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I am using a Bresser AR102s 102/600/f/5.9 refractor for visual.
I am having to use 2 spacers screwed into to the eyepiece barrel to achieve focus!
Questions;
1. Has anyone had the same issue with this or any other refractor?
2. What’s causing this?
2. Is there another fix apart from spacers?
Any thoughts,
JackIf I understood correctly, I would say that the travel of the eyepiece holder tube, i.e. the focuser, is too short for the diverter (prism or mirror) not to be inserted. It is obvious that without a diverter, the focal plane remains very far out in relation to the extrusion of the eyepiece holder tube. I have the same problem with a Russian telescope. That is if I have not misunderstood.
Saluti
GiovanniYes, this is typical and a diagonal is normally required. All my modern refractors are the same. It allows for lots of backfocus for Cameras, filter wheels and OAGs.
Ian.
Giovanni,
You have understood correctly.
So, I am using spacers to achieve focus.
I was not aware this could be an issue with some telescopes!
Regards,
JackIan,
I was using it with a camera no issue.
I am using a diagonal with 2 spacers screwed into to the eyepiece barrel to achieve focus for visual.
I was not aware this was an issue with some refractors.
That’s a question people should ask when buying for visual use as I suspect it won’t be mentioned in the specs!
Regards,
JackYes, it is not even a particularly modern development. I recall a Japanese 50mm refractor that I tried in a department store in the late 1970s that did not focus without the diagonal, and of course gave an upright image with the diagonal. I had read in all the astronomy books of the time (by Moore etc.) that astronomical telescopes always gave an inverted image. As this issue was not mentioned in any of the books (Moore himself seems to have never used a diagonal) I was much puzzled, as were the shop staff, and eventually I bought a Newtonian.
So, I agree, it is a detail which should be explained in specifications, but never is.
Giovanni,
You have understood correctly.
So, I am using spacers to achieve focus.
I was not aware this could be an issue with some telescopes!
Regards,
JackI wish it was an issue with my telescope!
There is insufficient back focus to use an active optics unit with the current camera, off-axis guider and filter wheel. However, I have a cunning plan …
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