Eye relief

[REG78]

Hi was just wanting to find out if th fov in th supplied with scope 25mm super wide MA EP would be th same as a 25mm plossl

[michael.h.f.wilkinson]

I trust you mean the Super MA 25. The eye relief and FOV are roughly the same as a Plossl. Contrast in the Plossl is better.

[Dave In Vermont]

It is impossible to say what the F.O.V. would be on a 'super wide MA' is without, at least, knowing who manufactured/sold it. With a Plössl, it's a safe bet it's around 50° or so.

Dave

[spike95609]

If it's the same Super MA that comes with the Skywatcher scopes - i.e. this lot http://www.rothervalleyoptics.co.uk/skywatcher-super-ma-eyepieces-125.html - then the 25mm is 50° and the 10mm is 52°. So yes, the same as a plossl.

[Dave In Vermont]

A MA is usually a Kellner, so it stands to reason a 'Super' is likely an added lens-element. So, yeah - likely about the same ballpark. For anyone who'd like a representative chart of eyepiece configurations, feel free to grab this:

Enjoy!

Dave

[Jimtheslim]

On 4/25/2016 at 09:56, Dave In Vermont said:

A MA is usually a Kellner, so it stands to reason a 'Super' is likely an added lens-element. So, yeah - likely about the same ballpark. For anyone who'd like a representative chart of eyepiece configurations, feel free to grab this:

Enjoy!

Dave

just wondering which of these Celestron X-cel's and BST's would fall into?

[Ricochet]

Apparently this is the BST

 

[John]

Many manufacturers use designs which are an evolution from the designs shown in the graphic that Dave posted. For example, there are now 4 slightly different Nagler designs on the market from Tele Vue. The Pentax XW range uses 3 different (maybe 4 ?) optical designs to cover their focal lengths from 40mm to 3.5mm.

The way an eyepiece actually performs is as much to do with the quality of the execution of the design as it is the optical design itself. By execution I mean the appropriateness and quality of the glass types used, the coatings applied to them, the way the lenses are mounted, and the way that light scatter is controlled within the eyepiece through baffles and blackening. I've used excellent, decent and mediocre examples of the same basic optical design so it is possible to some exent to compromise the performance of a potentially good design by not quite getting the execution right.

These days though, most eyepieces are well made and perform to a good standard. There are very few real "dogs" about

[Jimtheslim]

what's the 'tolles' piece all about then? Just one big lump of glass?

[YKSE]

7 minutes ago, Jimtheslim said:

what's the 'tolles' piece all about then? Just one big lump of glass?

Yes, that's it. therefore also called "poor man's monocentric"

[Jimtheslim]

what do the colours and numbers on the chart correspond to?

[YKSE]

Numbers are abbe numbers, and colours (with Letter) are different glass types.

You can get better picture of different eyepiece designs by reading the page than only looing at the pictures:

http://www.quadibloc.com/science/opt04.htm

[YKSE]

Celestron X-cel LX looks like having the same design as BST,

http://www.cloudynights.com/topic/428526-x-cel-lx-lens-design/?hl=%2Bx%26%238208cel