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New Refractor OTA recommendations/suggestions

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#1 javaruba

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Posted 21 June 2019 - 12:06 PM

Hi all,

I have plans to acquire a new refractor telescope, however, I'm having difficulties in finding one to meet my objectives. Perhaps the good folks here on Cloudy nights can help me determine the best one.
I've compiled a list of some great candidates, not sure if it is a complete list but I'm happy to hear some opinions.

My objectives are as follows:
  • Focal length of at least 575mm
  • Focal ratio between f/5.5 - 6.5
  • Refractor element: Triplet
  • Focuser: exceptional
  • Finder scope (optional)
  • Diagonal (optional)
  • Use: Astrophotography (Deep space)
  • Budget: $1,500 - $2,500
Note: the camera and other equipment that shall be used is described in my signature below.

The list of OTA up until now (click to view for better quality):
Telescope list.JPG

Any opinion, recommendations, and experiences are highly appreciated.

Greetings,

Jairo

Edited by javaruba, 22 June 2019 - 07:35 AM.


#2 Hesiod

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Posted 21 June 2019 - 01:02 PM

At 600mm or less you have to figure in a field flattener, or get a model with natively flat field (e.g. the Petzval-like 4-5 lenses).

Also, an exceptional focuser (e.g. MoonLite, FeatherTouch) is pretty expensive and could eat a substantial share of the budget.

 

By the way, you have a 700-ish mm refractor, so my guess is thata) want to upgrade it b)want more field of view; so, among those listed, my vote would go to the Esprit due to its 550mm f.l.


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#3 javaruba

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Posted 21 June 2019 - 02:05 PM

At 600mm or less you have to figure in a field flattener, or get a model with natively flat field (e.g. the Petzval-like 4-5 lenses).
Also, an exceptional focuser (e.g. MoonLite, FeatherTouch) is pretty expensive and could eat a substantial share of the budget.

By the way, you have a 700-ish mm refractor, so my guess is that) want to upgrade it b)want more field of view; so, among those listed, my vote would go to the Esprit due to its 550mm f.l.

Thanks for your prompt reply. Indeed, my current scope has a focal length of 714mm and yes I want to upgrade. The ultimate reason is a lower focal ratio with a refractor.

Best regards,

Jairo

#4 gnowellsct

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Posted 21 June 2019 - 11:47 PM

The only one with an exceptional focuser would be the 80mm CFF which at E$2300 would be approximately $2300 by the time you pay taxes and shipping to have it in the U.S. (You would get export discount but the shipping and U.S. import tax push it back up)



#5 Hesiod

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Posted 22 June 2019 - 04:46 AM

Thanks for your prompt reply. Indeed, my current scope has a focal length of 714mm and yes I want to upgrade. The ultimate reason is a lower focal ratio with a refractor.

Best regards,

Jairo

If it is just a matter of focal ratio, probably a focal reducer sounds a better option than a new optical tube.

To gain a stop you have to drop to f/5, meaning a rather expensive astrograph or a dedicated photographic lens (if want to stay with glass).

If I may, why you want a faster lens/refractor?



#6 javaruba

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Posted 22 June 2019 - 08:09 AM

If it is just a matter of focal ratio, probably a focal reducer sounds a better option than a new optical tube.
To gain a stop you have to drop to f/5, meaning a rather expensive astrograph or a dedicated photographic lens (if want to stay with glass).
If I may, why you want a faster lens/refractor?


Well, given my location in the lower part of the Caribbean I don't get a lot of nights with prolonged clear skies. Long periods of clear skies are scares, so lots of overpassing clouds. That's one of the main reasons I wanted a faster scope. On the other hand, I know that probably a fast reflector astrograph would be much better in my case. But I do like the versatility of a refractor nonetheless.

Best regards,

Jairo

#7 bobhen

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Posted 22 June 2019 - 08:37 AM

HERE is a link to the TS's (Telescope Service) page showing their 80-100mm (and other sizes) "Quardruplets" with field flatteners. They fall within your budget.

 

HERE is a link to the TS's (Telescope Service) page showing their 80-130mm "Tiplets".

They fall wthin your budget. Some with and without flatteners.

 

Quality is about the same as Stellarvue or other Chinese imports. Reviews are generally positive.

 

Prices are in "Euros" and you will need to pay for shipping but you "do not" pay the VAT tax.

 

Have fun.

 

Bob


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#8 Hesiod

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Posted 22 June 2019 - 08:59 AM

If want speed and glass, I'd suggest a model at f/5 or less; I would also prefer one with a dedicated focal reducer, in the case even f/5 would too slow.
Another option could be to upgrade the camera: you may gain a stop or more through ISO/gain


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