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#1
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Extra load on an LX200 (how much?)
How much extra weight can I attach to an LX200 and still be in with a chance
at taking photographs? As a pre-emptive follow up question, is the 10" better suited to photography (and can it take more weighty attachments) than its larger brethren because it's on the same forks as a 12", or is that missing something? I'm envisaging a 4" guide scope (or smaller), plus cameras on the guidescope & the SCT. Regards, Michael Kreuzer |
#2
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Extra load on an LX200 (how much?)
On Mon, 24 Nov 2003 06:31:26 GMT, "Michael Kreuzer"
wrote: How much extra weight can I attach to an LX200 and still be in with a chance at taking photographs? As a pre-emptive follow up question, is the 10" better suited to photography (and can it take more weighty attachments) than its larger brethren because it's on the same forks as a 12", or is that missing something? I'm envisaging a 4" guide scope (or smaller), plus cameras on the guidescope & the SCT. Regards, Michael Kreuzer There is no sudden cut-off, the more weight then the more flex you get, so the tracking gradually degrades. The 12" is indeed on the same fork as the 10" so it's already fully loaded.. You don't need such a large aperture (i.e., heavy) guidescope, a small refractor (60/70mm) is adequate for guiding with a CCD autoguider. Remember that whatever extra weight you mount on the top of the OTA will need to be balanced with counterweights underneath it. Accurate balance is the key to success (that, and fixing the mirror flop if you're not using an off-axis guider). Also, if putting extra weight on the forks then reduce the slewing speed to 4deg/sec or less. Despite the mechanical limitations of the Meade fork mount people have used the system to get good results. ChrisH |
#3
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Extra load on an LX200 (how much?)
On Mon, 24 Nov 2003 06:31:26 GMT, "Michael Kreuzer"
wrote: How much extra weight can I attach to an LX200 and still be in with a chance at taking photographs? As a pre-emptive follow up question, is the 10" better suited to photography (and can it take more weighty attachments) than its larger brethren because it's on the same forks as a 12", or is that missing something? I'm envisaging a 4" guide scope (or smaller), plus cameras on the guidescope & the SCT. There is no simple answer to this. The more weight you add, the more problems you introduce. I can give a reference point, though. I'm using a 12" LX00 classic, and have the following equipment: filter wheel, ST8i, 50mm dia guidescope with ST237 guider using Losmandy mountings. There is also a RoboFocus motor on the primary. This is all counterbalanced by a Losmandy 3D weight system on the bottom of the scope, and I also have a couple of pounds on the east fork. With this system, I don't have any problems with flexure, tracking error, or resonance. Film, with its lower sensitivity and lower resolution, is more tolerant of tracking problems than CCDs. I don't think you will have any problems with either a 12" or 10" LX200. You can save weight with a smaller guidescope- what you are proposing using is larger than it needs to be. _________________________________________________ Chris L Peterson Cloudbait Observatory http://www.cloudbait.com |
#4
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Extra load on an LX200 (how much?)
[good reply snipped]
with counterweights underneath it. Accurate balance is the key to success (that, and fixing the mirror flop if you're not using an off-axis guider). Also, if putting extra weight on the forks then reduce the slewing speed to 4deg/sec or less. Despite the mechanical limitations of the Meade fork mount people have used the system to get good results. ChrisH Many thanks for the info. I haven't yet properly considered off axis guiders, that's the alternative, to be sure. Regards, Michael |
#5
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Extra load on an LX200 (how much?)
There is no simple answer to this. The more weight you add, the more
problems you introduce. I can give a reference point, though. I'm using a 12" LX00 classic, and have the following equipment: filter wheel, ST8i, 50mm dia guidescope with ST237 guider using Losmandy mountings. There is also a RoboFocus motor on the primary. This is all counterbalanced by a Losmandy 3D weight system on the bottom of the scope, and I also have a couple of pounds on the east fork. With this system, I don't have any problems with flexure, tracking error, or resonance. I suppose comparisons like this were what I was after really, many thanks for that info. Film, with its lower sensitivity and lower resolution, is more tolerant of tracking problems than CCDs. I don't think you will have any problems with either a 12" or 10" LX200. It's a choice, I think, between a 10" and a 14" scope, with the immobility of the latter being a big consideration. Yet to read much about using the latter photographically, either. You can save weight with a smaller guidescope- what you are proposing using is larger than it needs to be. That's creeping aperture fever kicking in again. :-) OK, if I go the guidescope route I'll limit myself to 60mm, there's a very nice Tak 60mm that I can still also use visually. Regards, Michael |
#6
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Extra load on an LX200 (how much?)
On Mon, 24 Nov 2003 23:12:28 GMT, "Michael Kreuzer"
wrote: That's creeping aperture fever kicking in again. :-) OK, if I go the guidescope route I'll limit myself to 60mm, there's a very nice Tak 60mm that I can still also use visually. Regards, Michael I recently started using a TV Pronto as a guidescope, good for guiding prime-focus film through a 4" APO, but I would use a 2x barlow for guiding an OTA of longer focal length. The Pronto is a nice rich-field scope in it's own right, and it has a great 2" focusser. It's a wee bit heavy but otherwise ideal. I'd thought of the Ranger as it's much lighter but the focusser cannot be locked in position. ChrisH |
#7
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Extra load on an LX200 (how much?)
I suppose I'm really just trying to have my SCT cake and eat it too (i.e.
also have a nice, small, wide field refractor), but there's no way my budget will stretch as far as a second good mount. Using the refractor as a guide scope makes buying it slightly more feasible because it'd save me some money on the camera & off axis guider ... The alternative (the much more expensive alternative) would be to get a Losmandy G11 mount & Celestron 11" OTA with the option of interchanging the scope with a refractor purchased in the future. It's _a lot_ more expensive here though, and there's no celestron dealer in this country (Australia), so for more money there's no service ... On photography: Maybe I'll just go for an sbig camera with its own off axis autoguider, not doing that could be a false economy. Shelve the refractor plan for a few more years. Thanks for your input, always nice to chat about scopes, Michael I recently started using a TV Pronto as a guidescope, good for guiding prime-focus film through a 4" APO, but I would use a 2x barlow for guiding an OTA of longer focal length. The Pronto is a nice rich-field scope in it's own right, and it has a great 2" focusser. It's a wee bit heavy but otherwise ideal. I'd thought of the Ranger as it's much lighter but the focusser cannot be locked in position. ChrisH |
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