Somre more questions...

[dpastern (Dave Pastern)]

OK, what's the difference between plossls, orthos, panoptics, radians etc? Are some better for specific types of observation, and why? Where do they rate in the IQ (image quality) scale of things, i.e are radians optically better than plossls, etc etc.

Dave

[Coen]

Check:
Straight forward overview (layout of lens etc)
http://members.shaw.ca/quadibloc/science/opt04.htm

Expanded:
http://www.astrosurf.com/re/evolution_of_eyepieces.pdf

General:
http://www.astro-tom.com/telescopes/eyepieces.htm

http://en.wikipedia.org/wiki/Eyepiece

Simulation of view: http://www.mydob.co.uk/eyepiece_simulator.php (does not really work for me, but might for you)

Try also: http://www.stargazing.net/naa/scopemath.htm

[dpastern (Dave Pastern)]

Thank you, some good reading there, and it answers my questions, well most of them. It doesn't touch on what panoptics or radians are, how they compare with other designs, when to use them, strengths/weaknesses etc.

I found this page as well, which talks about exit pupils and other things, and is quite good (at least I think so):

http://www.bpastro.org/index.php?pag...ting-eyepieces

Dave

[Coen]

Radians: it is a naming thing - http://www.scopereviews.com/radian.html

Also: http://www.cloudynights.com/category..._id=123&pr=2x7

[Coen]

Reviews of various eyepieces:
http://www.cloudynights.com/item.php?item_id=271

http://www.cloudynights.com/item.php?item_id=1438 (note the sketches)

http://www.cloudynights.com/item.php?item_id=274

http://www.cloudynights.com/item.php?item_id=256

[dpastern (Dave Pastern)]

Thanks Coen, digesting all of the information in those links ;-)

If I understand correctly, Radians offer a wider FOV and better eye relief than plossls, with minimal distortion and aberrations. Given the poor eye relief on plossls in the higher mm range (2mm, 4mm etc etc), then would it not be wise to consider a Radian style design? I presume the problem that I described with the Andrews 4mm is a result of the poor eye relief of the plossl design?

If I'm digesting some of the information correctly, panoptics are great for wider FOV eyepieces, little distortion etc. Radians might be good for high magnification planetary eyepieces (better eye relief than plossls). I wonder if Ortho style eyepieces might be the go here - they also seem to have better eye relief, but slightly narrower FOV when compared to plossls (and have a flatter FOV and slightly sharper).

I'm basically trying to determine what types of eyepieces will be best for high magnification planetary observation, DSOs and medium eyepieces that fall in between the 2 extremes.

There doesn't really seem to be a page that I've found that gives you the pro/cons of each type of eyepiece design when compared to each other, and recommendations for what type of visual use to use them in...that'd be really *hand* to newbies imho.

Dave

[Coen]

I have not found anything like you are asking for for I have asked myself the same questions.

Being of a theoretical background I naturally have a theory on it which I might well pose at some point.

I think with eyepieces there is a lot of subjectivity hence it is hard to get definitive answers (everyone's eye is different and there are different desires when viewing).

Regarding planetary - if you want detail etc then go back to basic designs and for me it is orthos.

Coen

[Coen]

http://www.excelsis.com/1.0/section.php?sectionid=22

(posted elsewhere on this forum)

Gives reviews (some better than others) of lots of eyepieces but not necessarily head-to-head.

[dpastern (Dave Pastern)]

Thanks Coen. BTW, with your name, are your Irish or Welsh, or is it just a nickname?

Dave

[Coen]

Dutch heritage

[dpastern (Dave Pastern)]

Ah. My dad hails not far from the Dutch border - Duesseldorf. He used to frequently ride his bike into Holland all the time to see his girlfriend. I can only remember a few Dutch swear words that I learnt from my dad ;-)

Dave