To Ortho or not to Ortho, that is.......

[Greenswale]

I am working towards observation of carbon and double stars. The equipment I now have is good for me, but I have to wonder if less glass between my eye and the object will give me an improved result. Lets include a bit of planetary work too!

Thus the question - will a quality Orthoscopic be of value? I would be particularly interested if you are able to provide opinion based on real life observation experience using Pentax XW (or similar!) and orthos.

In support, I have done a whole lot of trawling with variable outcomes, tracking performance of my scope is excellent, I am concerned at the possible lack of comfort in use (eye relief) for prolonged viewing, I note that orthos and plossls are common sale items, and would welcome mention of performance of products from various manufacturers.

[MattT]

I'd say yes....specially if you binoview. I like Volcano tops over the flat tops and binoviewing 18mm orthos with 1.6- 2-3x barlows is very relaxing for extended views....seen more with 18mm VT Orthos than I have with a single XW 7mm for example...only a tiny bit in it though.
Matt

[Greenswale]

Thank you for the fabulous offer Matt!!!!!

Will get back to you via PM.

[dannat]

i agree with Matt, orthos are hard to beat when eeking out fine details, either splitting stars or seeing features on luna/planets

[N1]

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.


In my experience, a modern ortho is the best value EP type out there.


Ideal, but by no means essential for an OR! I use them in my 1250mm FL dob from time to time.


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.



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.

[MattT]

I did sell my XW's 10 7 5 and 3.5 as I prefered Orthos specially with bino's for planet and lunar viewing.

I have ES 82º eyepieces for wider views in the short FL area too.

[Tropo-Bob]

In my opinion, an ortho EP is a touch sharper at the very centre of the field of view than a plossl EP, but then is less sharp almost immediately away from the centre. So I would recommend having one high magnification ortho for close double stars and if impressed with that, maybe less powerful ortho EPs for planets. Eye-relief is not a worry as once found and centred on your target (assuming that tracking is good), then one can move the eye away from the eyepiece and still see what was being viewed. (True anyway with small objects like double stars and planets.)

However, orthos and plossls rarely go head to head with the same focal lengths. The difference in viewing at the centre of each eyepiece may in the end not be as important, as having the right magnification for your task.

[dannat]

"but then is less sharp almost immediately away from the centre"

ive found this a bit f/l dependent, at f4 they struggle -but at f6-7 they remain god

[Greenswale]

Thank you for the replies.

Matt has made me an offer that is too good to pass up, so I will be able to form an opinion by the end of next week. (Thanks again Matt!)

I will be using at F10, but can do F6.6 although it means more glass in the light path. Will be an interesting experiment and will include my Pentaxes, outcomes will be posted here.

[HCR32]

Jumping in a bit late on this one but if your going to concentrate on star splitting then the most important factor in your ep selection needs to be scatter control. I've spent alot of spare change on EPs buy and trying over the years and your best bet would be to source a top tier minimal glass ep. Zeiss abbe or Astro Physics SPL's. Their not cheap but take it from me they will do the best job for what your considering in your viewing plans. If your budget doesn't allow for such expense then I would look at something like Baader genuine Ortho or the new HD KK's they are super cheap and super affective.

[Greenswale]

I had an opportunity to play with the eyepieces. The test was over about four hours. Seeing was variable, improving as time progressed. The outcome of the experiment can only be considered indicative, for any number of reasons.

The UO orhtos gave a 'more pleasing view' of individual stars than the Pentax. Jupiter looked about the same, but revealled a separate problem! Anything else saw the Pentax ahead, very much so on DSO.

Adding the focal reducer produced the same outcome in the comparison. The best views from both types came with the reducer installed.

I suspect the standard Celestron diagonal is not good, scattering light. Neither type of eyepiece gave brilliant views of the planet.

The experiment has been a success, in that I have seen the value of of orthos, and will purchase a 12mm and 25mm (and maybe a 6mm), and a quality diagonal.

Again, thanks to Matt for lending the UO eyepieces!!!!!