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Richard136

Eyepiece upgrade for Newt and 'Frac

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I'm wanting to upgrade some of my eyepieces. Thinking of moving to 2" where I can, or just higher quality / wider fov.

My current collection is:

Vixen LV 4mm
Meade 140 2x barlow
7.5mm generic ED
20mm sliver plossl
Carton 16.8
Meade 4000 32mm plossl
Meade 4000 15mm plossl
Meade 4000 12.4 plossl
Pentax smc xf 8.5
Sw 28mm 2"

Used on a 10" f4.8 Newt and an f7 triplet refractor and a f6 travel refractor for wide field.

All are 1.25" with the exception of the SW 28mm.

There are some good ones in here but the size of glass at the exit always feels small to me. I want to explore upgrading, if worthwhile and affordable. Also considering a wider field EP into the collection.

I've looked at the Baader Hyperion range, but am not sure whether they would be an upgrade on my existing ones or not. Input helpful.

I mostly view star cluster and the moon but obviously don't want to limit general purpose use, too.

I am highly sensitive to optical errors and defects.

Without going to the Televue or Pentax series, which I think would be outside my comfort zone on price, what options are there that would be upgrades to my current set?

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Only advantage 2" eyepieces offer is larger field stop. That means larger AFOV at longer focal lengths.

In order to fit larger field of view / lower magnification in eyepiece you need wider field stop (surface at focal plane that lets light in - larger it is - larger field of view it will allow). At some point you simply run out of space in 1.25" eyepiece format - at about 27mm - you need a bit of space for eyepiece body and filter thread and soon you are at 31.5mm - or 1.25".

To circumvent that - eyepiece makers use 2" format.

Some 1.25" eyepieces have 2" "converter" - it is just fitting so you can use them with 2" focuser / diagonal - it is essentially the same thing as you already have in your focusers / diagonals - 2"-to-1.25" adapter - just a piece of hardware used to hold EP in place - it does nothing optically.

In any case - don't choose eyepieces based on 1.25" / 2" format.

Eye lens will be larger if eyepiece has larger AFOV (apparent field of view) and longer eye relief. If you like eyepieces with larger eye lens - you could be in fact liking eyepieces with longer eye relief. These are often described as more comfortable to use as you don't need to get in too close with your eye to use it.

Too long eye relief can also cause problems, especially on smaller exit pupil - it can be hard to hold your eye properly positioned and you can experience blackouts because of that.

Anyways, here is my list of EPs that should suit your scopes good, provide you with what you want and cost less than TV or Pentax:

budget:

BST Starguiders

Upper tier:

Explore scientific 68 degrees and 82 degrees series (I can recommend 5.5mm 62 as well - managed to finally try out mine and I like it).

Top tier (close in prices to two mentioned brands but not quite that level):

Baader Morpheus

I think that you can safely go with ES 68 / 82 but be aware - that will depend on how much you value eye relief. While ES eyepieces do have longer eye relief - It is not always as comfortable as can be - for example 82 degrees 11mm and 68 degrees 16mm - although they have 15.6mm and 11.9mm eye relief respectively in their specifications - in use they feel about the same in terms of eye relief - on edge of comfort that long eye relief provides.

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what fov ep are you thinking of the 60 degree? 70 80 90 or 100? of course price keeps going up with each level and whats the price you looking at per ep?

joejaguar

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When an eyepiece weighs more than 1 pound, I personally prefer that the barrel is 2". It feels safer on the focuser to me.

Having the whole eyepiece set with the same barrel size also eliminates the need of reducers. 

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For widefield low power, you could have a look at a 32mm Panaview. It's supposed to be pretty good in 70%-80% of the field at f5 (with 70° AFOV) and you can pick one up second hand for £50.

I can't give you first hand experience as I'm supposed to have mine delivered today.

 

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The Aero ED eyepieces are pretty decent 2 inch eyepieces. They can be bought for around £50-£60 apiece on the used market. They are better corrected than the lower cost 2 inch eyepieces and also reasonably light for 2 inchers. They have a 70 degree apparent field of view and come in focal lengths of 30mm, 35mm and 40mm.

The range of focal ratios of your scopes (F/4.7 to F/7) is reasonbly wide. The F/4.7 will pose the greatest challenge for an eyepiece in terms of remaining sharp across the field of view so you may need to accept some compromise there unless you are prepared to spend big bucks or stay with a smaller apparent field.

 

 

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