Coma corrector spacing

[Leeps]

Hi all, 

I have a astro revelation coma corrector, and I can't work out quite what I'm doing with it. I went out a couple of nights ago and wasted a whole precious clear one while messing with trying to focus it and plate solve. It's frustrating as there's no manual I can find anywhere online, and I have no details at all with it... It's literally just an object to me lol. I want to know the spacing between the sensor and whether it changes the focal length. I've seen conflicting information all over the place for it - I was expecting to find a manual after I bought it that would make it all clear.

It's mounted on a Nikon D5100, and I was getting a bunch of what looked like Coma when using it (which was with a T adaptor, and a 10mm extension, then straight onto the CC. About 75mm). The system completely wouldn't plate solve my images either, which makes me wonder if the FL has changed. 

Does anyone have one of these things? I hear it's the same as the GSO... There's a guide around for that for visual use, but I want to use it for imaging. 

[Louis D]

The working distance is around 75mm as you say.  It magnifies 1.10x (10%).  I usually only use it visually.  I did use it to capture the 2016 Mercury transit image below, so I know it can be used with DSLRs.

[Leeps]

So that's 75mm from the sensor to the 1st glass element? And you have the revelation astro, or the GSO? 

Nice pic! 

[Louis D]

I'm pretty sure it's 75mm from the sensor or eyepiece field stop to the top of the M48 threads on the optical nose piece.  You may have to adjust it a bit to find the optimal spacing.

I have the High Point (now Apertura) version, IIRC.

[Waldemar]

Info : 

https://www.telescopehouse.com/revelation-2-coma-corrector-for-newtonian-telescopes.html

So, if you are using 75 mm bf, you will get severe coma...

 

 

[Leeps]

I had a go last night, and couldn't get it at all. Wasted an entire night of clearness on it

I tried no spacer, 5mm, 10mm and 15mm, and then a 30mm nosepiece, then the nose pice into the adjuster supplied with it. Focussed all of those options, and all of them resulted in coma. Really not sure what I'm doing wrong. I'll post some pictures later so you can see what I'm doing

[Davey-T]

Is it the same as the William Optic one ? if so there are instructions of a sort somewhere on the web listing various  settings, I did have a link but lost it in a Windows  browser  update.

Dave

PS: I use a Baader Varilock on mine

[Waldemar]

Baader Varilock is the right accessory for perfect adjustment. 
Attached a file to show which way to go.

FF distance to sensor.docx

[Leeps]

Sorry I haven't had the time to get back to this, but thanks for the advice. I guess I'll have to grab that adjuster and go from there, since none of my parts are getting me where I need to be. That word doc is super useful