Wren, the Abbe style orthoscopic has been a revelation to me. I had been used to Naglers, Panoptics, 68 ES, Plossls and Hyperions until about a year ago. I also had a 5mm Radian until recently. ER and AFOV aside, I really struggle to find anything the new Japanese ORs won't do
at least as well as any of the above, at a fraction of the price. My main scope is a short and non-tracking refractor. I also favour the ORs on some DSOs, such as the Flame neb. You really don't want Alnitak in the same FOV, so a Nagler or even a Pan aren't very good for that, since you are straining your eye looking "round the corner" at the field stop the whole time.
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Originally Posted by Greenswale
Thus the question - will a quality Orthoscopic be of value?
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In my experience, a modern ortho is the best value EP type out there.
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Originally Posted by Greenswale
tracking performance of my scope is excellent
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Ideal, but by no means essential for an OR! I use them in my 1250mm FL dob from time to time.
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Originally Posted by Greenswale
I am concerned at the possible lack of comfort in use (eye relief) for prolonged viewing
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This is perhaps the most subjective of all the criteria. I too was concerned about this until I got my short ER orthos, including the impossibly tiny 4mm unit. Personally I find the ER on the 4mm to be comparable to that of a type 6 Nagler with the eyecup folded
up, or the 16mm ES 68 with the eyecup folded
down - in terms of overall comfort (the eye cup on the 68 is very soft, so does not affect things hugely). I'm aware of the specs of these, but that's what I've found in the field, on my eyes. Besides, short ER is only an issue if you must see the field stop all the way round, at all times. On planets or stars, this is the last of my worries, effectively making short ER a non issue.
All my orthos except one are flat top type. I have a 5mm volcano top but don't use it anymore because the protruding central area felt like it was getting uncomfortably close to the cornea without any way to judge exactly how close. On a flat top, the skin around my eye rests on the edge of the eyepiece, which is great for this purpose and adds a lot of comfort.
Try this out if you can. In any case though, if you don't like your eye lashes making contact with the eyepiece, or if you must wear glasses, short FL orthos may not be for you.
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Originally Posted by Greenswale
I note that orthos and plossls are common sale items, and would welcome mention of performance of products from various manufacturers.
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I'm not in a position to expand too much on this on a forum, but a recent conversation with a competent source gave me the impression that you might as well let the price, rather than the brand, be your guide when buying any of todays Japanese made orthos. This is consistent with reviews & comments finding no difference in performance between today's brands, as long as they were made in Japan. Second hand is a different story. I've heard of "Orthos" that were around in the 80s that somebody pulled apart and found a poorly executed (read cheap) plossl inside.
My only complaint would be the fact that the print is showing signs of wanting to come off on my most-used units. I don't care about the "Japan" or "fully multi coated", but it's kinda important to know the focal length, especially at the shorter end of the scale, where the little buggers are hard to tell apart. So there's something that may be different on an "expensive" ortho - the writing might be engraved rather than printed on.
I hope this helps.
