Astrotrac first test run results

Esteemed List Members:

I was asked to report results from my first real usage of my Astrotrac mount.  My summary is as follows:

- I am a noobie, so any results need to be taken with a grain of salt.  That said, the mount assembled easily and operated as stated.  It was a breeze to setup.

- Polar alignment is easy if you pay attention.  I did not pay sufficient attention, likely related to the large margarita I had with dinner.  But, my errors were discovered later and corrected.

- Even with margarita-influenced alignment, the mount takes good photos for medium focal lengths.  To use it for longer focal lengths requires careful attention to details.

- My camera is an Oly OM-D EM5 and test images were gathered from 7.5mm, 17.5mm, 28mm, and 300mm lenses.  The Oly has a 2.0 crop factor, so these were really 15mm, 35mm, 56mm and 600mm effective focal lengths.

Exposures varied from 30 seconds to 235 seconds (3.9min) while tracking.  ISO 400, no NR in camera, no image stabilization, sunlight white balance.  Results are below:

Zeiss 28mm M-mount lens at f2.8, 3.9m exposure, ISO 400, manual focus.  Full frame.

I examined the photo above using LR at full pixel level and there is no evidence of motion slurring of the star images.

Zeiss 28mm M-mount lens on Oly OMD-EM5 Iso 400 235 sec exposure.

This is a crop of the first image.  Note the nice, crisp resolution of the main stars in Orion's belt.  The nebula is visible and is crisp as well, with no evidence of slurring.

Voightlander 17.5mm f/0.9 lens at f/2, OMD-EM5 at ISO 400, 117 second exposure

The Voightlander lens is a f/.9 lens but shows expected softness fully-wide open.  But, take it down a stop, it works well.  The photo above is a pixel-level photo.  Note the purple fringing on some of the stars.

Oly OMD-EM5 with Canon FD 300mm fully manual lens.  235 second exposure.

Note in the last image that there is substantial star trails.  My alignment o the pole was either fully wrong for this long shutter speed.  More precision is needed.  The mount is up to the task, but the operator needs better pointing skills.

I will eventually get better.

best bc

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BC
Team Thor Expeditions