CCD Camera decisions - Mono vs OSC, FOV, Filter wheel etc...

[AndyUK]

Hi all - Although having fun with the DSLR, I know that my future lies in CCD imaging, so I've started saving... but the question is what to aim for? I'm not yet looking specifically at any brand, but at the basic stage...

Mono vs OSC

I understand the technical difference between OSC and Mono and that Mono will be far more sensitive as no bayer matrix is necessary, but are OSC's more sensitive than DSLR's(?). Also is a single 600s image with an OSC more or less the same as 3 x 200s each RGB with a mono? And if I wanted to move into Narrow Band imaging later, could I still do so with an OSC?

Filter Wheels

I understand the principal of mono LRGB imaging, but is a filter wheel ACTUALLY necessary? The electronic one's aren't exactly cheap and, being lazy, it's yet another piece of kit (complication) in the light path and comes again with considerations of in- and out-focus (which I find difficulty wrapping my brain around!)

I was imagining I might be able to avoid the need for buying one and simplifying the whole process simply by splitting imaging with each filter over separate nights and then, if time allowed, switching to a different object for the remainder of a session (if you get my drift) - I'd effectively have 2 "projects" on the go at the same time...

Field of View

For sake of discussion, I've been comparing the Atik 314 with the Atik 383.

The FOV with the 314 is REALLY tight, but it's output is only 1.4MP. The output of the 383 is 8.3MP, but the FOV (using http://www.12dstring.me.uk/fov.htm) looks pretty similar to my DSLR... I don't want to get sucked unecessarily into the idea that more MP must be better, but would a crop from an 8.3MP image give a similar output to that of an uncropped 1.4MP?

1.25" vs 2"

Is there any significant benefit going for the larger format?

(Apologies if these are rather silly/naive queries - This CCD thing is anathema to me at the moment, but their ability to deal with noise is very attractive!)

[Deneb]

Buy a mono, unless you live somewhere where you have very little light pollution. Especially when you narrow band. I was wondering the same Buying a 383 or a 314 ?

I bought the 314L instead only due to buying a EFW2 9x1.25" filterwheel, the Baader Premium CCD LRGB Filters & a full set of narrowband filters. From what I read the Sony 285 chip is a very sensitive clean & very low noise chip.

I think with the 383L+ to get rid of the vignetting I would have to buy 36mm or 2" filters, it will make you cry when you see the price of 2" LRGB & Narrowband filters.

Nadeem.

[riklaunim]

DSLR is less sensitive than for example QHY8L OSC that also has APS-C sized sensor (big). It's also cooled and 16-bit. Mono cameras (314L, 383L) will be better for narrowband and for more challanging R,G,B color imaging.

OSC like that QHY also work nicely (just an ALP filter and you are ready to go). You may use H-a filter with it, but you use only 25% of the pixels (so the image won't have high resolution. It's not dedicated for narrowband.

Filter wheel? Manual are cheap. There are also filter drawers etc. If you go to OSC you don't need one. For mono you would probably benefit from one. Unscrewing the camera to change the filter isn't fun / easy at night, and you should be able to shoot more than one band during one night.

[Deneb]

Sorry Andy, Don't mean to be annoying ! But I was just doing a test run on M51 the other night & found with even just a 2min exposure was getting enough data, which would have taken an DSLR at least 30mins to gather. CCD's are a lot more sensitive then DSLR's.

Nadeem.

[Whippy]

You don't need a filter wheel but if you're using more than one filter in an evening (ie: RGB) it makes life a lot easier. Otherwise the filters screw into the nosepiece of the camera as normal. I only have my RGB filters in my wheel as they don't get used very often while my LP and Ha filters get used a great deal more so they go in the nosepiece. You don't have to have an electronic wheel either, a manual one works just as well, only you have to do the work instead of your laptop!

Cropping something from an image depends of the resolution of your image. Let's assume that the chips in the 314 & 383 cameras have the same size pixels then the resolution is the same so cropping something from the 383 image down to the same FOV as the 314 should have the same amount detail as the resolution is identical.

Tony..

[AndyUK]

Cheers all - That really helps... Although I said that brand wasn't really an issue at this time, my first thought was the 314L, but then I got distracted with OSC's. However, for my needs, I think your responses really confirm that mono is the way I need to go.

I hadn't intended on changing the filter on the same object during a session - I'd anticipated using the same filter but on a different object - but if 2 mins CCD exposure is equivalent to 30mins DSLR, I may well have to rethink this strategy... I can imagine planning to image a couple of objects per night using the same filter or maybe even 3, but not a shedload!

I can certainly appreciate how much more the 2" filters are than the 1.25", but this is why I wanted to get this right from the outset - I don't want to find in a year or so that I should have gone "bigger". I'd set myself an initial budget (excluding narrowband filters at present) between £1.5-£2K, and I know it will take me quite a while to save up that sort of cash, but it looks as though for that money a 1.25" mono CCD is where I should be aiming...

Cheers again...

[ollypenrice]

It is quite untrue that OSCs are 'far' less sensitive than monos. They are a little less sensitive. I have both versions of the Atik 4000, historically because I was writing a back to back test for Astronomy Now, Atik lent me the colour camera and I ended up buying it. I'm not banging the drum for OSC but just trying to get the facts straight.

In fact with experience it is more complicated... On some objects I do seem to struggle with the OSC, notably on galaxies where now I always reach for the mono. Not a clue why this is. Also your guiding needs to be a little better with OSC simply because it likes longer subs. It gives great results on nebulae and can be used with camera lenses. OK you could use a mono with lenses but would you want to? Take off the camera for each filter change... Noooo!!! On my camera to lens adapter you need deft little fingers and daylight for the job.

If I only had one it would be mono and in LP I suspect Nadeem is right but I don't have any to try this out in. I'll leave it that way I think! Mono is more flexible and, contrary to popular belief, faster - partly because of the slightly improved sensitivity but mainly because you can bin the colour. In fact I often cheat and use mono Ha with OSC colour. For me the big gain is that I can tend two rigs at the same time if one is OSC but 2 monos would drive me nuts.

You do need a filterwheel but I use a manual because of reliability. I have had my own electric one not recognized a few times and seen others not going back to the right place, so mucking up flats etc.

The 8300 chip can use 1.25 filters, just. You have to get the filters close to the camera. The best way is the QSI system with integral (electric) wheel. But you can do it with the Atiks. Flats are essential to cure vignetting, but they are essential anyway.

The Sony 285 is the chip of chips, but small. Square mm per square mm it is better than the others. Small pixels are not, in astronomy, what they are in the daylight. But, yes, it is frustratingly small.

Olly

[AndyUK]

Thanks ever so much Olly - I did initially look at the Atik 4000's, but they're way over my budget... Otherwise it would be pretty much top of my list.

I certainly would like to get into narrowband one day (when funds allow), but when you say "guiding needs to be a little better with OSC simply because it likes longer subs" is it fair to assume that we're talking about shorter subs than using a DSLR? I seem to be fairly confortable with 10-15 min guiding at the moment (even with my "lowly" Synguider ) and if an OSC is more sensitive than a DSLR then maybe that would have done (narrowband aside...)

I think the quandary I had was that I was looking at either a 1.25" mono + filter wheel + RGB filters @ 1.4MP or a 2" OSC @ 8.4MP, but as my skies aren't anything like yours [ENVY!] and I certainly DO need an LP filter, I think I'm still swaying towards the mono route, especially as one day I'd like to get into narrowband as well.

By the looks of it, my plan A is possibly still in the frame - A 314L + Hutech IDAS LP + RGB filters... but I guess I AM going to have to save up for the filter wheel as well . However, that will still be well within the £2K budget... Or might it be worth stretching the budget a little further and maybe looking at a mono 2" 383? Does that extra 0.75" really make that much difference?

(Noise aside and based purely on signal, has anyone heard of a comparison of exposure lengths between MONO+RGB, OSC's and DSLR's?)

[ollypenrice]

The French mag did a study comparing signal strength on, if I remember, the Atik 314L and a DSLR. I will try to find the copy in a couple of days but guests are in residence till Thursday so I can't rummage! Obviously the CCD did win.

If you can do 10 to 15 mins you are laughing. The thing about the cooled cameras is that they can expose for longer while DSLRs heat up. But even in Ha 15 mins will do most things at f7 or below. I have started doing 10 or 15 min L subs and 5 min RGB at F7 on most targets. However, that is from a dark site.

An anecdote on the 8300 OSC: a guest had an SBIG but was really disappointed in it. It needed longer than his cooled DSLR and in the end he gave up on it and opted for the mono version. I wondered whether the small pixels suffered too much under the Bayer Matrix. He is coming with the new camera at the end of this month so we'll see what gives. However, Harel is getting good (more than good!) results with his, though he uses a super fast scope which might help and he shoots from the desert.

This week's POW is from the mono 285 chip. It doesn't leave much room for criticism!!

Olly

[MikeWilson]

Hi Andy and everyone,

This *IS* an interesting thread and such a timesaver too as it's saved me posting almost exactly the same question but with one slight twist to the tale.

I'm also thinking about moving from my modded DSLR to a CCD setup. However, I don't have the budget for mono + filterwheel + filters that I'd like (not even for a 314). The ubiquitous 314L+ setup that many people seem to like has a very small field of view and whilst a DSLR may be noisier, a processed DSLR's image can be sampled down to eliminate a great deal of the noise and still retain that APS-C sized view.

Enter the QHY8L. A OSC cooled CCD. Almost double the Quantum Efficiency as my DSLR while retaining the same sensor size and almost the same (makes no practical difference) resolution. Rather than looking at the QHY8L as a "less sensitive than a mono CCD" or "bad, bad Bayer matrix", I prefer to consider it as a doubly-sensitive, cooled version of the the DSLR that I currently use. The QHY8L is also cheaper than the 314L+ and doesn't require a filterwheel or RGB filters.

I have severe light pollution at home, but I can access dark sites. Yes, mono would be better, but mono is much more expensive. The drawback is obvious - ~25% resolution on narrowband imaging. However, this is no different to using a DSLR and yet ~twice as sensitive and much less noisy thanks to the cooling.

With a OSC camera, one can put off the expense of the filter wheel and RGB filters until later.

In summary, if you've got the £2k budget, I'd step over the OSC choices and go straight for mono camera. If I had consistently clear skies, I'd go for the 314L+ and make mosaics (Olly P planted this idea in my head a while back). However, for approximately half of the outlay of the full mono solution it is possible to get something mid-way that has a larger sensor and wider field of view.

Mike

[shaunster]

A filter wheel need not cost more than £60 second hand for the atik manual version... and that does just fine.

A filter wheel isnt going to break the budget!!

for 1.25" filters the cost need not be more than £2-300 more than the OSC costs and the extra cost is well worth it IMO (for LRGB filters)

If you have one cam make it a mono one as in the long run its much much more versatile

[MikeWilson]

A filter wheel need not cost more than £60 second hand for the atik manual version... and that does just fine.

A filter wheel isnt going to break the budget!!

Filling it with glass would though

[shaunster]

Filling it with glass would though

Edited above with more explanation

1.25" filters dont cost as much as people think and the better LRGB sets come in under £200 and the cheaper baader set is just £73, hardly a budget breaker

[MikeWilson]

Shall we put some numbers on this? *EDIT: Cheaper filter wheels are available - see below conversation*

1. Atik 314L+ Mono: £1098 (FLO)

TruTech SuperSlim Manual 1.25" Filter Wheel inc T-Threads: £254 (FLO)

Baader 1.25" LRGB filter set: £183 (FLO)

RGB Imaging Subtotal: £1,535

Optional narrowband filters:

Ha ~ £100

OIII ~ £80

SII ~ £80

Grand Total: £1,795

--------------------------------------

2. QHY8L: £899 (Modern Astronomy)

RGB Imaging Subtotal: £899

Optional 2" filter wheel (as above): £254

Optional narrowband filters:

Ha ~ £160

OIII ~ £120

SII ~ £120

Grand Total: £1,299 without filter-wheel, £1,553 with filter-wheel

The second option probably doesn't need the 2" filter wheel and the 2" filter wheel and filters would be good long term investments. I've not included a light pollution filter in either cost estimate though.

Have I missed anything?

[shaunster]

Its clearly set in your mind about the costs, you choose the most expensive of everything just to prove your point

Ofc mono is more expensive, but it doesnt have to cost THAT much more was the point I was making

[MikeWilson]

Its clearly set in your mind about the costs, you choose the most expensive of everything just to prove your point

Ofc mono is more expensive, but it doesnt have to cost THAT much more was the point I was making

Hi Shaunster,

Not at all - I think our posts just crossed across the wire so to speak.

Incidentally, if you know of cheaper prices please feel free to list them. I found those prices within a few minutes of searching - if you have cheaper ones, I really really want to know I'm being serious about the pricing as I'm prospectively thinking of a move to CCD myself and wanted Andy to consider OSC as an alternative to mono, especially if going widefield on a budget is a concern.

Best,

Mike

[shaunster]

Ok, heres my take on this

Atik 314l+ £1100

Manual filter wheel £99 (modern astronomy)

LRGB set £75 cheaper set or £180 better expensive set

So you can be doing mono LRGB imaging for just £175 more than the same cameras OSC equivilent ... ofcourse if you want to buy better filters then its will be £275 more expensive

The real big price increases come with 2" filters where I agree the price of mono + filters is budget breaking

[shaunster]

Not at all - I think our posts just crossed across the wire so to speak.

yeh probably

I think like all things in astronomy you can spend as much or as little as you want

From a dark site I would probably choose a good OSC cam just for its ease of use

[MikeWilson]

Ok, heres my take on this

Atik 314l+ £1100

Manual filter wheel £99 (modern astronomy)

LRGB set £75 cheaper set or £180 better expensive set

That's a good find on the Brightstar filter wheel. I didn't know about them. Surprisingly they are quite a bit cheaper than the equivalent from FLO. Is there a large quality difference between them?

So you can be doing mono LRGB imaging for just £175 more than the same cameras OSC equivilent ... ofcourse if you want to buy better filters then its will be £275 more expensive

Both Andy and I have DSLR's, cameras which give the benefit of that larger APS-C field of view. Taking this into consideration, the cheapest APS-C size CCD that I could find is the QHY8L. It happens to be OSC and not mono. I can't find a mono APS-C size camera for < £1k.

The real big price increases come with 2" filters where I agree the price of mono + filters is budget breaking

I've got a single 2" Ha 7nm filter from FLO which I've used briefly on my DSLR. I don't feel it is an inconvenience to decide on any night that the camera will be in 'Ha Mode' and to screw the filter onto the 2" MPCC attached to the camera. FLO sell the Ha 7nm, OIII and SII 2" filters for £405, which isn't too bad as a proportion of the gargantuan cost of the rest of the system

As I'm mentioning this QHY8 a little, I'll compare it to the 314L+ to give an idea..

ATIK-314L: 6.7mm x 9mm chip @ 1.77 arcsec/pixel.

QHY8L: 13.8mm x 19.6mm chip @ 2.14 arcsec/pixel.

1000D: 14.8mm x 22.2mm chip @ 1.57 arcsec/pixel

Essentially this means the whole Rosette Nebula, which currently fits nicely onto my 1000D and would still fit onto a single frame of the QHY8L would require the 314L to take a four-pane mosaic. The same seems to be true for M42 + Running Man or indeed M31 from corner to corner of the frame.

Clearly budget is important otherwise we'd all just put in our orders for those beautiful full frame Atik 11000 Mono's (still a lot of camera for <£4k!)

Alternatively, I might just sell off all my current imaging bits and pieces and then wait for someone to offload their setup onto the For Sale section

I'll leave Andy's thread alone now (sorry Andy!)

[shaunster]

Clearly a lot of decisons to be made after the budget has been set

there is for and againsnt in this thread and any other mono VS OSC threads you find online all with valid points

the QHY cameras certainly do represent good value for money

[Deneb]

Also we have to look at Product Support, Build Quality, I would also consider that into the equation. Then the choice is yours.

Nadeem

[lukebl]

Sorry to throw another thing into this thread, but I have been watching it with great interest.

Just wondered what the difference in output between an older (i.e. cheaper and second-hand) Atik 16HR and the new 314L, as they have exactly the same chip. I know there will be operational differences, like the USB 2.0 and different cooling characteristics of the latter, but will the results really be noticeably different?

[markarian]

QHY9: Mono, 383 chip and 2" filters and electric wheel for within your budget Andy.

QHY10 QHY12 QHY9 QHY8 QHY6 QHY6 Pro QHY5 QHY2 Pro Exclusively @ Modern Astronomy £1759

Anyone use the QHY9?

[riklaunim]

Most people probably went the Atik 383 way, which is more compatible with 1,25" filters.

[ollypenrice]

Sorry to throw another thing into this thread, but I have been watching it with great interest.

Just wondered what the difference in output between an older (i.e. cheaper and second-hand) Atik 16HR and the new 314L, as they have exactly the same chip. I know there will be operational differences, like the USB 2.0 and different cooling characteristics of the latter, but will the results really be noticeably different?

No. The 16HR was and is a brilliant camera. If you go for the 314L with set point cooling you get a small advantage but since the chip is so quiet this is a tiny gain. I doubt that Atik would have bothered with set point cooling if the 285 were their only chip. But they devised the electronic platform around other, noisier chips and the 285 jumped on this bandwagon. Should you buy a second hand 16HR? You should!

What worries me about the QHY is that there have been lots of gremlins discussed on the forums. Poor software, misty chip windows... I think Nadeem is discretely hinting along these lines. I have seen literally world class images taken on the 285 (again, POW this week or Rob H's Cocoon Nebula etc etc) but cannot say the same for any QHY8 pics I have seen. Maybe I just missed them, to be fair.

Olly