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Low power EP advice

Sirius Bizness

By Sirius Bizness
in Discussions - Eyepieces

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Sirius Bizness

Sirius Bizness

Posted
Posted

I really like the wide FOV from my low power EPs however I have been disappointed by the star shape from around 60% of the FOV onwards. I started with the 32mm Panaview but the stars look like lines towards the edges. I upgraded to the 31mm Hyperion but the same again. I have recently been using my MN190 so can't recall exact performance in the ED120. I thought the MN190 was coma free so I am assuming all the effect is from the EP? Therefore I am looking to upgrade again.

I can't afford the 31mm Nagler so I am looking at the 35mm Panoptic. However I am wondering if any EP will give me the pin point stars I am looking for across the FOV in my scopes. Is the 35mm Panoptic a good choice? Will it work well with my MN190?

Any advice greatly appreciated.

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Capricorn

Capricorn

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I don't think I have read of any wide eyepiece giving point stars across the whole field.

I would say that you are gaining field at the expense of edge sharpness.

For a simple arguement, lens are spherical, spherical is not the ideal and at the edges of the lens the errors and aberrations are maximised. Adding more glass can minimise some errors but they in turn add errors. Eventually you cannot get any more out of the system.

Read that a good idea is to stop at 68 degrees.

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John

John

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All the Tele Vue eyepieces are individually tested to work well down to F/4. Mine are sharp right to the edge with my ED102 F/6.5 and ED120 F/7.5 refractors and my 250mm F/4.8 newtonian although the latter does show coma of course.

I think the mak-newtonian design has around 30% of the coma of a similar aperture / focal ratio newtonian so it's much reduced but not coma-free.

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DirkSteele

DirkSteele

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I have the 35mm Panoptic, which I use with all my scopes, the fastest of which is the the f/6.2 APM TMB 105 Apo refractor, and it produces pin point stars across the 3.4 degree field of view. I think it is an excellent EP, and well worth the investment.

Clear skies,

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Naemeth

Naemeth

Posted
Posted

Stars looking like lines sounds like Astigmatism (the very same effect I get, very noticeably, when I take my glasses off when looking in the eyepiece). TeleVue eyepieces are all tested down to F/4, and if you can't afford a Panoptic, how about a nice used 32mm TeleVue Plossl? After all, wide fields only have a point if the field is sharp enough to make use of it.

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michael.h.f.wilkinson

michael.h.f.wilkinson

Posted
Posted

The MN 190 is F/5.3, so a Panoptic 35 gives an exit pupil of 6.6mm, which can produce washed out backgrounds. Why not go for the Explore Scienitific 30mm, which over here is cheaper than the Panoptic, and at an exit pupil of of 5.66 will produce a darker background. The reports on these EPs are very good indeed.

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alan potts

alan potts

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The only eyepieces that will give you point stars across the full field are all expensive, My 30mm Meade UWA is as good as you would want in the 190mm M/N I have one, but even that is 250 pounds, the 24mm is less at about 200 but that is still a fair bit of money. Other than that it is S/H Televue and you would still be looking at 200 plus for the F/L's you want The Televue 35mm Panoptic would be a great buy if you look for one S/H, I use it a lot in my scope.

Alan.

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alan potts

alan potts

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I don't think I have read of any wide eyepiece giving point stars across the whole field.

I would say that you are gaining field at the expense of edge sharpness.

For a simple arguement, lens are spherical, spherical is not the ideal and at the edges of the lens the errors and aberrations are maximised. Adding more glass can minimise some errors but they in turn add errors. Eventually you cannot get any more out of the system.

Read that a good idea is to stop at 68 degrees.

You should take a look at Televue eyepieces or Pentax, stars are pinpoint, right to the edge even at 100 degree FOV but at a price.

Alan.

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Damo636

Damo636

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Posted

I would cast a vote in favor of the Explore Scientific 30mm. Its very close in performance to the 31mm Nagler & half the price. The ES & the Meade 30mm UWA that Alan has already mentioned, probably share the same optics. The 35mm Panoptic is a great eyepiece, but I personally found eye placement very fussy. If you still fancy a 35mm Panoptic theres one for sale here...

http://www.astrobuysell.com/uk/propview.php?view=61893

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Mike73

Mike73

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Posted

Get the one on the left, the one on the right isn't bad but does suffer right around the edge.......

I had the Baader and it was great at f/6 but suffered as soon as I put it in my f/5.

Nice to see a size comparison between the Baader and XW though, the 30mm XW looks quite small for a low power 2" EP. :)

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alan potts

alan potts

Posted
Posted

Damo,

The Meade 30mm UWA was on the market a good deal of time before ExSc was a company, I find it funny that there are so many copy F/Ls between the two stables, I mean it is laughable. I would like know who it copying who.

There is no doubt Meade was around first and offered many of the F/Ls long ago.

Take the 100 degree range, no doubt ExSc was there first, only a few months back Meade bring out a strange cotton reel thing and then try and charge more for some focal lengths and less for others. I would really love to know if they are identical, love to know. If they are, a mix of both would be in order but the look of the Meade is enough to keep my money in my pocket.

I think this Extreme as it is called and the newish SW 82 Degree range are amoung the worst looking eyepieces I have seen.

Anyone disagree?

Alan.

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John

John

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Posted
...... I would like know who it copying who.......

They are both copying Tele Vue !

I agree that Meade got there 1st though. The SWA and UWA 5000 series have been around for years with the 4000's preceding them.

The ES brand is a relative newcomer to this niche. I still wonder if the ES are the same optically as the Meade's but in a nicer body and with better marketing.

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E621Keith

E621Keith

Posted
Posted

Damo,

The Meade 30mm UWA was on the market a good deal of time before ExSc was a company, I find it funny that there are so many copy F/Ls between the two stables, I mean it is laughable. I would like know who it copying who.

There is no doubt Meade was around first and offered many of the F/Ls long ago.

Take the 100 degree range, no doubt ExSc was there first, only a few months back Meade bring out a strange cotton reel thing and then try and charge more for some focal lengths and less for others. I would really love to know if they are identical, love to know. If they are, a mix of both would be in order but the look of the Meade is enough to keep my money in my pocket.

I think this Extreme as it is called and the newish SW 82 Degree range are amoung the worst looking eyepieces I have seen.

Anyone disagree?

Alan.

The original Meade S5K UAW and ES 82 were both made by JOC. Meade USA fell out with JOC and JOC is now selling their 82deg under their own brand - ES. Meanwhile Meade found another OEM to make their current waterproofed S5K UWA.

I agree the Meade 100 deg Xtreme wide is extremely ugly.

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alan potts

alan potts

Posted
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Keith,

I got one of the new Meade UWA eyepieces while I was in England The 5.5mm, it was only 113 quid I couldn't resist. It is a very good eyepiece. I have had it in the F7 refractor a few times but not given it a full work out yet and I don't know if I will keep it but first impression look very good indeed. I still think the 24mm 30mm of this range take some beating. We know they are not as good a s Televue but at less than half the price and I don't have an F4.5 scope, well it makes sense to me. But.

Alan.

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fredster

fredster

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I got to find out why you pay all the money for a Televue last night. Popped round a friends house as he had just bought himself a couple of new eyepieces. He recently bought an Orion Optics 200 F4.5 newtonian and to his despair found his complete set of Hyperion eyepieces were 100% hopeless in a newtonian that fast. So he sold them to a fellow club member and replaced 7 Hyperions with just 3 Televue eyepieces. They are the 20mm T5 Nagler, 14mm Radian and 3-6mm Nagler Zoom, all secondhand.

The difference at the eyepiece was staggering, the Hyperions truly are next to useless at the focal ratio. The 20mm Nagler was an amazing experience, sharp over 90%+ of the field. While 14mm Radian was sharp over 95% of the field. We tried my ES 82series eyepieces, which i know are pretty good at F5, and while they were comfortably better than the Hyperion, they didn't fare well in comparison to the TV eyepieces. Only sharp over 70% of the field. :( We also tried a Meade 5K UWA 14mm, compared directly with my ES 82 14mm, the view was near identical. We all agreed that we would forgo the 82degree field in favour of the pin sharp 60degree field of the 14mm Radian.

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