Jump to content


Recommended Posts


you need to replace the 1.25 inch visual back (supplied with the scope - the bit that screws onto the back of the scope) with a 2 inch visual back.

i do not know if the visual back is removable on your scope, it can be unscrewed on the 8" version, you will have to give it a try.

If it does unscrew then you also need to buy a 2" star diagonal to fit into the 2" visual back.

you then need to buy some 2" eyepieces to put into the 2" diagonal.




You can get these items second hand to save some dough.




Link to post
Share on other sites

Before you do this get some measurements of your replacement parts to check once connected up you have enough clearance from the EP end to top of mount as you raise the altitude. Should be OK with a 6, but the 8 and 9 are very tight and might need a slew limit added. You can and should front load an Evo to maintain accurate tracking.

Link to post
Share on other sites
8 minutes ago, Itabot said:

Will this diagonal SCT fit, take 2" EP's without the requiring a seperate 2" visual back?  on a Celestron Nexstar SE8 or have I got it wrong?



Yes, you screw the diagonal onto the rear port of the scope in place of the visual back.

You just need to make sure that the larger diagonal will clear the mount when the scope is pointing upwards.

Edited by John
Link to post
Share on other sites

Yes it will fit.

Just means you have to leave the diagonal permanently mounted to the scope. You could always get the visual back later if you find it a pain. For example, if you want to put a filter onto the diagonal then you need to remove it from the scope to add the filter.



Edited by alanjgreen
Link to post
Share on other sites

Thanks John & Allan, I'll wait and see how get on with my 1.25" EP's before spending any more money, as I only have one 2" Skywatcher Panaview 32mm EP, I may decide to sell?

Edited by Itabot
Link to post
Share on other sites

There's no rush, the stars come around every year!

Switching up to 2" is worth it as you get a wider view which is great to frame objects most notably large open clusters and large nebulas (Veil Nebula is a good example where it is simply too big to frame in a smaller EP and the extra light from the 2" can reveal more detail).

But it can be expensive by the time you add in all the bits you need. You may also want to add 2" UHC filter to the list of "potential" bits & bobs.

Edited by alanjgreen
Link to post
Share on other sites

I don't think 2" eyepieces let in any more light and reveal any more detail. The additional field width can be useful / nice for framing larger DSO's though.


Link to post
Share on other sites
1 minute ago, alanjgreen said:

The 1.25 inch visual back blocks several mm (.75 inch) of the (hole diameter) light path from the SCT tube to the eye, this must have some sort of "light reduction" effect


I don't think it does otherwise no SCT would be able to perform to the resolution limits of their aperture when using with 1.25" accessories, which they clearly do, or at least all the ones that I've owned have.


Link to post
Share on other sites

The Celestron 6" has a rear baffle tube size of 27mm and this will restrict the field of view. Any eyepiece with a field lens of 27mm or greater will vignette on this scope. You may find the 2" diagonal and eyepieces disappointing.

Link to post
Share on other sites

You can get longer 1.25 inch focal lengths.

celestron xcel 25mm are pretty reasonable. See FLO website.

televue do a 32mm and 40mm plossl in 1.25 inch format. See widescreen centre website.

i believe there are longer ones too.

Edited by alanjgreen
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.

  • Similar Content

    • By CKERR
      I am new to using a telescope but am an avid manual reader and usually a fairly quick study.     I have bought a pre-loved Celestron Nexstar Evolution 9.25 {originally purchased in Sydney Australia in 2014} and am struggling to do the 2 star alignment.   I have reset the scope to Factory Settings and have added my location, correct time, STD or DLS time; time zone etc.     I take the scope out and level it, align the marks on the base of the motor and on the arm that holds the scope.   I point the scope whilst still levelled and marks aligned North.     I try to align to Sirius and the scope points to my feet.    I have tried following the steps but nothing is working.   
      I have tried using the SkyPortal App and that is more of a success but still not quite.   I try to align Sirius and it will point up and very close to the star but not aligning with it.   I ask it to GoTo the stars in Orion’s Belt and it will be close but not quite so not aligned....at least it isn’t pointing to my feet.
      Any suggestions would be welcomed.   Thank you.
    • By StarGazingSiouxsie
      Can you help me solve this mystery, please?
      I have a 2020 Celestron 8" Edge Evolution Ltd Edition 60 Anniversary model. The OTA is carbon fibre and some of the artwork is different but for in tents & purposes it's a standard 8" Edge Evolution
      The Problem
      The problem is, when the mount is switched off. the telescope will not maintain its calibration between Star Sense (SS) camera and the OTA. Please not I am not talking a SS alignment here - I'm talking about the calibration between the SS camera and OTA. 
      This is what happens - I will do a SS Auto Alignment and the goto will be out by some margin IE. way outside of a 25mm eyepiece. So, I then calibrate the SS camera to the OTA, re-align, and everything is working perfectly. The goto is more or less in the middle of a 12mm eyepiece. Next time I reboot the mount, I do my SS Auto alignment and the goto is way off again  and I have re calibrate the SS camera to the OTA. Once I do that, everything works fine again. And so the cycle continues.  
      Have you experienced this problem yourself or do you have an idea of what may be happening? Before you offer your suggestions, please read this list as what I have done to try and solve this issue:
      1. The tripod and OTA are absolutely level before booting up the mount. 
      2. Once I have booted up the mount, I enter time and my location, using GPS co-ordinates. I am extremely precise about this and am entering the correct time (and daylight saving as needed) to within 2 seconds. The GPS co-ordinates of my location as absolutely spot on as well - they are the same co-ordinates I use for all my telescopes and they are working perfectly. So this is defs not a time, date or location issue. 
      3. The SS camera is mounted perfectly It does not move at all. I have the calibration problem even after rebooting without moving the telescope's position at all. 
      4. I have even tried a new SS camera and handset. Exactly the same issue persists. 
      5. The handcontroller, mount and camera have all the latest updates. 
      6. The battery is working fine and holding it's charge perfectly.  
      As I mentioned earlier, once the SS camera is re calibrated, everything works fine and the goto is accurate. The problem only arises after rebooting the mount. 
      Any ideas, suggestions or sharing of similar experiences gladly welcomed, thank you. 

    • By Ade Turner
      I’ve been using my 8’ Edge HD on an Evolution mount for a couple of years now and I added a wedge to it a few months back. Using SkyPortal with StarSense I’ve never really had any major issues getting it aligned. 
      Last night I was setting up to photograph Mars and went through my normal procedure. StarSense took its images but, after confirming success with the third plate, instead of just winding up a bit and parking it proceeded to pitch the ota towards the north well below the horizon.
      Fortunately nothing snagged. I skipped the ASPA and instructed it to goto Mars and was surprised to find it was spot on (better than usual actually).
      Anyone any ideas why it took that nose dive? Thanks.

    • By J_1
      I wonder if someone could please advise me on a few issues I seem to be having with my new Celestron Evo Edge HD 8" Telescope. 
      The motors appear make a strange sound. This occurs when the scope is stationary, when adjusting the position manually or going to an object automatically. I have made a short video demonstrating the sound and can be heard during the first part of the video. Then after adjusting the position slightly it stops, then later on returns again. I don't believe this is a tracking noise as it intermittently occurs. Please note I am not referring to the louder motor noise but the quieter noise in the background.  
      Another issue I am having is when I connect my tablet to the Telescope via the inbuilt Wi-Fi, the power status light, wifi light and tray light all appear to flicker slightly as if there is an electrical issue. I can't believe that I should expect the tray lighting to flicker???
      If anyone could advise if the above is normal or not, I would be most grateful. 
      Thanks, Jamie.
    • By williamnohair
      does anyone use 'Skywire' via Skysafari to control a Celestron Evolution with the starsence accessory fitted?
      My queries are these: What is the maximum cable length that can be used and are there any suppliers?
      and does Skysafari recognise the starsence accessory for initial Goto alignment ?
      Thanks people
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.