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Possible to rotating the OTA for diffraction spike alignment?

Planewave CDK14 Reflectors Equipment
6 replies•273 views
jego avatar
jego avatar
Perhaps kind of a silly question, but it appears from pictures that the dovetail on the OTA is fixed, and I’m wondering if the design allows one to move it or somehow otherwise rotate the OTA to an arbitrary position without compromising the rigidity or performance. On a newtonian you can usually just spin the OTA within the rings to the desired position, but a truss obviously doesn’t work that way and I’m not sure if the plate moves.

The purpose would be to align the diffraction spikes to any desired angle, either for aesthetic reasons (if one prefers an X shape vs a + shape) or to combine with other data that has spikes in a different orientation with minimal processing headaches.
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Alan Brunelle avatar
Alan Brunelle avatar
The orientation of the spikes are determined by their orientation to the desired field.  So, if your OTA tube rings allow for a loosening and thereby rotation of your OTA, then yes.  Otherwise an opening of the rings may be required.  Care is necessary to not drop your OTA.  Once the objective has been achieved, then the camera will need to be rotated to get back to the originally framing.

if you do this routinely and your rings are a pain, you could upgrade them.  I'm sure someone has developed rings that are like lockable bearings.  Heck with a little engineering you could motorize it to be able to do it remotely.

Good luck!
jego avatar
jego avatar
Alan Brunelle:
The orientation of the spikes are determined by their orientation to the desired field.  So, if your OTA tube rings allow for a loosening and thereby rotation of your OTA, then yes.  Otherwise an opening of the rings may be required.  Care is necessary to not drop your OTA.  Once the objective has been achieved, then the camera will need to be rotated to get back to the originally framing.

if you do this routinely and your rings are a pain, you could upgrade them.  I'm sure someone has developed rings that are like lockable bearings.  Heck with a little engineering you could motorize it to be able to do it remotely.

Good luck!

There are no rings - this was posted in the CDK 14 forum, the question was intended for those OTAs specifically
Alan Brunelle avatar
Alan Brunelle avatar
Alan Brunelle:
The orientation of the spikes are determined by their orientation to the desired field.  So, if your OTA tube rings allow for a loosening and thereby rotation of your OTA, then yes.  Otherwise an opening of the rings may be required.  Care is necessary to not drop your OTA.  Once the objective has been achieved, then the camera will need to be rotated to get back to the originally framing.

if you do this routinely and your rings are a pain, you could upgrade them.  I'm sure someone has developed rings that are like lockable bearings.  Heck with a little engineering you could motorize it to be able to do it remotely.

Good luck!

There are no rings - this was posted in the CDK 14 forum, the question was intended for those OTAs specifically

Oops!  Well, as designed it showed up in the main section.  Maybe they could indicate where these get posted with something other than the smallest sized print under the full sized title!  That said, maybe mention the specific scope in the title until changes are made.
jego avatar
jego avatar
Alan Brunelle:
Oops!  Well, as designed it showed up in the main section.  Maybe they could indicate where these get posted with something other than the smallest sized print under the full sized title!  That said, maybe mention the specific scope in the title until changes are made.

Haha, yeah, no problem...appreciate the help anyway! Unfortunately I can't edit the post title to fix that or correct the grammar error.
Willem Jan Drijfhout avatar
Willem Jan Drijfhout avatar
Perhaps kind of a silly question, but it appears from pictures that the dovetail on the OTA is fixed, and I’m wondering if the design allows one to move it or somehow otherwise rotate the OTA to an arbitrary position without compromising the rigidity or performance. On a newtonian you can usually just spin the OTA within the rings to the desired position, but a truss obviously doesn’t work that way and I’m not sure if the plate moves.

The purpose would be to align the diffraction spikes to any desired angle, either for aesthetic reasons (if one prefers an X shape vs a + shape) or to combine with other data that has spikes in a different orientation with minimal processing headaches.

Hi Jego, no, the CDK's cannot rotate within their rings. the dovetail is connected directly on the truss-design. You could add extra dovetails at 90° increments, but even if you'd use that to rotate the whole scope, it won't help you with your spike orientation.
The best way would be to add a rotator, and position it such that the spikes have their preferred orientation. Obviously your target will rotate as well. For galaxies, clusters, planetary nebulae etc. this might not be a problem. For larger nebulae you may have to find a compromise between composition and spike orientation.
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jego avatar
jego avatar
Thanks, that’s kinda what I thought. Camera rotation doesn’t really work, as it just rotates the field. Not a huge deal anyway.