Which Telescope, Schmidt Cassegrain or Refractor?

[AGF]

Good afternoon guys,

I am hoping to get started in astrophotography and wonder if forum members can help me out. I am interested initially in the Solar System but would like to move on to DSO’s later. So, my investment in equipment would have to cater for both. I have a budget of around £1000 and thinking this would be about the cost of a suitable guider system, reducer / flattener and main imaging camera when it is required.

To help with my query I already have the following equipment I use for visual observation:

·         Celestron Edge HD 8” 2032mm F10

·         William Optics Megrez, 90mm, 558mm F6.2

·         Celestron Mount AVX with Starsense

·         EOS 50D + Olympus OM, both unmodded (thinking about a suitable ZWO or similar main imager as well)

·         Eye Pieces. Tele Vue:  Radian 5MM, Nagler 9mm Type 6, Nagler 20mm Type 5. Meade super Plossl 26mm, Meade 2x Telegative Barlow.

·         William Optics 2” Dielectric Diagonal, Meade UHTC 2 “Diagonal, plus various 1.25 Diagonals.

 

The AVX can handle either of the smaller scopes for eyepiece viewing at any one time without much trouble but not both!  I want to continue using the AVX, so I would like to know which scope is better for astrophotography. To use either at any one time would be great but my budget is prohibitive, and each scope requires different accessories for upgrading,

For instance, the Edge weighs about 14 lbs and requires a Celestron .7x reducer. Faststar is out of the question because of my budget restriction. With other additional accessories this is near the limit the of the mount, probably too heavy as payload capacity is listed at 30Lbs, which is never truly accurate. For guiding, an OAG is an option in terms of weight and preventing flexure, but I’m not sure how much advantage this is with the associated dimmed light?

My favoured option, the Megrez, on the face of it, seems the better option, as this weighs 7Ibs, which is lighter on the AVX mount and might be more manageable with the extra weight of accessories. For guiding, I would need a guider scope or OAG and guider camera. The only problem is the apparent lack of a suitable focal reducer/flattener. Those listed as satisfactory for this scope are the William Optics 0.8 Reducer/Flattener AFR-IV and the TRF-2008 but I cant seem to find either. Do you know if there are other alternatives?e scopes and instead Pro or Esprit 80 ED Pro, but this would have to wait until I save more cash.

Any help to get me started appreciated!!

Thank you, 

Anthony

 

 

Anthony

[newbie alert]

The edge is too much for the AVX for dso long exposure..yes oag is the way to go but I'd suggest a different mount.. The megrez on the other hand is a perfect size for the avx,Superb bit of kit..

I use a zs80d with the dedicated .80 reducer which I'm more than happy with..can use it with my 100d or as is now the case with a second-hand Atik 

[AGF]

Thank you for your quick reply and comments. Yes, I agree with you re: the edge long exposure characteristics and the light mount.  I shall put thoughts of this combination aside and focus on the Mefrez 90 and AVX  for my imaging plans. Issue is the scarcity of the William Optics 0.8 Reducer/Flattener AFR-IV or the Tele-Vue TRF-2008. I texted some of the well known astro retailers and they suggested these items but unfortunately no stock or availability. I shall need to keep looking for one of these or find a similar alternative.

Thanks 

Anthony

[JohnSadlerAstro]

https://www.365astronomy.com/William-Optics-0.8x-Reducer-Flattener-IV-Field-Flattener.html

1 left, if this helps?

On guiding, I use the SW 50mm finder with an ASI120MC, and it seems to work ok with my 130pds. (Although Pudsy is of quite short focal length, 650mm, the tiny guidecam sensor vs the table-sized 1000d one means the fovs are almost the same, lol). Focusing with the finder was quite awkward and it needed some weird adapter, but I believe @FLO are now selling a pack with a 50mm ZWO finder/guider and the required adapters? If only that had been around when I got my kit ! 

John

[Handy_Andy]

I use an Altair Astro Lightwave 0.8x reducer/flattener with my ED80 and that works a treat, take a look at those.

With your guiding question, I use a 50mm finder as my guidescope and it corrects the AVX a treat when I'm imaging with my ED80.

[cjdawson]

I am interested initially in the Solar System but would like to move on to DSO’s later.

 

Just be aware that you are asking two very different and in reality opposing questions.     Allow me to explain why.

 

Planetary imaging requires lots of "magnification" what do I mean.  For my setup, I've got an 8" SCT with a focal length of 2000mm.  When I attach a camera, Juptier only takes up a very small portion of the image.  I need to use a Barlow to increase the size of the planet in the scope.  I've found the best results working at F/20 so that's with a focal length of 4000mm.   The exposures required are still very short.   This is why you'll find that planetary stacking software takes the input as a video.  That way lots of frames (in the case of registax upto 2000 per file) is used to stack and remove noise from the image.

 

Deep Sky photography however is a completely different challange.  Take M42 as an example.  It's a challenging target, but fist things first.   It's bigger than a full moon!   Jupiter on the other hand is about the size of Tycho.    So whilst you might think "small, dim, long way off" actually they're "big, dim, long way off" For M42, there's several layers - the central bright region, this needs short (ish) exposures, maybe 15,20,30 seconds depending on what you are after.  The outer part can make use of exposures up to an hour, or longer!     The means that you'll be wanting a fast scope (low F/ratio) wide FoV, and you'll need to be able to guide to help with those all important long exposures.

 

I'm making do with my Meade LX-90.   For planets, I'm able to take the camera off, add a barlow (or two!) then take movies.    For the other end, I've got a couple of Focal Reducers.  They change the focal length from F/10 down to F6.3 and F3.3!   I've not had any luck getting the F3.3 to focus yet (but I only tried once and didn't try hard, I think it'll work)  Doing this will make for a much wider FoV, but it's compromising the scope as it's not really using all the power of the scope.  Also F3.3 reducers are not common, I was lucky to to get one.

 

That said, it's possible to twist any scope to be able to do it.  That said, the Best DSO's that I've seen so far have been from small fast scopes.  Hope that helps you.

[AGF]

Thanks John,

Followed up on this lead re: reducer/flattener a few days a go and was informed that its actually out of stock! I shall need to keep looking..? Thanks for the information on guiding, the ASI120MC looks interesting in conjunction with the SW 50mm finder. I will need to look closely at the WO Megrez 90 and check the best way to attach a guider system to this scope. I think attaching it directly to the top of the 90mm cnc scope rings by means of a dovetail bar might be the most secure method.

Anthony

 

[AGF]

Thanks Handy_Andy,

Thank you for your suggestion re: 50mm finder, this seems to be a popular method. How do you attach it to your telescope? From what I've just read I can convert my Celestron 50mm finder scope to a guider scope using a finder/guider adaptor or buy a new guider-scope directly from FLO.  It seems there is a lot of choice!

Re: the Altair Astro Lightwave 0.8 reducer/ flattener, i'm not sure if this will work with the 90mm Megrez. I shall make further enquiries.

Anthony

 

[AGF]

Thank you CJ.

Most enlightening information on the capabilities and use of the 8" SCT, for both Solar System and DSO's, especially the barlow magnification / focal reducer use in conjunction with the desired fov and long /short exposures. A need for further study is required now that you have got my thinking processes working. On interest alone I shall follow up on this subject.  I believe the LX-90, in the hands of a capable user, as a self contained unit with a fork  mount  and wedge is a very able scope and very much up to the task, however, due to budget considerations, I am not at this time able to buy a more capable mount, which leaves me with the Celestron AVX (very weight sensitive for any load over about 50% of its total capacity of 30Lbs) so I think that leaves my small 90mm megrez refractor the only reasonable choice at this time. But I take heart from your final comment that .. 'Best DSO's that I've seen so far have been from small fast scopes'.. 

This does indeed help!

Thanks 

Anthony

 

[cjdawson]

In another post I recently said to someone who was starting out (think it was in the equipment channel somewhere)

Rather than going straight for the big bucks stuff - get the scope that you would want to use as the guide scope to start with.   In my case that would have been an ST-80.   It's a good scope in it's own right.  You could use that to start with, then as you get to grips with the processes of imaging, upgrade the kit.  Then, when you have the cash, get that big heavy mount.  Then get that scope of your dreams, and use the ST-80 (or whatever you get) as the guide scope, or maybe even drop it all together and use it manually as a drop and go scope whilst the main kit is doing that imaging stuff.

For this reason, I'm starting to look at maybe getting a 130p or similar to use whilst my imaging rig is busy doing it's thing and I have to wait for it.

[Handy_Andy]

The choice of adapting your existing finder or buying all new gear is entirely up to how you want to allocate your budget, as I had my finder just lying around I adapted mine and bought the baader guidescope mounting. This just slots into a synta style base. I also made my own dew heater as I kept getting dew after a while.

Had the Evoguide been released a few months earlier I would have had that and used it as a travel scope too, but that's the way things go, mine works well as it is so not worth laying extra cash out to have a pretty one. Who can see it in the dark after all?

[JohnSadlerAstro]

Hi,

I use the finderscope shoe, as well. I haven't had much trouble with flexure, although if I had the cash I think I would go for rings on a dovetail--its a bit annoying to have to put the guidescope on after you've found the object, especially with a non-goto. With dew, I just made a long extension out of black paper and taped it on!  

John

[AGF]

Hi, Newbie...., John, Handy Andy & CJ.....Thank you all for your excellent responses and advice.  It has been a pleasure to share my thoughts and I appreciate your expertise. I would love to use the Edge 8" for imaging as both a challenge and sense of accomplishment and I can see myself doing this as part of a long term plan, sooner if I can get the AVX to work favourably with the Edge, so I may just try it out first, knowing I may have to put it aside until I can get the heavier mount and the appropriate OAG later on! In the meantime I shall concentrate on the WO 90 Megrez and buy either the ST-80 or the Evoguide guider system. I like both but may go for the ST-80 + ZWO ASl 120mm bundle because of its immediate availability. The EvoGuide is 40-60 day delivery and may also have a waiting list. I think I will do just as well with the ST-80 and as mentioned, I can always use it later on as a drop and go scope

I now have to look at which main image camera to use, DSLR or ZWO, + software, but I have not yet given this much serious thought! I suppose the first question is do I need a 'modded camera' and which EOS is the best. I do a bit of daytime photography and don't want to tamper with my EOS 50D although I will use it to practice on the night sky. I could instead buy a cheaper modded DSLR or one of the better ZWO cameras. Regarding software, I am familiar with Lightroom but where to go with the other post processing software. I see Deep Sky Tracker and Registax seem the most popular?

Anthony

[JohnSadlerAstro]

Hi,

So if you are planning to start off with planetary, you'll be wanting a high frame rate astro-webcam. In fact, I'm using the ASI 120MC for this at the moment, as it can get over 100fps on lower resolutions. My results aren't really very good, but this is probably because of my inexperience in the planetary field. As you won't be needing to auto-guide when planetary imaging, I guess you could do the same, to be honest!  

For DSOs, you'll need something capable of long exposures. I use an old 1000d DSRL which I removed the infra red filter from, but really when it comes to cameras a more expensive CCD is where it's at. The noise with DSLRs is really quite limiting, although it's fun to work around issues like these.

If money is an issue (and we're talking BIG £££ for CCDs ) and you do choose the DSLR route, you wont need to modify straight off. It is only the objects emitting in near-infrared which will be substantially improved. These wavelengths are given off by excited Hydrogen atoms, hence they are called Hydrogen Alpha and Beta (HA & HB). Reflection nebs like the Pleiades, many planetaries, and all star clusters and galaxies wont be affected much by the IR filter cutting out HA, as they really don't emit much. However objects like the Horsehead, Rosette, Trifid, Orion Neb, Lagoon, etc etc will improve no end with modification.

If you choose to go down the CCD route, (I don't actually own one, someone else with more experience should be able to help you out more in this area) you have 2 options, 1 shot colour (like a DSLR, so it takes a colour image) and monochrome. Mono gives more flexibility, as you can specify particular wavelengths and then create colour images out of them like Hubble does. The downside of mono is that for an ordinary colour image you will need images captured through a Red, Green and Blue filters and probably with no filter on for getting the full brightness. As a result imaging sessions will be more complex and money-consuming--you'll notice that mono cams are more expensive than their colour counterparts, even if they are the same model cam.

John

[ollypenrice]

There are a few 'beginner mistakes' to avoid. The first is regarding payload as being the definitive factor with mounts. It is't, necessarily. In deep sky imaging it is far more helpful to think in terms of accuracy of tracking under guiding. How accurate does your tracking under autoguiding need to be? A rule of thumb would be to say that your guide trace RMS in arcseconds needs to be no more than half of your imaging pixel scale in arcseconds. If it is more than about half it will impact on your real resolution of detail. (Beginner error 1b is to believe that round stars prove adequate guiding. They don't, they just mean that your guiding might be equally inadeqate in both axes.) This http://www.12dstring.me.uk/fovcalc.php is a handy website for finding the pixel scale of a given rig. Now, what kind of accuracy can your mount deliver? You need to try it to find out. I find that my premium mounts (Mesu) consistently deliver about 0.3 arcsecs under guiding while my EQ sixes are variable but can generally deliver about half that precision, which is still not bad. (Note the abundant use of the term 'about' in this reply because that is the name of our game.)

The other beginner mistake is to take a naive view of F ratio. In the camera world the focal length doesn't vary when the F stop is changed so it's the aperture which varies. In this case the 'F ratio rule' makes perfect sense. When both aperture and focal length vary the rule goes straight up a gum tree and leads to confusion, brawls and long nights in detention...

?lly

[JohnSadlerAstro]

1 hour ago, ollypenrice said:

(Note the abundant use of the term 'about' in this reply because that is the name of our game.) 

I think it would be fair to point out that astrophotography is about a lot of things. ?

Yes ok I'm sorry I just killed so many of your brain cells. ?

0.3 arcsec is crazy accuracy for me, lol. Although with 650mm focal and a full-frame DSLR, its not too much to worry about, I guess.

John

[cjdawson]

7 hours ago, AGF said:

Hi, Newbie...., John, Handy Andy & CJ.....Thank you all for your excellent responses and advice.  It has been a pleasure to share my thoughts and I appreciate your expertise. I would love to use the Edge 8" for imaging as both a challenge and sense of accomplishment and I can see myself doing this as part of a long term plan, sooner if I can get the AVX to work favourably with the Edge, so I may just try it out first, knowing I may have to put it aside until I can get the heavier mount and the appropriate OAG later on! In the meantime I shall concentrate on the WO 90 Megrez and buy either the ST-80 or the Evoguide guider system. I like both but may go for the ST-80 + ZWO ASl 120mm bundle because of its immediate availability. The EvoGuide is 40-60 day delivery and may also have a waiting list. I think I will do just as well with the ST-80 and as mentioned, I can always use it later on as a drop and go scope

I now have to look at which main image camera to use, DSLR or ZWO, + software, but I have not yet given this much serious thought! I suppose the first question is do I need a 'modded camera' and which EOS is the best. I do a bit of daytime photography and don't want to tamper with my EOS 50D although I will use it to practice on the night sky. I could instead buy a cheaper modded DSLR or one of the better ZWO cameras. Regarding software, I am familiar with Lightroom but where to go with the other post processing software. I see Deep Sky Tracker and Registax seem the most popular?

Anthony

 

Moving on to the software then.   There are loads of programs out there for various jobs.   Again you can spend loads, or not very much.    Lightroom will help, as will Photoshop.  If you have both, they're great tools and should keep you going for a long time.    As for capture software.    FireCapture and SharpCap are good for running a ZWO against planets.  BackYardEOS would be great for you 50D (just try your unmodded camera, you'll get good results)  For stacking, there's DSS, AstroStakart.    From that lot only Backyard EOS is paid for.

For guiding when you get to that PHD2 is the way to do.

And as for deep sky imaging.  SharpCap will work, frankly, I'm getting to grips with Sequence Generator Pro 3.  It's all singing all dancing.   Even with it using all my gear, I'm still not using all the features available in that software.  It's going to help solve alot of problems for me.

 

[AGF]

Hi, Newbie...., John, Handy Andy, CJ....., Ollypenrice,

Thinking over what was said yesterday, there is a lot to take in and it kind of gets jumbled up, 'information overload' so taking the advice of some other helpful imaging enthusiasts I shall try, for better clarity, to put together the semblance of a draft plan from your collective advice to use and follow through, changing it as appropriate as I make progress!

Plan A.

1. As I'm starting with planetary imaging I would like to see what the Edge 8" / AVX combination can do using the telescopes f10 focal length and then add a 2x or 3x barlow for extra magnification.
2. Buy a ZWO ASI 224 or 120MM-S as a guide camera. Planetary use also as main camera. (Decided to leave the DSLR alone at this stage) 
3. Get a suitable guidescope(must work with ZWO) ST 80, ZWO or Evoguide. PH" guiding.
4. For short exposures, use Lightroom, photoshop software for editing, FireCapture, SharpCap,  Registax et al...
5. Think about imaging DSO's when feeling more confident (what extra accessories will I need?).
6. If the AVX guides well enough then consider buying the 0.7x reducer & OAG and trying it on DSO's.
7. Think about getting hyperstar if everything satisfactory with AVX.
8. Think about getting some Ha, UHC-S, etc. filters.
9. If the AVX doesn't perform well enough then consider a 'hypertune' or put it aside until I can afford a more suitable mount.

Plan B.

1. Concentrate on the WO 90 Megrez, (no reason to believe the AVX will not do the job but keep 'hypertune' in mind).
2. Use accessories as listed above and appropriate i.e. camera, guiding and software and add necessary upgrades for longer exposures, Sequence Generator Pro etc.
3. Wondering about the unavailability of the TRF-2008 Reducer / Flattener for the WO Megrez 90mm 6.2 scope. Being restricted to 6.2 means I cannot use this scope to its full capability! What to do? Get another Refractor with readily available reducers/ flatteners?
4. Start with planetary imaging. 
5. Think about and progress to DSO's as experience is gained.
6. Invest in a better imaging camera.
7. What other filters, accessories required?

Notes. I've looked at the '12 Dimensional String FOV Calculator / Telescope simulator by David Campbell' for finding the pixel scale of a given rig and this is indeed a useful tool! Thanks Olliepenrice.

The above plan, although lacking in any great detail, seems a little more orderly, so I can understand better! Please revise as appropriate, as I appreciate all the advice I can get!

Anthony

 

•  

[newbie alert]

Hi Anthony.. 

Plan A And B,with several ideas in place..i try to answer how id do things which might suit you,it might not ..

Plan A

1..The AVX and edge combo is plenty capable planetary setup..you could add a Barlow but start without..i rarely use a Barlow as good seeing conditions needed

2..A 224 is a fantastic camera,think it has the same sensor size as the 120,but usb3..if going to double up as a guiding camera then buy mono as it's more sensitive..link to zwo specs..https://agenaastro.com/zwo-astronomy-cameras-buyers-guide.html

3..you can convert a 9x50 finder in to a guider do the a adapter to replace the eyepeice end if you want to save some money..i preferred mine to the 60mm altair one I have now..

4..you will use Photoshop,registax firecapture,sharpcap etc ..only one I don't use is Lightroom..

5..you can use the avx with edge ,100d for short exposures of say 1-1.30but PA would have to be pretty good to avoid drift..choose bright targets..

6..a focal reducer will help but on the edge they'e not cheap,oag..keep in mind that a really sensitive camera such as a lodestar maybe needed and I don' think the celestron oag works with the edge because of back focus distance

7 ..hyperstar! Great system but high cost and may take time to understand the setup

8..Ha filters will need a modded DSLR or a mono camera to work.. a light pollution filter,think about what you're trying to block or filter out..cls type won't help for led lighting

9..hypertuned mounts...you don't need to hypertune to get it to perform..lots of people use standard factory mounts, will a hypertuned avx perform better than a standard £1300 mount..?

Going to do some work before plan b..but I've tried to look up the megrez.. I can find the specs but not the price..just thinking if you'e having trouble locating the reducer then something along the same lines maybe worth a consideration 

[AGF]

Hi John,

Thanks for your reply. Followed your thinking through, all good. A couple of queries:

I see your point about the OAG and I will look for a better Edge match if available! Maybe I will just stick with the separate guider scope depending on whether flexure occurs or not!

Re: the Edge reducer, yes you are right, more expensive than for most 8" SCT's. Did you mean that using the 0.7 reducer will mean a more sensitive camera will be needed as a result? Therefore, not as simple as just buying the reducer which is expensive enough but adding a lodestar too. Still, if necessary then when the time comes (after some practice) I will have a look at the options carefully and hopefully have a bigger budget!

I think the 'Hyperstar' addition is more of a flight of fancy but it would be nice to have!

I find the Megrez  a good scope for visual use as is, and if necessary I can continue to use it for this purpose (I think it cost about £850 when I bought it a good number of years ago). Not many affordable good 90mm refractors around now it seems?, but a number of well thought of 80MM scopes, such as the Skywatcher Esprit 80ED Pro Triplet FL 400mm F5 with available Flattener or cheaper still the Skywatcher Evostar 80DS-Pro FL 600mm F7.5 with available Reducer / Flattener. 

Anthony 

 

[AGF]

Sorry Newbie, my last post was meant as a reply to yours.

[JohnSadlerAstro]

3 hours ago, AGF said:

Plan B.

1. Concentrate on the WO 90 Megrez, (no reason to believe the AVX will not do the job but keep 'hypertune' in mind).
2. Use accessories as listed above and appropriate i.e. camera, guiding and software and add necessary upgrades for longer exposures, Sequence Generator Pro etc.
3. Wondering about the unavailability of the TRF-2008 Reducer / Flattener for the WO Megrez 90mm 6.2 scope. Being restricted to 6.2 means I cannot use this scope to its full capability! What to do? Get another Refractor with readily available reducers/ flatteners?
4. Start with planetary imaging. 
5. Think about and progress to DSO's as experience is gained.
6. Invest in a better imaging camera.
7. What other filters, accessories required? 

So telescope wise, imo you are mostly sorted for planetary and DSOs. The 8" will be perfect for planetary, and although f/6 is a tiiny bit slow for some of the faintest DSOs, if you're using a DSLR to start with you wont have much trouble with FOVs. From what ive heard, WOs are amazing quality. (You can always expose for that bit longer, if youre autoguiding ). I'm really not convinced that you will need to buy any more scopes.  

Buying a reasonably cheap guidecam and using it as planetary cam as well would probably be quite a good move; you could probably get something of higher quality than the ASI 120 but for me it still does a good job. ?

Progressing to DSOs after a while will be a very good move--its really a lot more stressful and irritating than planetary, and the processing and control etc really get complicated, even if you just use a one-shot-colour DSLR like I do.

When moving from planetary to DSOs, you will probably want to invest in a light pollution filter. (I got the mega-cheap SW 2"one, and it works very nicely ) There are some good filters out there specially designed for DSLRs, if you choose to keep away from CCDs.

On the DSO imaging software: I use Deep Sky Stacker for sacking; you could consider using StarTools for processing, I know its seen as a bit of a "quick fix" for the lower levels of astrophotographers, but it works so well I cant recommend it enough. Its very simple feeling program which does a lot to improve data which isn't of hubble space telescope quality! For cam control, I use Astrophotography Tool, APT, which is free (!).

Planetary I use SharpCap and Registax.

I agree that it is overwhelming, I ended up getting my setup a bit at a time, and gradually learning each bit as I went along. (I still haven't quite learnt how it all works, lol )

John

[newbie alert]

1 hour ago, AGF said:

e: the Edge reducer, yes you are right, more expensive than for most 8" SCT's. Did you mean that using the 0.7 reducer will mean a more sensitive camera will be needed as a result?

Sorry should of explained myself better..i think there's an issue with the backfocus on the edge in combination with the celestron oag..there isn't enough so can't come to focus..at least that's why the guy that sold me his oag said..

I didn't realise that you already own both scopes..thought you was looking to buy a megrez but hesitant as finding a reducer was hard work.. I understand now..dont worry if catch up in a year or 2!

As you own the scope try it without the reducer..you got nothing to lose,no harm in trying.. I use a w/o myself although only a doublet..and also a 8sct but not the edge version

[Handy_Andy]

Just a quick fyi on the reducer, it reduces the amount of backfocus from 133mm without to 105mm with it. Just something to keep in mind planning your setup 

[ollypenrice]

Regarding the Hyperstar, take everything Starizona say about it with a large pinch of salt. I regard some of their claims as flirting with the advertizing standards laws. There will never be anything 'easy' about imaging with an F2 system whose light cone is so steep as to make the focal depth only a matter of microns. This is a problem when the rather primitive moving mirror focus of the SCT is all you've got and it also means that the slightest tilt will see you in focus on one side and out on the other. In the smaller sizes it is important to have a camera which doesn't intrude into the light path and in all cases you have the problem of how to route the cables in order not to create odd diffraction effects around stars. As regards cutting down on exposure time, it does and it doesn't. Take M51 without the Hyperstar and you'll get a screen-filling galaxy. With the Hyperstar you'll get a wide starfield with a tiny galaxy in the middle. It is hardly fair to say that this will reduce imaging time because the images have little in common. On the other hand it is a very fast system for widefield. 

I'm not saying don't do it, I'm just saying don't be persuaded that it is going to be easy. And once you have sorted out the system with Hyperstar in place, are you going to swap it back and forth with the long FL system? I very much doubt it...

Olly