Orthoscopic eyepieces - what viewing are they best for?

[Star Struck]

This is probably a naive question, but what kind of viewing do people use orthoscopic eyepieces for?

My underlying assumption is that they are used for planetary viewing but I am interested in what else I can get out of them.

How may people use 18mm or 25mm orthos and what do they use them for?

Lots of questions, I await with interest the answers.

[astrofox]

Planetary observations but down in the 6-8mm sizes to give decent magnification. Moderate field of view but doesn't matter on planet images. Good orthos like BGO's are tack sharp.

Frederick

[Moonshane]

anything that can fit in the field. the reason they are so good is that they have great light transmission and sharpness across the field of view. these qualities are also good for galaxies, star clusters and nebulae. they are also very light so aid easy balancing.

[Pete Presland]

mostly used for planetary observation, but no reason why the can not be used for anything really. nice clear, sharp views!

[philj]

I use circle t orthos for just about anything. The 18 mm along with 12,5 mm are firm favourites and I regularly use the 25mm.

They are superb lunar and planetary but on double stars they are particularly useful

[melsky]

Also the eyepiece of choice for my Lunt HA scope.

[timwetherell]

Orthoscopics are my favourites for lunar observations. They seen to deliver an especially crisp and "textural" rendition of the surface. Pretty good on planets too though to my eyes the monocentrics are just a smidgen better in that role. Though it depends what telescope you have. At the moment I'm using an alt az mount in Australia whilst my big equatorial runs the gauntlet of Somali pirates on its way back to Blighty. A  monocentric (or an ortho for that matter) in an un-guided mount has an inconveniently small field of view - So I'm using an Ethos for planets at the moment.

I remember in my youth reading Patrick Moore wax lyrical about the joys of orthoscopics and always dreaming of owning one as I fumbled with my 0.96" Huygens EPs. How times have changed!

[glynnlondon]

I use my bcos for everything moon planets clusters galaxies etc and they perform great. As stated by others above the images are very sharp and I find the field of view fine at 50 degrees.

[YKSE]

I have both 18mm and 25mm abbe orthos, actually a pair of both, for binoviewing the Moon and planets

18mm BCO was my DSO hunter in my first scope SW 130P(f5), all faint Messiers I bagged in my backyard, over dozens of them, was with 18mm BCO in 130P, it works very well as medium-low power in f5 scope, with good eye relief.

When I upgrade to SCT C8(f10), 18mm becomes median-high in this scope, so I bought the 25mm orthos, partly to go with the binoviewer, also it should serve as faint DSO hunter.

As others have already said, orhos works both for DSO and planets.

John has made two detailed reviews on orthos here which had been of great help to my choices:

http://stargazerslounge.com/topic/219151-5-years-of-reviews-and-reports/

[John]

BCO's Astro Hutech and Fujiyama orthos all perform equally well and are fine eyepieces to use on a wide range of objects. I do find that I need to be in the right mood to use the shorter focal length ones though (ie: 7mm and shorter) and frankly often reach for my wide or ultra-wide eyepieces first on most nights. They really don't give much away to orthos with todays glass and coating technologies applied with expertise by Tele Vue and Pentax 

It's good to have some orthos in the eyepiece case as well though and I'm glad they are still available at reasonable prices. For a while a year or so back I wondered if we were going to have to manage without !

[Dude_with_the_tube]

i have 2 full sets of orthos starting from 4mm and ending with 28mm.I use them on everything:starting from planetary,finishing with any type of DSO+white solar. high power will have tight eye relief(not that i have any issue with that),but as soon as you move into low powers like 12mm down to 25 or 28 eye relief becomes very generous.very nice eye pieces for very little money.Not every ones cup of tea.Buy one,try one,you might be surprised

[Star Struck]

Thank you all for your thoughts.

I already had a 12.5mm Astro Hutech and have just ordered an 18mm Astro Hutech from FLO.

I intend to use a barlow to get the higher magnifications as I don't fancy the tight eye relief of the smaller sizes.

[alan potts]

I have an 18mm Orthoscopic made by Kasai which I believe is much the same a BGO's.  I use it mainly for my LX 12 inch and 180mm Mak both of which have long focal lengths, the shorter F/L's (6,7 & 9mm) just do the same job in shorter scopes, the job being planerary/Moon observations.

[jetstream]

I use my bcos for everything moon planets clusters galaxies etc and they perform great. As stated by others above the images are very sharp and I find the field of view fine at 50 degrees.

You have a well thought out eyepiece selection.Someday I'll try a 10mm BCO on galaxies,it will most likely rank with the best.

[nightfisher]

I have a good set of circle T ortho`s and they are by far my most used ep`s, i only use ortho`s for planetary observing, and thats about all i do

[Scosmico]

I do have the 18mm BGO and it is a very good small  and/or faint DSO finder on my 12"Dob. Also used for Large DSO in the same Dob. I recomend an eyeguard or eyeshield, as others call it.

Just check the required size.

http://www.365astronomy.com/rubber-eyeshield-i-for-diam-31-325-mm-p-596.html

[timwetherell]

That seeing gif is excellent - best illustration of seeing grades I've seen

[jetstream]

That seeing gif is excellent - best illustration of seeing grades I've seen

I find the seeing representation excellent too,and use this site and one other to help pick objects and EP's ,when grade 3+ the orthos come out.I love the KK Fujis http://weather.gc.ca/astro/seeing_e.html

Interesting to note scope size effects the given rating.