41. If I ever get desperate for a dedicated guide cam separate from the planetary imager then I can always throw in a QHY5 for peanuts anyway. That'll keep me going until I go big sensor next year.

_________________
Canon DSLRs: 7D, 5D2, 1D, 600D, 450D full spectrum, 300D IR mod
Lenses: EF 35/2, 50/1.8, 85/1.8, 135/2+SF, 28-80 V, 70-300L, 100-400L, TS-E 24/3.5L, MP-E 65, EF-S 15-85 IS
3rd party: Zeiss 2/50 makro, Samyang 8mm fisheye, Sigma 150 macro, 120-300 f/2.8 OS, Celestron 1325/13
Tinies: Sony HX9V.


Top
 Profile  
 
PostPosted: Wed Jun 06, 2012 11:40 pm 
Offline

Joined: Thu Jul 31, 2008 4:31 am
Posts: 291
Nothing beats Point Grey or Lumenera when it comes to planetary imaging. They are more expensive but they are much much much better then Imaging Source. My choice was to wait until I can afford an Sbig with integrated auto-guiding chip. I haven't done any tracking, long exposure in what seems to be forever. Where the DMK is great for is they are cheap to acquire and perform very well. You will always have a compromise so it better to have a camera for each type of capture you want to do. Welcome to AP. Its get expensive real quick :-)

_________________
Canon T2i (550D)- Tamron 17-50 F2.8 Non-VC, Sigma 70-200mm F2.8 EX DG OS HSM, Canon EF-S 55-250mm F4.5-F5.6
http://www.astronomyphotography.com


Top
 Profile  
 
PostPosted: Thu Jun 07, 2012 9:11 am 
Offline
Moderator
User avatar

Joined: Sat Sep 30, 2006 4:30 pm
Posts: 9784
Location: UK
.
Mmmm, that Point Grey FL3-U3-32S2M-CS looks very tasty. 2.5 µm pixels would out-resolve my TEC 140's theoretical 3.8 µm resolution at the focal plane by a factor of 1.5x and if I can source an adaptor to fit it behind my FLI CenterLine filter wheel I've just found my ideal planet-cam. But ouch, by the time it's got through customs it'll be close to $1,000 and Point Grey won't ship directly outside of Canada and the USA anyway so I dread to think what the price would be from their UK distributor. :evil:

Bob.

_________________
OM-D E-M1 + ED 12-40mm f/2.8, H-F007014E, M.ZUIKO DIGITAL 45mm 1:1.8, M.ZUIKO DIGITAL ED 75mm 1:1.8, L-RS014150E.
OM-D E-M5, H-PS14042E, Gitzo GT1541T, Arca-Swiss Z1 DP ball-head.
Astrophotography: TEC 140 'scope, FLI ML16803 camera, ASA DDM60 Pro mount.


Top
 Profile  
 
PostPosted: Thu Jun 07, 2012 11:47 am 
Offline
User avatar

Joined: Sun May 25, 2008 12:48 pm
Posts: 7997
Location: UK
Symtex, I think you have me confused for a lottery winner! My goal isn't to get the outright best here. I don't have the budget to go near that. My optimisation is to get the best at a price level.

If I were to get a guide cam that does nothing but that, QHY5 would probably be the choice. Then scope creep sets in. Complete the following, and repeat: "For a little more I can get..." After a few iterations of that I'm designing a moon based observatory. :D Then I scale back again to something attainable.

I have set a rather arbitrary absolute max of £500 for a planetary imaging CCD as long as it doubles as a useful guidecam. If it goes above that, I might was well stretch for the big CCD for deep field anyway. But I have to balance it by not aiming too low, as there is a lot out there that is little more than an overpriced webcam.

Further note, when I say planetary, I really mean solar/lunar. Planets are outside the effective reach of my current optics and I'm not planning on "going large" any time soon. At most I'll have a 120mm refractor this year, unless I impulse buy a big dob but I doubt that'll be fun for chasing a planet with.

Choosing astro CCDs really frustrate me. I know they *could* be a lot cheaper than they are, but they don't have the benefits of volume that consumer products get to drive it down. The worst part for me is I see many nice big CCDs with a decent number of MP and a (relatively) low price. And they're ALL in colour. You want the mono version? Add 30% to get less. I can only imagine that's a knock on effect from consumer uses of the colour sensors driving their prices down. At least astro optics are far cheaper than similar spec photographic ones... :)

_________________
Canon DSLRs: 7D, 5D2, 1D, 600D, 450D full spectrum, 300D IR mod
Lenses: EF 35/2, 50/1.8, 85/1.8, 135/2+SF, 28-80 V, 70-300L, 100-400L, TS-E 24/3.5L, MP-E 65, EF-S 15-85 IS
3rd party: Zeiss 2/50 makro, Samyang 8mm fisheye, Sigma 150 macro, 120-300 f/2.8 OS, Celestron 1325/13
Tinies: Sony HX9V.


Top
 Profile  
 
PostPosted: Thu Jun 07, 2012 2:23 pm 
Offline

Joined: Thu Jul 31, 2008 4:31 am
Posts: 291
My findings are there is no such camera that can do it all. That is my frustration. You can invest into 1 devices and make it perform equally as well on all task. Its is the nature of AP. If you are on a budget (like me), this is the best option :

Sun : DMK31/41. I took the 31 for the 30fps so if I want to do planetary, I can.
Lunar : DSLR with T-connector. Resolution is key here.

Planet : I love a refractor but for planet imaging, you need focal length. Nothing beat a good SCT for that. I have a used 8" SCT that I got for pretty cheap and that can do wonder. You don't have to spent that much money. If you get an F6.3 focal reducer, you can also do lunar shot with it.

DSO : I have an friend who does 30 sec unguided exposure in the city with his HEQ5 and does wonder with an Canon T1i. He impress the hell out of me. his polar alignment technique is out of this world. its when you want to do longer exposure and don't want to speed hours of post-processing with dark/flats that is gets really expensive. Personally, I rather wait until I can afford the SBIG dual sensor camera. I already got an 5" refractor and my 8" SCT on an HEQ5. Like you mention before, I don't want to deal with flex on a separate guiding scope so I rather wait.

notes : Monochrome camera are really worth the extra on Solar and DSO. BTW, Point Grey head office is about 20km away from where I live. If you want to buy from there, I can help you facilitate.

_________________
Canon T2i (550D)- Tamron 17-50 F2.8 Non-VC, Sigma 70-200mm F2.8 EX DG OS HSM, Canon EF-S 55-250mm F4.5-F5.6
http://www.astronomyphotography.com


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 26 posts ]  Go to page 1, 2  Next

All times are UTC


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to:  

All words, images, videos and layout, copyright 2005-2012 Gordon Laing. May not be used without permission.
/ How we test / Best Cameras / Advertising / Camera reviews / Supporting Camera Labs

Webdesign by Alphabase IT
Powered by phpBB® Forum Software © phpBB Group