Meade 4000 or Orion Optiluxe

[Glom]

Orion Optiluxe 32mm 58° for £140

Meade 4000 26mm 70° for £100

Both in the end produce similar actual fields of view (1.55° for Orion vs 1.52° for Meade on our Ten Inch). The Meade does it with a wider apparent field of view, while the Orion does it with a longer focal length.

I'm leaning towards the Meade because I prefer the FOV over focal length approach. Long focal lengths mean larger exit pupils and the 32mm is close to limiting so the Meade will be less likely to waste light. Also, the larger FOV will look cooler. Then there's the fact that the Meade is £40 cheaper.

However, is there a tradoff with the larger FOV? Does it ruin the image quality? Is my FOV over focal length a wise approach or is the Orion's focal length over FOV the way to get better images? Presumably, the Orion gives better quality images hence why it is more expensive, but is the better quality worth an extra £40?

[redshifter]

I have the 32mm Optiluxe for my 10" dob and it is unusable IMO. It's very difficult to find the correct eye placement to see anything through this eyepeice, and moving your eye around in the field causes the image to distort. I don't know what the term is that describes this phenomenon, but this is the only eyepiece in my collection that does this. I don't know if it has something to do with the focal lenght of my scope either (f 4.7, an orion XT10), but this info might help you make your decision.

[aurora]

"kidney bean" might be a term for what you are describing.

[Dave Mitsky]

Kidney beaning is used as a descriptive term for what is technically known as spherical aberration of the exit pupil. The original 13mm Nagler was infamous for kidneying beaning. The type 2 Naglers were developed so longer focal lengths could be manufactured that weren't prone to kidney beaning.

Dave Mitsky

[Glom]

So go for the Meade?

[Dave Mitsky]

That would be my choice between the two options. However, be advised that there will be some field edge astigmatism (commonly incorrectly referred to as coma) present when an uncorrected wide-field design such as the QX is used in a fast telescope.

Dave Mitsky