UO ortho

[beren]

Gday, just a brief first impression of a 9mm University optics HD ortho I purchased/received this week . I was hoping to get a first impression and follow up with a more detailed write up but since Tues {18th} the weather hasn't been flash so i thought i would write something at least :roll: .
I already own a 9mm eyepiece , a Nagler type 6, but i was keen to try out one of these Orthoscopic designs particularly the University optic brand and see for myself how well they stand up to the reputation many people have of them.

The eyepiece comes in a neat package with caps both ends ,rubber eye-guard and a recessed chrome barrel . Its physical dimensions including its eye/field lens is half that of the Nagler .The Ortho has a eye relief of 7.2 mm and a AFOV of 45' , I must admit these two characteristics of the UO ortho line have made me reluctant to try/purchase them .

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Ok to Tuesday night where I tried it for the first time in poor to average conditions {5/10} through my 10"SCT yielding a magnification of 277x and a TFOV of 0.16 {Nagler TFOV 0.2}. Heres a generated map from Cartes du ceil for the night showing the FOVs for each eyepiece .

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First striking impression I had of the ortho was the eye relief was comfortable and the FOV was good , no worries on both accounts . At that magnification I had to fold down the rubber guard to prevent myself from inducing vibrations but it was surprising easy to look though and take in the view...granted the LX200 tracking helps. Seeing wasn't very good but with a little patience surface features on Jupiter popped in and out . The most prominent feature where a series of white spots in the SEB and distinctive blotching in the NEB . Interestingly I took some quick AVIs with the TouCam and it recorded a series of blueish festoons off the NEB and some white spots in the sth temperate belts. These features I didnt see through the eyepieces.


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In quick comparison to the Nagler the Ortho performed identically to my eyes . I really couldn't tell a difference and it would be a case of splitting hairs , maybe better conditions may reveal something . The Nagler has that beautiful trade mark immersing feel but to take in the complete field of view the eye has to come very close to the eye lens .The Ortho on the other hand is less distracting but still comfortable . Im not sure which is better that a relatively cheap eyepiece can perform {at this stage anyway} as well a top model or a multi element eyepiece like the nagler can be on par for sharpness as a ortho {at this stage anyway}.
I hope to add some more comments when conditions improve but the UO ortho range has me certainly thinking of adding a couple more to my collection.

[Merlin66 (Ken)]

Back in the 70's I changed from a 6" f8 to a 12" f5 telescope and found my old ramsden eyepieces could not cope with the fast f5, I changed to UO orthos and they worked reasonably well. As my eye become more "trained" over the years I found the distortions to be more and more objectionable and ended up selling them to go to TV Plossls. The orthos only have three glass elements, and although the quality of glass has improved, my opinion is that the basic design is still limited to shorter EP focal lengths and slow systems ie > f8.

There's not much to beat a good plossl or Nagler, especially on fast systems < f5.

[gts055 (Mark)]

I beg to differ here, orthoscopic eyepieces are a 4 element design, while huygens and kellner have two and three elements respectively. The ramsden is a variation of the huygens. Orthoscopics are very well corrected, albeit narrower field than the plossl. Plossls may be 4 or 5 element.
Regards Mark

[Merlin66 (Ken)]

You are indeed correct! Got mixed up with the single eyelens. No excuse!

[ausastronomer (John Bambury)]

Merlin,

I was reading down and noticed you rectified your confusion between the UO orthos and the older 3 element designs like Ramsdens and Kellners

I own a full set of the newer UO HD orthos, in addition to a set of Pentax XW's. I have a 10"/F5 newt and the UO HD orthos give excellent views to the Edge of Field in my F5 scope, which is as fast as I have used them in. I think they may struggle at anything faster than F5.

I really have no need to keep the UO HD orthos as the Pentax XW's cover all bases, but I just like them because they are so small, light and easy to handle and give superb image quality. They also make great "loaners" if someone needs something at a specific focal length at a star party in a hurry.

CS-John B

[MarkN]

ausastronomer

Hope you can assist here.

I'm in the process of deciding on a high power UO HD EP for the new 10" Dob. As can be seen, I already have an 8 mm TV Plossl which yields 156X and am looking for something around 220-250X.

As there are HDs in 5 mm and 6 mm, I'd be iinterested to read what have you determined to be the useable limit in power from your HD EPs? in your 10" Newt.

Mark.

[Starkler (Geoff)]

Mark , I think the 6mm would get a lot more use than the 5mm

[ausastronomer (John Bambury)]

Hi Mark,

If you are only buying 1 of them, my choice would be clearly the 6mm in preference to the 5mm. As Geoff says, the 6mm will see a lot more use than the 5mm. On steady nights you are going to wish you had more power available than the 6mm, so at a later stage you may wish to look at also buying the 5mm. I would definately buy the 6mm before the 5mm.

CS-John B

[MarkN]

Geoff & John,

Thanks fellas, duly taken on board. Will be talking to Daniel very soon.
Damn these dobs; been looking at the Obsession site a bit too much lately.
Just as well I can't afford one just yet!

Mark.