LukeJones
18-09-2011, 03:14 PM
I'm currently "getting ready" for an Edge HD, but am intrigued by the LX800, and am very interested in knowledgeable opinions. I think my situation would be very similar to many others.
For me it's all about astrophotography, and my history is the mistake of upgrading my 8" LX-90 to a an 8" LX-200 ACF, expecting "pin point stars". Several purchases later I finally found the WO PFLAT-4, a field flattener that does a reasonable job, but is big enough to make the use of an off-axis guiders impractical. Instead, I go with piggyback guiding, and constantly deal with differential flexure issues.
I've got my eyes on an 11" Edge HD with CGEM DX mount.
Expected benefits:
- Genuine flat field. I can put my flattener in the draw, and actually use my off-axis guider. I expect that guided tracking would be as good typical seeing - so that's the end of mount quality issues???
- Going price of $US3,700
- Focal length of 2800mm, which is great for everything but large nebulas - and I have my piggyback wide field refractor for that. Also have a farstar option. Perfect.
- From the 11" with central obstruction I'm effectively getting 87 sq. in. light gathering surface area.
Differences with a 12" LX800:
- Guiding built into the mount. Sounds great, as long as you don't end up fight differential flexure issues, and end up going for off-axis guiding instead. Early indications here are that everything will be much "tighter", right down to the OTA mirror - so perhaps flexure might not be an issue.
- Going price of $US9000
- The marketed "Ultimate Imaging Platform" appears to be just ACF. Bad memories for me. It would seem that imaging is useless unless you pay for a flattener. The big kicker here is that a flattener forces you to go to F5 from F8.
- Focal length of 2438mm, effectively reduced to 1523mm by compulsory flattener. Feels like a deal breaker to me.
- From the 12" with central obstruction I'm effectively getting 94 sq. in. light gathering surface area. No big difference. The larger obstruction halves the gain of 12" compared 11".
Conclusions: ???
- In truth I've always gone Meade, and I'm comfortable there. Looks, however, like I'd be paying over twice the price to go backwards in focal length by the time it's a genuine imaging platform.
- A built-in guider can't explain that price difference, and it seems like I'm risking differential flexure issues.
- Would the mounts be that different in quality, and would I see that difference with auto-guiding in average seeing conditions?
- Am I missing something else?
For me it's all about astrophotography, and my history is the mistake of upgrading my 8" LX-90 to a an 8" LX-200 ACF, expecting "pin point stars". Several purchases later I finally found the WO PFLAT-4, a field flattener that does a reasonable job, but is big enough to make the use of an off-axis guiders impractical. Instead, I go with piggyback guiding, and constantly deal with differential flexure issues.
I've got my eyes on an 11" Edge HD with CGEM DX mount.
Expected benefits:
- Genuine flat field. I can put my flattener in the draw, and actually use my off-axis guider. I expect that guided tracking would be as good typical seeing - so that's the end of mount quality issues???
- Going price of $US3,700
- Focal length of 2800mm, which is great for everything but large nebulas - and I have my piggyback wide field refractor for that. Also have a farstar option. Perfect.
- From the 11" with central obstruction I'm effectively getting 87 sq. in. light gathering surface area.
Differences with a 12" LX800:
- Guiding built into the mount. Sounds great, as long as you don't end up fight differential flexure issues, and end up going for off-axis guiding instead. Early indications here are that everything will be much "tighter", right down to the OTA mirror - so perhaps flexure might not be an issue.
- Going price of $US9000
- The marketed "Ultimate Imaging Platform" appears to be just ACF. Bad memories for me. It would seem that imaging is useless unless you pay for a flattener. The big kicker here is that a flattener forces you to go to F5 from F8.
- Focal length of 2438mm, effectively reduced to 1523mm by compulsory flattener. Feels like a deal breaker to me.
- From the 12" with central obstruction I'm effectively getting 94 sq. in. light gathering surface area. No big difference. The larger obstruction halves the gain of 12" compared 11".
Conclusions: ???
- In truth I've always gone Meade, and I'm comfortable there. Looks, however, like I'd be paying over twice the price to go backwards in focal length by the time it's a genuine imaging platform.
- A built-in guider can't explain that price difference, and it seems like I'm risking differential flexure issues.
- Would the mounts be that different in quality, and would I see that difference with auto-guiding in average seeing conditions?
- Am I missing something else?