6 1/2 Inch Refractor from Explore Scientific

[Commanderfish]

21 hours ago, John said:

D&G in the USA go up to 11" in aperture:

http://www.dgoptical.com/refractor.htm

Istar do an 8" as do APM:

http://www.apm-telescopes.de/en/telescopes/refracting-telescopes-ota/achromates/apm-designed-203-1800-fraunhofer-refractor.html

John Pons makes some nice big ones too

 

 

Well those are awesome, though I was thinking more along the lines of something shorter tubed, i.e. a bigger version of the 152mm F5.9, or an achro version of the above 165mm ES Apo.  Any ideas?

[Peter Drew]

A folded refractor would give you a much shorter tube, more bulk and weight though.  

[chiltonstar]

1 hour ago, Commanderfish said:

Well those are awesome, though I was thinking more along the lines of something shorter tubed, i.e. a bigger version of the 152mm F5.9, or an achro version of the above 165mm ES Apo.  Any ideas?

That perhaps is why Mr Cassegrain's inventions are so popular........

Chris

[John]

3 hours ago, Commanderfish said:

Well those are awesome, though I was thinking more along the lines of something shorter tubed, i.e. a bigger version of the 152mm F5.9, or an achro version of the above 165mm ES Apo.  Any ideas?

The Istar I mention is an F/5.9 8 inch achromatic doublet. Here is a review of it:

http://astronomynow.com/2015/03/29/istar-wxt-204-6lt-refractor-review/

Not really my cup of tea to be honest but at least 1 manufacturer does them.

 

[Telescope40]

Hi.  That link to the Istar is rather a sight to behold.  Given the right EP's how would it perform on Planets and Lunar.  Average, Super or Fantastic. Maybe none of the above.

Apologies for my ignorance. I have seen the term " rich field scope " in the article .

 

Thanks   John

[John]

An 8" F/6 achromat is going to show heaps of false colour even if it's optical quality is top notch. It's a rich field scope primarily.

One the other hand, a <£300 8" Skywatcher dobsonian can do both deep sky and planets with ease and no CA

 

[Telescope40]

Thanks John.  Yes. I missed the word " achro" didnt I.  DOH    Back to my cave.

 

John

[Commanderfish]

8 hours ago, John said:

The Istar I mention is an F/5.9 8 inch achromatic doublet. Here is a review of it:

http://astronomynow.com/2015/03/29/istar-wxt-204-6lt-refractor-review/

Not really my cup of tea to be honest but at least 1 manufacturer does them.

 

Love it! Want one!! First thing to do is sell the SCT, then a kidney, then a child...

[Tyson M]

Those Istars make perfect solar scopes. I want one or two some day.   

 

That Explore scientific is a thing of beauty, nice glass and aperture. 

[DirkSteele]

That is quite a lot of triplet for the price. The 6" APM LZOS are a known (high) quality but are 152mm compared to the165mm here and are (+/-) the same price. The next LZOS up is the 175mm f/8 which breaks through the £15,000 mark so this ES scope is positioned at an interesting point in the market. It could be an excellent performer. We know the Chinese scopes have become very good over the last few years but there is still more variation between samples than the top makers and it means (in my opinion, at least) that one might be taking more of chance than you should be when handing over that amount of money. Hopefully some reviews appear to give some clarity on the performance. In particular the quality of the lens cell, baffling, overall mechanicals as well as quality of the lens itself.

[nicks90]

On 12/05/2016 at 16:17, John said:

An 8" F/6 achromat is going to show heaps of false colour even if it's optical quality is top notch. It's a rich field scope primarily.

One the other hand, a <£300 8" Skywatcher dobsonian can do both deep sky and planets with ease and no CA

 

but everyone seems to be talking about 10K scopes John - so lets do price for price and compare it to a 20" f5 obsession dob and you would still able to afford the latest SIPs and a box full of green n black eps to look at stuff. 

[Commanderfish]

I don't have the space for a 20" dob and it still wouldn't have the contrast

[Commanderfish]

On 13/05/2016 at 12:40, chiltonstar said:

That perhaps is why Mr Cassegrain's inventions are so popular........

Chris

Got one. Nice, but field is too tight and contrast a bit low and the stars aren't points...