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Evostar 90 / 660 on AZ Pronto??


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I've not seen this one before... It's interesting that if you had the 90/900 you might wish for a shorter focal length for better wide field views, but with the ST80 80/400 you'd wish for a bit more focal length and a little more light power.... This one seems to fit the bill...

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Indeed - this looks like sweet spot for versatile scope.

Read somewhere (not really credible source - description on retailer website) that it has color correction comparable to 90/900.

That might actually be true if more exotic but not overly expensive glass was used (for example Bresser 102/460 has some sort of ED glass in it, it still shows quite a bit of false color, similar to Skywatcher ST102 - but at 4" difference between F/4.6 and f/5 should be obvious).

There are couple of scopes that have this focal length - 102/660. There is Celestron model and Bresser model. I wonder how this one compares to those two.

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  • 2 months later...

I’m very interested in this scope as an OTA. It seems like the perfect combination of price, size, light weight, focal length and manageable CA. Unfortunately it’s out of stock everywhere in Australia (as are most of the cheaper telescopes. COVID strikes again)

Love to read a review if anyone has bought this scope 

Edited by Sky Toast
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I am certainly no expert. But suspect its exactly the same achromatic lens as the SW 90/900 ?  just with the usual extra feild curvature and extra CA. Nothing in that report suggests comparable CA to the 90/900 just comparable  sharpness and contrast ( with a smaller sweet spot ) no doubt. I personally am buying the 90/900. But realize some may want a more portable refractor

Edited by neil phillips
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4 hours ago, neil phillips said:

I am certainly no expert. But suspect its exactly the same achromatic lens as the SW 90/900 ?  just with the usual extra feild curvature and extra CA. Nothing in that report suggests comparable CA to the 90/900 just comparable  sharpness and contrast ( with a smaller sweet spot ) no doubt. I personally am buying the 90/900. But realize some may want a more portable refractor

I think you are probably correct.

I have a Celestron branded (same as the SW) 90/1000 (F/11.1) optical tube which also looks exactly the same but longer. Same objective cell, dew cap design and same focuser design. The F/11.1 version would be too much for the AZ-Pronto though. The F/7.3 version might be OK though - maybe thats why they introduced the shorter tube version, to give lighter mounts a chance ?

 

 

 

Edited by John
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It might be motivated by mount capacity, but what if they think of creating whole new line? :D

We have F/5 line of fast achromats, starting with ST80, then ST102, ST120 and ST150

Then there is evostar line of slow scopes - most of them F/10-F/11 with the exception of largest ones being F/8

This is second scope in "middle ground". There is already very sweet little Mercury 70/500

https://www.firstlightoptics.com/startravel/skywatcher-mercury-705.html

which is F/7.1 scope

and now above 90/660 - which is again F/7.3

Maybe they'll introduce 110mm F/7.5 and 130mm F/7.7 to complete this odd "middle" line :D

Both "middle" line of scopes and Evostar would converge on 150mm F/8 model

In any case, I think that there is room for this middle line that will further be balance between portability, speed and CA. ST102 is too colorful for you and Evostar 102 too long? Get 90/660 instead, or perhaps 110 / 825 :D

 

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3 hours ago, wibblefish said:

I have this telescope, I am a beginner though so not sure how much use a review would be but happy to answer some questions / give some thoughts if you wanted :)

Hi

 

I'm looking at possibly getting this scope too

Couple of questions 1. How long is the tube? Looking at getting something fairly compact as storage is at a premium. (can't seem to find it on the net) 

2. How is the scope at high magnification on Planets etc is the there a lot of chromatic aberration and better suited to wide views? 

 

Thanks in advance 

 

 

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3 hours ago, wibblefish said:

I have this telescope, I am a beginner though so not sure how much use a review would be but happy to answer some questions / give some thoughts if you wanted :)

Just your general impressions of both handling and view. What you like and what you dislike in regular use.

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I have no experience with this 90/660 scope, but I'm pretty sure it will be a good rich field refractor. I'm basing this on the fact that I've used the Star Travel F5 refractors in all their apertures extensively over the years, and given they are specialist wide field instruments, I think they are terrific scopes in the right hands. I found the CA in the Star Travel's is really very good all things considered. Similarly, the 90/660 is a specialist scope that should perform admirably on targets its intended for. But its aperture may actually work to its advantage, in that CA may not be too detrimental to a lunar or planetary view, making it a reasonably good all round grab & go. With a barlow, it could be quite good for moon & planets.

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1 hour ago, John88 said:

Hi

 

I'm looking at possibly getting this scope too

Couple of questions 1. How long is the tube? Looking at getting something fairly compact as storage is at a premium. (can't seem to find it on the net) 

2. How is the scope at high magnification on Planets etc is the there a lot of chromatic aberration and better suited to wide views? 

 

Thanks in advance 

 

 

Let me see.

1) the tube is roughly 75cm from where the diagonal ends to the front of the telescope (fully retracted). The tripod with legs extended is slightly wider than this.

2) It is more suited to wide views. I have only been able to view Mars and under highish magnification (12mm and x2 barlow) whilst small it does resolve some detail if the seeing is good (shadowing on surface only). There is definatey some CA, I found it bothered me more on star splitting Rigel for example has a bright halo rather than Mars. On lower magnification it hasnt bothered me overly nor when viewing the moon though again it is present at the edges to a degree. The main issue I found with high magnification is focus shake likely from the light tripod. I also had issues with running out of focus trying to use a short barlow plus filter. 
 

There is definately curvature at the edges of the view where you see some stars becoming an elongated shape. It seems pin sharp in the main field of view and focuses fairly well.
 

That said the handling is very good, the pronto head moves well and holds where it is aimed. Slow motion works well and I have tracked a fast moving satellite or some such the other night. Its nice and lightweight generally and I have had zero issues with cooldown or dewing during sessions. The supplied eye peices the 25mm is good but the 10mm is not, both lack decent eye relief.
 

It excels at wide fields, bright star clusters, though I have found brighter nebula, some DSO and split some doubles (Castor etc). Likely its more limited by my experience than the telescope itself.

Hope that helps.

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14 minutes ago, wibblefish said:

Added some phone camera shots of the moon the other day maybe help judge CA etc?

Nice and sharp images.

Photos tend to exaggerate CA since sensors are more sensitive in those wavelengths than human eye - but you can give comparison of subjective feel you had at eyepiece. Is it less or equal to that in images?

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5 minutes ago, vlaiv said:

Nice and sharp images.

Photos tend to exaggerate CA since sensors are more sensitive in those wavelengths than human eye - but you can give comparison of subjective feel you had at eyepiece. Is it less or equal to that in images?

I would say much less, I was actually surprised to see the purple fringing in my photos as it wasnt readily apparent in the eyepeice observation.

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6 hours ago, wibblefish said:

Added some phone camera shots of the moon the other day maybe help judge CA etc?

02162B38-984F-4990-A4D6-9BA5BE116D41.jpeg

A64B6879-5760-4D96-845F-9EFA787D8E40.jpeg

Thanks for the pictures and the info gonna be tough choice eventually between the 90/660 or a Skymax 102 I think although I will probably change my mind before they come back in stock again 😁

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15 minutes ago, John88 said:

Thanks for the pictures and the info gonna be tough choice eventually between the 90/660 or a Skymax 102 I think although I will probably change my mind before they come back in stock again 😁

Interestingly that was pretty much my choice and in the end I went for the refractor mostly on a punt because it was in stock. Be good to know how you fare with either of them! 

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