My New Astrophotography Setup

[weixing]

Hi,
I have just try out mounting the C90 on the counter-weight bar... I need to take out the finder scope to achieve proper balance without adding extra counter-weight.
:k-happy:

Anyway, is there any foreseeable problems in this setup??? :k-worried:

Thanks and have a nice day.

[ariefm71]

i'm still worried about that "N" between the tripod legs thing, especially now you have more loads. Have you tried to gently push the mount from behind to see if it will fall?

[kayheem]

Hi,
I have just try out mounting the C90 on the counter-weight bar... I need to take out the finder scope to achieve proper balance without adding extra counter-weight.
:k-happy:

Anyway, is there any foreseeable problems in this setup??? :k-worried:

Thanks and have a nice day.

Just be careful when you turn the OTA. The C90 may hit the mount.

Kay Heem

[Jeremy]

Hi Weixing,

just a suggestion about the general stability of your set-up. I have the same Vixen tripod and it's more stable if you attach the accessory tray to the (Y-shaped) tripod spreader. If you don't have a tray, you can simply cut a triangular shaped piece of piece, like plywood.

Hope that helps.

Go well!

Jeremy

[MooEy]

a quote from Philips Perkins

Schmidt-Cassegrains (SCTs): The SCT has, as a fundamental part of its design, a moving mirror system. An SCT cannot operate as an SCT unless its main mirror is able to move freely. Since the telescope is moving the entire time that an exposure is in progress, the centre of gravity of the mirror changes constantly and it is inevitable that it will shift during an exposure. The amount and timing of such shift cannot be predicted - all that can safely be predicted is that the longer the exposure, the more likely it is that the mirror will shift. The consequence is that, for high quality, long exposure astrophotography, a guidescope cannot be used successfully with an SCT. The worst scenario of all is to use a small Maksutov-Cassegrain (such as the Meade ETX) as the guidescope for an SCT. Here, one moving mirror system is trying to guide another moving mirror system, and the situation is obviously hopeless. If the objective is to take high quality long exposure astrophotos, then the user should not attempt to use a guidescope mounted on an SCT. Instead, an OAG should be used (see below).

http://www.astrocruise.com/guide.htm

~MooEy~

[weixing]

Hi,

i'm still worried about that "N" between the tripod legs thing, especially now you have more loads.

The load do not increase actually, the smaller counter-weight is replace by the C90. I hope I don't need to use the smaller counter-weight .

Have you tried to gently push the mount from behind to see if it will fall?

I don't think it will topple... it is quite stable actually. Anyway, will test it next time I setup the scope.

Just be careful when you turn the OTA. The C90 may hit the mount.

Ya... I'll be carefull and I think the C90 may have problem in "seeing" some object in certain portion of the southern sky.

just a suggestion about the general stability of your set-up. I have the same Vixen tripod and it's more stable if you attach the accessory tray to the (Y-shaped) tripod spreader. If you don't have a tray, you can simply cut a triangular shaped piece of piece, like plywood.

I got the accessory tray... just too lazy to put on while taking this photo.

Schmidt-Cassegrains (SCTs): The SCT has, as a fundamental part of its design, a moving mirror system. An SCT cannot operate as an SCT unless its main mirror is able to move freely. Since the telescope is moving the entire time that an exposure is in progress, the centre of gravity of the mirror changes constantly and it is inevitable that it will shift during an exposure. The amount and timing of such shift cannot be predicted - all that can safely be predicted is that the longer the exposure, the more likely it is that the mirror will shift. The consequence is that, for high quality, long exposure astrophotography, a guidescope cannot be used successfully with an SCT. The worst scenario of all is to use a small Maksutov-Cassegrain (such as the Meade ETX) as the guidescope for an SCT. Here, one moving mirror system is trying to guide another moving mirror system, and the situation is obviously hopeless. If the objective is to take high quality long exposure astrophotos, then the user should not attempt to use a guidescope mounted on an SCT. Instead, an OAG should be used (see below).

Hmm... Never think of this problem, but I think my setup should be OK. The image will be taking through the newtonian and the C90 will be the guidescope. Also, the C90 is different from most SCT/MCT, it don't have a movable primary mirror. It is focus through moving the secondary mirror via rotating the upper part of the OTA, so I don't think it will have mirror shift problem while tracking. I'll test out on the field when the sky clear up.

Thanks for all the comments and have a nice day. :k-thankyou:

[kamayok3]

nice setup then!

Well done