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Eyepiece Designs and Sacrifices


Naemeth

Eyepiece Design Sacrifices  

54 members have voted

  1. 1. What is the most important characteristic?

    • Astigmatism Control
    • Distortion Control
    • Field Curvature Control
    • Lateral Colour Control
      0
    • Cast of Colour Control ('Warm' vs 'Neutral' Tone)
      0
    • Good Contrast
    • Internal Reflection Control
    • Eye Relief
    • Kidney Beaning Control
    • Ghosting Control
    • Sharpness
  2. 2. What is the least important characteristic? (that you are willing to sacrifice)

    • Astigmatism Control
    • Distortion Control
      0
    • Field Curvature Control
    • Lateral Colour Control
    • Cast of Colour Control ('Warm' vs 'Neutral' Tone)
    • Good Contrast
      0
    • Internal Reflection Control
    • Eye Relief
    • Kidney Beaning Control
    • Ghosting Control
    • Sharpness
      0


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As most people know, (and if you don't - you should), all eyepiece designs come with drawbacks, no eyepiece is perfect in every regard, and they always have at least one aberration (eg Naglers and Pincushion Distortion, Abbe-Orthoscopics and low eye relief and small field of view, Erfle and often astigmatism below F/6 etc.). My question to you all is this - what is the most important characteristic that you need, and what would you sacrifice?

I realize that priorities may be different for Deep Sky, Planetary, Lunar and Solar and so I have allowed multiple choice ;). If you have any other suggestions then please comment :).

Looking forward to hearing everyone's thoughts :).

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I use slow scopes (F6 or slower), so my priority is sharpness, contrast and stray light (scatter, internal reflection, ghost ...)

Correction for coma, astigmatism, spherical aberration and other corrections associated with fast scope doesn't really concern me as much.

Colour cast depends as much on the scope as the eyepiece, so it's even less relevant

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For me personally :):

Eye relief can be sacrificed (<2.5mm exit pupil)

FOV can be sacrificed (sorry I didn't put that one in :()

Lateral Colour (doesn't bother me)

Colour Cast (doesn't bother me)

Most important:

Contrast and Sharpness, without a doubt.

I've come to learn that Ghosting really annoys me, and internal reflections are equally annoying.

Thanks for your input everyone, keep them coming :).

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I put coma correction as an eyepiece concern and although that is true I would expect to buy a dedicated coma corrector to work on all my eyepieces rather than pay for each eyepiece to have that specifically factored into the design.

All my scopes are fast and I dont see that changing in the future, they may get faster perhaps.

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Just to pick up on internal reflections. It depends what you are looking at but ,take Sirius, that gives some strange light flash in the FOV in some of my better eyepieces and none of them are bad, it only seems to be on Sirius though. Maybe this effect is not internal reflection at all but something else, it don't seem to happen all the time either. What ever it is the Meade 5.5mm seems to get it more than others.

Alan.

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Just to pick up on internal reflections. It depends what you are looking at but ,take Sirius, that gives some strange light flash in the FOV in some of my better eyepieces and none of them are bad, it only seems to be on Sirius though. Maybe this effect is not internal reflection at all but something else, it don't seem to happen all the time either. What ever it is the Meade 5.5mm seems to get it more than others.

Alan.

I'm not sure whether or not it is Alan, how is it when you look at Jupiter? What I've noticed is some eyepieces aren't very well controlled with regards to internal reflections, which can mean you get light from Jupiter without it actually being in the FOV (when it's just outside of the FOV). This is the kind of thing that is very off-putting.

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Interesting that color cast rates as relatively unimportant at the moment. On the Cloudynights website they go on about this issue all the time - it seems a really big deal to some !

Light scatter is my particular bug bear at the moment when viewing dim objects close to bright ones, eg: Sirius A & B, Enceledus & Saturn. Slight variations in light scatter control can make the difference between seeing and not seeing such objects.

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Interesting that color cast rates as relatively unimportant at the moment. On the Cloudynights website they go on about this issue all the time - it seems a really big deal to some !

Light scatter is my particular bug bear at the moment when viewing dim objects close to bright ones, eg: Sirius A & B, Enceledus & Saturn. Slight variations in light scatter control can make the difference between seeing and not seeing such objects.

Indeed, I read that all the time. I just can't understand why it's a big deal, as long as the view is sharp and contrasty, it doesn't really matter ;). Each to their own I guess...

http://www.cloudynights.com/ubbthreads/showflat.php/Number/4798653

Sorry if this is putting you on the spot at all John, but which eyepieces do you feel best control light scatter, and can you think of any that haven't managed to control it?

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....Sorry if this is putting you on the spot at all John, but which eyepieces do you feel best control light scatter, and can you think of any that haven't managed to control it?

The best I've used at this was a TMB Supermonocentric. The Baader GO's and CO's, Pentax XW's and Ethos (in that order) are pretty good too.

I've tried too many to list that don't quite match the above but they were probably still decent eyepieces.

I rate light transmission quite highly too. There were some tests published on this a while back with some quite surprising results such as certain multi-element eyepieces having greater light transmission than "low glass" designs. I've not seen a more recent set of tests covering current models though.

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The best I've used at this was a TMB Supermonocentric. The Baader GO's and CO's, Pentax XW's and Ethos (in that order) are pretty good too.

I've tried too many to list that don't quite match the above but they were probably still decent eyepieces.

I rate light transmission quite highly too. There were some tests published on this a while back with some quite surprising results such as certain multi-element eyepieces having greater light transmission than "low glass" designs. I've not seen a more recent set of tests covering current models though.

So I think I'll go for the BCOs at some point ;). The Monocentrics are out of production aren't they?

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I thought those on CN who complain about colour cast are the ones who owned all the top eyepiece (sometimes in pairs) and many others. May be they just reached a stage where everything is near perfect and there is nothing else they can complaint about, so they have a go on the colour cast.

For light scatter Pentax XO > Nikon NAV HW > BGO > Nikon SW/MC wide* > Vixen LVW >> Pentax XL Zoom

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Naemeth,

I never really have a problem with Juipter with any eyepiece that I can recall. I mentioned one or two time in Delos work that if you get the planet in the rigth place outside of the FOV you can sometimes see a ghosting inside the FOV, but this is not my classic understanding of ghosting. No Sirius seems to like to mess about and believe me I have spent enough time looking at it in the last two months or so. I think it is some type of reflection effect but not a normal one.

This is what you wrote, sorry I didn't read it fully, be up since 0400 looking a Antares. I gather this annoys you, it is not the sort of thing that you would expect from a Televue eyepiece but I am sure I have seen it in a few. Because it is no big deal to me I can't remember which. When the planet is in the FOV I never see a problem

Anyway congratulations on a very interesting thread.

Alan

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Naemeth,

I never really have a problem with Juipter with any eyepiece that I can recall. I mentioned one or two time in Delos work that if you get the planet in the rigth place outside of the FOV you can sometimes see a ghosting inside the FOV, but this is not my classic understanding of ghosting. No Sirius seems to like to mess about and believe me I have spent enough time looking at it in the last two months or so. I think it is some type of reflection effect but not a normal one.

This is what you wrote, sorry I didn't read it fully, be up since 0400 looking a Antares. I gather this annoys you, it is not the sort of thing that you would expect from a Televue eyepiece but I am sure I have seen it in a few. Because it is no big deal to me I can't remember which. When the planet is in the FOV I never see a problem

Anyway congratulations on a very interesting thread.

Alan

Haven't looked through a televue eyepiece yet ;).

Ghosting, to me anyway, is an effect similar to that when you look through a window at a bright light, only the window is covered in condensation, this causes a visible halo around the light, dimming it. This is what happens when you look at Jupiter through eyepieces with ghost issues.

I believe internal reflections cause the effect of seeing light from outside the FOV in the FOV.

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I thought those on CN who complain about colour cast are the ones who owned all the top eyepiece (sometimes in pairs) and many others. May be they just reached a stage where everything is near perfect and there is nothing else they can complaint about, so they have a go on the colour cast.....

Well put and dead accurate I reckon Keith :grin:

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I put coma correction as an eyepiece concern and although that is true I would expect to buy a dedicated coma corrector to work on all my eyepieces rather than pay for each eyepiece to have that specifically factored into the design.

All my scopes are fast and I dont see that changing in the future, they may get faster perhaps.

coma can't be corrected by an eyepiece, it's a feature of the primary. the astigmatism of lesser quality eyepieces can mask coma though, although when you replace the eyepiece with a better one, the coma is then revealed in all it's glory (until you then buy a corrector of course!). and the treadmill of spending trudges on :grin:

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it depends on the type. I have a Paracorr which is more like a Barlow. they are pricy new but I got mine used at a bargain price.

the Baader one screws into the eyepiece threads and would have to be swapped about.

there's also what looks like a very good GSO one but better start a new thread if you want to discuss in detail.

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For a start, colour cast is irrelevant for DSO observer.

It's more important for planets, until you start using filters, which makes it irrelevant again. A Neodymium or LPR filter is go to have far greater effects on the colour balance than the eyepiece.

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For a start, colour cast is irrelevant for DSO observer.

It's more important for planets, until you start using filters, which makes it irrelevant again. A Neodymium or LPR filter is go to have far greater effects on the colour balance than the eyepiece.

I would say it may make some difference to clusters, but certainly not galaxies. I at least know filters can have a dramatic effect on colour of clusters (M45 for example).

I wasn't sure whether the Baader filter made any difference to the colour balance, but good to know :).

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