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

[Beyond_Vision]

Is that equal exposure time Olly on the same scope?

[shaunster]

Theres a starlight H9 on astro buy and sell

[AndyUK]

Cheers again guys - As I said, Kev's QHY8 OSC certainly did make me think a little bit, but I'm still decided that for me, and especially given all the information / comments from everyone above, a 314L is the way to go...

Olly - I'd be interested in more info on the 2 frames you've posted too - That's a significant difference...

Shaunster - Yes... I saw that SXV-H9 on AB&S last night when I got back home (it had had 11 views at the time). I was VERY tempted (especially as it's £300 less than a new 314L!) but I do like the idea (as Olly pointed out) of set point cooling, even though it would seem that darks are all-but redundant with a 285 chip. However, although I do regret not emailing the guy last night, I still have the hurdle of getting formal approval from SWMBO, and I haven't REALLY mentioned the idea to her yet, let alone presented her with a "business case"! [but I do have a "0" birthday in 3 days time which might help ]

Buy the 314L Andy, you know you want to...:evil6:

Yes I do

[MikeWilson]

Thanks Rob.

So (for instance) the QHY8 with a 6 megapixel sensor would be using approx 1.5 mega pixels in narrowband, versus the 285 chipped CCDs which have also 1.5 megapixels?

Of course, the mono CCD will have more sensitive pixels.

^ Yup

A like for like comparison (there's an awesome site that I've forgotten the link to) reveals the main difference - the increased sensitivity of the mono equivilent and by extension - the reduced sensitivity caused by the bayer matrix. The same report demonstrates that OSC isn't 'quicker' than mono at all, especially since it's colour data requires more processing than the individual mono frames do.

Having said this, for me when you factor cost into the equation - the QHY8(L) is almost perfectly placed between the modded DSLR and the mono CCD with filters.

One other consideration between large format OSC and small/medium format mono - the mono camera will have a smaller field of view so will require compositing/a mosaic. This is either a good thing or a bad thing depending on how much time you have for a project. Therefore I expect the mono 314L+ will outperform the larger framed and cheaper OSC QHY8 as it is more sensitive and would ultimately (with a mosaic) give a better resolution. It might be the *only* feasible way to get high quality images of smaller nebulae and galaxies too.

Ultimately, all roads seem to lead to mono CCD imaging.

[fatwoul]

I'm in a similar position to lots of other people in here - MN190 and I want to get a camera for it - and this thread has given me anxiety. I knew I wanted a 383 - for its pixel size and vast chip - but now I don't know what I want! I still want mono, despite living somewhere with few clear nights, because of living under polluted skies, but after seeing a lot of other people doing good stuff with MN190+314, I'm starting to wonder.

My reservation is an aesthetic one - I do really like seeing lots of space around DSOs. I love images of - for example - M51 or M13, where they are sitting deep in the middle of a blanket of stars. Space is called space cos there's lots of space, and when I see close-cropped DSOs, they seem a little claustrophobic. Mosaicing simply for the sake of those starfields would frustrate me, so I'm still torn between the 383 and 314...

[rfdesigner]

I'm in a similar position to lots of other people in here - MN190 and I want to get a camera for it - and this thread has given me anxiety. I knew I wanted a 383 - for its pixel size and vast chip - but now I don't know what I want! I still want mono, despite living somewhere with few clear nights, because of living under polluted skies, but after seeing a lot of other people doing good stuff with MN190+314, I'm starting to wonder.

My reservation is an aesthetic one - I do really like seeing lots of space around DSOs. I love images of - for example - M51 or M13, where they are sitting deep in the middle of a blanket of stars. Space is called space cos there's lots of space, and when I see close-cropped DSOs, they seem a little claustrophobic. Mosaicing simply for the sake of those starfields would frustrate me, so I'm still torn between the 383 and 314...

In which case how about combining shots in a different way.

Use a focal reducer to grab a deep widefield shot, then go prime focus for the DSO, combine the two and you have a lovely pic of the DSO in a single widefield shot that won't take for ever to image.. half the focal length and the shot length can go down by 4x or more depending on noise.. of course getting a focal reducer for an f5.3 scope might be interesting, but if you don't have a large format camera you can be a lot less discerning

You might then care how deep inside the camera the CCD is placed, that I just don't know.

just a thought

Derek

[AndyUK]

A similar quandary to the one I was in then...

I'm not sure that it will really help you with your decision, but if I had the budget I would have liked to have considered the 383 as at least that way you can crop in if you want to, or leave it as a wider field (I know what you mean about liking "space" around the object ). As you've mentioned, you can also try mosaic, but obviously that's yet more imaging time - My thought process (in those situations) was to use my Equinox 80, although that thread by Catanonia re: focal reducer for an MN190 could be very interesting...

For me, the full cost of a 383, LRGB / Narrowband filters (probably 2" as I don't like the idea of possible vignetting) and a suitable filter wheel was going to be about 50% more expensive than the 314 - As it's going to be difficult enough presenting the business case for the 314 setup, I saw little chance of me being able to afford the 383!

[MikeWilson]

A similar quandary to the one I was in then...

I'm not sure that it will really help you with your decision, but if I had the budget I would have liked to have considered the 383 as at least that way you can crop in if you want to, or leave it as a wider field (I know what you mean about liking "space" around the object ). As you've mentioned, you can also try mosaic, but obviously that's yet more imaging time - My thought process (in those situations) was to use my Equinox 80, although that thread by Catanonia re: focal reducer for an MN190 could be very interesting...

For me, the full cost of a 383, LRGB / Narrowband filters (probably 2" as I don't like the idea of possible vignetting) and a suitable filter wheel was going to be about 50% more expensive than the 314 - As it's going to be difficult enough presenting the business case for the 314 setup, I saw little chance of me being able to afford the 383!

Andy,

Have you thought about neglecting the SII and OIII and Hb filters for now in order to reduce costs? I've seen some lovely HaRGB and HaLRGB images which while they could benefit from some SII and OIII, it saves a little money. Also I've read that the 383 will accept 1.25" filters without unacceptably vignetting (I'm happy to be corrected, I haven't seen a comparison yet).

Still, the 314L+ with your MN190 would give you plenty to get on with while working up the business case for the 383 later!

Mike

[AndyUK]

Hi Mike - Thanks for the thought, but I initially hadn't included them, but then decided I needed to bring them in as ultimately I do know I'll be going down that route... Also I needed to cost them in for my "business case" as I've been showing my wife hubble pallette images of late as part of my cunning plan - She loves them and of course it presented the opportunity to mention that I could take similar images if I only had a CCD camera ... She's not stupid though - She knows where it's leading, but I think she's waiting for me to grovel... however, she might well baulk a bit at £2k, let alone £2.5k (I can't blame her - I would too if she told me she wanted to spend a similar amount on herself!)

I've also seen a review on here (referred to from the FLO website) which does seem to mention that you don't HAVE to use 2" filters with a 383 and stating that vignetting is minimal... but I must admit, I would like to see what the difference is between 2" and 1.25" filtered frames. However, we'd still be talking about an extra £450 on the 383 alone, so I don't really think it's a goer... and as you say, the 314 would give me plenty to play with for a few years (until I can afford the £9k+ for an SBIG STX 16803 :p!)

[fatwoul]

Derek, that is a very good point which is worth considering. The only hiccup I can see is the uncertainty about using focal reducers with the MN190. I recall a recent thread on the matter that suggested the MN190 had insufficient back focus to accommodate (I think that's the same thread Andy mentioned). I guess I could do a similar thing by using my MN190 for the DSO, and the moving the camera over onto the 80ED for the surrounding widefield. If that still wasn't wide enough (any wider and the DSO would be a speck!), I could still use a reducer on the 80ED.

I am fortunate. I have a girlfriend who I don't yet live with, and who has her own potentially expensive hobbies. Still living with our respective parents, neither of us have the enormous monthly expenditure that proper grown-ups have, so I am able to spend what little money I earn on nonsense like telescopes and domes and cameras.

Also, as a photographic technician and photographer, the 383 appeals to me because its chip size makes it feel more like a camera. As part of my work, I have access to very large format printing, so would eventually want to be able to make use of this with my astrophotography. 12,000 pixels in one direction, and as long as I want in the other. That's a lot of mosaic'd 383s, but a LOT of mosaic'd 314s!

[Psychobilly]

Use the "humble" DSLR to grab the star field and combine with the data from the CCD... Registar would do this without breaking into a sweat... but its not free software...

RegiStar Home Page

The bees knees for mosaic building combining data from any combination of camera scope etc...

Olly & TJ are the masters

[AndyUK]

I am fortunate. I have a girlfriend who I don't yet live with, and who has her own potentially expensive hobbies. Still living with our respective parents, neither of us have the enormous monthly expenditure that proper grown-ups have, so I am able to spend what little money I earn on nonsense like telescopes and domes and cameras.

[ENVY....]

I'll have to look into this registar thing - I've seen it mentioned before a few times, but not really understood how you can combine differently scaled images... but I'm assuming that this is somehow what it does...? Cool!

[ollypenrice]

Registar is astounding. It makes you look like a master (very kind of you Peter!!) when in reality all you do is click.

OK, to get mosaics seamless is a bit more involved afterwards but Registar does all the hard stuff.

Olly

[AndyUK]

Ooooh! Major result on the budget approval - SWMBO has agreed she's happy for me to buy the 314L+ (A birthday treat !)

I can't afford the WHOLE kit in one go, but I think I'll follow Nadeem's suggestion and go for an Ha filter (and also a license for Registar )

[MikeWilson]

AWESOME news, Andy.

I bet you can't wait

[fatwoul]

Congratulations, Andy. And there you were worrying...

Of course, this thread has still mithered my something terrible, but I'm glad someone else has formulated a plan.

[ollypenrice]

But surely a large OSC chip with 1.5 MP active is spanning a larger piece of sky than the small chip with 1.5MP so you are not comparing like with like. Don't we need to be thinking abouyt something like 'active pixels per arcsecond?'

Olly

[AndyUK]

Cheers guys! I do have to wait until the end of the month (school fees have to be paid first), but then I'll be on the phone to FLO...

I can understand why you're still undecided, Fatwoul - The wider FOV / extra pixels provided by a mono 383+ is certainly attractive, it's just way out of my budget... and I'm just too impatient to wait until the end of the year or so before being able to save up the extra

It was the Atik galleries that helped decide it for me - To me, there seems pretty little difference between the results, and if I can get anything near as good as any of those posted, I'll be well chuffed! I had to add Registar to the shopping list though as I suspect that, especially when using the MN190, mosaics may well become fairly frequent (another learning curve) although I can also see my Equinox potentially being used more as well (it's only had one outing in the last 3 months)...

Olly - That's an interesting thought about larger format OSC's... especially as the 1.5MP active pixels out of 6MP are across a much larger FOV. It would seem that active pixels/arcsecond would actually be lower than a 1.5MP mono if that's the case ()

[Zakalwe]

Nice one Andy. I'm bet your glad that the accountant has signed the budget off! ;-)

I'm waiting on a QHY8L to arrive from Modern Astronomy....compare big OSC sensor to small mono?

[AndyUK]

Nice one Andy. I'm bet your glad that the accountant has signed the budget off! ;-)

(Yes.... I wonder if I could have gone for more ...? No, probably not )

I think there'd be quite a few people interested in reading about a direct comparison of the two... but I won't be able to afford to get my LRGB filters and filter wheel for quite a few months and I suspect you'll be flying with your QHY8L by then! However, it would still be a very worthy exercise - I'll get in touch when I've got the remainder of the bits and we'll see what we can plan...

[Helen]

I assume you've seen this. U.K. Astronomy Buy & Sell Seems a bit overpriced given the new price, but you could try an offer....

Helen

[AndyUK]

Cheers Helen - Yes, I did see that this morning and I did quickly check my spreadsheet... Unfortunately it's not just the camera that pushes the budget, but also the cost of the 2" filters and filterwheel - I understand that it is possible to get away with smaller filters with "minimal" vignetting, but I'd want to make ever so sure, and the narrowband filters especially are serious "ouch" material... But thanks very much for pointing it out

[ollypenrice]

Thanks Rob.

So (for instance) the QHY8 with a 6 megapixel sensor would be using approx 1.5 mega pixels in narrowband, versus the 285 chipped CCDs which have also 1.5 megapixels?

Of course, the mono CCD will have more sensitive pixels.

...but in one case the 1.5 megapixels are covering a widefield image and in the other a more restricted one. They are not equivalent.

Olly

[ollypenrice]

[quote

Olly - That's an interesting thought about larger format OSC's... especially as the 1.5MP active pixels out of 6MP are across a much larger FOV. It would seem that active pixels/arcsecond would actually be lower than a 1.5MP mono if that's the case ()

So it would seem to me but I'm happy to be put straight!

Olly

[MikeWilson]

[quote

Olly - That's an interesting thought about larger format OSC's... especially as the 1.5MP active pixels out of 6MP are across a much larger FOV. It would seem that active pixels/arcsecond would actually be lower than a 1.5MP mono if that's the case ()

So it would seem to me but I'm happy to be put straight!

Olly

This has to be the singular big advantage (and it's quite a big one) to a mono camera.

I haven't got access to CCDCalc on this machine (it's a Mac) but from a cursory comparison of the QHY8 versus Atik 314L, it seems that one could expect an apparent increased resolution of ~2x with the 314L+ over the QHY8.

Certainly the tool of choice for a fixed pier setup

@Zakalwe - I had also contacted Bern about reserving a QHY8L. I haven't pulled the trigger (can't yet) and I look forward to your first (and second, third, et. al) reports

Best,

Mike