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Refractors... how many do you need?


Ags
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I have noticed that many refractor owners seem to become refractor collectors, having a range of scopes in various focal lengths and ratios. I can't imagine going to those extremes, but whenever I look at my lovely little Zenithstar 66, I think about getting another one. A 100 mm ED doublet would be nice. But then I would need to keep the ZS66 for travel, so maybe an F6 ED80 would maximise aperture while retaining travel capability? But that's a compromise, and astronomy is NOT the art of compromise (you only have to look at the ELT to see that).

So assuming I go for 100 mm option, is the Altair Ascent really that good? Price is no way to judge a scope, but it is a lot cheaper than a Tak, and there has to be a reason?

 

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2 hours ago, Ags said:

So assuming I go for 100 mm option, is the Altair Ascent really that good?

I've had the f/11 version over the last year and I can't fault it for the price, super sharp. Others on here speak very highly of their f/7's.

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1 hour ago, Space Hopper said:

I only have two, but i'm sure theres room for a Takahashi in there......i've never had (or even looked through) a Takahashi before.

You have a TEC and a APM so I'm sure you're not missing anything, but I understand the temptation, especially if its a refractor that fills a gap.

Edited by mikeDnight
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There is interesting fact - with say 120mm refractor - you have more scopes in one. You also have 100mm and 80mm refractor. They are however equally long and weigh about the same and need same class mount. :D

 

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15 hours ago, Ags said:

I have noticed that many refractor owners seem to become refractor collectors, having a range of scopes in various focal lengths and ratios. I can't imagine going to those extremes, but whenever I look at my lovely little Zenithstar 66, I think about getting another one. A 100 mm ED doublet would be nice. But then I would need to keep the ZS66 for travel, so maybe an F6 ED80 would maximise aperture while retaining travel capability? But that's a compromise, and astronomy is NOT the art of compromise (you only have to look at the ELT to see that).

So assuming I go for 100 mm option, is the Altair Ascent really that good? Price is no way to judge a scope, but it is a lot cheaper than a Tak, and there has to be a reason?

 

Regarding the Ascent, if you want to keep expenditure to a minimum and have an achromatic beating 102mm f7 telescope, then yes it is great for the price. Build quality is up there with some of the more expensive variants. The only difference I can see is the fpl51 glass rather than fpl53. They're internally baffled with a nice 2.5" rack and pinion, 10:1 fine focuser. The tube finish and rings are the same.

If you can justify the expense, of course go for the fpl53 FLO Starfield, Altair EDR, Tecnosky or TS Optics Photoline to squeeze every ounce of performance from the aperture and focal length aided by the fpl53 glass. I wanted the best new 100-120mm refractor possible with a maximum budget of £500 and I'm happy I have it.

Regarding collecting, after much research the TS Optics 125/975 is calling out to me...

 

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I have Esprit 120 , with reducer it is kind of two scopes in one. 

Have also 50mm Askar. That covers FL range reasonably . Would like to have another one (100mm) though. Found myself in a situation that I have two mounts and two 2600 cameras . Would be nice to run RGB (with OSC) on one and narrowband on another at the same time. Unfortunately I sold my kidney😄  for a mono camera and 3nm filters, so have to wait until it grows again 

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17 minutes ago, Stefek said:

I have Esprit 120 , with reducer it is kind of two scopes in one. 

Can you actually use that reducer for visual?

I've searched quite extensively for focal reducer that can be used for visual - to maximize FOV in slower refractor - and there is only one that has sufficient back focus - Astro-Physics 27TVPH which has 118mm working distance - and that is just about right for 2" diagonal + any adapters needed.

16 hours ago, Ags said:

So assuming I go for 100 mm option, is the Altair Ascent really that good? Price is no way to judge a scope, but it is a lot cheaper than a Tak, and there has to be a reason?

There was rather interesting thread not long ago - about expensive scopes, so worth checking out if you are keen to get answer if there is reason for Tak being so expensive :D

In any case - if you want ED refractor that is portable in 4" class and don't want to spend silly money - then yes, it's going to be compromise. Question is - what are you willing to compromise.

A bit of aperture and go for 80mm scope instead (there is crazy deal at Svbony for 80mm F/7 with FPL51 glass - think of it as ST80 with much better color correction and retracting dew shield and decent focuser)? A bit of color correction and go for faster yet lighter and shorter scope? Portability? in that case - go for 4" F/7 version that actually comes in two flavors - cheaper + some residual color or more expensive but virtually color free. Then there is F/9 version - it has excellent color correction, but mechanical side and portability suffer.

For portability maybe look into this scope:

https://www.teleskop-express.de/shop/product_info.php/info/p13519_TS-Optics-ED-Apo-96-mm-f-6-with-2-5-Inchl-RAP-Focuser---ED-Objective-from-Japan.html

It is 460mm long for transport and only 3Kg.

Adding some sort of crazy reducer will make it very fast for EEVA as well (with Long Perng x0.6 it will turn into F/3.6 system that is pretty good match for cameras like 533 or 183 or two new ones that you found interesting 485/482).

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3 minutes ago, Stefek said:

Vlaiv, sorry for brevity of my post. I rarely do visual, so was writing exclusively from AP perspective. 

Yes, I see.

Shame that most reducers have such short back focus of only 50-70mm.

I have AP CCDT67 - or rather TS/Chinese clone of that reducer - CCD47, but unfortunately that one has only 85mm of back focus. I was hoping to use it with my F/10 4" achromat to get somewhat wider fields - but it simply won't come to focus when trying with 2" diagonal.

Must try it with 1.25" diagonal, although I'm sure that same FOV can be had with 2" eyepiece without reducer.

Reducers are nice way to extend scope collection - much like barlows.

Should we count these as well into our total refractor count? :D

 

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