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CDK 12.5 focuser comparisons?

Equipment Focuser Request for feedback Buying Advice
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JohnAdastra avatar
JohnAdastra avatar

Hi All:

This post follows through from an earlier thread about finding a larger aperture telescope. I have a line on a used CDK 12.5 which comes with the original Hedrick focuser and the EFA control box. However, I see many users have changed out the stock focuser for other brand units apparently in search of improved focusing. Can anyone who is a user of the Hedrick comment on the performance of using it or why would it need to be abandoned? They appear to be a solid construction, so perhaps the issue is with the operation of the electronics. Our imaging group also has an Optec FocusLynx on another scope that is working well. But the Hedrick appears to slide directly into the back of the CDK and is secured by a surrounding custom flange. What adapters that would be required to get threaded into other gear is unclear.

If anyone is operating a Hedrick focuser, or has made a change to something else, your comments would be greatly appreciated.

Thanks,

John

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Pete Bouras avatar
Pete Bouras avatar

John,

I had a Hedrick on my CDK14 S/N 0002. It worked, kinda, but I had issues with deflection, never solved that problem, tightened up the focuser to reduce the deflection freeplay of the tube, but then the motor would stall. I never got to a happy place with it. Don’t know if the motor was weak or what.

Another issue was that it is very slow to move during focusing. Now the CDK14 is fairly stable thermally, so you don’t have to refocus a lot on temperature change, so the focusing speed is not a huge deal. Another downside is that there is no rotation, if that matters to you.

I ended up getting the 3.5” Nitecraweler and couldn’t be happier. It is fast and precise and built like a tank, and the built in rotation is nice if you ever feel the need to frame a shot at another camera angle.

CS - Pete

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JohnAdastra avatar
JohnAdastra avatar

Thanks Pete. That’s the kind of feedback I was looking for. I’d love the Nitecrawler though I know they’re fairly pricey. Rotation is not a huge deal for me though. I am curious how you were able to mount to the back of the OTA.

Regards,

John

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Pete Bouras avatar
Pete Bouras avatar

Moonlite supplies the adaptor that bolts the focuser to the CDK backplate in the same spot where the Hedrick bolts on. Installation is dead simple. 3 bolts to remove the Hedrick, and the same three bolts to install the Nitecrawler.

📷 2765.jpg2765.jpgYes it is a bit pricey but other solutions are similar or even more expensive, but consider the caliber of the scope its going on, and the focal length, you need precision. In the future as you enjoy the quality and the function of the 3.5 Nitecrawler, the price will long be forgotten

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