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Eyepieces for f4.7 dob

Mike_S

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John

John

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I guess the options range from the 32mm Skywatcher Panaview at £72 to the Tele Vue Nagler 31mm at £629.

The Panaview will work quite well in the central 60-70% if the field of view but in the outer parts the stars will be distorted somewhat.

The more you pay, the more of the field of view will be sharp. The reason for this ? - it's difficult to design and manufacture an eyepiece which will deliver sharp views across most of the field of view when the focal ratio of the scope gets faster than around F/6.

The eypieces which will not work well in your scope would be the low cost 30mm 80 degree types. With those the distortions in star images will be such that they get really distracting and detract from the wide field experience.

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alanjgreen

alanjgreen

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20 minutes ago, MSammon said:

Been recommended a few by Martin. This sounds good to me :)

https://www.firstlightoptics.com/baader-planetarium/baader-hyperion-aspheric.html

I would read up on these as from what I remember they are not good in fast scopes such as your f4.7.

I would go with ES or Televue if you want guarantee they work at fast speeds.

I had a 31mm aspheric when I owned an 8" SCT and it worked ok at f10. As soon as I purchased a Panoptic41, I was astounded by how washed out the background on the aspheric was compared to the Panoptic in the same scope. I sold the 31mm aspheric immediately!

Alan

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alanjgreen

alanjgreen

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Just now, MSammon said:

It’s only for visual not AP, does that make a difference? He also recommended some more expensive ones but they’re more like £275+ I would sooner cope with the narrow angle for now. 

Dont think you need eyepieces for AP :) 

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alanjgreen

alanjgreen

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10 minutes ago, MSammon said:

Actually also the explore scientific 68 degrees is £211 in 34mm and the 82 degrees range in 30mm is £278. 

If I were you and just starting out with a fast dob then I would get one of these very good APM 100 degree eyepieces...

https://www.apm-telescopes.de/en/eyepieces/more-74-ultra-wide-angle/apm-lunt-eyepieces/apm-hdc-xwa-20-mm-100-eyepiece.html

They are superb eyepieces and do not worry about purchasing from Germany. APM are super reliable and super quick to deliver!

Also, there is no import taxes to pay as its from the EU.

Send a PM to these two guys for some feedback

@DRT

@Littleguy80

Alan

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Louis D

Louis D

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I have a 3.5mm Pentax XW that I rarely use due to the tiny exit pupil and paucity of objects needing that much power.  I would instead look for a 4.5mm to 5mm eyepiece.  I have the 4.5mm Meade HD-60 and I think it does just as good a job at f/6 as my 5.2mm Pentax XL.  There's also the 4.5mm Morpheus which is good in the center but reportedly suffers from edge of field brightening (EOFB) from 70% out to the edge.

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Mike_S

Mike_S

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Well some luck, found a second hand Baader Aspheric 31mm for £90 posted on an astronomy Facebook page.

I really don’t know if the eyepieces I have are much good. I will find out but what make and model do you recommend for my medium and short length? There is the Baader zoom and Baader zoom Barlow. Are they suitable for F4.7?

or get separate ones like Televue 50 degree Plossls?

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John

John

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The Baader 31 Aspheric will be poorly corrected in the outer 50% of the field of view with an F/4.7 scope. I've owned one. It was not too well corrected even at F/7.5.

The zoom and zoom barlow will be pretty good though. The zoom is better corrected in faster scopes than the Hyperions / Hyperion Aspherics.

 

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bingevader

bingevader

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I know it might be frustrating when you are desperate to get your hands on some new glass, but you might be better off saving and waiting. :)

The second hand market it really very good in the field of astronomy, people tend to look after their kit and are generally decent and reasonable.

You can pick up very good offers if you are prepared to wait.

Wide angle EPs do tend to be a fair bit bigger (especially in 2"!) and to get one suitable for an f4.7 you are going to have to spend some money.

I have the Panaview, it's super in my 8" dob at f5.6, but even in that it is a little fuzzy round the edges.

If it's extra field of view you are after then there's not much point buying an EP and losing some of it to fuzziness! :D

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bingevader

bingevader

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Oh, just seen the price on the 34mm MV!

However, in your f4.7 that's going to be a large exit pupil!

They are tidy EPs though and should be good in your 'scope.

I think John might have reviewed it previously.

If you are still considering the Panaview and the Baader Aspheric, I wonder what the trade off between them and the MV would be?

Poorly corrected Panaview and Baader, or large exit pupil MV?

Any thoughts john?

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Louis D

Louis D

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4 hours ago, bingevader said:

However, in your f4.7 that's going to be a large exit pupil!

So what?  When looking for wide fields of view in a "finder" eyepiece, losing a bit of light to your iris is far preferable to me, at least, to putting up with a fuzzy edge that isn't useful for finding anything.  I've struggled with poorly corrected wide field 2" eyepieces in the past that made it impossible to locate planetary nebula because of the horrible field curvature, edge astigmatism and general lack of sharpness in the middle.  You'd think using an over large exit pupil was some sort of crime punishable by the astro cops around here.  "How dare you use an eyepiece that doesn't let you use the full aperture of your scope" would read the charging papers.  Sure, the background is a bit brighter than in a 31mm Nagler T5, but it's not that much brighter.  And when you compare the prices, it's no contest at all.

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