Telescope Reviews: Wedge or autoguider?

Hi Nick,
this topic has already been discussed many times. Wedge or de-rotator field ... autoguiding or not autoguiding ... To be or not to be!
As in life, even here we must accept some compromises. It all depends on the kind of priority that you wish to assign to these compromises, and accept the negatives that will meet, and that you will have to deal with. Do you want long-exposure photography "SERIOUSLY" with a LX200 fork mount telescope?
A wedge works well (with telescope guide or OAG and very accurate PEC), but with large telescopes (12" or more), not mounted permanently, can become awfully uncomfortable assemble and disassemble the equipment every night and do the drift method for polar alignment whenever. This, in time, could become a nightmare.
A de-rotator field, in this case, is much faster, easy and comfortable, and it works very well! In 10 minutes you are able to fit all the equipment and you can photograph immediately, without polar alignment and without drift method! To do this, however, we need specific accessories and software adequate control, but all this is very expensive to get very good results.
Certainly, the final results will vary based on how much and quality investment in equipment accessory. An LX200 "out of box" will always give poor results in astroimaging, both wedge that with a de rotator field. These are wonderful visual instruments , but to do astroimaging SERIOUSLY, you must spend time and money to optimize this type of equipment.
Let us remember that they are tools that, even with the use of focal reducers, maintain focal lengths very difficult to manage, requiring a high tracking accuracy, out of the reach "nominal" of any LX200, naked and raw, without a proper tuning, with the right accessories required for accurate tracking possible.
WARNING! In your specific case, you have a LX200 "Classic", the de-rotator field Meade 1220 NOT work!
Autoguiding in alt/az, without de-rotating field, will not correct the rotation of the field in the main camera.
Alt / az configuration will work perfectly ONLY autoguiding radial (off-axis) with de-rotator field (long exposure). Any other configuration alt / az mode DOES NOT WORK.
Autoguiding in alt / az mode, without de-rotator field, help you get a better tracking for single frame of 30/40 seconds. With this small exposure time you can also use a guidescope parallel rather than an OAG. Final stack will have to undergo a substantial crop the photo to remove the rotation between the individual frames.
My advice goes against the current.
Step 1: +1 to autoguiding camera (a used Meade DSI PRO is perfect).
With a small telescope guiding economic achromatic in parallel you can start to use the telescope in alt / az mode and see how you are using an autoguiding and start doing some photography without stars elongated (always no more than 30-40 seconds).
Step 2: (when you can) buy a wedge (good and solid) and PemPro. At this point you have the right acessories to make long-exposure photography with good results.
In my humble opinion this is the right priority in the purchase of accessories, because a wedge without autoguiding ... will give results unexciting.
Marco

Edited by Markigno (10/06/12 03:19 AM)