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Re: [C14] Re: CM 1400 GT
Angel
开云体育Paul,
?
Could not agreed
with you more. I will eventually move to a larger mount...
someday!
?
Angel
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Re: [C14] Re: CM 1400 GT
Angel
开云体育Paul,
?
It a matter of
personal preference, but one must see them side by side to get a feel for what
I'm talking about. Take for example the anodizing on my G11 looks new after
almost 6 years. On the other hand the CI700,?purchased January 2001 and
already?the finish is?much less lustrous than the G11 with less
significantly less use. The counterweight bar on the CI700 is showing some minor
rust spots. Not only fit and finish but little things like the encoder mounting
and the clutch knobs which are way too SMALL, specially the dovetail plate
clutches. Once in a while I tighten them too much and it makes it a pain at the
end of the night to?remove the C14.
?
I can go on and on,
as you have to "live" with both mounts to appreciate the G11. So you might ask,
why did I keep both mount? Well, I sold the CI700 tripod and have it mounted on
a Losmandy GM8 tripod which makes it a very heavy duty and portable alternative
to my G11. I briefly owned a GM8 and sold the head just because of the ability
of the CI700 to carry a larger payload. It handles my C9.25, AP155 for visual
use without any fuzz.
?
Regards,
?
Angel
?
?
? ?-----Original Message-----
From: paulatkinson22@... [mailto:paulatkinson22@...] Sent: Monday, June 03, 2002 8:50 AM To: C14@... Subject: Re: [C14] Re: CM 1400 GT Angel, |
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Re: [C14] Re: CM 1400 GT
Angel,
Thanks for you input on both mounts. ?My earlier comments on the CM 1400 GT were not intended to bash the CI-700. ?However, I agree with you on many of the points you made. ?I feel having seen the CI in action that it isn't a great combination with the C14. ?It seemed way to flimsy, especially the tripod/leg issue. ?In fact, I used one prior to buying my C14 and that is why I made the decision to go with another mount. ?As such, I was indicating my view that in the long run they would probably be much more happy with at least a G11 or larger. ?In my opinion, the G11 is about the smallest mount I would consider. ?It is my humble opinion that Celestron mounts are seriously lacking. ?Look at the June 2002 issue of Astronomy and read the Celestron 9.25 review (if you haven't already). ?That review is perfect example of Celestron as a whole. ?GREAT optics on seriously inadequate mounts. ?Celestron is trying to keep cost down ?as much as possible. ?I can appreciate that fact. ?However, I think that it also hurts them in the long run. ?The C14 is their Cadillac. ?However, they are putting their Cadillac on cheap tires. ? In a dream world, if money were no object, the AP900/1200 or the GM200, or many other larger mounts are probably the best choices for this optically superior instrument. ? Paul Atkinson |
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Re: [C14] Re: CM 1400 GT
Angel
开云体育In my opinion a C14
is no less stable atop a CI700 than a G11. I own then both and have not been
able to tell any difference stability wise. Fit and finish, that's another
story.
?
Angel
?
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Re: [C14] Carbon Fiber
W. Gondella
To reiterate, aluminum expands and contracts, carbon fiber does not. The
more aluminum the more the difference. Therefore the possibility exists that the carbon tube might reduce or mostly eliminate one of the major causes of the need to refocus. However, there are many sources of focus shift, and you cannot detect them visually as the camera is more sensitive. What looks sharp to the eye, may not cut it for the camera. When observing, one refocuses with every eyepiece, person and new object. In imaging, tube material aside, one is always recommended to check focus repeatedly throughout the night. Why would go through all the expense and effort for astrophotos (expecial good ones) and not do a simple focus check every so often? Cheap insurance. Sure, carbon fiber might help with focus drift, but it is an expensive option, it cracks rather than dents, is essentially unrepairable if it does crack, and is not available on many scopes. Nor is it usually needed. Look at Ed Graftons pictures. CCD exposures are relatively short, and the software provides for focus recalibration. Also, depth of field is greatest at the prime focus (f/11) where the scope was designed to operate best. All a moot point, unless you want to custom make your own C14 tube. Wayne E. Gondella, CGA South Hills Coordinator Amateur Astronomers Association of Pittsburgh AFA Engineering Company Pittsburgh, Pennsylvania |
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Re: [C14] Re: New Images
brian
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Re: New Images
Hi Brian. These images were all done with an SBIG ST237. Way
oversampled! The M57 is f11, L 400sec,R 200sec, G 180sec, B 180sec. The exposures are way too short, un-binned, and just plain wrong to get the correct color balance! I was just fooling around to see what the AP1200-C14 was capable of doing, and I am impressed. Next time out I will try to be a bit more systematic about it! Ken --- In C14@y..., "be01753" <brian@l...> wrote: Nice images Ken, thanks for posting. Interesting to see how crowdednew madeones are M13, M51, and M57. These were some quick exposures I shotwith my new AP1200 mount. Really improved performance. The M57 M51is at f11. Did it just to see how well the mount would track. and M13 are with a 3.3 reducer that gives about f4 with the C14. |
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Re: New Images
be01753
Nice images Ken, thanks for posting. Interesting to see how crowded
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the core of M13 is. How long was the M57 exposure? Like the colours, especially the m27 shot. What sort of camera have you got? Brian --- In C14@y..., "kberna1376" <kberna1376@a...> wrote:
I posted some new images to "Ken Images" in the Files area. The new |
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Re: New Images
be01753
Nice images Ken, thanks for posting. Interesting to see how crowded
toggle quoted message
Show quoted text
the core of M13 is. How long was the M57 exposure? Like the colours, especially the m27 shot. What sort of camera have you got? Brian --- In C14@y..., "kberna1376" <kberna1376@a...> wrote:
I posted some new images to "Ken Images" in the Files area. The new |
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Re: [C14] Digest Number 128
Good evening Wayne:
My experience with the carbon fiber tube of the NexStar 11 GPS indicates otherwise. I was able to go through entire nights of CCD imaging without refocusing with the carbon fiber OTA. With my C-8 Deluxe, hourly focusing is a must, especially with the blue-filtered images. I guess that's not "critical" but it certainly is a demonstrated advantage. Clear skies, Kevin Dixon ksbtk@... From: "W. Gondella" <gondella@...> Carbon fiber is a mixture of carbon fibers and epoxy resin. It is used inback in the direction it came. It cools quickly itself, but does not let heaton one side transfer through to the other. It is expensive. It has a verylow coefficient of expansion. Its only advantage or need in telescopes are in |
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Re: [C14] Digest Number 128
your the best ! Thank you for your information ! ? "W. Gondella" wrote: Ok, I will try to address several issues here. As far as locking down the Do You Yahoo!? - Official partner of 2002 FIFA World Cup |
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Re: [C14] Digest Number 128
W. Gondella
Ok, I will try to address several issues here. As far as locking down the
primary for use with an external focuser, the supplied screws are too short. One might try taking a piece of all-thread about an inch or so longer, and grinding it down to remove all but the first 6 threads on one end, and about an inch or so on the other end. After reaching focus at infinity, try threading the "screws" in through the back and into the holes in the primary where the normal lock screws go. Be careful. After you are successful, you might find the other end tried to thread into the rear casting. You probably need to take more thread off so that it doesn't do this. Once you can screw it into the mirror and the back is free, try screwing a thumb-nut down on the protruding end. You might need a washer or two. Tightening these nuts will lock the mirror. Do not get carried away. Light pressure is all you need. Carbon fiber is a mixture of carbon fibers and epoxy resin. It is used in airplanes, spacecraft and some bicycles like Treks. It is lighter than metal, but a poor conductor. It does not hold heat, and reradiates it back in the direction it came. It cools quickly itself, but does not let heat on one side transfer through to the other. It is expensive. It has a very low coefficient of expansion. Its only advantage or need in telescopes are in very high end optical units where tolerances are very critical, like Ritchey-Chretiens, which often used micrometer-controlled secondary focus and INVAR spacing bars. Other than that, save your money for an eyepiece. As far as this TASCO thing is concerned, we can only expect Meade will be as sleezy as usual, and only hope that Celestron turns out for the better! Wayne E. Gondella, CGA South Hills Coordinator Amateur Astronomers Association of Pittsburgh AFA Engineering Company Pittsburgh, Pennsylvania |
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Re: [C14] Carbin Fiber tube
brian
开云体育Both would go below air temperature for same reason
that scopes dew up? (unbalanced radiation loss on the sky-side of the
scope).
?
I am no expert but I think the carbon fibre is
supposed to be optically more stable because it has a low coefficient of thermal
expansion - so the temperature drops, just like aluminium, but the tube does not
shrink nearly so much which means?the focus does not need
adjustment.
?
Brian
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Re: [C14] wheeley bar
I dont know,? I am going to get one with CM 1400 GT ? paulatkinson22@... wrote: Does the CI-700 not allow you to level each leg individually? Do You Yahoo!? - Official partner of 2002 FIFA World Cup |
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Re: [C14] Carbin Fiber tube
开云体育Good afternoon Paul:
?
I don't pretend to understand this very well
either.? I am just going by what some folks who are experts in composite
materials tell me.? I don't understand the mechanism behind it but one of
the properties of carbon fibers (besides being lightweight and very strong) is
the ability to achieve and maintain thermal equilibrium.? Aluminum
apparently does not share this characteristic.?
?
I do have empirical experience to back this
up.? When imaging with a NexStar 11 GPS, it was not necessary for me to
refocus throughout the night.? With both my C-14 and my C-8, refocusing
must be done every hour or so.
?
That's about the extent of my knowledge on the
subject.
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Re: [C14] Locking down mirror for Optec TCF-S
Mark Lancaster
开云体育The only reason to lock the mirror down is for long
exposure photography. The mirror can "rock" over the course of time,
particularly when crossing the meridian during?an exposure. Otherwise,
don't worry about it. BTW, improper locking of the mirror can bring its own
headaches if not done properly!
?
Mark
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