Jump to content

Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.

Look left

Focal reducer on SCT6SE

Recommended Posts

I,m looking to put a 0.63 Celestron Focal Reducer on my Celestron 6 SE to reduce FL to speed up OTA for imaging in EAA.

Do i put Reducer directly onto scope,then fit Crayford to this then ZWO 120 mc onto this.

all assuming I have the right back focus to do this. If so I can use motor focus on the Crayford.

or do I have to put Crayford onto scope,reducer ontomthis then Camera. Or forget Crayford and install reducer directly onto scope fir spare and the camera and use the course original focus knob ?

Share this post


Link to post
Share on other sites

I'm not familiar with the 6 SE, but the Celestron 0.63 FR has a working distance of 105mm - that is the distance from the back glass element of the FR to the front of the sensor. 

I think putting the Crayford after the FR would allow you to change the working distance but not the focus. 

So you would need to put the Crayford onto the scope, then the FR, and then a spacer to get to 105mm. 

I don't know if you would get sufficient back focus though.

/callump

Share this post


Link to post
Share on other sites

I am also unfamiliar with the 6SE having a MAK180 but the two are similar and I have been playing with a focal reducer on that. According to the book of words, to achieve the stated focal reduction, the focal reducer should be installed at the visual back. I would guess that without a Crayford focuser the VB on a 6SE is the same as on the MAK and the FR is fitted into the VB adapter. You then need 105mm between the FR and the EP to get the full focal reduction. I would suggest that if you have a Crayford focuser fitted, the FR should go before the focuser, but that is a just a guess.

On mine, with the FR fitted at the VB, after focusing, bang slap in the middle was a huge great secondary mirror making the thing a waste of time. However, by continuing to play and fitting the FR at different positions, and using different spacing's you can still get focus and the secondary disappears. The best I found was to fit the FR to the EP, what the actual focal reduction was I have no idea but it was still significant.

Hope it helps.

Share this post


Link to post
Share on other sites

Thanks very much guys for coming back. Here's the setup and thanks to Callup and M40 for the distance.

Stash _old ,s link shows the Reducer fitted to the FC on the SCT with a spacer between the reducer and the camera. However that means yourbrelying on the OTA focus knob to gain focus. On my Celestron 6SE you cannot get a great focus on it hence going with the Crayford. Now I know what I,m trying to achieve with the distances I,ll experiment.

IMG_1632.JPG

Share this post


Link to post
Share on other sites

Does this mean that the 105 mm from the reducer to the camera focal point? Would this also take into account the travel of the Crayford, or go for 105mm ish and then use Crayford just to nail it.!

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.