To many/most people ER and AFOV form part of the optical performance. An ortho with tiny field and eye relief is no use to me since I like simple alt az undriven mounts.
Hi Morton
I just discovered these myself and am really impressed with them - various manufacturers (Vixen was first) have made their standard AZ mounts and then an after market gadget from JMI called 'train and track' is a set of small motors which when attached to the mount and via simple movements will learn to follow a target. So you get the quasi tracking of a computerised mount without the hassles.
So - no goto but it will learn to track objects via you simply moving the mount yourself and thus mimic your movements when following a target. They are small and portable and gives your AZ mount and whole new lease on life
I just discovered these myself and am really impressed with them - various manufacturers (Vixen was first) have made their standard AZ mounts and then an after market gadget from JMI called 'train and track' is a set of small motors which when attached to the mount and via simple movements will learn to follow a target. So you get the quasi tracking of a computerised mount without the hassles.
So - no goto but it will learn to track objects via you simply moving the mount yourself and thus mimic your movements when following a target. They are small and portable and gives your AZ mount and whole new lease on life
Hi,
Yes, I've seen them, and they can be fitted to my mount, but then I need a power supply and the "simplicity" of the mount is lost. Plus it requires extra cash!
I've seen a number of reviews saying that Pentax XW and Tele Vue Delos give performance that is close to orthos but with extra field of view and comfort, and I think that's why people pay the big money for those brands, not because of glitzy magazine ads.
Yes, I've seen them, and they can be fitted to my mount, but then I need a power supply and the "simplicity" of the mount is lost. Plus it requires extra cash!
I've seen a number of reviews saying that Pentax XW and Tele Vue Delos give performance that is close to orthos but with extra field of view and comfort, and I think that's why people pay the big money for those brands, not because of glitzy magazine ads.
Ironically, I don't have any orthos myself however I have had Delos and do have both Pentax XW and Takahashi LE eyepieces. There is strong debate over Delos v XW and from my experience/eyes I found the XW still to be better.
Now, in side by side comparison between the 5mm XW and Takahashi 5mm LE - The XW does indeed have 'more' eyerelief and a larger field of view.
I found the Takahashi 5mm LE still quite comfortable with about 12mm of ER and only has about 52 fov. However, as far as sharpness, lateral colour etc etc and generally being able to perceive more - it is discernably the better EP
To many/most people ER and AFOV form part of the optical performance. An ortho with tiny field and eye relief is no use to me since I like simple alt az undriven mounts.
No problem - point taken - but as I clearly stated - excluding ER and AFOV - otherwise you are engaging in an apples v oranges analysis.
If you need ER and more AFOV then the best eyepiece in existence including value for money has to be IMHO the Pentax XF 8.5mm
With these points in mind and putting aside the variables of AFOV and ER I haven't seen any Televue eyepiece which wasn't easily beaten in optical performance by some Japanese made simple ortho's which can be bought for about 25% the cost of most Televue eyepieces
I certainly have no loyalty to Tele Vue...heck, I only have one Tele Vue product in my inventory, a 2x Barlow! I do agree that there are Japanese and other sources that produce eyepieces as good and even better in some respects. My eye and observing needs decided that the Pentax XWs were best overall over Delos, Ethos, Radian, Panoptic, Nagler. But the XWs are a far cry from being 1/4 the price of the Tele Vues If you can find me something that performs as well as a Pentax XW, that is Japanese made, comes in a full range of focal lengths, has the same operating parameters of ER and AFOV, similar robust construction, optically as precise, and costs street only $80 or so please let me know!
And also for many of us, it is more than just the on-axis image. So AFOV is important, as is eye relief, as is lateral color, off-axis astigmatism, rectilinear distortions, edge of field brightening, overall background blackness, exit pupil behavior (i.e., blackouts, kidney bean, overall comfort), stray light suppression, contrast, physical housing construction robustness, size, weight, ability to handle fast focal ratios, etc. So many many factors that each of us weight differently. And one really can't say a 40 degree eyepiece is the same as a 70 degree eyepiece, or if one wants more TFOV simply use a longer focal length. These are not valid as the exit pupil changes and how well the target is portrayed then changes. So in all fairness, if one is comparing an 82 degree product, then need to stay at or near the same AFOV. And if one is comparing a 20mm ER product, they need to stay apples-to-apples and only assess it against other similar long eye relief products.
Anyway, my 2 cents
Last edited by WilliamPaolini; 29-07-2015 at 04:57 AM.
I think it was pretty clearly stated that folks need to be attentive in not going off the rails with their reasoning/explanations and thus 'not' fall prey to 'apples v oranges' comparisons.
The 1/4 the price statement is in reference to good quality orthos NOT Pentax XWs
The moment you start introducing other factors of ER and AFOV you are going beyond what was represented and stated as the bnefit of the orthos
I certainly have no loyalty to Tele Vue...heck, I only have one Tele Vue product in my inventory, a 2x Barlow! I do agree that there are Japanese and other sources that produce eyepieces as good and even better in some respects. My eye and observing needs decided that the Pentax XWs were best overall over Delos, Ethos, Radian, Panoptic, Nagler. But the XWs are a far cry from being 1/4 the price of the Tele Vues If you can find me something that performs as well as a Pentax XW, that is Japanese made, comes in a full range of focal lengths, has the same operating parameters of ER and AFOV, similar robust construction, optically as precise, and costs street only $80 or so please let me know!
And also for many of us, it is more than just the on-axis image. So AFOV is important, as is eye relief, as is lateral color, off-axis astigmatism, rectilinear distortions, edge of field brightening, overall background blackness, exit pupil behavior (i.e., blackouts, kidney bean, overall comfort), stray light suppression, contrast, physical housing construction robustness, size, weight, ability to handle fast focal ratios, etc. So many many factors that each of us weight differently. And one really can't say a 40 degree eyepiece is the same as a 70 degree eyepiece, or if one wants more TFOV simply use a longer focal length. These are not valid as the exit pupil changes and how well the target is portrayed then changes. So in all fairness, if one is comparing an 82 degree product, then need to stay at or near the same AFOV. And if one is comparing a 20mm ER product, they need to stay apples-to-apples and only assess it against other similar long eye relief products.
Anyway, my 2 cents
Yep - I have to agree - other than ER and AFOV I tend to think the simple ortho can outperform most Televue eyepieces on all the attributes you mention and they cost a quarter of the price.
Unfortunately, I wouldn't even dream of making any statement concerning what are the supposed "preferences" of the majority of astronomers
Having two unguided 10" dobs I totally agree. That's why I went down the Delos route as I wanted a comfortable middle ground between ER and AFOV.
I'd love an eyepiece range with 20mm ER and 72+ AFOV for a quarter of the price of the Delos, though.
I own nothing that tracks or guides. I used to think my Naglers (the first EPs I owned) were virtually essential for dobbing and other modes of altazzing and med-high powers, until I decided to actually take note of how often I observe objects outside of the field that, say, a plossl would show. The answer was: approximately never. Instead, I found myself centering the target much more often than the Nags would require. My ortho and plossl collection has been growing ever since.
I own nothing that tracks or guides. I used to think my Naglers (the first EPs I owned) were virtually essential for dobbing and other modes of altazzing and med-high powers, until I decided to actually take note of how often I observe objects outside of the field that, say, a plossl would show. The answer was: approximately never. Instead, I found myself centering the target much more often than the Nags would require. My ortho and plossl collection has been growing ever since.
Exactly
Folks - please don't misunderstand me - Televue has given us that widefield experience and options for people who can't tolerate crushing their eyeball
However, putting those design innovations aside a good quality classic such as ortho's and plossls still pack a huge wallop
Ironically, inspired by this dialogue last night I tried out an old genuine Takahashi .96 4mm orthoscopic (it took me two weeks to get an adapter for it)
I put it into my refractor last night which was a particularly clear and cold night. Pointed the scope at Saturn and almost fell out of my chair
Probably one of the best views with a 'small' refractor I have ever seen
The best analogy I can give from life experience was the first time I looked at a full HD television.
I decided to actually take note of how often I observe objects outside of the field that, say, a plossl would show. The answer was: approximately never. Instead, I found myself centering the target much more often than the Nags would require. My ortho and plossl collection has been growing ever since.
I don't doubt the visual qualities of an ortho or a plossl eye piece, but you already answered in your second last sentence why I prefer a wider field in an eye piece - less centering of the target. And the eye relief is usually horrible in an ortho or a plossl.
I don't doubt the visual qualities of an ortho or a plossl eye piece, but you already answered in your second last sentence why I prefer a wider field in an eye piece - less centering of the target. And the eye relief is usually horrible in an ortho or a plossl.
I think "horrible" is a strong word - certainly some eyepieces have more than others. Hence the subjective preferences to astronomy
Astronomy equipment is all about compromises - in this case it is a matter of trading comfort for optical clarity
Which if I am not mistaken essentially appears to bring us full circle in that setting aside the parameters of ER and AFOV most good quality ortho's will optically outperform most Televue eyepieces and at approximately a quarter of the price
Which if I am not mistaken essentially appears to bring us full circle in that setting aside the parameters of ER and AFOV most good quality ortho's will optically outperform most Televue eyepieces and at approximately a quarter of the price
If you can find me something that performs as well as a Pentax XW, that is Japanese made, comes in a full range of focal lengths, has the same operating parameters of ER and AFOV, similar robust construction, optically as precise, and costs street only $80 or so please let me know! 
