Maybe the Astrotelescopes 102mm f11? There is also the Vixen 105mm.

 

In my limited experience the answer to your question is no. Let me explain: I own a vintage C80 an 80mm f/11 achromat which I find to be a good compromise between chromatic aberration or false color and a reasonably manageable optical tube. However most observers and collectors would put the f/11 telescope in the moderate or medium focal length category.

Most amateur astronomers will quite possibly agree that the long focal length telescope is somewhere in the f/16 range. This scope presents us with the long focal length experience i. e. better contrast and a much longer focal range , which enables the scope to "snap" into focus very easily.

The closest I could come to a currently manufactured reasonably priced long focal length telescope is the Vixen A80Mf an achromatic refractor with 80mm of aperture. Its focal length is 910mm which gives us a f ratio of 11.4, which falls in the moderate or medium focal range. Of course this is my opinion and I could be wrong but that's my story and I'm sticking to it.

 

I have seen them many times in the Hands on Optics website, never saw the Astrotelescopes website before. The only difference I can notice is the focuser on the Hands on Optics offering, it's much better. They have received good reviews from what I have seen.

Yeah, the Vixen 105 is a bit expensive...

FWIW, I had a NexStar 102GT (same optics as a Omni XLT 102) and it provided very views with very little CA.

 

I would consider either the Skylight Telescopes of London AT101/15 this has an f/15 TeleVue achromatic objective. I have one and they are exceptional performers for their aperture.

Also, Istar produce high focal ratio achromats either lenses in cell for home build or complete telescopes.

I have always considered an f/10 achromat to be a bit of a compromise. I have both long and short refractors. The extremes being a 6" f/5 which excels at low power wide field work and the Skylight 4" f/15 which provides some Superb lunar and double star images.

 

Nowadays, an f/10 achromatic refractor is considered a rather "slow" dinosaur compared to what's commonly available (f/4- f/7.5). Today's fast scopes are attributable to improved glass technology and lens designs that just weren't available in the days when long-focus refractors ruled. In those days, an f/10 was considered a fast scope.

To be sure, I own a couple of modern, short-focus apochromatic refractors which are more portable and better suited for astroimaging than their long-focus ancestors, but I am a visual observer so do I really need one of these modern wonders?

I also own a 1980s Celestron-Vixen 102mm f/9.8 achromat that, in my opinion, performs equally well, except for some very slight residual color. I actually use it more often, but I had to buy it used. Such scopes today have limited interest among amateur astronomers and occupy a very small niche market, which is why you have to look long and hard to find a company that makes them.

 

Nowadays it's easy find objective, eyepieces and barlows made with SLD glass (super low dispersion) and ED glass (extra low dispersion). Some filters like the Baader Contrast Booster reduces secondary spectrum with few change in the color balance. Achromatic refractor Skywatcher 150mm F/8 can be compared a Jaegars 150mm F/10. The refractor 150mm F/8 is still maneuverable using HEQ5 with extender pillar.

 

Eduardo,
Can you post a picture of your 150mm f/8 scope? I once owned the f/15 version of that lens.

 

Hi!
This is a old picture I made for insurance company. Nowadays I use HEQ5, it's a little higher, enough to sit a stool.

 

Hi again Eduardo,
You have a very nice looking setup! I hope you use yours more often than I do mine. I took this picture in July of my Celestron-Vixen C-102 on a Takahashi mount. (As you can see, I used my good old Telrad reflex finder instead of an optical finder.) This was my first use of the Baader-Planetarium Mark III Zoom eyepiece that I purchased from Agena AstroProducts a month or two earlier. I'm very happy with it and intend to use it a lot. This scope is also equipped with the Baader-Planetarium T2 Zeiss prism diagonal which was purchased from the same vendor. I'm just as pleased with it.

And, yes, you are right. Being able to sit down comfortably while observing makes all the difference in the world, especially when you're old and stiff like me.

P.S. I see from your polar axis that you live at low latitude. Mine is 34 degrees N. What's yours?

 

Hellow Lewis

Thanks !!! (about setup)

Sao Paulo is 23 degrees S, the Tropic of Capricorn is a 10' north of my current home. Sao Paulo has a very complex climate system, there is the intersection of three climate zones: equatorial, subtropical of mountain *1 and semi arid. The metropolitan area has 35 million people, even so we have few nights with high atmospheric pressure, dry air, few clouds, visual magnitude limited to 5, unfornatelly most nights are not like this.

I would like to use this telescope more often too. I use my Hyperions, this refractor and the amazing Stellarvue diagonal to observe DSOs.

I will will move to the city of Amparo next 3-4 years, the observing conditions are better. Amparo inaugurates its new astronomical center today during the eclipse. The nearby towns have small local observatories and Atibaia city have a radiotelescope.

I loved the mount and the tripod. Your scope has a classic look when compared with the modern equipment and I like this. Is your refractor a Polaris? In positive case it is a refractor with excellent sharpness, polishing of optical surfaces made by Vixen ensures an image with excellent resolution.

*1 I'm not sure subtropical of mountai is the better translation to "subtropical de altitude", this wheater is more cold 0-25 Celsius degree (32-77F)

 

I have an Altair Astro 70mm ED as part of my grab and go as well as for AP. Not sure if they sell in the US.

Great short tube F5.7 with 10:1 focuser, came supplied in a very good padded case along with a good quality diagonal and 17mm quality EP.

Weighs in a <2.5Kgs and with an extendding dew shield collapses down to 400 mm.

I did have a SW 80ED but although it was a great OTA it was too big for what I wanted so I sold it on.

The AA70ED along with a Canon DSLR also sits on my Skywatcher Star Adventurer mount without overloading it, so brilliant for AP and still light weight even with a good quality tripod.