Just received my 1st scope and learning to set it up. It came with an officina stellar 50 ml finderscope, if i attach the eyepiece to the diagonal and the barrel focuser that came with it, no problems, but if i replace it with a 9mm meade reticule eye piece i can't quite get enough inward focus.
Is there a way to correct this? Any help will be will be appreciated
I assume you are talking about the finderscope. I don't know anything much about your particular finderscope. I assume, according to the specs on the web, that it is a 10x50mm finderscope and that it already has an illuminated EP.
If the finderscope has at least a 200mm focal length, then the EP that comes with it is probably about 20mm. 200/20=10x.
It would defeat the purpose of the finderscope in using a 9mm EP as this would change the finderscope into a 22x50mm with a much narrower field of view. I am guessing that the finderscope would not have enough in focus with the diagonal to go from a 20mm down to a 9mm.
Thanks Rob,
I am beginning to understand about focus, your assumptions were correct but the finder scope came without a reticule so I was going to use the 9 mm just for aligning the scope but since a few nights observation I find that having a crosshair is nice but not critical ( will I eat my words later ?) I find that I can align terrestrially and then fine tune when observing.
Thanks again for your reply
George, you can also add a set of cross hairs to your eyepiece. I've done this several times myself to different eyepieces, even to the eyepiece of a set of binos. All you need is a wire strand from an old phone line and some fast set glue. Most eyepieces today have a 'field stop', a ring that is placed at the focal point of the EP so that the eyepiece has a nice sharp edge to its field of view. The wire is placed on this ring as it will be in focus. I've attached a couple of pics of a grid reticule I put on one eyepiece, and how I attached it to the EP of a set of binos. The binos was tricky in that there was no field stop, so I used a small drill bit to make two holes to wrap the wire ends around.
If you have access to optic fiber, you can use this too - that's what I used in the 2" eyepiece grid reticule.
