Re: Adjusting cone error with camera and no view of pole?

Christopher Erickson

First, if you are using APCC-Pro, modelling compensates for cone error so you don't have to shim or adjust anything. It's all taken care of via APCC software in the model.

Second, I prefer adjusting cone error during the day. Too hard for me to go from a dim eyepiece to a flashlight and tools and bolts and shims and back to the dim eyepiece. I pick a distant terrestrial object near straight East or West on the horizon, turn off tracking and flip back and forth over the meridian on that object, taking into consideration the parallax distance as I flip back and forth. And I use the sides of pop cans cut with scissors and a paper punch for shims. I shim between the dovetail bar and the OTA rings or radius blocks.

And make sure your OTA is very carefully collimated before evaluating or adjusting the cone error. No big deal on refractors but a big deal on reflectors.

Cone error, a.k.a. orthogonality a.k.a. perpendicularity, is the relationship between the DEC axis and the optical axis, not the OTA axis.

"My advice is always free and worth every penny!"

-Christopher Erickson
Observatory Engineer
Summit Kinetics
Waikoloa, Hawaii

On Sat, Aug 28, 2021 at 8:11 AM Tom Blahovici <tom.va2fsq@...> wrote:
How does one adjust cone error if you have no view of the pole and use a camera?

Join to automatically receive all group messages.