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strutsinaction

Wide-field imaging rig from scratch

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Hi


I would like to set up an ASCOM/EQMOD-driven wide-field imaging rig from scratch and need some advice on a suitable mount, scope, guiding solution and CCD. I've read the excellent 'Making Every Photon Count' so understand the principles. I now need to put that theory into practise and start spending some money!


My budget for the whole rig is around £8k (mount/scope/guiding/CCD/accessories/software).


My current scope is a Celestron 8SE which I've used for both visual and planetary imaging (with an ASI120MC). In addition to wide field imaging with a short focal length refractor, at some point I'd like to be able to use the 8SE OTA for imaging DSOs that the short focal length tubes are not suitable for. Therefore, if appropriate, equipment that can be used for both short and long focal length imaging would be nice in order to avoid additional expense.


I live in rural Cambridgeshire but the skies are hardly dark. There's some white light LP from a nearby garden centre and RAF base. I don't have a obsy or pier. Also, portability isn't a consideration for me.


Mount

Top of my list is the AZ EQ6-GT. This seems to have had some good reviews and should be suitable for a short focal length refractor and my 8SE. There's also the added benefit of Alt-Az mode for my 8SE for visual use.


Scope

The SW ED80 DS-Pro seems to be popular and the price tag of £450 is great value. I've also looked at the WO GT-81 triplet for £725, Esprit 80 ED PRO triplet for £995, right up to the Tak FSQ-85 for around £3000. So, quite a difference in price! My budget does stretch to the Tak but is it worth the extra expense? I guess I would need a FF for the cheaper refractors, but not so for the Tak? There's also the CCD to consider - see later.


Guiding

For guiding, I'm told a ST80 guidescope works well. I'm thinking an SX Lodestar (mono) for the guidecam. As an alternative, how easy is it to use an OAG with a short focal length refractor? If straightforward, then maybe an OAG would be best as it can then be used with the 8SE later on?


CCD

I'm thinking mono + filter wheel rather than OSC. Atik One 6.0, or Atik 460EX + EFW2, or maybe the QSI  660, 690 or 683? Or something else? Another thought I had. In the future when I do start DSO imaging with the 8SE OTA then I'll need an OAG. So maybe the Atik One + integrated OAG or QSI-660/690/683 + integrated OAG would be the more versatile choice? Would these work well with the short focal length refractor for guiding or is it best to have 2 guiding solutions i.e. guidescope for short focal length and OAG for long focal length?


Hopefully I can put together a rig that will keep me entertained for me a few years without having to upgrade  too soon. That's the plan anyway!


So, over to you, good people of SGL. Any advice gratefully received - I look forward to hearing your views/experiences/recommendations!


Regards

John

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well John i think you have certainly done your home work, 

the mount is a belt driven mount so will be very good,

scope, don`t 100% certain the tak is worth the extra £2200 compaired to the williams gt, you`ll properly need a stepper motor focuser on either of the scopes also, real pain when trying to focus manually and yopur away from the pc screen. 

ccd camera, the 460 is the same camera as the atik one 6, any of the choices you mentioned are top quality although i`ve read lots of views and spoken to people that have the 460 and they always have good things to say about it.

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John,

One thing that's unclear is how much imaging experience you have. I ask, because going from zero to an 8k imaging rig in one step involves quite of lot of learning (and a lot of frustration, too).

There is a nice, reliable "recipe" for starting widefield imaging that will set you back about £2k

  • One of the 80mm ED refratcors, somewhere around F/6 + field flattener
  • An NEQ6 or HEQ5 Syntrek + EQMod
  • Canon 1100D body
  • 60mm guider + QHY5
  • Additional "bits" as necessary: e.g. T-ring adapter for DSLR, power supply, focusing aids, mounting plates, paid-for software, dedicated computer

There are a lot of people who have this, or something very similar - so there are lots of people who can share the benefit of their experience. Plus, this type of setup produces some extremely acceptable results. This base configuration is also upgradable without too much difficulty, after you have exhausted its possibilities. For example: moving up to a faster, larger or triplet refractor, changing the DSLR for a dedicated OSC and or then on to a mono CCD + filter wheel. Since all of the items listed are popular, they can easily be sold s/h (or even: bought s/h to start with) so the cost of, say, ab ED80 can be mostly recouped and put towards a pricier 'scope,

Edited by pete_l

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I started with zero experience with a Canon 1000D that I immediately modded. Can't say I recommend that to anyone. I learned very little and the real learning - positive learning without frustration - came with a mono CCD and a filter wheel. But that's me ;)

/per

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Astrophotography - it means nothing if you can't track the star movement accurately & reliably. Add to that in the UK that wasted subs are painful due to the cloud cover.. 

My personal opinion is that I would immediately go for the middle ground mounts - not the beginner - with that budget. EQ8, Mesu etc..

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Widefield imaging rig - A term that in the context of this post I am finding a little ambiguous. Here's why, just from the CCD and scope point of view.

I had a 460 chip and I use it with a Tak FSQ85 - I love widefield stuff, but have found this combo to require a lot of mosaics to get that real wide field feel. In my mind widefield means something huge a sweeping, the sort of thing that the big chip 11000 camera's are getting. That IS widefield. In order to get a couple of widefield images, I've had to resort to some serious mosaics with the 460 chip.

For example : https://www.flickr.com/photos/swag72/9855898385/ This is a 3x2 mosaic, as is this https://www.flickr.com/photos/swag72/11835230684/ - This is a lot of work and over 70 hours of imaging time for each.

If I could, for widefield I would consider either a larger QSI683 or a QSI690/660 perhaps with a 200mm camera lens.

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Thanks for your suggestions so far!

red dwalf: I'll take another look at the WO GT81. Do you use it with a FF?

pete_l: Yes, I originally looked at DSLR imaging but this approach doesn't appeal to me. I want to get stuck in to mono CCD imaging from day 1, even though the learning curve is steep. That's part of the challenge ;-)

perfrej: Yes, mono CCD + LRGB + NB appeals to me on a technical level.

NickK: Interesting point. I had assumed the AZ EQ6 GT would be fine if not heavily loaded. I did consider the EQ8 but it seemed rather bulky for my needs. I'll take a look at Mesu.

swag72: Now that is wide field! Stunning images - not what I have in mind though when I refer to wide field. I've used the excellent 'Imaging Toolbox' tool to get an idea of the FOV I can expect with various combinations of refractor and CCD so I'm sure something like the ED80/GT81/FSQ85 + 460EX/660 will be fine for me.

I appreciate that this is not an easy decision to make. My equipment list changes daily ;-) Maybe I should just make a cheque out to FLO and say ' surprise me' !

John

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Yes john, I use my Williams with a reducer, makes the scope faster to about f4.75, spacing fine with a canon dlsr but a bit of fiddling required with a mono ccd and filter wheel to get the spacing the correct distance.

I think the eq8 is alittle overkill for the short refractor even with a guide scope and a couple of cameras, the neq6 or the newer gt model will easily cope with that configuration, more portable too.

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Widefield to me is a 12mm f2.0 lens on a camera on a tracking mount. :)

Do that and depend the rest on some trips to Lanzarote, Southern Hemisphere etc. :)

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red dwalf - Ah, yes, I have yet to experience the joys of FF, back focus and spacing. I think the FSQ85 already has a very flat field so can be used 'native' with a CCD i.e. no FF required. That would avoid the fiddling! The WO GT81 does look nice though. Some good reviews and images that I'dbe happy with. I'll need to check the specs to see if a GT81 + FF can accomodate a QSI 660 WSG-9 (or just ask Ian King for advice).

IanWatkins: Hehe. Maybe I should have said 'CCD imaging rig with a short focal lenght refractor' and avoided the term 'widefield' ;-)

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NickK: Interesting point. I had assumed the AZ EQ6 GT would be fine if not heavily loaded. I did consider the EQ8 but it seemed rather bulky for my needs. I'll take a look at Mesu.

John

An EQ6 will happy do up to 1 meter fl.. the issue is accurately doing this over and over so that mosaics can be made.. alternatively - you could put two or three scopes on the mount.

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pete_l: Yes, I originally looked at DSLR imaging but this approach doesn't appeal to me. I want to get stuck in to mono CCD imaging from day 1, even though the learning curve is steep. That's part of the challenge ;-)

That's fair enough. You gotta respect a man who's prepared to jump straight in.

In that case I'd suggest allocating about half your budget to the mount: something like an Avalon LINear or if you want cutting edge a CEM60. Half to the CCD+filter wheel (plus filters: LRGB, Ha, Sii and O3 - a 7 position wheel) and the "other half" :grin:  to the telescope. Depending on just how wide you want to go (and remember that 90% of the Messiers are smaller than 40 arc-minutes) a 65mm triplet could be the most suitable OTA. With an ATIK 490 that 400mm F/L would give you a 1.8°x1.4° field at just under 2 arc-sec per pixel - pretty much optimum!

For widefield work you would still only need a modest guider, so the 60mm + QHY5 would suffice.

Edited by pete_l

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Quick update. With the help of IKI I've narrowed down the equipment list to the following. Just need to decide which mount to go for now. Head says Sky-Watcher (I like the dual mode, very capable mount, good price), heart says Avalon (looks great, impressive performance, but no dual mode).

Avalon Linear Fast Reverse EQ Mount + Geoptik Hercules Tripod
or
Sky-Watcher AZ-EQ6 GT
Takahashi FSQ-85 OTA
Takahashi 6x30 Finder + Bracket
Takahashi CA35
Takahashi M54 to T2 Adapter
Takahashi 72mm Auxilliary Extension
Parallax Tube Rings
Losmandy Mounting Plate
QSI 660 WSG-8 Mono CCD
Baader LRGB 1.25" filters
Baader Ha, OIII, SII 1.25" Narrowband filters
Starlight Xpress Lodestar X2 Autoguider
Mains to 13.8v PSU
Thoughts?
Regards
John

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Excellent choice from where I stand. I favour the Avalon mount over the SW FWIW.

cheers

Steve

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This is very similar to my setup and I love it.

The Avalon Linear has proved to be a most excellent mount. I really do rate it. It's accurate and guides really well. This is so important.

The FSQ85 is a dream in my opinion. I really like it, sharp optics and a great build. I will not part with mine. I would definitely be looking to see if the budget can stretch to the reducer though. 329mm loveliness at f3.9 - Superb.

The QSI660 - I am interested to hear why this one was recommended over the 690.

RGB filters are fine, but if you could stretch more still how about 3nm Narrowband filters. Madly expensive, will cost you almost £1k, but yum yum!!!

So, I'd say an excellent choice all round, perhaps a couple of additions from my own experience.

Hope that helps.

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...
Thoughts?
Regards
John

Motorised focuser?

from the original post:

My budget for the whole rig is around £8k (mount/scope/guiding/CCD/accessories/software).

What software for image processing? If you're spending ££££ on the hardware, the software (and a suitable, big, "pro" level, calibrated screen) deserves some attention, too.

Edited by pete_l

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The QSI660 - I am interested to hear why this one was recommended over the 690.

My future plans include longer focal length imaging with a 9.25 EdgeHD. I thought that the larger pixel size of the 660 (4.5um) would favour this scope rather than the 690 (3.7um). I also took the following into account:

http://www.firstlightoptics.com/blog/atik-460ex-v-atik-490ex.html

Same sensors as the 660 and 690 I believe so I assumed the same reasoning would apply. I'll check back with IKI for clarification. What's your view?

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My view, based on chatting with IKI is that the 690 is a better compromise. I have the reduced Tak at 329mm and also a C9.25. For this I use it 2x2 binned to get a decent image scale. See what Ian says.

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The Avalon Linear has proved to be a most excellent mount. I really do rate it. It's accurate and guides really well. This is so important.

After further research I finally made a decision - today I ordered the Avalon Linear Fast Reverse + Geoptik tripod from IKI. Price was reduced last week so I'm glad I procrastinated  :smiley:

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By Gad Sir, I do believe you beat me by seconds to that last in-stock Avalon! I don't hate you though. Not at all. May I recommend that you image with a 20mm Tasco achromat? Marvellous scope, ideally configured with a large crack in the objective!!   :grin:  :grin:

More seriously, is the Tak worth it? Yes, it certainly is.

While I greatly admire the 8300 QSI cameras I'm not entirely convinced that they are worth the increase over the Atiks. Not having done a back to back comparison I'll bow out though a friend with both has done so and is swaying Atik-wards at the last time of speaking. Heresy indeed! But economical heresey, at least. Word of caution; I like Atik, the people and the cameras, and they are on the right side of the pond.

Olly

http://ollypenrice.smugmug.com/Other/Best-of-Les-Granges/22435624_WLMPTM#!i=2266922474&k=Sc3kgzc

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Those Sony sensors sport very small pixels and tiny chips. Not much of the sky gets caught. I personally go for larger chips in order to get more sky in the frame, and the noise situation with chips like the KAF-8300 is not as bad as people lead you to believe.

I have an SBIG ST-8300M and a QSI 683 WSG8. The SBIG is nothing compared to the QSI, but I think Olly has a point regarding the Atik one; I think it may be best value for money. So I say Atik 383, not Sony.

/per

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Well, I guess I'm an even wider field junkie and put up with the deafening racket of the full frame 11 meg Kodak chip - though, then again, with the right calibration it is pretty sweet and clean. Well, fairly!

Olly

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By Gad Sir, I do believe you beat me by seconds to that last in-stock Avalon! I don't hate you though. Not at all. May I recommend that you image with a 20mm Tasco achromat? Marvellous scope, ideally configured with a large crack in the objective!!   :grin:  :grin:

Sorry  :grin:  However, IKI told me that the Geoptik tripod was not in stock so I have to wait a couple of weeks anyway, maybe longer. Were you given a lead time for your Linear?

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Those Sony sensors sport very small pixels and tiny chips. Not much of the sky gets caught. I personally go for larger chips in order to get more sky in the frame, and the noise situation with chips like the KAF-8300 is not as bad as people lead you to believe.

I have an SBIG ST-8300M and a QSI 683 WSG8. The SBIG is nothing compared to the QSI, but I think Olly has a point regarding the Atik one; I think it may be best value for money. So I say Atik 383, not Sony.

/per

I'm still unsure about the CCD choice but I like the idea of an all-in-one solution i.e. CCD/OAG/FW, hence the QSI.

If you recall, my goal is LRGB + NB imaging with a TAK FSQ85 and later on an EdgeHD 9.25". I'm hoping to do this with just the one CCD.

Initially I thought the QSI-660 WSG-8 would suffice. Working through sampling rates with IKI indicated that the QSI-690 WSG-8 might be a little more versatile overall (swag72 would agree with this I think). Having said that, IKI also advised not to get too hung up on sampling  :laugh:

More research needed perhaps, although I've already suffered with 'paralysis through analysis' when choosing the mount. At least I can tick that off now.

Any advice regarding the CCD gratefully received!

Regards

John

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Sorry  :grin:  However, IKI told me that the Geoptik tripod was not in stock so I have to wait a couple of weeks anyway, maybe longer. Were you given a lead time for your Linear?

He thought it might be a week or two. It will be interesting to see how we get on.

Olly

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