Sharpstar triplet APO

[vin_ap]

Hi All,

I am looking at buying a used Sharpstar APO triplet refractor CF80. I dont know much about these telescopes. Could anyone who owns one or has used one let me know what they think of it for visual and astrophotography ?

- Vin :)

[Ukastronomer]

I am always concerned when I google things like "Sharpstar APO triplet refractor CF80" and get not one review

I never buy unknown makes, sorry

I like the guarantee of a customer service base, guaranteed returns and help at the end of a phone from a large company

My personal feelings, others may differ, you know where you are with known brands, perhaps they are well known outside of the UK though

[Marke]

They are all pretty much out of the same factory have a look at an Orion cf80 Apo probably the same scope.

[vin_ap]

Hi Jeremy, Mark,

The only seller that I found for this telescope is
https://www.astronomyalive.com.au/telescopes/advanced/sharpstar-cf-80-carbon-fibre-80mm-f6-5-ed-glass-triplet-apochromatic-telescope.html

A friend of a friend is selling one and the price is attractive along with its specification but its still a lot of money and I 'm not sure. Unfortunately I can test it before I buy it :(

Vin

[Marke]

It should be a good scope most Chinese Apos are from the same factory and generally very good just the focusers vary.
Here's the Orion as an example probably sold under half dozen different names.
https://www.telescope.com/mobileProduct/Orion-ED80T-CF-Triplet-Apochromatic-Refractor-Telescope/101422.uts

[casstony]

Sharpstar has a decent reputation. If your friend can vouch for the scope and the price is good it should be a good scope.
I had a sharpstar 106 triplet which had very good optics and focuser.

[Ukastronomer]

I think this is the main problem, countries vary, what is well known in one is never hear of in another

I know people who swear they would never touch cheap "rubbish" Orion or Skywatcher scopes of any kind, is it SNOBBISH I wonder

[AstroApprentice]

Hi Vin,
Don’t go off AstronomyAlive prices when determining a fair price for your friend’s Sharpstar scope. The CF80 triplet is available on Aliexpress for $600 cheaper than AA incl delivery.
https://www.aliexpress.com/item/new-SharpStar-CF80APO-REFRACTOR-80MM-480MM-F6/32842279222.html?spm=2114.search010 4.3.73.3f3860d6W9WGwk&ws_ab_test=searchweb0_0,searchweb20 1602_3_10065_10068_10130_10547_319_ 317_10548_10696_453_10084_454_10083 _10618_10307_537_536_10131_10132_10 902_10133_10059_10884_10887_321_322 _10103,searchweb201603_51,ppcSwitch _0&algo_expid=029278f2-88d6-4c7a-bf77-4bd599f8d867-11&algo_pvid=029278f2-88d6-4c7a-bf77-4bd599f8d867&transAbTest=ae803_4

[Slawomir]

Hi Vin,

The AA website has photographs of two different scopes; I would personally avoid the design with a short overlap between focuser's flange and the carbon fibre tube, as it may lead to flexing between the tube and the focuser (Please look closely at two images in the second row under the link you have provided).

I had two brand new units of 80ED CF triplet from another manufacturer and both were flexing big time due to the way the carbon fibre tube was attached to focuser's flange. Replacing focuser won't fix that, but a good amount of epoxy will...

[vin_ap]

Hi Suavi,

You make a valid point, I did not notice that there where 2 two different types, the 1:10 knob between them are different as well which is how I managed to initially differentiate the two models.

Hi Jason, thanks I did not know that Aliexpress sell them as they are considerably cheaper than what I originally thought.

Oh my what do I do ?

Sharpstar CF80 or its big brother CF90 (which looks attractive for its aperture) or make the leap to a ESPRIT 80ED ?

ESPRIT 80 and CF90 will work out to be similar in price by the time you add all extras but 10mm less aperture on the ESPRIT :(

The CF80 would be cheaper than the two but its a gamble not know re focuser and flex.

:shrug::rolleyes::shrug:

[Slawomir]

Carbon fibre does not seem to be a very popular material amongst manufacturers making refractors. Although I have not used one, my vote goes for the Esprit :thumbsup:

[gregbradley]

Roland Christen is against carbon fibre for refractor tubes. Thermal currents and mismatched expansion rates. Carbon fibre hardly expands and contracts whereas the lens objective does. The focal point shifts. Aluminium tubes expand at a similar rate so focus shift with temperature shifts are not so different. FSQ designs are the exception.

He knows his stuff so I would be careful about ignoring it.

Having said that I have no experience of using a carbon fibre tubed refractor but I do notice the top manufacturers don't use them for refractor APOs.

Tak, AP, TEC, APM, CFF.

Perhaps others who have used carbon fibre refractors can comment whether the scope suffered from focus shift with temperature changes and also softer images due to internal thermal currents inside the tube.

Carbon fibre is great for mirrored scopes.

Greg.

[Wavytone]

Greg, agreed.

The objective glass itself expands and in so doing the focal length shifts proportionately. For an objective used in a professional observatory this coefficient of change of focal length would be measured. It's desirable to have a tube with a coefficient of expansion that roughly matches that of the focal length, and aluminium is a better match than carbon fibre.

Some designs I've see went to the extent of including inconel spacing rods to tune the coefficient of expansion of the OTA to exactly match that of the objective.

[Ukastronomer]

I have been into astronomy for too many years, I am NO astronomer, not like people here, I just have many many years of getting it wrong under my belt.

I chose the Esprit.

By the way, in case anyone has hear of Patrick Moore he was a good friend of mine, and it was ME who arranged all the reviews of the Skywatcher scopes and it was I who along with Patrick did the reviews you read on sites.

They all arrived from OVL on a Friday and it rained ALL weekend, just clearing up later afternoon Sunday, they were going back to OVL Monday :)

[vin_ap]

Thanks to everyone, I think I have a clear idea which way I should go.

Vin :thumbsup: