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Old 28-12-2016, 01:00 PM
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Planetary

Do I really need to try and find a Pentax XO5mm for planetary and double star work in a 120mm APO? Perhaps there is a viable alternative?
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Old 28-12-2016, 01:24 PM
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How fussy are you? What eyepieces do you have already?
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Old 28-12-2016, 01:41 PM
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There is a much better alternative for planetary observing, binoviewing. I have a 5 XO, great eyepiece, but I see more using my Abbe Orthos and Denk bino viewer.

I only took up bino viewing about 3 years ago, but I've been converted. Everything in the Solar System just looks so much better. For deep sky, I still prefer single eyepieces.

If you are looking for a good quality, cheaper alternative to the 5 XO, then the Fujiyama Ortho is value for money.
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Old 28-12-2016, 02:44 PM
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Gentlemen,

Thank you for the prompt responses. In answer, I am really picky, and have a set of Fujiyama HD Orthos.

Allan, I have sent you an email regarding binoviewers.
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Old 29-12-2016, 06:47 PM
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I'm using Vixen SLV's with my 130!mm triplet APO which is f/7 .. these are very very nice imho especially the 4 and 6 mm. They are an improvement on the older LVs - not a hint of colour, and sharp to the edge with 20mm eye relief. Also very comfortable to use, which orthos aren't.
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Old 29-12-2016, 08:44 PM
ausastronomer (John Bambury)
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Originally Posted by Greenswale View Post
Gentlemen,

Allan, I have sent you an email regarding binoviewers.
Hi Wren,

Just be aware that binoviewers aren't for everyone. Some people love them, some people don't. It's maybe 50/50.

About 8 years ago Scott Mitchell (WavelandScott) very kindly loaned me his binoviewers and several pairs of premium eyepieces for me to trial, with a view to buying a pair for myself. The pair he loaned me were the top of the line Denkmeier model at the time and the eyepieces were all premium pairs, including 14mm and 21mm Denkmeiers. I also had access to pairs of 24mm Panoptics, 13mm Nagler T6's and 8mm Radians, which were the eyepiece pairs that went with the 12" 3RF binocular telescope I was custodian for at the time. I spent hours and hours and hours trying to like those binoviewers; and as hard as I tried to like them I just never at any time preferred the view through the binoviewers over the single eyepiece view, on the moon, planets or anything for that matter. I tried them in my 10", 14" and 18" Newtonians on multiple occasions over many hours and at no time did they ever float my boat. I wanted to like them because I enjoy 2 eye viewing and have over many years spent a lot of time observing with premium binocular style optics including a 12" binocular telescope and a pair of 25 x 150 Fujinon Binoculars. Unfortunately, a binoviewer isn't quite the same and just didn't cut it for me.

I can only suggest you try (like I did) before you run headlong down the binoviewer path. You may well fall in love with them. On the other hand you may not. It's an expensive road not to like them.

Cheers,
John B
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Old 29-12-2016, 09:01 PM
ausastronomer (John Bambury)
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Do I really need to try and find a Pentax XO5mm for planetary and double star work in a 120mm APO? Perhaps there is a viable alternative?
Hi Wren,

The 5mm XO is a really good eyepiece optically, one of the very best. It's eye relief is very short and it isn't a comfortable eye piece to use for long periods IMO. I find that I can see just as much observing with an eyepiece like a 5mm Pentax XW because I am a lot more comfortable and relaxed, whereas observing with the 5mm Pentax XO is an effort, particularly for longer periods. If you're striving for the very best then a top class simple eyepiece like the 5mm Pentax XO, or TMB Supermono, or Astrophysics SPL, or Zeiss Abbe will give up a fraction more in moments of steady seeing than a high class long eye relief widefield, but there isn't a huge difference either.

I would rather be comfortable and relaxed with good detail, than straining to use the eyepiece, notwithstanding it may show a fraction more. The way I look at it is that a 5mm Pentax XW in my 10" or 14" Newtonians is going to show me a heck of a lot more than a 5mm Pentax XO in a 120mm APO, so I am not missing anything compared to owners of 5mm XO's and the like.

Cheers,
John B
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Old 30-12-2016, 12:12 PM
SkyWatch (Dean)
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Hi Wren,
I find my 3-6mm Nagler is a great eyepiece for planetary and doubles. Very sharp and good contrast, and ideal for nights of variable seeing, plus 10mm eye-relief makes it very comfortable.
Maybe the purists might be able to pick a slightly better view with a top of the range fixed eyepiece- but I'll leave it up to them to comment... I find the ability to find the ideal power for the conditions a real bonus (and it holds focus across the magnification range).
I have seen them advertised second-hand here occasionally.
All the best,

Dean
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Old 31-12-2016, 04:08 PM
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Thank you for the many replies.

Following discussion with Alan, and from advice here, binoviewers are not for me. Astigmatism in one eye, and 120mm aperture rule them out.

Until recently, I enjoyed a full range of Pentax XW in a variety of Newtonians. With the physical effects of age, and reducing aperture, I found that eyepiece image was better for me on reduction of the amount of glass between me and the object. Thus the move to Orthos, and the departure of the quite brilliant XWs.

While recognising the convenience advantage of a zoom type eyepiece, a search suggests that use of individual focal lengths will present better views.

I still have one excellent eyeball and wish to take advantage of it while it lasts! Tight eye relief is not an issue, my 4mm has a quoted 3.4mm eye relief, thus the thought of a the XO.

Summarising, advice given and my preference suggests a minimal glass, fixed focal length type eyepiece. So, what eyepiece offers direct competition to an XO?
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Old 01-01-2017, 12:06 AM
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At 5mm, the only comparable eyepieces to the XO would be the TMB SMC and AP SPL.

I've had the SMC's and the eye relief is more generous than the XO. They don't work well in fast dobs, but will be nice in your refractor. The tiny 30 degree field of view did eventually get to me.

The AP SPL's are exceedingly hard to get hold of, and that fact alone virtually rules them out. They also have better eye relief, but the XO generally gets more favourable reviews.

I chose the 5 XO because it was easy to acquire and works well in all my scopes and I preferred it to my 5 TMB SMC.

So, I think you're back to where you started from.
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Old 01-01-2017, 07:09 AM
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Thanks Allan, time for me to work the 'Wanted' ads.

I really do appreciate the learned responses to my question, thanks people!
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Old 01-01-2017, 11:59 AM
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Quote:
Originally Posted by Greenswale View Post
I still have one excellent eyeball and wish to take advantage of it while it lasts! Tight eye relief is not an issue, my 4mm has a quoted 3.4mm eye relief, thus the thought of a the XO.

Summarising, advice given and my preference suggests a minimal glass, fixed focal length type eyepiece. So, what eyepiece offers direct competition to an XO?
Quote:
Originally Posted by ausastronomer View Post
If you're striving for the very best then a top class simple eyepiece like the 5mm Pentax XO, or TMB Supermono, or Astrophysics SPL, or Zeiss Abbe will give up a fraction more in moments of steady seeing than a high class long eye relief widefield, but there isn't a huge difference either.
Hi Wren

As Allan mentioned, at "exactly 5mm" your choices are limited to the Pentax XO, Astrophysics SPL or the TMB Supermono. The 30 degree AFOV of the Supermonos doesn't work for me and neither does their poor off axis performance in faster telescopes. The 5mm Astrophysics SPL is extremely hard to obtain, so as Allan mentioned you're back to where you started and the 5mm Pentax XO is likely to be your best option.

If you're striving for the very best optically and you move away from "exactly 5mm" your options expand to include the 4mm and 6mm Zeiss Abbes (version 1 or Version 2 are both exceptional) and the 3.8mm Pentax XP. The 3.8mm Pentax XP has a .965" barrell and about 2.8mm of eye relief, but it's an exceptional performer optically. It is normally sourced with the adapter supplied as well, either in Aluminium or Delrin. The 4mm and 6mm Zeiss Abbe's and the 3.8mm Pentax XP would likely be marginally better performers optically, than whatever else you might currently be using at these focal lengths.

Cheers
John B
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Old 02-01-2017, 07:29 AM
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Thanks John. Should my search for the XO fail, Zeiss will certainly Become a target.

I have had another thought. Going to have a look at the Baader BBHS diagonal, certainly some gains for me there.
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Old 09-01-2017, 12:52 PM
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Thanks John. Should my search for the XO fail, Zeiss will certainly Become a target.

I have had another thought. Going to have a look at the Baader BBHS diagonal, certainly some gains for me there.

G'day Wren, good idea to look at the diagonal. Not sure if this works for you (physique or preference may mean it doesn't), but leaving the diagonal out altogether whenever you can might result in a greater improvement than going from KK5 to XO5 or SMC5. Cost: nil. I don't use mine for anything below about 70° anymore.

I expect an XO will be cheaper and/or easier to obtain than a ZAO.
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Old 10-01-2017, 09:22 AM
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Thanks Mirko. My preference would be no diagonal, however, being over 70 means that it can only remain a preference!

Might take up yoga.........
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Old 10-01-2017, 02:27 PM
N1 (Mirko)
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[...] I spent hours and hours and hours trying to like those binoviewers; and as hard as I tried to like them I just never at any time preferred the view through the binoviewers over the single eyepiece view, [...]
G'day John, sorry for the diversion but I'm quite interested in your observations with the binoviewers vs monocular vision. I've been thinking about binoviewers myself but never did go down that path but still kept wondering. Are you able to say what the main reason might have been, for you not liking them over single EP viewing? From your comments I'm assuming it wasn't to do with the usual focusing/weight/cost issues but the actual viewing? Cheers
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Old 11-01-2017, 06:44 AM
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A planetary eyepiece you might consider, because the spot diagram indicates it's the sharpest eyepiece they've ever produced, is the TeleVue DeLite.
It's 62°, so it could be a "general use" eyepiece as well.
And it's no accident the focal lengths start at 3mm, then 4mm, 5mm, 7mm, 9mm, etc.

There are many fine "planetary-oriented" eyepieces out there now. Some have long eye reliefs, some short, but you can find just about anything you want in a focal length from 1.6mm to whatever. It's a great time to look for short focal length ultra-sharp eyepieces.

Last edited by Don Pensack; 11-01-2017 at 06:55 AM.
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Old 11-01-2017, 06:50 AM
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G'day John, sorry for the diversion but I'm quite interested in your observations with the binoviewers vs monocular vision. I've been thinking about binoviewers myself but never did go down that path but still kept wondering. Are you able to say what the main reason might have been, for you not liking them over single EP viewing? From your comments I'm assuming it wasn't to do with the usual focusing/weight/cost issues but the actual viewing? Cheers
One thing you have to be aware of with binoviewers is that if the field is wide enough, you will not see either the right or left side of the field with direct vision--peripheral vision, yes, but not direct vision. You can raise and lower both eyes and see the top and bottom of the field at the edge, but rolling the head, even a little, to look at either the right or left edge of the field takes one of your eyes away from the exit pupil.
As a result, many hardcore binoviewer users prefer 40-60° fields, for that reason.

Another issue is substantial light loss and/or chromatic issues somewhere in the field, too. Maybe they're great for planets in a tracking scope, but I am like John B. and never really took to them like many. I always preferred the single eye view.

Now, my dominant eye has image resolution problems, so binoviewers don't even help planets. I can see the appeal, though, given it is often more comfortable to view with both eyes.
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Old 11-01-2017, 08:16 AM
ausastronomer (John Bambury)
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G'day John, sorry for the diversion but I'm quite interested in your observations with the binoviewers vs monocular vision. I've been thinking about binoviewers myself but never did go down that path but still kept wondering. Are you able to say what the main reason might have been, for you not liking them over single EP viewing? From your comments I'm assuming it wasn't to do with the usual focusing/weight/cost issues but the actual viewing? Cheers
Hi Mirko,

The problems were all to do with the viewing experience. Cost wasn't an issue, at the time; and weight wasn't a concern either. All my scopes were medium to larger scopes (10" to 18") and were all fitted with Feathertouch Focusers and Servocat tracking. At the time I had Scott's bino's Saturn was very well placed (at Zenith just before midnight) so I spent a lot of time on it and I also spent a lot of time on the moon, when it was around.

Don has pretty much hit the nail on the head.

With some of the wider eyepieces I kept losing the exit pupil trying to take in the full field of view. This was further compounded by the fact that I wear high quality multifocals when I observe and I often found I was looking outside the fully corrected area of my glasses trying to take in more of the FOV. I had observing with multifocals down pat with single eyepieces in learning exactly how to observe with them and not suffer any loss of image quality. The funny thing is I have no problem using binoculars with long eye relief combined with my multifocals, but both of my binoculars have a fairly narrow FOV for their size and aperture.

The other thing I really didn't like was the drop in image brightness on Saturn. Having observed with large aperture scopes for a long time I guess my brain was just accustomed to expecting Saturn to be at a certain brightness level. It was a bit the same on the moon. I observe the moon unfiltered in all my scopes including the 18", as I get more detail unfiltered. Again I guess I am accustomed to perceiving it should be brighter than what I was seeing. The moon in binoviewers would work for a lot of people because they can't cope with a really bright image and dimming it without the use of a filter would help them, but it wasn't for me.

The other thing was that I had spent quite a bit of time using a 12" binocular telescope and it just wasn't remotely close to the same experience in regard to the 3D effect on DSO targets like Eta Carina, 47 Tuc and the like. Maybe I had been spoilt somewhat in this regard and my expectations on DSO's were too high. I still have ready access to the 12" binocular telescope, so not much point in me buying a binoviewer.

Cheers,
John B
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Old 11-01-2017, 11:39 AM
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Do I really need to try and find a Pentax XO5mm for planetary and double star work in a 120mm APO? Perhaps there is a viable alternative?
I find that being comfortable at the eyepiece with decent eyepieces is more important when viewing planets. To me this usually means a 130mm apochromat on a tracking mount with binoviewers and a pair of NaglerT6 or Tak LE eyepieces while seated comfortably at just the right height.

This allows me to see detail that is only revealed in those moments of perfect seeing. If I am mono viewing I find that covering my non-viewing eye while keeping it open is better than closing it but for me binoviewers are a far more relaxing way to view planets.

I haven't tested the binovues in the big scope yet.....
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