Orthoscopics?

[Mak the Night]

51 minutes ago, John said:

I expect that Al Nagler is fed up of being asked if / when Tele Vue are going to produce an abbe ortho type eyepiece range.

Or why there isn't a 13mm Plossl anymore lol.

[Mak the Night]

39 minutes ago, jetstream said:

Nagler and his team have come up with an almost unbeatable Hyperwide set of eyepieces and I hope they continue their development, sorry to stray off topic.

Yeah, I love my 16mm T5 Nagler. It's too big for my bino though.

[Mak the Night]

I directly compared the 18mm Astro Hutech orthoscopic with a 17mm Celestron Plossl in daylight as they are the nearest focal length comparison eyepieces I have. The Celestron Plossl is originally from the Celestron Eyeopener Kit and is a pretty well engineered eyepiece for its class and size. The internal baffling seems fine and the body is almost exactly like the 15mm Celestron Omni Plossl in dimensions and appearance including the old-style safety undercut. It features a rubber eyeguard and barrel grip and feels well made, although significantly lighter than the Astro Hutech. The Plossl has a slightly larger eye lens than the orthoscopic.

I viewed a distant church steeple at roughly the same magnification (Plossl: 76x, Orthoscopic: 72x) and the difference in FOV was the first thing I noticed, not unlike with the TeleVue 20mm. Celestron claim that their Plossls have a FOV of 52°, which would make it 10° larger than the orthoscopic. Unlike the TeleVue 20mm Plossl, the Celestron didn’t seem quite so bright as the Astro Hutech and I suspect this is due to a less expensive lens glass being used in its construction. Either that or the slightly smaller focal length affected what I could perceive. It was the difference in contrast that was the most apparent though. There were details in the steeple that were not so readily apparent with the Celestron and I thought everything was a little bit sharper with the Astro Hutech. 

It is unfair to compare a Japanese built orthoscopic with a mass produced Chinese made Celestron Plossl, that probably cost a third of the Japanese eyepiece, but I was interested in how much difference there actually is. The Celestron Plossl is a decent eyepiece and will give very competent views for what it cost. I’m still quite surprised how sharp and contrasted the orthoscopics are compared to other types of eyepieces. All I need now are clear night skies to play with my orthoscopics more lol.

[michael.h.f.wilkinson]

Interesting thread. One thing I do notice is that quite a few fans of orthos use longer focal lengths with a Barlow or PowerMate. This means you do increase the number of groups in the optical train, and end up with something similar to most long eye-relief EPs, like the Vixen (S/N)LVs: A Smyth lens in front of a longer EP.

[Mak the Night]

2 hours ago, michael.h.f.wilkinson said:

Interesting thread. One thing I do notice is that quite a few fans of orthos use longer focal lengths with a Barlow or PowerMate. This means you do increase the number of groups in the optical train, and end up with something similar to most long eye-relief EPs, like the Vixen (S/N)LVs: A Smyth lens in front of a longer EP.

I think almost everything is some sort of compromise combination with optics. For my binoviewer; orthoscopics give me a high quality series of magnifications with superb contrast in a manageable way. The EP's themselves are physically small enough to be used in the bino and give me an alternative to my wide angle William Optics SWAN's and TeleVue Plossl pair. That way I have a range of magnifications and formats to choose from giving my binoviewer a flexibility and range to cope with a variety of conditions and targets. I aim to have 9mm, 12.5mm,15mm, 18mm, 20mm and 25mm pairs including modified Erfles (WO SWAN's), orthoscopics and Plossls in combination with two nosepiece Barlows. 

[michael.h.f.wilkinson]

Fair enough about the compromise. It is just that I often hear the claim that the combination of a longer orthoscopic EP with a Barlow is still crisper than the long ER EP designs, which actually sport the same number of elements and groups as an ortho + Barlow. In theory, if the number of air-glass interfaces is the same, one might even expect the long ER EP to outperform the ortho+Barlow combination, because the elements of the former are matched to each other in a single design. I think the main lesson to draw from this is that with modern coatings the number of groups is far less important than it used to be.
 

For me long eye relief is an absolute must, so 25mm is as short as I go with orthos

[Mak the Night]

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

Fair enough about the compromise. It is just that I often hear the claim that the combination of a longer orthoscopic EP with a Barlow is still crisper than the long ER EP designs, which actually sport the same number of elements and groups as an ortho + Barlow. In theory, if the number of air-glass interfaces is the same, one might even expect the long ER EP to outperform the ortho+Barlow combination, because the elements of the former are matched to each other in a single design. I think the main lesson to draw from this is that with modern coatings the number of groups is far less important than it used to be.
 

For me long eye relief is an absolute must, so 25mm is as short as I go with orthos

It's quite an interesting point though. I hadn't really thought about it in those terms. It was just a pragmatic way of getting the best combination of magnifications with my bino predominantly used with a small Mak at the moment. I'm planning on getting a 235mm SCT so every eyepiece I buy now I calculate for use with that as well. I doubt I'll need the Barlow quite as much with an aperture of 9.25". The 15mm TeleVues will give me 157x just on their own and the 12.5 Hutechs will give me 188x. Both are good lunar/planetary magnifications. What attracted me to the ortho's was that for a reasonable cost price I can get TeleVue quality views for my bino. I nearly fell off my observing chair viewing the Moon with the 12.5mm AH's during the Jupiter conjunction I was that surprised at the sharpness and contrast! Whether it was the overall seeing and conditions as much as the ortho's I'm not sure. 

[michael.h.f.wilkinson]

If you can handle the eye relief, orthos offer great value for money. Regarding magnifications: I use the XW 10, Delos 8 and XW 7 as my main planetary and lunar EPs in my C8 (at 203x, 254x and 290x respectively) and find those magnifications excellent in the C8. The XW10 is used more, of course, because it doesn't require the same level of seeing as the other two. On good nights, I have used the XW5 on the moon as well (406x :eek:) and it works brilliantly if the seeing is good. Your C9.25 (which has a better reputation for planetary than the C8) should be able to handle a good deal more than "just" the 12.5mm

[Mak the Night]

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

If you can handle the eye relief, orthos offer great value for money. Regarding magnifications: I use the XW 10, Delos 8 and XW 7 as my main planetary and lunar EPs in my C8 (at 203x, 254x and 290x respectively) and find those magnifications excellent in the C8. The XW10 is used more, of course, because it doesn't require the same level of seeing as the other two. On good nights, I have used the XW5 on the moon as well (406x :eek:) and it works brilliantly if the seeing is good. Your C9.25 (which has a better reputation for planetary than the C8) should be able to handle a good deal more than "just" the 12.5mm

I tend to find an eye relief of around 13mm the most comfortable for some reason. Although the 10mm of the TV 15mm Plossls and my T5 16mm Nagler is perfectly acceptable to me. I'm pretty sure magnifications of around 200x - 300x will be fairly easy on a 235mm scope with a 2350 f/l. The 4" Mak has a definite resolution limit. I'm going to keep the Mak as a planetary grab'n'go anyway, almost certainly used predominantly with the bino. It's a nice little scope and easy for me to manipulate. I think a maximum magnification of about 208x is its limit though. I've pushed it to 260x a couple of times viewing the Moon and Saturn but, not surprisingly, the image was darker and a little grainy. I think the theoretical limit on a 235mm (f/10) scope is 555x. I've calculated that an exit pupil of 0.5mm will produce 470x and an exit pupil of 2mm to 4mm will give a useful range of between 117x to 78x for fainter objects. I live in the greenbelt with low light pollution so it will be interesting to see how high I can get with a bigger scope than my Mak. I could easily get 300x with my 130mm Newtonian. 

 

[John]

I guess my 12" newtonian has a "theoretical" limit of 600x. What the useful maximum in practical terms is depends on the conditions and target through of course. Jupiter seems best at 200x-265x although I've used 318x on it when the conditions heve been really steady. For Saturn and Mars 265x-318x or even a little more for Mars, seems to work well. I have used higher power, up to 530x, on the Moon and for picking out faint planetary moons and central stars of planetary nebulae.

I'd much rather a sharper, contrastier image than a larger but less distinct image so I find myself dropping back the magnification to get that quite often.

 

 

 

[Mak the Night]

Yes, I think it's better to have a sharper more contrasted image. I read somewhere that the best image size for any particular telescope can be roughly calculated by what it would be with an eyepiece of a focal length approximately equalling the focal ratio of the telescope. This would make 102x the most defined and clear magnification for my Mak. I don't know how accurate the calculation is or its origin. Mind you, for Saturn or Jupiter I do find that anything between 100x - 130x to be the brightest and most clearly defined images. 

[Mak the Night]

The first testing with one of the Astro Hutech 25mm orthoscopics was in daylight with no Barlow deployed giving a 52x magnification. The target was a distant church steeple. In a direct comparison with the 25mm TeleVue Plossl the 22.2mm eye relief was the first thing I noticed compared to the 17mm of the TeleVue. In fact, the 25mm AH ortho’ has a slightly longer ER than the 22mm of the 32mm TeleVue Plossl! The AH’s field stop of 17.48mm is quite aesthetically pleasant although noticeably smaller than 21.2mm of the TeleVue’s. The Plossl’s eye lens is slightly larger than the 20mm of the orthoscopic’s and makes the TeleVue a very satisfying EP in use I find. The AH’s eye lens is pleasant to view through as well. Both produced bright, sharp images with the AH being slightly cooler and with more contrast to my eye. As TeleVue Plossls are renown for their colour ‘warmth’ it wasn’t unexpected. Out of curiosity I compared one of the giveaway Sky-Watcher 25mm 'Super 25’ Modified Achromats as well. Predictably; it gave a duller, less sharply defined image. 

Astro Hutech 25mm pair:

 

I started observing Jupiter at 02:00 GMT at 40.8°, azimuth 343° in Leo. At 41x in the 32mm Plossl I could quite easily see Io, Ganymede, Europa and Callisto in a line with Jupiter in between Io and Ganymede. Due to parallax Ganymede appeared very close to the planet, and throughout the session, Ganymede and Europa slowly moved positions until they were virtually vertically stacked with Europa being at the bottom of the pair (approx 04:15). After swapping the single 32mm Plossl that had I used to get Jupiter in frame to the bino with a 2x nosepiece Barlow and the 25mm AH’s to give me 104x I started observing properly. A Baader Neodymium filter was threaded into the diagonal nosepiece throughout the entire session.

02:00 (Celestron SkyPortal)

The seeing wasn’t quite as good as I’d hoped for as there was a slight atmospheric haze but the cloud banding was quite visible and the colour tones fairly well defined. It was not until around Transit (02:51, 41.9°) that the seeing improved slightly at intervals but gradually began to deteriorate as Jupiter started towards setting. Apparently the GRS was just becoming visible at around the time I finished observing (04:15) but I couldn’t discern it probably due to a combination of things. Possibly the 104x magnification wasn’t enough in the conditions and overall transparency. Plus there was the cold, my eyes becoming blurry after two hours of Jovian staring, and a desperate need for hot chocolate to take into account. The Moon had also risen and was visible by then but cloud soon obscured everything. 

04:15 (Celestron SkyPortal)

The longish 22mm eye relief of the 25mm’s took some getting used to at first with combining the images in the bino. The larger field stop was appreciated however and Jupiter tended to stay in frame quite well at 104x. Leaving the 2x Barlow in throughout the session I compared the 25‘s with the 15mm TeleVue Plossls (173x) and the 12.5mm AH ortho’s (208x). Although the image was obviously degraded a bit by the increased magnification, Jupiter still looked quite impressive at 173x and 208x with a 102mm aperture Mak. I went back to 104x with the 25‘s as I wanted a chance to test them more before the inevitable dreaded cloud event horizon lol. Again, the TeleVue Plossls produced their famous ‘warm’ feel in comparison to the cooler yet slightly more ‘contrasty’ Hutech ortho’s. 

I originally wanted to test the 25‘s on M42 at 83x as I find that is a good magnification for the nebula with my 16mm Nagler. Unfortunately there was too much cloud until later. Overall, I’m quite impressed with them from what I’ve seen and they will almost certainly come into their own with a larger scope.

[michael.h.f.wilkinson]

Sounds good!

[Mak the Night]

3 hours ago, michael.h.f.wilkinson said:

Sounds good!

What fascinates me the most is that until a couple of weeks ago I'd never used an orthoscopic eyepiece. Now I'm building a collection lol.

[Linda]

After reading a lot of positive things about orthos, I am putting a 6mm ortho on my wishlist. The goal is to get the maximum power out of my telescope (250x) when I really want to focus on a planet in good circumstances. My highest power eyepiece is currently an 8mm TMB planetary II that gives 180x magnification. In that eyepiece I see floaters. I have understood that that might happen less with orthos.

I see that the fujiyama eyepiece costs approx 115 euro. The Baader CO is sold at 65 or so. And the home made brand from the webshop is at 32 euro. Me being cheap, I incline to buy the cheapest model. Is that a really dumb decision? Or is the difference not enormous. I could also go for the Baader.

My goal is to finally see that red spot on Jupiter that I haven't seen yet. I would also like to see som surface detail on Mars in spring.

[Stu]

18 minutes ago, Linda said:

After reading a lot of positive things about orthos, I am putting a 6mm ortho on my wishlist. The goal is to get the maximum power out of my telescope (250x) when I really want to focus on a planet in good circumstances. My highest power eyepiece is currently an 8mm TMB planetary II that gives 180x magnification. In that eyepiece I see floaters. I have understood that that might happen less with orthos.

I see that the fujiyama eyepiece costs approx 115 euro. The Baader CO is sold at 65 or so. And the home made brand from the webshop is at 32 euro. Me being cheap, I incline to buy the cheapest model. Is that a really dum decision? Or is the difference not enormous. I could also go for the Baader.

My goal is to finally see that red spot on Jupiter that I haven't seen yet. I would also like to see som surface detail on Mars in spring.

Linda, floaters are normally associated with small exit pupils, so the type of eyepiece won't affect whether you see them or not.  If you see them in an 8mm with your scope, chances are they will be worse with a 6mm as the exit pupil will be smaller. Whether it is worth it for the extra mag only you will know.

[Linda]

Just now, Stu said:

Linda, floaters are normally associated with small exit pupils, so the type of eyepiece won't affect whether you see them or not.  If you see them in an 8mm with your scope, chances are they will be worse with a 6mm as the exit pupil will be smaller. Whether it is worth it for the extra mag only you will know.

Thanks, that is what I thought as well originally, before I got bitten by the ortho-bug. But if that is the case, I will seriously reconsider.

[John]

1 hour ago, Linda said:

After reading a lot of positive things about orthos, I am putting a 6mm ortho on my wishlist. The goal is to get the maximum power out of my telescope (250x) when I really want to focus on a planet in good circumstances. My highest power eyepiece is currently an 8mm TMB planetary II that gives 180x magnification. In that eyepiece I see floaters. I have understood that that might happen less with orthos.

I see that the fujiyama eyepiece costs approx 115 euro. The Baader CO is sold at 65 or so. And the home made brand from the webshop is at 32 euro. Me being cheap, I incline to buy the cheapest model. Is that a really dumb decision? Or is the difference not enormous. I could also go for the Baader.

My goal is to finally see that red spot on Jupiter that I haven't seen yet. I would also like to see som surface detail on Mars in spring.

Having compared them both, I'd probably go for the Fujiyama 6mm over the Baader Classic Ortho. There is not very much at all between them in terms of optical performance but the Fujiyama shows a little less light scatter and had a crisper field stop than the Baader CO 6mm that I compared it with.

250x might not be the way to see the GRS though whether through and ortho or other design. I find lower magnifications than that show the contrast differences between the Jovian surface features better. I could see the GRS quite nicely with my ED120 refractor a few nights back at around 100x for example.

 

 

[Mak the Night]

I think seeing the occasional floater comes with the territory. I believe if you can calculate the highest magnification you can get for an 0.5mm exit pupil on your scope it is the best you can do (208x on my Mak) before things start to get all floaty lol. 

I'm going to get an 18mm BCO pair for my bino to compliment the AH ortho's. The reason I have so many ortho's specifically for the bino is that I predominantly use it for lunar/planetary observing. The 15mm TeleVue Plossls I have are superb and the 20mm WO SWAN's give a nice wide field 66° view (although they’re actually capable of 72°). My 9mm SWAN's aren't really seeing much action though, and although I quite like them, they just can't compete with the TV's and AH's for sheer definition. The ortho's surprised me with their contrast, brightness and clarity and sacrificing 20 degrees of FOV seems a fair trade off.

To make room in my bino case the SWAN's have been a tad relegated to a vacant Celestron AstroMaster case. One thing about Celestron Kit cases is that they often turn out more useful than their contents lol!

[Mak the Night]

1 hour ago, Linda said:

 

My goal is to finally see that red spot on Jupiter that I haven't seen yet. I would also like to see som surface detail on Mars in spring.

This makes it look a lot more red for me. http://www.firstlightoptics.com/light-pollution-reduction/baader-neodymium-filter.html

The GRS revolves with Jupiter and isn't always visible. A combination of ortho' and filter made it really stand out for me.

[michael.h.f.wilkinson]

I tend to use higher magnification on Jupiter, but that's probably just me being odd.

[John]

1 hour ago, michael.h.f.wilkinson said:

I tend to use higher magnification on Jupiter, but that's probably just me being odd.

If the results are good then go for it !

I'll use high powers on it when the conditions allow but if I start to notice that the more subtle features are less distinct I back off a bit and find that helps. The GRS is usually quite obvious but features such as festoons and the white spots seem (to me at least) to stand out a little better at slightly lower powers.

Whatever works for you though, is good

[Mak the Night]

I think Jupiter seriously depends on conditions. One thing I've noticed with protracted Jovian viewing sessions is that it is so mutable. I can change magnifications regularly as the conditions change. I've found with my Mak that it seems to be at its best between around 104x and 166x. I once saw the GRS and a fair bit of detail, including festoons IIRC, at around 140x with A 5" Newtonian in twilight conditions. The background sky was blue in the eyepiece! I could see the Galilean moons too.

[John]

3 minutes ago, Mak the Night said:

.... I once saw the GRS and a fair bit of detail, including festoons IIRC, at around 140x with A 5" Newtonian in twilight conditions. The background sky was blue in the eyepiece! I could see the Galilean moons too.

Twilight is a great time to view Jupiter.

[Mak the Night]

1 minute ago, John said:

Twilight is a great time to view Jupiter.

Plus, you don't need a red torch so much! lol

I can still see Jupiter just hanging there in the blue sky in my mind's eye. It knocked me speechless. The detail really was quite good. I think moments like that make it all worthwhile. Of course, a viewing like that totally spoiled me lol.