Sorry, another 'which scope' question

[m37]

Hi all

Apologies for yet another 'which scope' kind of question. I can narrow it down a bit though; I want a short frac, minimal CA, nice solid focuser for my EOS1000D, will be mounted on my HEQ5.

I will be after mainly large DSO targets but might switch to my DMK21 for fun with smaller Messiers.

I am leaning towards smaller aperture / better quality than maximum aperture, I have a StarTravel 102 at the moment and I absolutely love it except for the frustration of various aberrations.

Budget is approx £1000 is and could go up a little for a matched F/R, the basic question is: while I would see a big improvement from a ST102 to Equinox 80, for example, would I then notice enough improvement (generally) between Equinox 80 and Esprit 80 to justify the extra £500 or so?

Also in the running is something such as the GT-81 from William Optics. I would like to purchase from FLO as I want a good reliable company that I am happy to trust with my hard-earned cash.

I've absorbed every bit of info and advice on here and elsewhere hence my mind is spinning but if any of the Olly/Steve guru type people would be able to chip in an opinion I would be super grateful. I basically have one shot at this as I will NOT be permitted to buy another scope again EVER. Mrs M37 is not to be trifled with.

cheers

Christoph

[emadmoussa]

Hello Christoph,

I'm sure a lot of people will think ''Dob'' for your aim is DSOs.

If you're after a small aperture high quality scope then I would recommend an ED refractor. However, a medium range 120mm (SW Evostar 120ED) will be more than 1K I'm afraid. There's the Starwave 102ED and Starwave 110ED. I've got the former one and it's superb.

Anyway, for what you want I believe a compact Schmidt Cassegrain will be ideal. I heard a lot of good things about the Celestron C8. It retails at slightly over £700. It's a combination of very good light grasp and portability. You'll have some cash left for useful accessories.

[ollypenrice]

Large DSO targets won't fit on the chip of an SCT. I think you're right to go for a good small refractor.

The difference between an ED 'semi apo' and the ST series scopes, used for imaging, is absolutely enormous. The ST range are awful for imaging with garish false colour, vast field curvature and inadequate focusers.

The Skywatcher ED80 is excellent optically and just about OK to get started with on the mechanical side, though a better focuser would be good. I haven't tried all the WO scopes but I doubt that the doublets really beat the ED80 on colour correction. There must have been something in the water when the ED80 lens was designed! You could go for the Equinox, which is a little faster, but I'd be wary of asking any doublet to go down to exotically fast F ratios with further reducers. You do need a flattener for any doublet or triplet, however exotic.

Once you get to the ED80 the world of enormous jumps in quality is behind you. Even a Takahashi FSQ106 is not 'in a different world.'  It has a much bigger flat field, is certainly better corrected, will give smaller stars and sharper resolution but on a smaller chip you will be taking comparable pictures. The Tak will win in the comparison, make no mistake, but you can take good pictures with the ED80. So I guess that might be my choice, with an upgraded focuser, ideally an R and P but a Steeltrack would do. On the other hand there is an assortment of 80/480 triplets of TMB design origins. These can be good. And, yes, the Esprit.

I wouldn't get drawn into arcane discussions over glass types and the number of lens elements. I'd have a good look at the picures coming in. Look for the control of bright blue stars.

Olly

[Alien 13]

The ED80 is a realy good scope but if you fancy something a bit different you could always get a 200mm f2.8 canon lens for realy wide field.

[Leveye]

If it's DSO's go for a Dob and around 1000mm in focal length and about 650 for a decent one. If it's a refractor you wish i highly recommend the AT65EDQ from Astro-Tech. It has a field flattener built in and is $650 dollars.The focal length is 465. The Williams Optics  at 478mm does not it looks and thats another 300 dollars keep in mind. All my recent pictures were taken using it. The Pleiades came out wonderful check my gallery. Objects like the dumbbell nebula though will be very small and a bit disappointing. Using a cropped sensor camera helps bring them in some.

[m37]

Thanks all, and merci Monsieur Penrice for summing up so much detail so succinctly; that has helped to organise the wealth of information in my little brain!

cheers

Christoph

[IanL]

Not sure why there are two posts recommending Dobs in a post in the 'Getting Started with Imaging' forum?  Dobs are not really suitable for imaging other than maybe planetary/lunar and very short exposure stuff.  Anyway you have already said you have an HEQ5 and I am assuming you don't plan to upgrade?  So it's a question first and foremost of what will work on a HEQ5 for long exposure imaging isn't?

I would steer clear of SCTs if you are new to this game; the long focal length makes it very difficult to do long exposure imaging.  I tried it on my NEQ6 and gave it up as a bad job in the end.  Could maybe get one good sub of a minute or two out of every five or ten.  Admittedly I was using an ST80 as a guidescope, but even if I had been using an OAG (better choice for moving mirror scopes) I still think it would have been a struggle.  On a HEQ5 even more so.

To my mind you're heading in the right direction with a short focal length refractor - easier to guide, less to go wrong, much less weight on the mount (which will help guiding accuracy in the end). Things to consider:

- Focal length should not be too long, so that you can guide it successfully on the HEQ5 (even more important if you are planning to start out unguided). 500-600mm should be manageable, but it gets harder the more you go above that.

- Focal ratio is the next issue to consider.  F6 or F5 would produce acceptable results with reasonable sub lengths.  F4 or below would be better of course, but getting a good F4 refractor is going to cost a lot more.  Higher f-ratios will need longer exposures and/or many more subs to get similar results.

- Weight of the imaging scope, guide scope and cameras needs to be about half the mount's rated carrying weight when imaging.  You could go a bit over that, but again the further you push it the harder it is to get good, repeatable results.

- Focuser needs to be able to carry the weight of the camera without slipping or drooping.

For my part, I absolutely love my SW 80ED DS Pro with the 0.85 reducer.  A steal really, especially if you go for the stripped down OTA packages that the likes of FLO sell.  You can fit M31 diagonally on an APS-C chip (i.e. your Canon), or M42 and the Running Man just about, so it has a nice wide field of view.  Intermediate sized galaxies also come out reasonably well, though small stuff is never going to be super-impressive at 510mm effective focal length.

The stock focuser is absolutely fine for a DSLR; haven't had any problems with slippage or rough action.  The only downside is that it isn't rotatable like the Equinox, but I have recently got the FLO adaptor for the front of the reducer plus a Baader Click-Lock which solves that problem.  If you were later planning to go for a heavier rig (CCD, filter wheel, etc.) then it would need upgrading or you should go for a similar OTA with a better focuser out of the box now.  I haven't used an Equinox but others have said that even that isn't really sturdy enough for a CCD, so ask around a bit more if that is a concern.

At F6.4 (reduced) it is a little bit on the slow side, but I'm a patient man (have to be with UK weather!)  The slightly faster Equinox might be better, but I didn't have the cash at the time.

The image quality is good for the price; there is an obvious difference in star sizes when you split the image in to RGB channels. That would be less of an issue with a mono camera and filters since you can tweak the focus for each filter, but with a DSLR/OSC camera it can lead to a few issues in processing (coloured fringes around stars when applying deconvolution for one thing).

The Esprit looks really nice, but it is still fairly early days in terms of users and results; there are a few threads floating around from those who have bought them so maybe search for them and ask for opinions if that is something you are considering.

[m37]

Thanks dude, that's really helpful and I appreciate it very much.

[lensman57]

Hi all

Apologies for yet another 'which scope' kind of question. I can narrow it down a bit though; I want a short frac, minimal CA, nice solid focuser for my EOS1000D, will be mounted on my HEQ5.

I will be after mainly large DSO targets but might switch to my DMK21 for fun with smaller Messiers.

I am leaning towards smaller aperture / better quality than maximum aperture, I have a StarTravel 102 at the moment and I absolutely love it except for the frustration of various aberrations.

Budget is approx £1000 is and could go up a little for a matched F/R, the basic question is: while I would see a big improvement from a ST102 to Equinox 80, for example, would I then notice enough improvement (generally) between Equinox 80 and Esprit 80 to justify the extra £500 or so?

Also in the running is something such as the GT-81 from William Optics. I would like to purchase from FLO as I want a good reliable company that I am happy to trust with my hard-earned cash.

I've absorbed every bit of info and advice on here and elsewhere hence my mind is spinning but if any of the Olly/Steve guru type people would be able to chip in an opinion I would be super grateful. I basically have one shot at this as I will NOT be permitted to buy another scope again EVER. Mrs M37 is not to be trifled with.

cheers

Christoph

Hi,

I would suggest that you investigate the TS APO65_Q too. It is a quadruplet with the flatner built in. This feature alone will save you lot of headache as there is no back focus distance to set. As you progress to a mono ccd and filter wheel in later years then the value of this feature becomes more obvious. The focuser is also a 2" RP type thatf is far more superior to any Crayford unless you wish to cough up for a MoonLight. As you are looking for widefield DSO imaging the 65mm aperture is not a problem. Both the GT81 and the new SW Esprit are as yet untested. 

Regards,

A.G

[Twisted Lip]

For what its worth I have a WO GTF81 (note not the GT81 which doesn't have the inbuilt flattener I believe) and I absolutely love it. Optics are great and its never fogged or iced on me even in -15C. Plus its white and who wouldn't want that? The the WO DSG focuser is one of the best I've used and holds my 1100D without any concern.

To give you an idea of what it can take (admittedly by me so its never going to be the greatest!) the following was M42 taken last Tuesday when we had a clear night. Un-processed with a similar camera (1100D) on a similar mount (NEQ6) to yours:

Another completely off the wall suggestion might be a Skywatcher Explorer 190MN DS-PRO. I've never used one for imaging myself but its in your price range and you'll see a load of people raving about them being proper astrographs on the forums here. Just a thought.

Good luck though, whatever you pick you'll have fun!

Will

[ronin]

If this is the be the one and only scope then go for something like the WO 81, either as the GT-81 or the GTF-81. The ED 80 have a good reputation but they are still a doublet and I do read of insignificant CA but that still means some CA.

I am guessing that the GTF-102 will be over budget, but people in the US who have managed to get one seem very keen on them.

The GTF-81 seems to have a real f number of around 7.2, the flattener makes it slower then the lens itself. WO do, or did, a dedicated flatener which used to be about £130. However I didn't see it on the FLO site.

I have no idea alternatives to the WO 81's, so that is the only one in that size and specification I can mention.

If not necessry that you get in now, perhaps visit Astrofest in early Feb in Kensington ans see what is available.

[m37]

This is great stuff guys. Solid advice. Cheers. The mulling continues...

[m37]

Hi,

I would suggest that you investigate the TS APO65_Q too. It is a quadruplet with the flatner built in. This feature alone will save you lot of headache as there is no back focus distance to set. As you progress to a mono ccd and filter wheel in later years then the value of this feature becomes more obvious. The focuser is also a 2" RP type thatf is far more superior to any Crayford unless you wish to cough up for a MoonLight. As you are looking for widefield DSO imaging the 65mm aperture is not a problem. Both the GT81 and the new SW Esprit are as yet untested. 

Regards,

A.G

I liked the look of this a lot but read a lot about odd shaped stars and I saw some evidence in online images. Shame as it looked perfect apart from that.

[Astrosurf]

+1 for the refractors! I'm wondering if when people say 'Dob' they mean 'Newtonian'?? The term Dobsonian just means the alt/az mount they're on. The OTA (Optical Tube Assembly) is still a Newtonian.

I use my WO frac for large DSOs and more wide-field and my Newt for the smaller DSOs. Yes, the Newt has a long focal length and is a bit of a sail in the wind, but it's been great and guiding has, for me, been quite easy. My M101 image below, was taken with my 200P. I only managed a few subs so it's a bit noisy, but reasonably successful!

But go with the frac for now.

Alexxx

[ronin]

Alex, I can get a picture almost like that if I defocus the camera a bit and aim it at an Isle of Man flag.

Do we have any Manxmen on SGL ?

[IanL]

+1 for the refractors! I'm wondering if when people say 'Dob' they mean 'Newtonian'?? The term Dobsonian just means the alt/az mount they're on. The OTA (Optical Tube Assembly) is still a Newtonian.

I use my WO frac for large DSOs and more wide-field and my Newt for the smaller DSOs. Yes, the Newt has a long focal length and is a bit of a sail in the wind, but it's been great and guiding has, for me, been quite easy. My M101 image below, was taken with my 200P. I only managed a few subs so it's a bit noisy, but reasonably successful!

But go with the frac for now.

Alexxx

Fair point about the Newtonian/Dob confusion.  I've not used one, but at 1,000mm focal length a 200p should be easier than a typical SCT at 2,000mm in terms of required guiding accuracy (but conversely weight and size of a typical Newt are the downside on a small mount).

[m37]

Well thanks everyone. 

Currently in the lead is the GT-81 because the images I've seen have been better for CA halos than the ED80 or equinox (both of which looked really good but there was generally a bit too much for me) and the stars have a nice consistent shape. Also it is slightly faster out of the box.Something tells me it will fare better brought down to f4.7 than the EDs. Maybe a bit of a gamble as it is less tested online than the classic EDs. I must follow my instinct so we shall see!

Oh, and it has a rack and pinion focuser  that looks VERY solid which is confirmed by all reviews. 2 year warranty can't hurt, it's very light and has a handle. And gold bits.

And a thermometer in the focus knob (?) so I will now need binos to see this from my toasty warm house. Or maybe I could get a camera on it...?

I will throw up some first light pictures when I can.

So, unless anyone has any warnings or last minute advice, that is that!

cheers again

C

[Twisted Lip]

Sounds like you've made your choice and i think its a good one so I reckon you'll love it.

One last thing - especially if you're getting from FLO - is to order a Bahtinov mask at the same time. FLO have someone who'll custom make one for you and you'll be able to start using it straight away.

Cheers

Will

[m37]

Yup, 99% certain unless I hear something horrible about them before tomorrow!

Good tip on the bahtinov.

cheers

[m37]

Does anyone know anything about this ?

http://www.altairastro.com/product.php?productid=16495

It is a 60 mm triplet with rack and pinion. Bit slower at f7 but with a ff/fr it would come down to a nice F5 ish.

It has fpl51 glass but I really can't see that making a world of difference.

[m37]

The trouble with OCD is I have serious issues with obsessing over minute details !!! but as was recommended I have been checking out images and looking for how they handle colour. I think weighing up quality of image across the whole field and of course cost after buying extras for things like tube rings, finder, something to store it in safely etc the Esprit 80 is looking more competitive than I first thought. It would also enable me to sell on some of my bits and bobs (keep an eye out on the classified section in days to come!!!).

Right. Decision made. Thanks everyone who helped out.

Christoph

End of topic.

I promise.

Probably

[lensman57]

Well thanks everyone. 

Currently in the lead is the GT-81 because the images I've seen have been better for CA halos than the ED80 or equinox (both of which looked really good but there was generally a bit too much for me) and the stars have a nice consistent shape. Also it is slightly faster out of the box.Something tells me it will fare better brought down to f4.7 than the EDs. Maybe a bit of a gamble as it is less tested online than the classic EDs. I must follow my instinct so we shall see!

Oh, and it has a rack and pinion focuser  that looks VERY solid which is confirmed by all reviews. 2 year warranty can't hurt, it's very light and has a handle. And gold bits.

And a thermometer in the focus knob (?) so I will now need binos to see this from my toasty warm house. Or maybe I could get a camera on it...?

I will throw up some first light pictures when I can.

So, unless anyone has any warnings or last minute advice, that is that!

cheers again

C

I have the baby ZS71 and the focuser is really good, the scope is not too bad either with just a little bloating in the blue channel. If the optics are good then the GT81 is a bargain IMHO.

Regards,

A.G

[Twisted Lip]

The trouble with OCD is I have serious issues with obsessing over minute details !!! but as was recommended I have been checking out images and looking for how they handle colour. I think weighing up quality of image across the whole field and of course cost after buying extras for things like tube rings, finder, something to store it in safely etc the Esprit 80 is looking more competitive than I first thought. It would also enable me to sell on some of my bits and bobs (keep an eye out on the classified section in days to come!!!).

Right. Decision made. Thanks everyone who helped out.

Christoph

End of topic.

I promise.

Probably

Haha, well i think astronomy (and particularly astrophotography) counts a higher rate of OCD in its population so you're in good company! Best of luck with the purchase!

Will

[m37]

Haha, well i think astronomy (and particularly astrophotography) counts a higher rate of OCD in its population so you're in good company! Best of luck with the purchase!

Will

Cheers bud! Well and truly excited. A brief exchange with Steve at FLO has confirmed my choice.

First light excitement awaits. Also cloud. Lots and lots of cloud. Take that all you East Midlands astronomers... 

[ronin]

Apologies for a late post. Just stumbled on this:

ES Scopes

ES 80mm

Fair bit less then the WO scopes.

Someone mentioned the 102 (I think) as the price was very good for a triplet.

I suspect they are competing against the WO scopes, ES do not seem to state the focuser and if a crayford it may struggle.