CCD or DLSR

[JohnC64]

What I'll try to fnd the time to do is take one of my images and use only a small fraction of the total data - say a total of 3 hours in LRGB - to demonstrate what can be done with a short LRGB capture. What I predict is that this will give a reasonable image though not one which can be presented at 100%. (This does require lots and lots of data.) It will need more noise reduction, which nobody likes, and it won't take as much sharpening, but it will (I reckon) kick any comparable DSLR capture into the middle of next week! (There, I've said it, so in the next week or so I need to see if I can deliver. I like a challenge!  )

Olly

As long as its as good as this 3hr DLSR image (1hr per pane)           

 http://stargazerslounge.com/topic/194189-ic-1396-sh2-129-elephant-trunk-and-flying-bat-nebula/#entry2033729

[ollypenrice]

As long as its as good as this 3hr DLSR image (1hr per pane)           

 http://stargazerslounge.com/topic/194189-ic-1396-sh2-129-elephant-trunk-and-flying-bat-nebula/#entry2033729

That's an interesting link! The gentleman responsible for this fine image is sitting two metres away from me as I write... Excellent it is indeed. But this always happens on dicussions of CCD versus DSLR; someone links to a stonking DSLR image and says, 'There you go!' And what do these stonking DSLR images have in common? NIne times out of ten it is something yellow, Japanese and F2.8. The Takahashi Epsilon. This is the case here. Let's say that the Epsilon is a slightly unusual instrument and allows any camera to perform out of its skin. How about linking to a DSLR image taken at F7? Not so easy to find a winner!

Olly

[javajunkie2121]

Olly,

What I would like to know what OSC camera was used on the left? And how much time was spend on that left image.

A good quality OSC camera (like the QHY10) has at least 50% QE in red and good dynamic range with 45k well depth.

Because all that Picture shows is that it's a pure Ha emision nebula. And then you are right that you would need 4 times more exposures to reach the same with a decent OSC.

But when we move towards galaxies and broader band nebulas and the immediate difference between OSC and Mono LRGB will be a lot less. All depending on the specs of the sensor.

The most Direct advantage of Mono cameras is broad band imaging. Mono then wins hands Down. No question. Sure you can do it with OSC too, but it will take more time to see "similar" results.

So personally (and no offence Olly), I think that comparison Picture of Simeis 147 is a little unfair to use and discredit OSC CCD imaging.

I will counter with this, to even the playfield between OSC and Mono a little.  

http://www.flickr.com/photos/ytoropin/7699660828/in/set-72157627512718101/

http://www.flickr.com/photos/ytoropin/6130606355/in/set-72157627512718101/

WOW..that picture of the flying monsters of scorpius is absolutely stunning...I am in awe....gosh, that is so incredibly beautiful

[Tiny Small]

CCDs also simply have a different look to them. Like comparing a DSLR to a Phase One digital back (also a CCD but none astro)... you can't really compare them as they are so different and it's nothing short of unfair to the DSLR. As said though, that doesn't mean you can't get very nice images on even a cheap DSLR.

[sharkmelley]

And what do these stonking DSLR images have in common? NIne times out of ten it is something yellow, Japanese and F2.8. The Takahashi Epsilon.

As a Tak Epsilon owner, I'm in full agreement - for DLSR imaging, the Tak Epsilon is the perfect match - overcoming some of the DSLR's inherent weaknesses.

In general though, a cooled mono-CCD using LRGB or HaRGB will produce wideband colour images in shorter imaging time than a One Shot Colour camera and for narrowband imaging a mono-CCD is really the only way to go.

Mark

[laser_jock99]

That's an interesting link! The gentleman responsible for this fine image is sitting two metres away from me as I write... Excellent it is indeed. But this always happens on dicussions of CCD versus DSLR; someone links to a stonking DSLR image and says, 'There you go!' And what do these stonking DSLR images have in common? NIne times out of ten it is something yellow, Japanese and F2.8. The Takahashi Epsilon. This is the case here. Let's say that the Epsilon is a slightly unusual instrument and allows any camera to perform out of its skin. How about linking to a DSLR image taken at F7? Not so easy to find a winner!

Olly

There are other F2.8 Newtonians out there- just not as well put together as TAK! Fast focal ratios and DSLR's do seem to work well in combination though. As you said at F7 you will struggle so hook up to a fast Newt if possible.

The other thing I'd like to 'chip in' to this debate is indeed chip size. If you're looking for a wider FOV then given the same scope the larger DSLR chips will cover more sky (perhaps not in the same resolution). Large, mono CCD's seem to get rather expensive as they get bigger! The benefits of going to full frame (36x24mm CCD sizes) are not altogether clear cut though. To cover this large area with a fully corrected, flat star field is going to need a really top notch scope with a large imaging circle - and there few that can do this (TAK FSQ106?). So in some ways the standard APS-C sized imaging sensor found in many DSLRs and a few more expensive OSC and mono CCD's is as large as most scopes can practically use anyway.

[ollypenrice]

There are other F2.8 Newtonians out there- just not as well put together as TAK! Fast focal ratios and DSLR's do seem to work well in combination though. As you said at F7 you will struggle so hook up to a fast Newt if possible.

The other thing I'd like to 'chip in' to this debate is indeed chip size. If you're looking for a wider FOV then given the same scope the larger DSLR chips will cover more sky (perhaps not in the same resolution). Large, mono CCD's seem to get rather expensive as they get bigger! The benefits of going to full frame (36x24mm CCD sizes) are not altogether clear cut though. To cover this large area with a fully corrected, flat star field is going to need a really top notch scope with a large imaging circle - and there few that can do this (TAK FSQ106?). So in some ways the standard APS-C sized imaging sensor found in many DSLRs and a few more expensive OSC and mono CCD's is as large as most scopes can practically use anyway.

Certainly. Big CCDs are expensive and the full frame Kodak seems to need a circle of at least 45mm from experience. The 44mm of the Baby Q certainly didn't cover it, though the 106 does so with ease.

Olly

[Russe]

Webcam for planetary, DSLR (used Canon body with live view capabilities) to practise whilst saving up for a mono CCD. The CCD will almost always win on noise...

[Dave_D]

Just out of curiousity, how do cameras such as the JTW range of modded DSLRs fit into the equation?

[laser_jock99]

Just out of curiousity, how do cameras such as the JTW range of modded DSLRs fit into the equation?

A modified camera (or one of the models factory made for astro work) has the standard infra red (IR) blocking filter on front the CCD removed or replaced. One of the key nebula emission wavelengths (H-alpha or 656nm) is mainly blocked by the standard camera IR filter. Remove the filter and the camera can see the nebula much better!

A standard camera records only the brightest red H-alpha nebulosity in Cygnus

The same are of Cygnus with a modified camera records more nebulosity and more quickly.

It also means you can usefully use a narrowband Ha filter to image these objects with a DSLR camera (modified) from light polluted sites.

Rosette nebula from light polluted site with modified DSLR 

[Dave_D]

A modified camera (or one of the models factory made for astro work) has the standard infra red (IR) blocking filter on front the CCD removed or replaced. One of the key nebula emission wavelengths (H-alpha or 656nm) is mainly blocked by the standard camera IR filter. Remove the filter and the camera can see the nebula much better!

Yeah i modded my 1100d and it's a lot better at picking up emissions. i much prefer imaging galaxies tbh tho. I was reading the JTW website about what they do to a dslr and it looks very interesting. whether or not their claims of 4x the sensitivity over a dslr and a major reduction in noise are true, it certainly looks like a possible alternative to a ccd, especially the mono modded versions.

I'm not quite ready yet to take the plunge in further mods to my camera, as i can't afford to replace it at the moment, but other threads on here seem to do almost the same thing so i'm really not sure if the cost of how a JTW stacks up compared to a dedicated ccd.

[hornedreaper33]

Good evening ladies and gents. I've recently bought my first telescope Celestron advanced VX 8" SCT and I already know I want to get into imaging. However, I can see the necessary research is going to be a mine field. While this thread has been fascinating, it doesn't really answer the original question. At the moment I'm thinking I'd rather get a DSLR, mod it for astro and eventually have the WOW moment when I can afford a mono CCD (still recovering from the initial purchase).

I guess I'm not real making a point. Just reminding people there are noobs reading. Oh and can I expect good results from my telescope? A lot of people seem to be using newts for astro imaging.

[RikM]

The original question has no correct answer. Both DSLR and CCD can be used. Both can produce good images in the right hands and with right equipment.

As I said earlier in the thread, it is easier to achieve best results with a CCD. If you have the budget for it, this what I would recommend.

I would also recommend you check out the images taken by the people offering advice so you can judge for yourself their level of skill/experience and if you should listen to them.

The general advice is that for deep sky imaging (which us what this thread is about) an SCT can be used but is not the easiest. A refractor is pretty much plug and play but expensive. A Newtonian is cheap and fast but needs correct set up. An SCT combines the worst of both. It requires correct set up, is optically slow, and is expensive, they also have a long focal length which makes it more if a challenge to guide accurately compounding the slow native speed.

It can be done, but isn't what I would choose.

[PhotoGav]

Good evening ladies and gents. I've recently bought my first telescope Celestron advanced VX 8" SCT and I already know I want to get into imaging. However, I can see the necessary research is going to be a mine field. While this thread has been fascinating, it doesn't really answer the original question. At the moment I'm thinking I'd rather get a DSLR, mod it for astro and eventually have the WOW moment when I can afford a mono CCD (still recovering from the initial purchase).

I guess I'm not real making a point. Just reminding people there are noobs reading. Oh and can I expect good results from my telescope? A lot of people seem to be using newts for astro imaging.

Hello hornedreaper33,

You can certainly use that scope for imaging, but I've no doubt that you will want to get guiding working with it to get decent results. At f10 it's relatively slow, so longer exposures will be required. Also the long focal length will mean that it is very sensitive to any error in polar alignment if not guided. However you can certainly get good results from it. I have the Celestron EdgeHD 800 on an HEQ5 mount and am getting good results using the OAG, easily guiding 1200s subs so far and feel that I could go longer if required. It has been quite a learning curve to get there, but the point is it's possible.

As for the chip... I use a modded Canon EOS 60D and am happy with the results I'm starting to get now I've made a million mistakes. So, certainly start off with a DSLR, but be prepared for noise, lots of noise! I am saving up for a cooled CCD and, like you, hope to experience that Wow moment on first light one day!

Recovering from the initial purchase.... Prepare yourself, that was just the nudge towards the event horizon of the AP Expense Black Hole!!! It's pull is irresistible and all consuming!

[hornedreaper33]

Can someone define the phrase "optically slow" for me please?

Just seen a nearly new 600D for £250...

[laser_jock99]

Can someone define the phrase "optically slow" for me please?

Just seen a nearly new 600D for £250...

"The focal ratio is the ratio of the focal length of the telescope related to its aperture. It’s calculated by dividing the focal length by the aperture (both in the same units). For example, a telescope with a 2032 mm focal length and an aperture of 8 in (203.2 mm) has a focal ratio of 10 (2032/203.2 = 10) or f/10.

It’s variously abbreviated as f-stop, f/stop f-ratio, f/ratio, f-number, f/number, f/no., etc.

Smaller f-numbers will give brighter photographic images and the option to use shorter exposures. An f/4 system requires only ¼ the exposure time of an f/8 system. Thus, small focal ratio lenses or scopes are called “fast” and larger f/numbers are called “slow.” Fast focal ratios of telescopes are f/3.5 to f/6, medium are f/7 to f/11, and slow are f/12 and longer. 

Whether a telescope is used visually or photographically, the brightness of stars (point sources) is a function only of telescope aperture--the larger the aperture, the brighter the images. Extended objects will always appear brighter at lower magnifications. The main advantage of having a fast focal ratio with a visual telescope is that it will deliver a wider field of view than slower f-numbers."

[Owmuchonomy]

I reiterate Photogav. There is no right answer. I've struggled my way through using a 600D on a. 9.25 SCT at F10 or F6.3. To be honest I've enjoyed the challenge and will continue to do so. For now I've just spent my money on an EDT 102 F7 refractor. The CCD will have to wait. You can throw masses of money at this hobby. I'd rather throw my thinking power at it and enjoy the challenges.

Enjoy!

Sent from my iPhone using Tapatalk

[hornedreaper33]

I've got it. Focal length/aperture. Longer exposure required.

Thanks for the info though guys