1.25 or 2" Eyepieces

[lonebod]

Hi. Dumb question of the day.... What are the pros and cons of 2" eyepeices over 1.25"?

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[ronin]

2" eyepieces are supposed to deliver a wider field of view. However with the number of 82 and 100 degree eyepieces I start to suspect that many 1.25" ones will perform much the same.

It may be that they can deliver the wider views easier and with lesser aberrations at the edge.

They are certainly bigger, as in a lot bigger. The extra 0.75" may sound small but it is anything but small. Easy idea is consider a coke can. They can be costly, the glass is bigger and needs more work on it.

Some people rave on them, myself I am not particularily bothered. I do have 1, and never used it in 6 or 7 years.

If you are thinking of highish magnifications then they are not really relevant, get a good 1.25", you can end up with a magnified Jupiter in a large field and it "looks" small.

To get the best from them the object really needs to be of some size. M31, M45 etc.

Something like M1 you are better off using a 1.25" if anythiong simply for the cost alone.

One aspect is if you have 1.25" ones at the same time then to swap between them is longer, you have to fit/remove adaptors and refocus.

[lonebod]

Thanks ronin. I've been trying to figure out if they really are worth the extra money. Doesn't really look like it. Thanks for taking the time to answer.

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[Zuben Elgenubi]

It probably depends on what you like observing. For solar system objects and smaller DSOs 2" eyepieces are not that useful. On the other hand, if you enjoy widefield views and scanning through the Milky Way for example, then lower power 2" EPs give you a different experience. I have a 24mm 82 degree Maxvision and the sight of the Double Cluster that it provides is simply stunning - far more satisfying than my widest 1.25" EP (a 30mm).

I suppose the best way to find out if they are for you is to have look through one!

[John]

Thanks ronin. I've been trying to figure out if they really are worth the extra money. Doesn't really look like it. Thanks for taking the time to answer.

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I think you are jumping to conclusions there. Many observers on this forum use a mix of 1.25" eyepieces for medium to high power viewing and 2" ones for low to medium power and wide or ultra wide fields of view.

If you want to view extended deep sky objects or groupings of them, 1.25" eyepieces simply can't deliver the width of field of view required to fit them in.

As Gareth says, try something for yourself before dismissing it !

[RikM]

I mainly use 1.25" eyepieces with 68°/70° apparent field of view. The longest focal length I have in this format is 20mm but with my scope, that can't quite fit some large objects like the Pleiades or the double cluster all in the view at once. I like looking at these kinds of objects and some large diffuse nebulae from dark sites, so to get that wider view I bought a 2" 28mm eyepiece with a 68° aFOV. I nearly went for a 30mm 82° eyepiece but prefer the 28mm. In the 1.25" format, the longest focal length you can get with 68° aFOV is a 24mm and that isn't quite long enough for what I want.

If you want low-power wide field views you need either a short focal length telescope or 2" eyepieces to deliver that. 

[Daz Type-R]

Tough call these days with the likes of TeleVue banging out their Ethos range (which I have). I have the TeleVue 13mm Ethos which has a 100 degree field of view, but is only a 1.25" EP, at 13mm the mag is quite high but I can get the double cluster in my FOV and M81and M82 in the same field of view. With it being quite high mag, the background colour is dark which helps bring out some detail.

Down side, cost!!!!!! But if you want high mag and wide FOV, TeleVue Ethos range are your best bet, I love mine and will never, ever get rid of it.

[RikM]

My ES 28/68° gives me a larger true field than the 17mm Ethos (also 2") and cost £130

The thing with eyepieces is they are a very personal choice. I don't like the 50° field of Plossls because it feels too restrictive, and I don't like the 100° field of the Ethos, makes me feel seasick, but 68/70° is just right for me.

[John]

My eyepieces go from 42 to 100 degrees and I enjoy them all. Varying the perspective on the Universe is fascinating and offers a differing experience of an object. Seeing something like the tiny smoke ring of M57 against a 100 apparent degree star field gives a wonderful sense of perspective but also seeing it dominate a much smaller high power field of view is impressive too. Variety is the spice of life, as they say