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Old 12-05-2021, 10:15 PM
Graman (GR)
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Eyepiece advice for SCT

Hi there, apologies in advance for the long post, but would like some eyepiece advice...

A bit of background about myself - I have gotten into the hobby about ~18 months ago, but last year's lockdowns and working from home has meant that I have had more opportunities to get into it that I originally anticipated. Really enjoying it!

Equipment: I have a Meade 8 inch SCT on AVX mount as my primary scope. I also have ED72 that I use for grab & go wide fields. May use it for astrophotography later on, but no plans just yet.

Viewing: Primarily from suburban Sydney, but hope to get out to dark sites more often going forwards.

Eyepieces: After starting out with generic plossls, I quickly yearned for something better in terms of quality, FOV and comfort. I upgraded to a 2-inch diagonal and started procuring 2 inch eyepieces in the longer focal lengths. I found using 2 inch EPs more comfortable - probably due to the larger lens size. I now have a decent collection, and while they are not Tele Vue or Pentax, I am quite happy with them:
18 mm: ES 82 degree
24 mm: ES 82 degree
30 mm: Bintel/GSO SuperView 65 degree (?)
38 mm: Agena/Sirius 70 degree

I also got a Bintel/GSO 2 inch 2x ED Barlow with the removable barlow element that can also give 1.5x magnification. I find this works well with above EPs giving me a range of focal lengths - depending on whether I use 2x or 1.5x barlow.

Range of focal lengths covered with Barlow:
9 mm, 12mm, 15mm, 16mm, 18mm, 19mm, 20 mm, 24 mm, 27mm, 30mm, 38mm

Questions/advice sought:

1. Given that my 2 inch EPs and barlow pretty much covers everything from 9 mm onwards, do I still need 1.25 EPs in the 9 to 18mm focal length range? What additional advantage do they bring? Is it more clarity/brightness because there is no barlow involved? Would it make a difference in dark sites? What will I gain from squinting through a small 1.25mm lens barrel instead of the more comfortable 2 inch barrel? Can someone enlighten me on the pros/cons?

2. If 1.25 inch EPs do offer benefits, what focal lengths should I be looking at to suit my SCT?

3. What about getting a good quality zoom instead of getting 2 or 3 individual 1.25 inch EPs? While Leica or Zeiss are out of my price range, would Baader or Swarovski zooms be comparable? Part of me likes the idea of popping a zoom with a 2-inch adapter into the diagonal and not have to mess with EP changes in the sub-18mm focal length. What are the pros/cons of this approach?

Any advice much appreciated. Thanks in advance and clear skies!

It looks like it will be a cracker in Sydney for the next week or so - hope it continues for the Lunar Eclipse end of the month - fingers crossed.
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Old 12-05-2021, 10:43 PM
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AG Hybrid (Adrian)
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Quote:
Originally Posted by Graman View Post
Questions/advice sought:

1. Given that my 2 inch EPs and barlow pretty much covers everything from 9 mm onwards, do I still need 1.25 EPs in the 9 to 18mm focal length range? What additional advantage do they bring? Is it more clarity/brightness because there is no barlow involved? Would it make a difference in dark sites? What will I gain from squinting through a small 1.25mm lens barrel instead of the more comfortable 2 inch barrel? Can someone enlighten me on the pros/cons?

2. If 1.25 inch EPs do offer benefits, what focal lengths should I be looking at to suit my SCT?

3. What about getting a good quality zoom instead of getting 2 or 3 individual 1.25 inch EPs? While Leica or Zeiss are out of my price range, would Baader or Swarovski zooms be comparable? Part of me likes the idea of popping a zoom with a 2-inch adapter into the diagonal and not have to mess with EP changes in the sub-18mm focal length. What are the pros/cons of this approach?

Any advice much appreciated. Thanks in advance and clear skies!

It looks like it will be a cracker in Sydney for the next week or so - hope it continues for the Lunar Eclipse end of the month - finger crossed.

1. Eyepiece barrel size is dictated by the eyepiece designs field stop. Generally speaking the most comfortable eyepieces to look through are actually 1.25" eyepieces. Pentax XW, Televue Delos, Baader Morpheus all have 20mm of eye relief and are about as comfortable to look through you could possibly find, they are also some of the sharpest.

2. The only reason 1.25" would provide an immediate benefit is - lighter weight vs 2". Also - accessory costs are cheaper. High quality diagonals, filters, and barlow lenses are cheaper with 1.25" format. Judging by your current set of eyepieces I would consider higher power eyepieces. 14mm and less. Pentax, Televue, Baader all have an excellent selection of sharp comfortable eyepieces from 14 and below.

3. keep in mind zoom eyepieces are a series of compromises for unmatched convenience. Current designs means when moving though the focal length settings the field of view changes. Example - Nothing wrong with the Baader Hyperion Zoom 8-24mm, but its field of view goes from ~68 degrees to 50 when moving from 8mm to 24mm. There's also compromises on sharpness at some settings. Most Zooms perform best at their higher magnification settings and soften at the lower magnifications. That being said, the Baader 8-24 is very usable in your 8" scope. In works well in all my telescopes. I do use a coma corrector for the fast Newtonian's though. You don't have that issue with your current setup.

Keep your ear to the ground though. APM are releasing a new zoom eyepiece in June - and its going to be an absolute ripper. I know its going to end up in my case.
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Old 12-05-2021, 11:37 PM
Dave882 (David)
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Agree with the previous advice. A couple of higher power pieces will do you well. I find with my 8inch sct the 200-250x magnification eyepieces get a lot of use for smaller targets. So that would mean 9mm or 6mm if you are using a 0.63 reducer.
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Old 13-05-2021, 11:00 AM
Graman (GR)
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Thanks Adrian and David for your replies, much appreciated!

@Dave - I agree...I used 200x magnification a lot last year while watching Jupiter and Saturn later in the season. I found that my ES18mm with a 2x barlow (9mm effective FL) yielded better results than a 10mm Baader Hyperion standalone. Hard to describe, but both Jupiter and Saturn appeared sharper to my untrained eye via the ES barlowed.

Is this to be expected? I must admit, it wasn't a very thorough assessment as I was still trying to getting familiar with the mount, tracking, balancing etc. so I didn't spend to much time doing A/B tests.

I haven't viewed through any high-end 1.25 EPs - Pentax WX, Televue or Baader Morpheus - so I guess I don't know what I am missing
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Old 13-05-2021, 11:02 AM
Graman (GR)
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The APM zoom sounds fantastic at least on paper. Will keep an eye out for it. Thanks for heads-up!


Quote:
Originally Posted by AG Hybrid View Post
Keep your ear to the ground though. APM are releasing a new zoom eyepiece in June - and its going to be an absolute ripper. I know its going to end up in my case.
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Old 13-05-2021, 11:41 AM
Dave882 (David)
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Originally Posted by Graman View Post
Thanks Adrian and David for your replies, much appreciated!

@Dave - I agree...I used 200x magnification a lot last year while watching Jupiter and Saturn later in the season. I found that my ES18mm with a 2x barlow (9mm effective FL) yielded better results than a 10mm Baader Hyperion standalone. Hard to describe, but both Jupiter and Saturn appeared sharper to my untrained eye via the ES barlowed.

Is this to be expected? I must admit, it wasn't a very thorough assessment as I was still trying to getting familiar with the mount, tracking, balancing etc. so I didn't spend to much time doing A/B tests.

I haven't viewed through any high-end 1.25 EPs - Pentax WX, Televue or Baader Morpheus - so I guess I don't know what I am missing
Doesnít surprise me. Iíve got the 82degree ES 4.7 & 11mm and they are absolutely brilliant performers in my sct. I also have the Hyperions but find Iím only reaching for them in lower magnifications.
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