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#51 Emanuel

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Posted 26 February 2021 - 12:57 PM

Yes, the main goald of the RST mount, is to be highly portable, but, like you said, due to the fact that it has harmonic drive motors, the periodic error is big, but my idea, besides of beeing as portable as possible, with all the equatorial features and gizmos that we like to have, is to use it with a automate system, like the Asiair Pro.

The FSQ106 weight is not a issue to the mount. but it is to me, because its against my concept of highly portable and furthermore, i dont feel safe by using such a expensive telescope on a mount without counterweights.



#52 Emanuel

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Posted 27 February 2021 - 03:04 AM

More and more i get frustrated with this situations.I just saw a site, presenting a new scope, with triplet lens made of FPL-53, and the same telescope, exactly the same, but with different colors,on another site, and they state that the telescope lens are made with FPL-55.

How can you thrust any of this? From my point of view, and i dont have anything to back this up, all of these telescopes are made with cheaper lens, apochromatic ok, and stated as beeing FPL-53, because its a strong point for selling.

So, what manufacturers can you thrust completly? Takahashi, Astro-Physics, TEC, LZOS, CFF, ??? undecided.gif


Edited by Emanuel, 27 February 2021 - 03:04 AM.


#53 Hesiod

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Posted 27 February 2021 - 05:13 AM

The RST is designed to work w/o CWs, it is its main reason of being!

As I said earlier, I do not care a **** about the material of the lenses: give a look to the spot diagram or polystrehl and decide by yourself. If not made available, simply ignore the product in favor of these whose specs are published.

Given your premises I would remove from the list Astro-Physics and TEC because they do not craft such small telescopes (the closest thing is the AP Stowaway, but have to find one used or put your name on the list and wait. And in any case is quite hefty, so could get the Tak fsq85 instead).

For small, light "astrographs" I would take in consideration Takahashi (FS60cb, fsq85; if are also interested in stargazing the FC76DF or FC100DF/DZ may be worth to be included too), Borg (theirs are the most specialized: if are not interested in stargazing and willing to jump in the mess of their modular catalogue are for sure worth a look) and Vixen (they have less models: beside the FL55 there is just the VSD100, which is IMHO not far enough from your fsq106 to be seen as a "smaller and lighter" alternative. I suppose that the SD81 may be employed also for AP with pretty good results, so could be an interesting alternative to the FC76 because its specific reducer/flattener kit is designed for FF sensors. Still both the SD81 and the FC76 are very close to the FC100 so, if want to stay in the same image scale of the fsq106, the latter seems the better option)


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#54 Emanuel

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Posted 27 February 2021 - 05:35 AM

Absolutely in agreed with you. Any manufacturer with respectable optics will place spot diagrams os strehl ratio. I think im narrowing my search to a very small number of models, and Borg is on that list. For the moment Borg 72, Borg 55, Takahashi FS60CB and Vixen FL55SS are the ones im highly interest on.

The Borg is something apart, its the Lego of telescopes. I never had one, but i have a astro friend that have two, the 71 and the 90 and he speaks only good things about it.smile.gif


Edited by Emanuel, 27 February 2021 - 05:44 AM.


#55 bokemon

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Posted 27 February 2021 - 08:58 AM

OMG, you're deciding between a bunch of doublets.


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#56 Hesiod

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Posted 27 February 2021 - 09:42 AM

Borgs are interesting, but I was too lazy to mess with their cataloguelol.gif

Very interesting is the fact that they can be rigged as telephotos, hampering the possibility to use them for stargazing but with rather obvious benefits for imaging


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#57 Emanuel

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Posted 27 February 2021 - 10:12 AM

OMG, you're deciding between a bunch of doublets.

Yes, but they are Fluorite smiley-char145.gif 
 And why there are no Triplet Fluorite refractors of this size?? Too expensive???



#58 Hesiod

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Posted 27 February 2021 - 12:34 PM

No, because there is no need for the third lens to attain an excellent control of CA/SA


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