2" Vs 1.25"

[cjmarsh81]

I am looking at getting some new eyepieces for my scope.

I would like a 6.3 or 4mm for higher magnifications, and probably a 28 or 32mm for low magnifications.

I want to get 2" eyepieces as I have read they give a greater FOV and allow more light into the eyepiece.

What are your experiences with 2" eyepieces? Do they give a noticeable increase in FOV? What brand of eyepieces provide top quality for a reasonable price? How good are wide-angle eyepieces?

[rumples riot]

Cost v benefit.

2" EP's cost so much more than 1.25" With so many companies now making UWA lens in 1.25 you could use 1.25 EP's and not really notice any difference. A good quality panoptic or a Nagler will give nice wide views and you will only lose a little.

I went with the 1.25" and think they are great.

[Merlin66 (Ken)]

This is pretty well covered in some of the other threads. Bang per buck probably the 1 1/4 is the cheaper way to go. The 2" is more wide field friendly so could be considered for the 30mm. I'm a TeleVue man myself.

[iceman (Mike)]

The GSO SV 30mm is a 2inch eyepiece, and is a good starters widefield eyepiece.

It's not sharp to the edge in an f/5 scope like mine or yours, but it's good for about 70% to the edge. For the price (under $75 I think), they're good value for money for a beginner.

They work well as a "finder", for scanning through the milky way looking for something fuzzy. They also work well for large open clusters.

If you want a widefield eyepiece that gives stars that are sharp all the way to the edge of the FOV, in an f/5 scope, you will need to spend considerably more - like above AU$300, most likely more.

[Robert_T]

seriously, if you're starting out you don't want to waste the considerable extra dollars on 2inch eyepieces. What you see through a telescope is as much the result of practice and concentration as anything else and the differences between many eyepieces are subtle enough to practiced amateurs and might be lost entirely on someone new to the hobby.

have a good look around first with the eyepieces you have so that you at least can measure in your mind the improvement (if any) you'll experience with new eyepieces.

cheers,

[astrogeek (Leon)]

I recomend going to a star party and looking through others EP's. This will give you a better idea about what visual differences there are.

[janoskiss (Steve H)]

Rule-of-thumb: 25mm or less: go with 1.25", more than 25mm: go with 2". If you don't want a wide field of view (more than 52 degrees), then 1.25" will cover you all the way up to 32mm or so.

It is not true that 2" EPs are expensive and 1.25" are less so. You can get a crummy 2" EP very cheap. And some of the most expensive EPs ever made are 1.25".

Like Mike said the 30mm Superview is a good wide field EP to begin with and not very expensive. I've still got mine but I'm looking to upgrade (hate those seagulls). 32mm Meade 5000 Plossl is one quasi-budget-wide-field option I'm considering ($230).

For short focal lengths eye relief will be a problem. Better just get a barlow me thinks or spend big on eye relief.

[ballaratdragons (Ken)]

For your 6.3mm & 4mm obviously get 1.25".

As for the 28mm it's debatable. (and personal choice)

As for the 32mm (or 30mm) the 2" will make it feel like you stuck your head out into space!!!

I have a 30mm GS 2" SuperView (complete with seagulls) and an Erfle 2" 32mm and enjoy them both! Great eye relief and BIG WIDE views.

And barlowed, they give great higher mag 'head in space' views.

Just my opinions and 3 cents worth!

[cjmarsh81]

I thought it may have been better to get the 4mm and 6.3mm as 2" eyepieces so I would get a larger FOV???

[Merlin66 (Ken)]

They don't always work like that! Trust us....the 1 1/4 will do the job very well.

[janoskiss (Steve H)]

Short focal length EPs don't need a big barrel for large FOV. They just need a big wallet.

I've drawn a diagram to explain this barrel size vs FOV business before; now where is it?

[janoskiss (Steve H)]

Here it is, in one of the threads linked at the bottom of the page:
http://www.iceinspace.com.au/forum/s...52&postcount=9

Since I made the diagram, I learnt the correct terminology. What I labelled d = image plane diameter, is actually called the "field stop". This cannot be bigger than your barrel size. But in practice it needs to be significantly smaller to fit everything in there.