This is a repost of a topic that I have posted in the Cloudy Nights forum.
I'm looking for the opinion of others on the performance of my recently acquired Tak FSQ106 EDXIII. Scope has been purchased on the second hand market and would be a few years old. I am seeing what I believe is coma and field curvature leading me to conclude that the only option would be to send the OTA to Takahashi for service. I am posting here to report on my testing and have my conclusions reviewed by others that have more experience with this OTA so please feel free to pull apart my analysis and provide your thoughts.
To save space here I have written a report on my testing and uploaded the report and some test files to my drop box.
Here is a link to the drop box folder.
I have tested the scope with two cameras; a ZWO ASI6200 and a QSI683. Both gave me the same results.
Attached are a 3:1 zoomed image taken of the Rosette Nebula taken with the ASI6200 and an image of the aberration inspector from the Pixinsight application. The zoomed in image shows what appears to be elongation or coma in the stars in the centre of the image. The aberration inspector image shows classic field curvature. I conducted a rotation test by rotating the CAA on the OTA by approximately 90 degrees. The coma elongation in the centre of the image rotated with the rotation in the image train. From this I conclude that the issue lies in the OTA and not in the image train.
There are no reducers in the image train and the image train is configured to bring the image into focus at the requisite 178mm backfocus for this OTA. SGP Pro was used for image acquisition and I took great care to make sure that the auto focus routine was giving the best focus possible.
The extent of these aberrations is sufficient to mean that I cannot use the OTA for imaging so it seems to me that the only option is to get a quote from Takahashi to service the OTA.
I would appreciate that thoughts and ideas of others on this forum that may have more experience with the FSQ106.
Thanks for looking,
Rodney