Starbase 'Orthoscopic Plossls'

[Shorty Barlow]

I suppose handling is easier this way with the smooth barrels in the brass compression ring of the Baader helical focusser. I recognize the difficulties with undercuts.
Since you have a nice set of Takahashi's too, can you do a quality review of the images they both generate? I am curious.

Not having an undercut makes life easier with any compression ring, especially if you have manual dexterity problems. I have a set of the Tak' ortho's and some of the LE's. I'll see what I can do, although I'll need the weather on my side. The main differences between the Tak' and Ohi ortho's is a matter of coatings and ergonomics. I'm pretty convinced the Tak' coatings give them a contrast advantage over the Ohi, although they do lose some transmission by comparison. Also, Tak' ortho's have a couple of degrees extra AFOV (bigger field stop) than the Ohi. They are an Abbe design though AFAIK and it tends to make the individual eyepieces feel a bit more comfortable than their Ohi equivalents.



The 32mm Tak' ortho' is a bit sui generis.

[John Baars]

So you mentioned four differences.
- Ergonomics in favor of the Tak's
- Contrast in favor of Tak
- Transmission in favor of the Starbase Ortho's
- Field of view in favor of Tak.

Can you tell us something about the behaviour in a relatively fast system, like f/4 to f/6? That all perform well in a slow system is beyond doubt. So don/t use your Mak or SCT for it.
For instance:

startest.jpg (11.02 KiB) Viewed 1195 times

In Z- shape:
Astigmatism, Coma, Perfect, Color, Correction for Field curvature ( the lack of it) Very often color comes in combination with one of the others. Not to be confused by the perfect round chromatic aberration of a short refractor.

Always on the very end of the field. At high magnification. A good way to judge is to see if the eyepiece is capable of holding the Airy disk as a defined round spot. Only the very best can do this, it is a good way to tell the difference between higher and lower quality. And if not, how is it deteriorated?

At medium to lower power it makes the difference between a complete field filled with needle-points, or just the center.

[Shorty Barlow]

So you mentioned four differences.
- Ergonomics in favor of the Tak's
- Contrast in favor of Tak
- Transmission in favor of the Starbase Ortho's
- Field of view in favor of Tak.

Can you tell us something about the behaviour in a relatively fast system, like f/4 to f/6? That all perform well in a slow system is beyond doubt. So don/t use your Mak or SCT for it.
For instance:
startest.jpg

In Z- shape:
Astigmatism, Coma, Perfect, Color, Correction for Field curvature ( the lack of it) Very often color comes in combination with one of the others. Not to be confused by the perfect round chromatic aberration of a short refractor.

Always on the very end of the field. At high magnification. A good way to judge is to see if the eyepiece is capable of holding the Airy disk as a defined round spot. Only the very best can do this, it is a good way to tell the difference between higher and lower quality. And if not, how is it deteriorated?

At medium to lower power it makes the difference between a complete field filled with needle-points, or just the center.

The fastest scope I have is an f/4.9 achromat and I rarely use orthoscopics in it. In ED doublets around f/6-7 the Tak's show no aberrations up to 42 degrees as far as I can tell. Although you'd expect that with an Abbe. However, they can exhibit edge astigmatism in the last 2 degrees of their 44 degree field. By 'Ohi' I was referring to the other Japanese Abbe OEM. These include Astro Hutech and Kokusai among other rebadging (Ohi made Abbe orthoscopics are often sold under other names). The Starbase are made by Kubota and are not true Abbe orthoscopics.

[Shorty Barlow]

Combination of Ohi and Takahashi Abbe orthoscopics.



AFAIK the Circle-T's were made with Ohi glass.

[John Baars]

(...)The fastest scope I have is an f/4.9 achromat and I rarely use orthoscopics in it. (...)

Okay.
But...., If we want a good impression of their real and ultimate behaviour, you have to test them in your f/4.9!

[Shorty Barlow]

(...)The fastest scope I have is an f/4.9 achromat and I rarely use orthoscopics in it. (...)

Okay.
But...., If we want a good impression of their real and ultimate behaviour, you have to test them in your f/4.9!

The downside to that is that it is a relatively inexpensive ST102.



It has a nice focuser however.

[John Baars]

(...)The fastest scope I have is an f/4.9 achromat and I rarely use orthoscopics in it. (...)

Okay.
But...., If we want a good impression of their real and ultimate behaviour, you have to test them in your f/4.9!

The downside to that is that it is a relatively inexpensive ST102.
(...)

We won' t tell anyone....
The focusser however, is perfect for focusing an f/4.9!

[notFritzArgelander]

Sorry to intrude. I have a ST120, the Starbase EPs, KKs and BCOs, and TV Plossls..... I am innocent of Tak Orthos though.

[Shorty Barlow]

I think there is an odd and puzzling mystique about Tak' ortho's bordering on mythology. In my experience they are just a well made Abbe with a couple of extra degrees of field. And they have a rigid rubber eyeguard. I have no idea why Takahashi have discontinued them. Admittedly the 32mm is one of a kind. They are expensive as they are made in Japan and have a high build quality. They do have good contrast in comparison to Ohi-made ortho's and the BCO's. Although, for me, the Ohi and BCO have slightly better transmission. Swings and roundabouts. I think the BCO's are made in Singapore. At the end of the day; they're all good. The Kubota Starbase are OK as well. If you don't mind the non-blackened lens edges and the single coating.

[Bigzmey]

Sorry to intrude. I have a ST120, the Starbase EPs, KKs and BCOs, and TV Plossls..... I am innocent of Tak Orthos though.

I think the consensus is that Tak Orthos are rebrand of KKs.

[notFritzArgelander]

Sorry to intrude. I have a ST120, the Starbase EPs, KKs and BCOs, and TV Plossls..... I am innocent of Tak Orthos though.

I think the consensus is that Tak Orthos are rebrand of KKs.

I can't argue with that. Others might.

[Shorty Barlow]

Sorry to intrude. I have a ST120, the Starbase EPs, KKs and BCOs, and TV Plossls..... I am innocent of Tak Orthos though.

I think the consensus is that Tak Orthos are rebrand of KKs.

They might be, but it's unlikely.

https://www.firstlightoptics.com/japane ... ieces.html

[Shorty Barlow]

Either way, s'all good lol.

[Lady Fraktor]

I can see a scenario where single coating can outperform budget multicoating in transmission. However, if we are talking about top performers, premium multicoating in my experience with faint galaxies always outperforms single coating. Of cause, it is apples to oranges since none of premium EPs are offered with single coating. There should be a good reason for that.

You do not consider Brandon eyepieces as premium?

I just never considered them, should I?

Brandon are very nice eyepieces and only use a single layer coating on the eye lens. When the glass is high quality and excellent polish the coatings can be kept minimal.
A recent example is nFA conmparing Antares and Orion psuedo-Masuyama, I have always claimed the 15mm Antares as a excellent planetary eyepiece and nFA has agreed after side by side testing. The Orion is FMC but the Antares is only MC. (They were made in the same factory along with the Celestron version)

[notFritzArgelander]

You do not consider Brandon eyepieces as premium?

I just never considered them, should I?

Brandon are very nice eyepieces and only use a single layer coating on the eye lens. When the glass is high quality and excellent polish the coatings can be kept minimal.
A recent example is nFA conmparing Antares and Orion psuedo-Masuyama, I have always claimed the 15mm Antares as a excellent planetary eyepiece and nFA has agreed after side by side testing. The Orion is FMC but the Antares is only MC. (They were made in the same factory along with the Celestron version)

Yes. Just so. The "whole system" of the Antares beats out the "whole system" of the Orion in contrast rendering. Deciding to prefer one eyepiece over another on the basis of FMC versus mere FC misses the point that it's the whole package that needs to perform.

[Shorty Barlow]

Well, the plans I had for an early morning session on M42 with the three newly-barrelled Kubota Starbase EP's got scuppered by my own body.