I am glad that I found this site as I see that APO127ED from NorthGroup is popular among you guys.
I wonder if anybody buying the APO127 very recently and equipped with new, advanced focuser and 2" dielectric diagonal has encountered a problem that I have.
I had a chance to take my new scope for first light just on Tue this week and had an unpleasant surprise. I could not get any focus!
After long e-mail exchange with Cloudynights members we jointly figured out that either main optical tube of the scope is too long (design flaw) and/or new, advanced focuser does not work with 2" dielectric diagonal also supplied by Northgroup. This is valid for both, 2” and 1,25” eyepieces what means that the scope with new set of quality accessories supplied by Northgroup is useless.
It turned out that the thing is not entirely hopeless. There is an interim solution but only for purpose of visual observations - you can get focus with 1,25" diagonal. This however does not satisfy me at all as I bought the scope for astrophotography, what means I need to get focus with 2" equipment.
I have sent several e-mails to Gilman asking for help but no response so far. Hope that he will be able to solve the issue.
Hi jerr,
Why would you be using a diagonal with a camera? I was at a friends observatory last week-end and his new 127 works fine with a camera and no diagonal.
hi jerr
you dont use a diagonal when imaging.
but not being able to use a 2" diagonal is a big flaw in the setup, at least i think so.
the best thing would be to get a focuser that changes the lenght of the light path, but this should be correct from the supplier, so i would demand that they supply a focuser that actually makes it possible to use 2" equipment.
The scope's optics are anyhow fantastic. I spent 3 hours today stargazing. With Moon at its best I had great views of M15. Stars were pinpoint sharp. No noticable CA. What I need is just that icing on the cake.
I've followed your thread on cloudynights. To add more information to the people here, Jerr couldn't get an eyepiece to focus with a 2" diagonal + 2" to 1 1/4" adapter + 1 1/4" eyepiece because there wasn't enough infocus. He couldn't get an eyepiece to focus with no diagonal, just the 2" to 1 1/4" adapter + eyepiece because there wasn't enough backfocus.
It is possible that the camera adapter will add the backfocus you need for astrophotography, the adapter will certainly add more backfocus than the 2" to 1 1/4" adapter + eyepiece.
For visual having a focuser installed that doesn't have enough infocus to bring the eyepiece to focus with the 2" diagonal is a flaw though.
Mine focuser looks different. First of all it has only 8cm of back travel once yours 12. Look at additional black ring behing red one on a picture that I post. I assume this is a sign of new, advanced focuser.
Did your friend also have problems with getting focus?
Does he use extension tube for astrophotography?
jerr
I don't believe so but I have sent him a link to this thread. His is a new one and has the new "advanced dual speed focuser for camera", I'm unsure if he has ever put an eyepiece in it
yes it is different. I know that they developed a focuser for astrophotography and visual - both were imporved models and some IIS people got the new focuser
Hello Jarek.
My ED127 has the new "improved" focuser. I asked for it specifically. I have not had any problem getting visual or imaging focus. But, I don't use a diagnoal. In imaging mode, I have used both a DSLR and QHY8. With the DSLR I have a short (40mm extension piece that I use, but only because the compression ring on the focuser is rubbish and won't grip properly on the T-Piece on the camera. So I use a little adapter with a slightly bigger diameter to get a snug fit - and then only use about 1 cm of back focus. With the QHY8 I was also using an Off-Axis guider and used an extensiuo tube after the OAG so I could get the imaging and guiding camera parafocal.
In visual mode, I also used a shorrt extension piece and very little back-focus. I'll and photograph it all tomorrow if you would find that helpful.
Peter
Thank you for the details. I will appreciate pictures of your set up. I am actually thinking about QHY8 so this will help me to do direct comparison. Can you also measure length of your scope’s main tube? Let say just white part of it end to end.
