Orthoscopics?

[Mak the Night]

Has anyone any experience using Orthoscopic type eyepieces that they would like to discuss? I know a bit about their design and history. They are supposedly very high contrast but have a limited FOV (usually 40°- 42° at best). 

[John]

I've used quite a few types of orthoscopic eyepiece and have written reviews on them for the forum. Here are a couple (still getting used to the new forum software !):

http://www.firstlightoptics.com/blog/baader-classic-ortho-plossl-review.html

 

 

 

 

 

 

[chiltonstar]

I use a couple of older ones (9mm and 6mm) for high magnification views of double stars and planets. Yes, the field is limited but the sharpness and contrast are high, and (quite important) you don't seem to get those annoying bright spots moving around (reflections off the eye) that you can get with some other designs.

Chris

[Moonshane]

Orthos are really excellent and offer premium optics at budget prices albeit with narrow field and short eye relief.

I like them but eventually concluded that for not much more you can get equal sharpness in a wider field with greater eye relief.

 

[michael.h.f.wilkinson]

I have had three orthoscopic EPs: a Circle-T 5mm and 25mm (0.965") which I sold along with the scope that had that type of focuser, and I recently got a Vixen Ortho 25mm which I use for solar H-alpha. I love(d) the 25mm and hated the 5mm. Nothing wrong with the image quality of the latter, but the eye relief was WAY too short for me with my glasses (astigmatism)

[Roy Challen]

When you get to the top tier of the eyepiece hierarchy, you'll find that most of them are orthos - Zeiss CZJ, Zeiss ZAO 1+2, Pentax SMC etc. Optically, they really are as good as it gets. But they're not cheap and you won't get them new anymore. Modern widefields from Tele Vue, Pentax etc can match the old school orthos, exceed their FOV by some margin (more than twice in some cases), with better eye relief, and for not much more money.

But I wouldn't give my CZJs away for anything.

 

[digital_davem]

4 minutes ago, Roy Challen said:

When you get to the top tier of the eyepiece hierarchy, you'll find that most of them are orthos - Zeiss CZJ, Zeiss ZAO 1+2, Pentax SMC etc. Optically, they really are as good as it gets. But they're not cheap and you won't get them new anymore. Modern widefields from Tele Vue, Pentax etc can match the old school orthos, exceed their FOV by some margin (more than twice in some cases), with better eye relief, and for not much more money.

But I wouldn't give my CZJs away for anything.

 

Roy

I see your sig now shows the re-worked scope. Time to give it a name, like Neil English does with his!

[Mr Spock]

If you can tollerate the small field of view they are as crisp, clean and detailed as anything out there.

[Mak the Night]

21 minutes ago, John said:

I've used quite a few types of orthoscopic eyepiece and have written reviews on them for the forum. Here are a couple (still getting used to the new forum software !):

http://www.firstlightoptics.com/blog/baader-classic-ortho-plossl-review.html

 

 

 

 

 

 

Thanks John, that's really informative. I've ordered one of the 12.5mm Astro Hutech ortho's from FLO as I'm curios about them as a design. Plus TeleVue don't do a Plossl around the 12-13mm mark and my 12mm & 13mm Celestron Plossls have older safety undercuts that don't play nice with the compression rings on some of my diagonals and Barlows. I like the 12-13mm f/l size as it suits my Mak and is about the limit before the squint factor starts to appear with smaller EP's IMO lol.

If the 12.5mm Hutech turns out OK I might be tempted to make a pair up for the bino. The smooth drawtube and overall size appeals to me although I don't know if the FOV will be practical on a bino.

The Astro Hutech technical specs can be found here: http://www.sciencecenter.net/hutech/vis-acc/ep/index.htm

The 18mm looks nice as well.

[Mak the Night]

18 minutes ago, Roy Challen said:

When you get to the top tier of the eyepiece hierarchy, you'll find that most of them are orthos - Zeiss CZJ, Zeiss ZAO 1+2, Pentax SMC etc. Optically, they really are as good as it gets. But they're not cheap and you won't get them new anymore. Modern widefields from Tele Vue, Pentax etc can match the old school orthos, exceed their FOV by some margin (more than twice in some cases), with better eye relief, and for not much more money.

But I wouldn't give my CZJs away for anything.

 

There are still a few moderately priced ortho's around.

[Mak the Night]

22 minutes ago, michael.h.f.wilkinson said:

I have had three orthoscopic EPs: a Circle-T 5mm and 25mm (0.965") which I sold along with the scope that had that type of focuser, and I recently got a Vixen Ortho 25mm which I use for solar H-alpha. I love(d) the 25mm and hated the 5mm. Nothing wrong with the image quality of the latter, but the eye relief was WAY too short for me with my glasses (astigmatism)

Yes, I believe below around 12mm f/l ortho's are no better than Plossls for eye relief.

[Mak the Night]

29 minutes ago, Moonshane said:

Orthos are really excellent and offer premium optics at budget prices albeit with narrow field and short eye relief.

I like them but eventually concluded that for not much more you can get equal sharpness in a wider field with greater eye relief.

 

I was thinking about a bino pair of 12.5mm. I think the eye relief compares well to others in the same f/l category, although the limited FOV could be problematical.

[Mak the Night]

32 minutes ago, chiltonstar said:

I use a couple of older ones (9mm and 6mm) for high magnification views of double stars and planets. Yes, the field is limited but the sharpness and contrast are high, and (quite important) you don't seem to get those annoying bright spots moving around (reflections off the eye) that you can get with some other designs.

Chris

Is the field limitation that noticeable compared to a Plossl?

[John]

5 minutes ago, Mak the Night said:

Is the field limitation that noticeable compared to a Plossl?

When I was testing orthos one of my comparison eyepieces was an 8mm Tele Vue plossl. I did notice the reduction in the field - it's 15%-20%.

If your scope is driven then it's not very significant. Mine are not though so you notice it more, perhaps ?

The other thing about the shorter focal length orthos is that the eye lens starts to get pretty small.

Optically though they are generally really good and you would need to pay loads more to get any better performance, if any.

 

 

 

[Moonshane]

Yes the 12mm ortho has decent eye relief if not wearing specs

[Mak the Night]

22 minutes ago, John said:

When I was testing orthos one of my comparison eyepieces was an 8mm Tele Vue plossl. I did notice the reduction in the field - it's 15%-20%.

If your scope is driven then it's not very significant. Mine are not though so you notice it more, perhaps ?

The other thing about the shorter focal length orthos is that the eye lens starts to get pretty small.

Optically though they are generally really good and you would need to pay loads more to get any better performance, if any.

 

 

 

I guess the FOV will be similar to my 40mm Plossl, I think I can live with that, although I will be expecting much greater magnification with a 12.5mm obviously. I have slo mo controls on the Mak, but my next scope will be GOTO so I should be OK I think. I've seen the tiny eye lenses on the smaller f/l's, they look as bad as my 6mm Celestron Plossls, worse probably!

I think the pros outweigh the cons for me:

Pros:

Will fit into the spaces left in my EP cases (important one that lol).

Reasonably priced.

Smooth drawtube (I almost bought a 12mm Pentax XF until I saw the old-style undercuts).

High quality sharpness and contrast comparable to TeleVue quality.

Light and small enough for me to manipulate easily (adding Barlow elements, filters etc).

Quality build.

Eye relief, eyepiece lens and field stop size comparable or better than Celestron and TeleVue near equivalents.

 

Cons:

Only a 42° FOV.

No eyeguard (I rarely, if ever, use these on anything less than a 25mm f/l anyway). 

I probably won't get the complete set so my advanced OCD will kick in lol.

 

 

[Mak the Night]

42 minutes ago, Moonshane said:

Yes the 12mm ortho has decent eye relief if not wearing specs

That's a relief lol! 10.41mm for the 12.5mm Hutech and 15.21mm for the 18mm. Compared to the 8mm ER of the TV 11mm Plossl & 14mm for the TV 20mm Plossl.

[Mak the Night]

2 hours ago, chiltonstar said:

I use a couple of older ones (9mm and 6mm) for high magnification views of double stars and planets. Yes, the field is limited but the sharpness and contrast are high, and (quite important) you don't seem to get those annoying bright spots moving around (reflections off the eye) that you can get with some other designs.

Chris

Thanks, that's interesting about eye reflections.

[jetstream]

There can be interesting differences between ortho brands under VG seeing and under dark skies. So far the 10mmBCO/VIP has equaled or bested not only the other orthos but some pretty good widefields and zooms. The other night was a prime example on the moon at high mag-the 10BCO/VIP was in the focuser the majority of the time. That night this was the combo.

 

The 12.5mm Tak ortho is VG for lunar/planetary but falls behind other EP's on DSO.

I can't imagine not owning orthos...

 

 

[Mak the Night]

5 minutes ago, jetstream said:

There can be interesting differences between ortho brands under VG seeing and under dark skies. So far the 10mmBCO/VIP has equaled or bested not only the other orthos but some pretty good widefields and zooms. The other night was a prime example on the moon at high mag-the 10BCO/VIP was in the focuser the majority of the time. That night this was the combo.

 

The 12.5mm Tak ortho is VG for lunar/planetary but falls behind other EP's on DSO.

I can't imagine not owning orthos...

 

 

The Tak ortho's look nice. I see ortho's more as planetary than anything else, but I believe the Tak's have a greater FOV than most ortho's. 

[astrofox]

The only orthos I have ever used are Baader BGO's. From 5 to 7mm they proviide good magnification and tak sharp images. FOV is narrow but as I use them on planets that is irrelevant.

[jetstream]

The Taks are very nice, similar if not the same optically as the KK Fuji's but with a very nice eyecup. The Baader Classics have a bit wider FOV and I think the Taks are about 44 deg. The 12.5mm & 10mm are a nice combo for me barlowed 2x- 6.25mm & 5mm and with reasonable eyerelief compared to my 5mm,7mm KK's.

 

I was fortunate to have some excellent seeing a while back and these orthos performed so well the fact cannot be understated. Some experienced DSO people use some orthos almost exclusively for threshold objects I hear.

[Mak the Night]

26 minutes ago, astrofox said:

The only orthos I have ever used are Baader BGO's. From 5 to 7mm they proviide good magnification and tak sharp images. FOV is narrow but as I use them on planets that is irrelevant.

Do they still make the BGO's?

[Mak the Night]

29 minutes ago, jetstream said:

The Taks are very nice, similar if not the same optically as the KK Fuji's but with a very nice eyecup. The Baader Classics have a bit wider FOV and I think the Taks are about 44 deg. The 12.5mm & 10mm are a nice combo for me barlowed 2x- 6.25mm & 5mm and with reasonable eyerelief compared to my 5mm,7mm KK's.

 

I was fortunate to have some excellent seeing a while back and these orthos performed so well the fact cannot be understated. Some experienced DSO people use some orthos almost exclusively for threshold objects I hear.

I noticed the eyecups on the Tak's. I'm sure ortho's work well on DSO's. It will be interesting to see what they're like. If the clouds allow it lol!

[faulksy]

12 minutes ago, Mak the Night said:

Do they still make the BGO's?

no, stopped a few years ago after the great sounarmy in japan