Recommend me a refractor

[swannies1983 (Dan)]

Hi all,

I'm really starting to get into imaging at the moment after about 1.5 years of not even taking any of my telescopes outside. My current scopes are an 8" dob and a Tal200K. I have recently taken up prime focus imaging using my unmodded Canon 400D with the 8" Newt on an EQ6. Firstly, it was just some unguided shots (out to about 90secs). Now I'm learning the ropes to guide using an old 60mm tasco refractor and an unmodded toucam.

While sometimes frustrating, it has been a fulfilling experience, producing some pleasing results, at least the unguided pics as I've just started guiding. However, the whole 8" Newt setup is quite bulky and I was thinking of perhaps getting a dedicated refractor for imaging. The Tal200K is a fantastic scope and you only have to look at Bert's work on here to see what is possible with the scope. However, the accessories required to make it into an imaging scope are just not purchases I want to make. Therefore, I was thinking of perhaps selling the Tal and using the funds to purchase a refractor.

In regards to a refractor, I'm thinking along the lines of between 80-100mm, probably an apo (doublet), unless I can be convinced to get an achro. My budget will be around the $1000 mark, but it all depends on what I can get for my Tal. I'm a complete novice when in comes to refractors (my cheap tasco doesn't count ), so any advice would be very much appreciated.

Daniel

[jjjnettie (Jeanette)]

You can't go past the trusty ED80, it's a real work horse.
There's enough big bright targets up there to keep you busy with it for a couple of years.
Don't forget you'll need to buy a field flattener to suit, otherwise you won't be able to take advantage of the full field of view because you'll be cropping the coma from around the edges.

[dannat (Daniel)]

Dan what r you wanting to use the refractor for? just DSO photography? ed80 would be the most popular choice people start with
achro is OK for visual or if you are just shooting mono

[Poita (Peter)]

A second hand ED80 can usually be had for under $400 and is a great place to start.

[swannies1983 (Dan)]

Originally Posted by jjjnettie

You can't go past the trusty ED80, it's a real work horse.
There's enough big bright targets up there to keep you busy with it for a couple of years.
Don't forget you'll need to buy a field flattener to suit, otherwise you won't be able to take advantage of the full field of view because you'll be cropping the coma from around the edges.

Yeah, I have considered the ED80 and it's certainly on the shortlist. I was perhaps hoping to get something with a little more aperature. However, accessories (flatterner) certainly will play a role in deciding on what to get.

Originally Posted by dannat

Dan what r you wanting to use the refractor for? just DSO photography? ed80 would be the most popular choice people start with
achro is OK for visual or if you are just shooting mono

Yeah, I will mainly use the refractor for imaging DSO. I will stick with the Newt + toucam for planets.

I was also informed about the William Optics Gran Taurismo 80mm or the William Optics 90mm Megrez.

I plan to stick with the 60mm f/11.6 refractor as a guidescope for now. I don't know if this will have an impact on what options I have.

[Waxing_Gibbous (Peter)]

Yep. Hard to go by the ED80.
Though if you're prepared to splurge a bit, hands-down the best quality-for-price scope in this range is (IMNSHO) the Sharpstar (aka Astro-Tech) 106mm f6.5.
They run about $1500.
Glorious scope!

[TheDecepticon]

http://www.iceinspace.com.au/forum/s...ad.php?t=79598

Try this.

[swannies1983 (Dan)]

hhhhmmmmmm....very tempting Deception!!

[TheDecepticon]

It is right on for your request, but the final choice is yours.

By the way, it is Decepticon, like transformers, not Deception.

[swannies1983 (Dan)]

haha, sorry, my mistake. Was written in a bit of a rush.

I'm not so sure about the ED100 now. A fellow IIS member has informed me there was a common problem with this scope that produces diffraction rings on some of the brighter stars when imaging, which has something to do with lens spacer. This issue has been discussed on cloudynights. Plus, if I were to get the scope you mentioned, I would probably have to upgrade the focuser to accommodate my DSLR and the slow f-ratio is a negative as well.

Too many options. On one hand, the ED80 seems like a good choice, and the cheaper cost will allow me to buy accessories. However, I do also like the William Optics 90mm Megrez. But it's closer to $1,000.

[g__day (Matthew)]

The other avenue you could consider possibly is guiding from your existing scope using an off axis guider into your guide camera, rather than use the 60mm tasco refractor.

[Terry B]

Have you thought about the 127mm APO from Gilman?

[swannies1983 (Dan)]

Originally Posted by g__day

The other avenue you could consider possibly is guiding from your existing scope using an off axis guider into your guide camera, rather than use the 60mm tasco refractor.

Yeah I had considered it but I already had the refractor and my dad made up some rings for it.

My guide camera is an unmodded toucam. I guess I would still run into problems finding a guide star using this setup despite more light gathering power.

[dannat (Daniel)]

there is the 90mm megrez in the classifieds -worth a look

[Hagar (Doug)]

Originally Posted by swannies1983

haha, sorry, my mistake. Was written in a bit of a rush.

I'm not so sure about the ED100 now. A fellow IIS member has informed me there was a common problem with this scope that produces diffraction rings on some of the brighter stars when imaging, which has something to do with lens spacer. This issue has been discussed on cloudynights. Plus, if I were to get the scope you mentioned, I would probably have to upgrade the focuser to accommodate my DSLR and the slow f-ratio is a negative as well.

Too many options. On one hand, the ED80 seems like a good choice, and the cheaper cost will allow me to buy accessories. However, I do also like the William Optics 90mm Megrez. But it's closer to $1,000.

Hi Dan, I don't want this to sound bad but it seems you have all the answers already yourself. You asked for educated recommendations from those who supposedly know more than you and openly dismiss the recommendations based on some posts on another site.

The thing to be aware of with negative posts on forums is that only the negatives seem to get posted. Very rarely does someone start a thread raving about a good scope.

Depending on the focal length you are looking for, it use in field or observatory, your physical ability and your limitted budget I would suggest you look at the ED range of scopes, either new or second hand. You also have to bear in mind that imaging with a doublet or triplet and a DSLR will require the use of a field flattener of one kind or another. The focusers on these scopes are not fantastic but are quite capable of holding a DSLR. Lots of things can be done to improve the focusers and to dismiss them is a matter of dismissing some of the greatest scopes for imaging that have ever been made and are the only cheap alternative to scopes like AP, Tak, TEC and the like.

My suggestion is you get hold of people who are using them and talk to them. Look at their images. Then decide which way to go.

[RobF (Rob)]

Another 9x50 guider you can modify as a finder/guider. Then you can use your 8" Newt for DSO imaging. Can be a bit of faffing around, but some people say you can get the odd decent image

Of course you'd still have to figure out how to spend the $1000 you'd save, and also find some way to use up the spare imaging time when your larger faster newt sucks down light 2 or 3 times faster than the refractor

[swannies1983 (Dan)]

Originally Posted by Hagar

Hi Dan, I don't want this to sound bad but it seems you have all the answers already yourself. You asked for educated recommendations from those who supposedly know more than you and openly dismiss the recommendations based on some posts on another site.

The thing to be aware of with negative posts on forums is that only the negatives seem to get posted. Very rarely does someone start a thread raving about a good scope.

Depending on the focal length you are looking for, it use in field or observatory, your physical ability and your limitted budget I would suggest you look at the ED range of scopes, either new or second hand. You also have to bear in mind that imaging with a doublet or triplet and a DSLR will require the use of a field flattener of one kind or another. The focusers on these scopes are not fantastic but are quite capable of holding a DSLR. Lots of things can be done to improve the focusers and to dismiss them is a matter of dismissing some of the greatest scopes for imaging that have ever been made and are the only cheap alternative to scopes like AP, Tak, TEC and the like.

My suggestion is you get hold of people who are using them and talk to them. Look at their images. Then decide which way to go.

Doug, my apologies if you thought my posts were quick to dismiss certain scopes. Only one person mentioned the ED100. I simply raised an issue that appears to have been reported by more than one person in regards to this scope. If this problem is not the norm, then I take back my comments.

Regarding focusers. I probably should asked if there any issues with the standard focuser when using the scope with a DSLR. Some people have mentioned there is slippage, particularly when the scope is pointed towards zenith.

I appreciate all the suggestions made in this thread and those made via PM. There are loads of opinions and I'm weighing up all the options.

[gregbradley]

I agree with the ED80 recommendation. I had one early on - doesn't everyone get one eventually?

I had a high end William Optics 80mm triplet super APO. Focuser was rubbish and produced terrible coma it was so badly out of alignment.

Perhaps mine was a lemon - but I'd check others feedback on William Optics before getting one. They are probably fine and I just got a bad one.

Astrotech are also very good value. I think a lot of these 80mm doublets I suspect use the same lens?? Astrotech also does an 80mm doublet and the little 66ED I use for autoguding sometimes is surprisingly well made for such a cheap scope. Microfocuser, locking mechanism, a rotatable focuser and nice finish.

There was an Orion 100mm triplet being sold at Opt (optcorp.com) for US$500 recently. I wonder if they have anymore of those. It seemed like a deal. Also there was a carbon fibre 100mm triplet for sale cheaply recently by I think it was Orion as well. My first refractor was an Orion ED80.

Greg.

[swannies1983 (Dan)]

Originally Posted by RobF

Another 9x50 guider you can modify as a finder/guider. Then you can use your 8" Newt for DSO imaging. Can be a bit of faffing around, but some people say you can get the odd decent image

Of course you'd still have to figure out how to spend the $1000 you'd save, and also find some way to use up the spare imaging time when your larger faster newt sucks down light 2 or 3 times faster than the refractor

Rob, an 8" Newt on an EQ6 is my current setup for deep sky imaging. I am using my 60mm as I had this spare but have certainly considered modifying another finderscope to act as guidescope. Do people get pictures equal to that of a larger focal length guidescope?

[swannies1983 (Dan)]

Originally Posted by dannat

there is the 90mm megrez in the classifieds -worth a look

Yep, had I have seen it and emailed seller several times