Small APO for visual (and imaging)

[andy435]

Looking for a APO mainly for visual but can be used for imaging futher down the road. CA correction is important.

Here's what I found so far:

Altair Astro Starwave 80ED-R doublet 560mm f7 FPL-53

TS ED 80mm doublet 560mm f7 FPL-51

Skywatcher Evostar 80ED 600mm f7.5 (FPL-53)

Explore Scientific ED APO 80mm 480mm f6 FCD1

Ascension 80ED Triplet APO 480mm f6 FCD1 (same as ES 80 ED????)

Little bit over my budget, but....

TS ED 80 triplet 480mm f6 FPL-53

[JimT]

I have used the SW Evostar 80ED Pro for both and gives good service.

Jim

[vlaiv]

+1 TS 80mm F/6 APO triplet (if CA is important) - have it, love it.

[michael.h.f.wilkinson]

I have the APM version of the TS 80mm F/6 triplet. Excellent little scope.

[Scott]

for me, it'd be the sw 80ED. That said, the only other brand from your list I've tried is the altair astro. I've not seen any evidence that they have solved the star bloating issues I had with mine. 

[andy435]

Thanks. The SW 80ED are proven and are very low priced at the moment. But the focuser is after what I've been told inferior to the TS focuser.

[JimT]

1 minute ago, andy435 said:

Thanks. The SW 80ED are proven and are very low priced at the moment. But the focuser is after what I've been told inferior to the TS focuser.

I did have a problem with mine so stripped it and just gave it a clean and have not had any problems with it since.

Jim

[andy435]

37 minutes ago, JimT said:

I did have a problem with mine so stripped it and just gave it a clean and have not had any problems with it since.

Jim

Good it can be easily fixed.

Is it big difference in CA between FPL-51 and FPL-53?

[Louis D]

I really like my AT72ED for visual use.  Despite using FPL-51, I only notice the slightest color once I get above 120x on planets, but I generally use my 8" dob on them anyway.  I added this field flattener to the front of my 2" diagonal to nearly eliminate the field curvature inherent in such a short refractor.  Field curvature annoyed me much more than any false color in this scope.  Can't say that I've tried any photography with it.

[JimT]

I use the skywatcher .85x reducer/flattener for ed80 with the DSLR.

Jim

[tich]

I love my ED80 my focuser suffered with some slippage when the camera was attached, but the focuser was easy to adjust and has been rock solid since. I think there's a post on astronomy shed somewhere but as I'm on my phone I can't give you the link.

[andy435]

How is CA on Evostar ED80?

I'm no expert but focal length of the doublets are better for visual?

The big question is how much better is a FPL-53 doublet over a FPL-51 doublet?

[ronin]

Myself I would opt for the ES scope. ES seem to be producing some good quality refractors at present. You might find an FCD-100 on the Bresser clearance section, also at this time of year there is Astofest comng up in London that may have ones slightly reduced. Depends on where you are however and therefore the possibility of a visit. The cost of visiting may exceed any saving.

Concerning CA on the SW ED80 there are reports of it and if imaging you really want to remove that. Agreed it is minor, usually not applicabl to visual but you want a scope for both, however it is reported.

[JG777]

I am only visual but my 80mm is the Skywatcher Equinox 80 which is F6.25 it is a cracking scope with a better build quality than its ED80 cousin, and a better and very smooth focusser. CA is practically zero just the occasional flash on very bright objects which disappears once you have focus. Lovely scope for dishing up those wide field views. Others have used it for AP so will let them comment on that and FLO sell a flattener for £69 

It has a retractable dew shield and comes in a aluminium case.

But I'm not selling mine anytime soon .....

[andy435]

19 minutes ago, JG777 said:

I am only visual but my 80mm is the Skywatcher Equinox 80 which is F6.25 it is a cracking scope with a better build quality than its ED80 cousin, and a better and very smooth focusser. CA is practically zero just the occasional flash on very bright objects which disappears once you have focus. Lovely scope for dishing up those wide field views. Others have used it for AP so will let them comment on that and FLO sell a flattener for £69 

It has a retractable dew shield and comes in a aluminium case.

But I'm not selling mine anytime soon .....

Thanks. I'm certain the Evostar is a good telescope for the price. I know one should not be fooled by appearance but my personal opinion is that the Evostar looks cheap. The Equinox however looks like a better telescope with better focuser. The price is almost double the Evostar but still compareable with the TS. What I dont like is the shoe mount as I perfer tube rings for stability (I think).

[JG777]

That would be my concern about the ED80 in particular the focuser which I would hazard a guess is its weakest link. I think many end up replacing the focusser for imaging. On my 100 ED it was the focusser that gave up the ghost in under 2 years of light to moderate use, the focusser on the Equinox is definitely a step up in quality. If you go with the ED80 consider fitting it out with a moonlite focusser and if you start imaging  don't forget you will probably want to add the flattener as well. The ED 80 flattener is more expensive than the one for the Equinox. Optically FPL53 is better behaved than FPL51 the SW scopes are FPL53 so something else to bear in mind. For imaging you would want that improved performance the FPL53 gives you. 

As for stability yes you may have a point for imaging, but that might purely be dependant on how you set up. Pretty sure I saw some pictures somewhere of someone who added tube rings to Equinox 80 for imaging. For visual I use the Equinox 80 on a Sabre AZ and UNI 18 which is totally over mounted in reality but still very portable to our dark sites and stability as you can imagine does not factor in. Can't emphasise enough about the importance of mounts for stability ?

As ever it's the imaging side of things that change the game and sometimes it seems visual and imaging never seem to meet in the middle too easily. Overall then an ED80 with a moonlite, a flattener and a decent mount will tick all the boxes of concern. An Equinox will do so visually without a doubt but maybe might need some mods depending on your type of imaging. 

[andy435]

I think I have managed to narrow it down a little bit:

TS ED 80mm triplet 480mm f6 FPL-53
TS ED 80mm doublet 560mm f7 FPL-53

Budget alternative:

TS ED 80mm doublet 560mm f7 FPL-51

[Anne S]

I've got the Altair Astro Wave 102 triplet. That's got FPL53 glass. It's superb for imaging. A friend told me once that RGB filters come to focus at the same point in a triplet scope. This doesn't always happen with a doublet, though I also have a William Optics Zenithstar 80ii which is a doublet but has FPL51 glass. Everything comes to focus correctly as far as I can tell. As to focuser, the Altair one is better but I have a motor focuser on both which makes it easier for imaging. This stops the focuser slipping when heavy equipment is attached. 

 

Anne

[Ben the Ignorant]

1 hour ago, andy435 said:

I think I have managed to narrow it down a little bit:

TS ED 80mm triplet 480mm f6 FPL-53
TS ED 80mm doublet 560mm f7 FPL-53

Budget alternative:

TS ED 80mm doublet 560mm f7 FPL-51

Been using a TS 80 f/6 triplet since 2012, it shows no chromatic blur at all up to 240x, and the image is still quite usable if air tremors are absent. That was an extreme test, in general I don't go above 204x (Explore 4.7mm and Ultima Barlow).

[Uranium235]

It would have to be the SW80ED for doublet, TS80 for the triplet.

FPL51 and FCD1 is definitely not the same as FPL53 (synthetic fluorite), so best to avoid the unknown quantity and go with what is proven to work.

[andy435]

34 minutes ago, Uranium235 said:

It would have to be the SW80ED for doublet, TS80 for the triplet.

FPL51 and FCD1 is definitely not the same as FPL53 (synthetic fluorite), so best to avoid the unknown quantity and go with what is proven to work.

I agree, it will definitely be a FPL53

[SonnyE]

I decided on a Triplet APO. Basically, it boiled down to I wanted to do Astrophotography. So since my telescope needed to primarily be a good lens, the Triple APO was the gravitational choice.

Here is a good example between doublet type, and triplet type refractors. https://starizona.com/acb/ccd/equipbasicsref.aspx

If you want to dodge CA, I would not even consider less than a triplet.