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Thursday, November 23, 2017

Optec's Fast Focus System

During the rainy season (summer), I was able to install Optec’s Fast Focus System. I was having reliability issues with the FeatherTouch focuser. The focuser often slipped even though the camera is under the weight limit of five pounds. Technical support was helpful, but the focuser could not reliably compensate for filter offsets or temperature compensation because of the annoying slippage. Due to the limited backfocus on the Edge HD, I decided to give the Fast Focus system a try. It’s a very robust system and designed to give reliable and repeatable focus. Installation took a couple of hours. I was able to perform collimation to within 1.5 (CCDAP) with the use of the easy-to-use push/ pull screws.

I like diffraction spikes around the larger stars so, I installed the split cable. It's simple to change the cable from the focuser to the controller to remove the diffraction spikes. 

The controller works very well with FocusMax. As soon as I’m confident with the operation of the focuser, I will install Optec’s Lacerta and the FocusLock system. Lacerta is designed to work with a Lodestar X2 autoguider. The FocusLock system is designed to constantly monitor focusing via a focused guide star. I haven't read any reviews of the system. I'll post my experience with the system as soon as I can. It's wise to install and test one new component at a time. 

The Feathertouch focuser is now being used as a spacer. The clutch is locked and shouldn't cause anymore problems.

Right now, I'm having issues with curvature on the corners my images. I believe the problem will be resolved after I adjust the backfocus. Backfocus should be 146.0 from the end of the reducer to the face of the imaging sensor (not including filter thickness), but I'm measuring 150.6. Removing a spacer should do the trick. The problem started after I changed the filter wheel from a 5 to an 8 position. Currently, my collimation is 1.7 and the tilt is under 6. Curvature is a whopping 32! FWHM improved from 3.2 on average to 2.4. I'm thrilled with that! Maybe, I can go even lower after I adjust the backfocus. Stay tuned...

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