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Tests on some Classic Orthos

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#1 bremms

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Posted 16 February 2013 - 03:43 PM

After a nice observing session , I decided to look at differences in some of my Orthos;
Used two different 12.5mm Orthos quite a bit.
UO 12.5mm Vs my unbranded 12.5 Visually the UB has a good bit wider field than the UO. Much to my surprise the Unbranded one(UB) was a tad sharper and had a little less scatter. It is a superb EP.
Used a Meade RGO 10.5mm Vs 12.5 and 9mm UO. Peolpe who claim the RGO is no better than the UO Orthos are not seeing what I am. The RGO has less scatter and incredible definition. A clear step up from the UO ortho.

Measurements
Unbranded Or 12.5. 46degrees fs10.0mm. el 11.0mm
UO Or 12.5. 39degrees. fs 8.4mm. el 9.8mm
RGO Or 10.5. 43.5 deg. fs 7.9mm. el 9.0mm
UO Or 9mm. 42.5 deg. fs 6.6 mm.
UO Or 7mm. 40.5 deg. fs 4.9mm

The Unbranded ortho has very good coatings, wider field and slightly better performance than the UO 12.5. No contest there..
The Meade RGO 10.5 showed as much detail as the 9mm UO with less scatter and was MUCH better than the UO 12.5.
The UO Orthos are good EPs, But did not perform to the level of the other two EPs
Used my C11 and D&G 5" F12

#2 mikey cee

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Posted 16 February 2013 - 06:05 PM

My Kohki 12.5mm orthos are not branded either. Mine are super performers. Maybe your's is one of their's. :crazy: Mike

#3 bremms

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Posted 16 February 2013 - 06:48 PM

Kohki orthos were made by circle t (Tani) and are the same as the UO. My unmarked one is from another maker. I was told maybe Pentax. Nice as the Circle T 12.5 is and it IS very good, this one is better. Wish I had more FLs.

#4 bremms

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Posted 16 February 2013 - 06:59 PM

Here is a lousy pic of the unmarked one and the UO 12.5

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#5 bremms

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Posted 16 February 2013 - 07:04 PM

here is a picture of the field stops. They are very different. The reflections from the outer surfaces indicate the surfaces have different curvatures. They are different for sure.

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#6 GeneT

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Posted 16 February 2013 - 08:59 PM

Nice report! Short, sweet, to the point--and you made your case. :applause:

#7 hottr6

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Posted 17 February 2013 - 09:17 AM

Kohki orthos were made by circle t (Tani) and are the same as the UO. My unmarked one is from another maker. I was told maybe Pentax. Nice as the Circle T 12.5 is and it IS very good, this one is better. Wish I had more FLs.

I thought Circle-T was Towa?

Shane in grey-zone NM

#8 bremms

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Posted 17 February 2013 - 12:18 PM

According to some pundits here Circle T is the Tani shop in Japan. I think it might be the old man's name. They just closed the shop in December. So no more circle T's.
Maybe a member with more knowledge can step in and correct me if I got things wrong.

#9 kansas skies

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Posted 17 February 2013 - 01:50 PM

While on this subject, I have a question that might fit here. Awhile back, I acquired a Cave 26.6mm Orthostar. At first, I found it a little uncomfortable to use for a number of reasons. For one, it presents a very bright field of view. Another would be the tremendous amount of eye relief.

To make a long story short, I continued to use the Orthostar, and it now has become my eyepiece of choice in that focal length. I find the subtle shades of contrast that it's capable of delivering to be nothing short of amazing.

I understand that the Orthostar is a true Abbe Ortho. I was thinking about trying to fill out the set, but would like to keep an open mind. I've heard that the early Meade RGO's were very similar to the Orthostar, but haven't been able to confirm this. I'm wondering if anyone has any experience with this.

Bill

#10 terraclarke

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Posted 17 February 2013 - 04:09 PM

Anyone know how the Baader Abbé orthoscopics stack up?

#11 bremms

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Posted 17 February 2013 - 05:59 PM

It makes sense the Orthostars and the RGO are at least related. I would say most likely made in the same factory. They have a physical and optical similarity.

Baader Abbe' orthos.. Are those classics or BGO's? UO sells a Chinese made Abbe' for 50 or 60 bucks. Never used any of those. The BGO is very well regarded but I have no experience there. Used a few Zeiss Abbe's and there is a reason the price of those is so high. They are VERY good.

#12 kansas skies

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Posted 17 February 2013 - 06:02 PM

It makes sense the Orthostars and the RGO are at least related. I would say most likely made in the same factory. They have a physical and optical similarity.


Would this be true of all production years, or just the earliest?

Bill

#13 Ruimteman

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Posted 18 February 2013 - 12:33 AM

Here's some info on the Kohki eyepieces:
http://www.kkohki.co...kohkiparts.html






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