Re: C-11 ota weights?


"Mij Adyaw" <mijadyaw@xxxxxxxxxx> wrote in message
news:dUFxe.17745$8o.10714@xxxxxxxxxxxxx
> What is the advantage of the carbon fiber over the aluminum OTA? Does
> the carbon fiber tube cool-down faster?
No, it cools down slower...
The key though is how much the focus shifts with temperature changes. I
use a RoboFocus system, with programmed temperature compensation. On an
aluminium tubed system, the typical focus 'shift' per degree, was eleven
counts. The CFZ for the scope is about 30 counts long on my setup, so a
temperature change of about 1.5 degrees, was enough (assuming you started
in the middle of the CFZ), to noticeably degrade the focus. On the carbon
fibre system, the shift is below 2 counts per degree, and in fact I can
run without using temperature compensation at all, over normal night
conditions.
Add a rear port cooling fan to accelerate the cooldown for initial setup,
and you are smiling. :-)
The effect on images of a not fully cooled system, is also slightly
'different'. On the alloy systems, you see a real 'plume' on one side of
the Airy disk. On the CF units, the plume seems to be slightly less well
defined, and possibly a little smaller.

Best Wishes

> "Roger Hamlett" <rogerspamignored@xxxxxxxxxxxxxxxxxxx> wrote in message
> news:0kDxe.15199$ZR1.7481@xxxxxxxxxxxxxxxxxxxxxxx
>>
>> "szaki" <szaki10@xxxxxxxxxxx> wrote in message
>> news:bbGdnQ7SyOnLcVvfRVn-pw@xxxxxxxxxxxxxx
>>> Doink wrote:
>>>> Why not email herb at Anacortes?
>>>>
>>>>
>>>> "Chris Patterson" <none@xxxxxxxxxx> wrote in message
>>>> news:lfQJc.12404$kK.11366@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
>>>>
>>>>>I'm having a hard time finding this info from the dealers. Seems
>>>>>like
>>>>>all
>>>>>the pertinent details are listed except weight. Looking for the
>>>>>weight, in
>>>>>pounds, of the following C-11 configurations:
>>>>>
>>>>>C-11 ota, aluminum tube
>>>>>
>>>>>C-11 ota, aluminum tube plus dovetail
>>>>>
>>>>>C-11 ota, carbon fiber tube
>>>>>
>>>>>Thanks,
>>>>>Christopher
>>>>
>>> I have an older Ultima C-11 OTA, weighs 22LB on my bath scale.
>>> Generally C-11-s are rated at 27-28 LB.
>>> Julius
>> Anacortes list the carbon fibre OTA with dovetail at 28lbs.
>> Remember that this is the standard Celestron dovetail, a Losmandy style
>> one adds about 2lbs. Also very old aluminium tube units are heavier
>> (some
>> over 30lbs on their own).
>> 22lbs seems very 'low', I'd have expected about 24lbs as the 'lowest'.
>> There is almost no difference in weight between the aluminium OTA, and
>> the
>> CF one, but the units with the Fastar assembly are about a pound
>> heavier
>> than those without.
>>
>> Best Wishes
>>
>>
>>
>
>



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