Celestron circle t orthos.

[djpaul]

What are your thoughts on the circle t volcano top orthoscopic eyepieces?

I'm looking to maybe get a 6mm or 7mm for planetary viewing .

Would they possibly give me better detail than my nagler zoom.

Paul 

[John]

Interesting question. I have the Nagler 2-4mm zoom and some Circle-T orthos down to 4mm in focal length. I've not done much in the way of comparisons but when I have the feeling I get is that that there is little to choose between them in terms of pure optical quality. The zoom though, does zoom, and has a slightly wider AFoV and more comfortable eye relief. It's a more comfortable eyepiece to use.

I'll carry on comparing them but I have the feeling that the overall result will probably be "honors even" in optical performance terms. So I suspect the answer to your question would be that a circle-t ortho will not generally outperform the Nagler zoom for planetary viewing in terms of seeing better detail.

It's possible that Baader Genuine Orthos or Fujiyama HD orthos might just have the edge on the zoom though.

The Nagler zoom is a pretty good high power performer and quite a hard act to beat.

 

[djpaul]

Thank you for a quick reply John. 

Yes I would never sell my 3-6mm zoom .

But was offered a 6mm ortho and just thought I would ask before purchasing. 

[martinl]

Like John I think it would be an even match, though the only circle-T ortho I’ve had was a 9mm. However, if I were to try to better my TV zoom I would probably opt for one of the more modern, multi-coated, orthos since the original circle-Ts only had single coatings. 

[Louis D]

2 hours ago, martinl said:

Like John I think it would be an even match, though the only circle-T ortho I’ve had was a 9mm. However, if I were to try to better my TV zoom I would probably opt for one of the more modern, multi-coated, orthos since the original circle-Ts only had single coatings. 

Brandon eyepieces are still only single coated, and lots of folks on CN rave about them.  For them, it's all about the fine polish and lack of surface roughness that would increase scatter and decrease contrast.  The argument goes that multicoatings increase surface roughness over a single coating.  I don't know if there's any truth to that, but that's what I've read was the justification for single coatings.

[martinl]

Interesting. I hadn’t heard about multicoatings increasing surface roughness before. Might well be true - optics is a science of many variables, after all. On the other hand, whenever I hear about legacy equipment being unquantifiably better than the modern equivalent I tend to think “conservatism” or “nostalgia”.

I’d love to see a statistically significant double blind test of modern and legacy equipment!

[Louis D]

6 hours ago, martinl said:

Interesting. I hadn’t heard about multicoatings increasing surface roughness before. Might well be true - optics is a science of many variables, after all. On the other hand, whenever I hear about legacy equipment being unquantifiably better than the modern equivalent I tend to think “conservatism” or “nostalgia”.

I’d love to see a statistically significant double blind test of modern and legacy equipment!

Here's an interesting read about possibly the finest planetary oculars ever made, the Zeiss Observatory Monocentrics, and they had to have been made years and years ago.

[Merlin66]

I have a Carl Ziess Jena "Monocentric Ockular f= 6mm" which belonged to W. R. Finsen, astronomer at Republic Observatory in South Africa probably dates from the 1950's(?). (Finsen found 73 new double stars, examined over 8 000 stars, and measured the orbital motions of many binaries.)

 

[John]

I had a 5mm TMB Supermonocentric for a while. It was probably the finest planetary eyepiece that I have ever owned and used. Eventually I decided that the narrow (~30 degrees) apparent field, tiny eye lens and short eye relief was not really enjoyable when used with my undriven alt-az mounted scopes so I let it go. Back then the TMB Supermonos were bought and sold used for around £100. Today the figure seems to be 3x-4x as much

I believe that the TMB Supermonocentrics were manufactured by ex-Zeiss opticians in Germany.

[Stu]

I think I would say that my 6mm BGO just edges the Nag Zoom at 6mm. It seems from reviews that BGOs are a little better than the older Circle-T orthos so I suspect there wouldn't be much in it. Eye relief would be tighter on the ortho of course.