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BGO's out of favour?

A McEwan

By A McEwan
in Discussions - Eyepieces

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FLO

FLO

Posted
Posted

We are agreed that a BGO is 40' FOV thought ???

That is my understanding.

For brightness, clarity and lack of distortions, orthos are excellent!

If Ernst Abbe (a designer for Carl Zeiss) had designed them today everybody would be talking about them but they were designed in the 1800's (for taking accurate measurements from microscope slides) so pass under most peoples radar undetected.

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great_bear

great_bear

Posted
Posted
From what I have read I was under the impression to get the 50' another lens was required

No, it's actually the lens configuration which achieves this effect. An Ortho is a triplet and a singlet, whereas a Plossl is two achromatic doublets which are typically identical (but back-to-back) in today's Plossl-derived designs.

and this is what distinguished the super plossl from a standard plossl.

No, but it's a common misconception. The sad truth is that there is no such optical design as a "Super Plossl" - it is merely a marketing term that is meaningless. The original Meade Series 4000 "Super Plossls" were 5-lenses (in this case, used to provide better correction rather than increased field-of-view) but for many years - even whilst still being made in Japan - the Series 4000 "Super Plossls" have since been a simple, symetrical 4-lens design.

(the 5-lens Meade Series 4000 Plossls can be identified by either being of the "Smoothside" design (no rubber used anywhere), or by having "Japan" stamped on the black barrel and not on the chrome nosepiece)

It's interesting to note that some people think that the Meade Series 5000 Super Plossls (which are of a five-lens design) would have been better if they hadn't tried to use the extra lens to increase the field of view to 60 degrees, and if they had instead - like the Antares Elite - merely used it to improve the correction.

We are agreed that a BGO is 40' FOV thought ???

That's the "official" line, but I doubt it. :)

For reference, the old 12.5mm Volcano Top Ortho has been measured at 39 degrees, whereas the Baader Genuine Orthoscopic 12.5mm has an Apparent Field of View which looks significantly larger than that.

Nice that (for once!) you seem to get more than what is advertised! ;)

rgds,

Jeremy.

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cs1cjc

cs1cjc

Posted
Posted

I have measured the field stop on my apparently similar Antares orthos and, for the published focal length and an undistorted (orthoscopic!) field, the apparent field of view is approximately:

9mm 39 degrees

12.5mm 42 degrees

One other issue on orthos that has not come up here is that BGOs apparently do not work well with very fast optics. The first Abbe orthoscopic design of 1880 had a field of view of 30 degrees and a critical f-number of 6.5 (see: http://www.brayebrookobservatory.org/BrayObsWebSite/BOOKS/EVOLUTIONofEYEPIECES.pdf) but the modern BGO is more surely somewhat forgiving than this. I generally use the orthos with a 2X barlow, effectively doubling the scope f-number, so I can provide no useful observational evidence.

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spaceboy

spaceboy

Posted
Posted
At the time of writing, there's also 6, 7, 9 and 18mm BGOs on =Eyepiece-Barlow-Diagonal-Reducer&titlechoice[]=For+Sale&statuschoice[]=Active&minprice=&maxprice="]AB&S at the moment ;)

They all sold to one person. Lucky fellow.... bet it was MoonShane :)

I'm sure if you can live with the tight ER you will be impressed by the BGO's Mark. For me they have the edge over the 3-6 zoom. If only Baader did an ortho zoom.

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spaceboy

spaceboy

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Now there seems to be a couple every other day!

I think this is because everyone reads reviews on how good they are hastily buy them then realize they can't put up with the tight eye relief. For the money I have not looked through a better EP so I'm prepared to put up with eye strain for the improved sharpness and contrast but some may consider it too much of a price to pay. I would be the first to agree the 5mm is hard work after 10 minutes.

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Damo636

Damo636

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Posted

The 5mm is tiresome after a short while. The 7mm was my favourite of the 3 i had. I intend to replace the 6 and 7mm at some point if my astro pot ever recovers! Bang for buck i would totally agree they will not be beaten.

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Neil English

Neil English

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Hi,

I seem to remember that at the beginning of the year the whole world was crying out for Baader Genuine Ortho's. I myself completed a set of them, selling some volcano-top circle-T ortho's to help fund them.

Just now there seem to have been an awful lot of adverts for BGO's on the classifieds. Now having used them for solar and nighttime observing for the last several months, I can't find any obvious flaws with them so will be keeping mine as I love the views that they give.

Is it the eye relief that people can't put up with, or the slightly narrower than a Plossl field of view? I'm happy to "put up" with both for the intensity of the views that I get through them...

Ant :)

Hi Ant,

Naah, I love these eyepieces. They're probably amongst the best value for money on the market. I have almost the entire set and frequently use the shorter focal lengths for observing planets and doubles with all my long focal length refractors.

I think they appeal particularly to the minimalists amongst us.

Simple telescopes and simple eyepieces always work well together.

Best wishes,

Neil.;)

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MjrTom

MjrTom

Posted
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Yeah I would have had the 9mm if I had seen the updated advert of johns... :)

I suspect the 5mm will be a bit tiresome with an eye relief of ~4mm but I shall see how I get on. I ultimately fancy getting the 5,7 & 9mm orthos for my planetary viewing. Might even get the 6mm if I am feeling flush one month. ;)

If the 5mm happens to have too tighter eye relief I shall send it back and swap it for the 6mm :headbang:

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Nexus 6

Nexus 6

Posted
Posted

would add the 7mm I use has given some superb views of the Moon, am lucky that the tight er is not a problem for me, also used it on other scopes from the local astro society to give members an idea of how they perform. For some it was a struggle, due to said er, but the consensus was they are very good eyepieces for the money.

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spaceboy

spaceboy

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looks like im getting my first ortho.....gone for the 6mm UO circle t.......still lookinfg for a 12.5 though

Going out on a limb.....I'm not sure if the VT's are considered to be on the same level as the BGO's due to the better coatings of the Baader's

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John

John

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Going out on a limb.....I'm not sure if the VT's are considered to be on the same level as the BGO's due to the better coatings of the Baader's

I found the views much the same but the Baader GO's control light scatter around bright objects a little better and I felt the light transmission was a little greater. Conversely the "vocano tops" seemed to me a little easier to use as their shape made it a little easier to get your eye close to the eye lens.

I've just picked up a University HD Ortho 5mm and I'll be interested to see how that performs - I'm expecting it to be pretty close, if not the same, as a Baader GO. That's my "love / hate" relationship with Ortho's rearing it's head again ;)

The University is supplied with a winged rubber eyecup but I'm not sure if I'll bother using it :)

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John

John

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Are these the ones that look the same as the BGO John ??

Yes, they look very similar, even the colour scheme. I'd be pretty surprised if they did not come from the same factory as the BGO's. The coatings on the eye lens certainly look the same as the "Phantom" coatings that the Baader's use too.

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MjrTom

MjrTom

Posted
Posted
looks like im getting my first ortho.....gone for the 6mm UO circle t.......still lookinfg for a 12.5 though

If your interested I will be selling my Circle T 9mm Ortho when the BGO 9mm arrives. Well unless I find out it's better but we shall see :)

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great_bear

great_bear

Posted
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Im looking forward to trying these ortho`s, the 6mm will give x450 in my 180 pro

For planetary use I've never managed less than 9mm (300x) in my Mak 180 - and only for very short periods. Of course, your mileage may vary, so good luck! :)

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nightfisher

nightfisher

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For planetary use I've never managed less than 9mm (300x) in my Mak 180 - and only for very short periods. Of course, your mileage may vary, so good luck! :)

I have that in mind, whats the highest mag you have managed on lunar views with the 180?

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