CCD vs modded DSLR

[iapa]

My budget may run to £1200, which does bring full frame DSLR in the equation.
I already have a Canon 70D.
My budget allows for either modding this and replacing with a different modem for general use, or a CCD in the same price bracket.

An ATIK 414 will cost around £1100 - model picked at random to get a price point.
A Canon 70D, £800, plus around £100 to mod.
Weight wise, both run about the same 1lb or so.

My feel is that the Canon would be a slightly better option (20MP vs 1.5MP) so more pixels per star - even with the Bayer in place.

The 10% larger size, 5µm v 6.5µm, of the ATIK, would mean longer exposures for the Canon 120s on the ATIK would add about 10s using the Canon.

The downside, as I see, for the modded DSLR is the exposure duration. I would need longer exposures to get the same light per pixel, or just more exposures. Will need to stack anyway.

The main question left then is the QE of the different sensors.
The Cann will probably end up with more noise I expect - not found the numbers yet.

My current preference is DSOs - my wife things spirals are wonderful!!!

Any views on this?

 

 

 

[riklaunim]

Mono cooled camera gives more imaging options. And the exposure time doesn't have to differ that much, or be long. I pretty much do 16x3min on average with Atik 314L+ and that is sufficient for non-hard targets. More noisy DSLR would require more processing and maybe more frames to counter the noise.

[gnomus]

You will also need filters and (probably) a wheel to go with your CCD.

[iapa]

HI @riklaunim

Thanks for the reply.

If I used the money CCD, then I need to add a filter wheel and filters. DSLR negates that need - and therefore has less impact when loading the mount.

In my previous I was noting the the Canon DSLR would need longer exposures to capture the same 'light', my finger and toe calculation gives me 11s for the Canon to get the same photons as the CCD - roughly, ignoring QE and filters impact etc.

My preference is DSOs at the moment - which I'll not in the original post.

[Scott]

until a dslr is cooled and debayered, there's no comparison inho. yes there are some imagers doing remarkable stuff with dslr's but in general ccd's are better in almost every way for astro.
 

obviously others will shoot me down  

[gnomus]

6 minutes ago, Scott said:

until a dslr is cooled and debayered, there's no comparison inho. yes there are some imagers doing remarkable stuff with dslr's but in general ccd's are better in almost every way for astro.
 

obviously others will shoot me down  

I agree, but there is no getting away from the significantly greater cost of CCD.  And many people are producing great images with their DSLRs - way better than would have been imaginable a few years back.

[iapa]

@gnomus - the ATIK is same price for Mono/Colour from FLO, I was thinking the Colour model given the . 1lb+ for a filter wheel (I weighed mine:))

@Scott - Debayering a DSLR is something I'd not want to do

Weight wise, a mono CCD plus filter wheel, which I would need to do if we are comparing mono CCD with debarred DSLR, with it's concomitant increase in load on the mount will make me less stable.

I only have an AVX. With the DSLR, 200P-DS OTA, guide scope & cam, finder scope, I am running at around 85% of the mount max load. Everything I have seen recommends 50%-75% is where you should run.

 

[Scott]

1 minute ago, gnomus said:

I agree, but there is no getting away from the significantly greater cost of CCD.  And many people are producing great images with their DSLRs - way better than would have been imaginable a few years back.

you are quite right, the cost is higher for a ccd, however, a nissan micra is not better than an audi r8 because it's cheaper :). I see zwo is bringing out a cmos imaging rig conciderably cheaper than ccd http://astronomy-imaging-camera.com/product-category/new-products/ No idea how it might perform

[riklaunim]

16 minutes ago, iapa said:

HI @riklaunim

Thanks for the reply.

If I used the money CCD, then I need to add a filter wheel and filters. DSLR negates that need - and therefore has less impact when loading the mount.

In my previous I was noting the the Canon DSLR would need longer exposures to capture the same 'light', my finger and toe calculation gives me 11s for the Canon to get the same photons as the CCD - roughly, ignoring QE and filters impact etc.

I don't even use filter wheel for DS imaging, only for planetary. Usually one DS imaging night is on one filter - either CLS or H-alpha. Exposure time depends on many things so don't bet on calculating it before actually setting up given imaging chain.

[Scott]

on

4 minutes ago, iapa said:

@gnomus - the ATIK is same price for Mono/Colour from FLO, I was thinking the Colour model given the . 1lb+ for a filter wheel (I weighed mine:))

@Scott - Debayering a DSLR is something I'd not want to do

Weight wise, a mono CCD plus filter wheel, which I would need to do if we are comparing mono CCD with debarred DSLR, with it's concomitant increase in load on the mount will make me less stable.

I only have an AVX. With the DSLR, 200P-DS OTA, guide scope & cam, finder scope, I am running at around 85% of the mount max load. Everything I have seen recommends 50%-75% is where you should run.

 

One thing we have not mentioned (or i've missed it  ), where will you be imaging from? ie. is there much lp? From my  garden I struggle with colour but narrowband I can get away with

[gnomus]

3 minutes ago, iapa said:

@gnomus - the ATIK is same price for Mono/Colour from FLO, I was thinking the Colour model given the . 1lb+ for a filter wheel (I weighed mine:))

.....

It is.  But then you may limit your options - many people use narrowband (especially Ha) with their mono CCDs.  There is also the question of real estate.  There is quite a difference in FOV between the DSLR and the 414.  I'm not arguing at all that the DSLR is superior, but FOV is a significant consideration for many people, Screenshot from the wonderful Astronomy tools webpage run by FLO:

[Scott]

also field of view is something to concider http://goo.gl/igvRnR

[pete_l]

39 minutes ago, iapa said:

My feel is that the Canon would be a slightly better option (20MP vs 1.5MP) so more pixels per star - even with the Bayer in place

CCDs and DSLRs both have pixels of roughly the same size: 4µ vs. 6.5µ so the number of pixels per star won't be drastically different. In fact this is one aspect where CCDs and DSLRs are very similar: pixel size and therefore resolution (but not field of view, since the sensor sizes can be quite different).

[gnomus]

12 minutes ago, Scott said:

you are quite right, the cost is higher for a ccd, however, a nissan micra is not better than an audi r8 because it's cheaper :). I see zwo is bringing out a cmos imaging rig conciderably cheaper than ccd http://astronomy-imaging-camera.com/product-category/new-products/ No idea how it might perform

And (same point as my last one) a Seat Alhambra is much cheaper than a Porsche 911 - but try getting 7 people into a 911.  

[ollypenrice]

CCD cameras are miles better than DSLRs. But they are more expensive. Forget the number of pixels, which has no relevance, on its own, to anything. Look at the pixel size. There is no point in having a pixel size which gives a resolution too fine for the guiding or the seeing to allow. Small DSLR pixels are only suitable for short focal lengths. Then, as the others are saying, look at chip size and what will fit on that chip. What can you live with?

Pete, CCD pixels vary enormously in size, from around 3 microns to around 9 microns.*

Mono imaging is great because you can use moonlit nights to catch Ha, other narrowband filters beat LP as well, and it is faster than one shot colour but can be more frustrating!

I'd have a look for a good used CCD camera. They come in on budget.

Olly

* Edit: Monochropme CCD pixels can also be binned into bigger pixels when the focal length is too long for the unbinned pixel size.

[Scott]

8 minutes ago, gnomus said:

And (same point as my last one) a Seat Alhambra is much cheaper than a Porsche 911 - but try getting 7 people into a 911.  

Haha, very true... and to that end we can never really compare ccd-dslr

 

[iapa]

aaarrrggghhh

I was hoping, nay, praying (with added goats blood and chicken bones) that no-one would introduce CCD vs CMOS  

Yes, I know the Canon is a CMOS sensor. 

[iapa]

Looks like consensus is CCD. then

[StuartJPP]

The best camera for the job is the camera that best suits your needs. Everybody has an opinion, including me, they should be used as a guide only. Ask a similar question "Which cars are better, diesel or petrol?". When it comes to MPG, the diesel will probably win hands down...so why aren't all cars diesel? Of course a dedicated cooled astro CCD camera is the best for image acquisition, but not always the best solution overall.

In my situation it is a DSLR all the way, especially modified full frame. I can take it abroad and not need a mini power station to run it as I can power it via internal batteries, external batteries or via mains. It can run autonomously, totally self contained, and I can see the results almost immediately. It can be controlled by a PC if I want to. It fits my lenses perfectly. I can use the optical viewfinder to frame targets when not tethered. I can focus remotely when using my lenses, either tethered or not. There are a lot of pluses for me and my imaging style/methods.

 

What people might not realise or remember, especially those who have been doing this for a while, is that not everybody finds B/W, Hubble images appealing. I certainly didn't when I first started. Why would I want a B/W image when I could have a nice (to me) colour image? I think that most people want to start with (L)RGB...though I may be wrong.

 

[ollypenrice]

In advocating monochrome cameras I don't advocate monochrome pictures (though I like them well enough.). 

For portable imaging a DSLR has all the virtues Stuart suuggests.

Olly

[pete_l]

14 hours ago, iapa said:

Looks like consensus is CCD. then

Yes. When you ask a group how they should spend someone else's money, the most expensive option is frequently the most popular.