Field performance of the LX600/800
Posted 09 December 2012 - 07:53 PM
I was reading in the mount forum about the latest on the LX800 mount based on some images that Jason Ware has published. He has taken the time to contribute to the thread and posted a good bit of detail about his experience so far. Looks like they are finally making some progress.
As part of many people critiquing the images, Jason included some details about the optical system and it's performance (a 12" f8 version). In a recent thread on this forum (that eventually got locked...) where the field performance about the LX800's was being discussed, specifically around it's flatness performance, there were some comments made that these Meade's were just as good as the Celestron Edge HD's.
The details posted by Jason Ware and his test images have shown a more accurate picture of the Meade's performance, and it is not as good as the Edge HD. I would estimate that the Meade has about half the diameter field where the flatness is good as compared to the Edge HD. In fact, it's only slightly better than a standard F10 SCT (I'm guessing related to the slightly lower magnification factor of the secondary).
Jason indicated that he was using a 6303 chip for his images, and in the outer parts of the field, you can see the shape of the star images starting to suffer. Interestingly, I thought that the images almost looked like they had coma, but perhaps it's something related to guiding issues the LX800 mount is still having or seeing. I would expect the seeing or the guiding errors would affect all star images across the field, but these are specifically in the outer edges and corners.
Here's a link to Jason's images:
LX800 Helix image
For reference, here are the Edge HD images with the chip overlay shown. You can see the 6303 chip is about half the size of the 16803 used for these images.
Flickr Edge HD Annotated Image
Here is a link to the thread in Mounts. Jason's very detailed update is near the bottom this page (p.2):
Jason Ware test images thread from Mounts forum
Anyway, good to finally see some actual real world images. It confirms my feelings that the Edge HD's are the better performing platform for me since I found the field curvature to be a real issue in the standard SCT for wide fields and longer FL EP's, and I'm glad I ended up going this route instead of the Meade.
Posted 09 December 2012 - 08:37 PM
This link points to Celestron EdgeHD SCT:
If you zoom the link you provided, you can see out of focused or coma stars at the edges. The link I provided shows far less coma stars.
Posted 09 December 2012 - 09:03 PM