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Thread: Ortho vs. DSO

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    Default Ortho vs. DSO



    Hello everyone,

    can you share with me your experiences with viewing DSOs with simple design EPs like orthos?

    I am tempted to buy the whole Baader Classic Ortho EP series.

    Thanks,
    Martin
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    Default

    Most (all?) of the simple designs are scaled ones.
    That means that to make a shorter focal length version, you scale all the optics down - which means you get a smaller eye lens (along with smaller versions of all the other lens elements), and a smaller eye relief - so you have to put your eye closer, which can make the shorter focal lengths less comfortable to use.

    The more complicated modern designs often manage to keep a long eye relief across the range of focal lengths (by changing parts of the design rather than just scaling things), and often manage a larger apparent field of view than the simpler designs.

    If you're OK with the limited eye relief at shorter focal lengths, and can live with the narrower AFOV, then you may well be happy with the Orthos - when I first started many years ago, orthos were the good eyepiece to have before the modern premium designs came along.

    Or you may prefer bigger fields of view and more eye relief - at the end of the day, there's a lot of personal preference in eyepiece choice. It all depends on what suits YOU and fits with your observing style and budget.

    Personally, I like the wider AFOVs and long eye relief of the premium designs - but that comes with a more expensive price tag.

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    Default Re: Ortho vs. DSO

    Until the Televue Delos series came along I always viewed orthoscopics in general as the ultimate for rendering delicate contrasts well. The only trouble with them is that they need focal ratios slower than about f6. I have f4 and f5 scopes (among other slower than f6) so I would have to Barlow the ortho in the fast scopes to an effective f8 or f10 in order for the ortho to live up to its potential. With that treatment (using a really good Barlow is critical) the orthoscopic is the equal of the Delos in my opinion. I honestly can't tell which is better in a fast scope, more research is required. Sometimes on a fast scope I think the Delos might be a tad better than the unbarlowed ortho but other nights..... I am quite certain that the Delos works much better than an unbarlowed ortho on a fast scope.

    On a slower scope the orthoscopic comes out on top for contrast on DSOs. So I prefer them on slow scopes for sessions when the scope is guided and I am settling in for a long visual study. The contrast is better (less glass can be a good thing) and I can frame the object OK. On DSO tourism nights I prefer Panoptics and Delos since acquiring the object with a wide AFOV saves time.

    I do like a wider AFOV at times and on Dobs that becomes essential. So I will rarely use the ortho on a fast untracking scope. I've done it just to do the comparisons. Guiding was a bit of a pain when sharing the views.

    I have to make a comment about brands of Orthoscopics though. I have two sets of the Baader Classic Orthoscopics (one of which is actually a Plossl) because I use binoviewers. When I got them I gave my set of KK Orthoscopics to my daughter. Although the designs are identical I think the execution of the KKs are a tad better. I miss them just a little bit. I should have gotten a second set but at the time I was being cheap but wanted to make sure my daughter got a good set of eps. Ah, well....

    Kokusai Kohki 1.25" Fujiyama HD-OR Orthoscopic Eyepiece Set (Japan) - 8 Eyepieces

    Getting them is tough though.
    j.gardavsky, DeanD, matob and 1 others like this.

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    Default Re: Ortho vs. DSO

    Drat a typo. Correction is underlined and in bold.

    Quote Originally Posted by not_Fritz_Argelander View Post
    Until the Televue Delos series came along I always viewed orthoscopics in general as the ultimate for rendering delicate contrasts well. The only trouble with them is that they need focal ratios slower than about f6. I have f4 and f5 scopes (among other slower than f6) so I would have to Barlow the ortho in the fast scopes to an effective f8 or f10 in order for the ortho to live up to its potential. With that treatment (using a really good Barlow is critical) the orthoscopic is the equal of the Delos in my opinion. I honestly can't tell which is better in a fast scope, more research is required. Sometimes on a fast scope I think the Delos might be a tad better than the barlowed ortho but other nights..... I am quite certain that the Delos works much better than an unbarlowed ortho on a fast scope.

    On a slower scope the orthoscopic comes out on top for contrast on DSOs. So I prefer them on slow scopes for sessions when the scope is guided and I am settling in for a long visual study. The contrast is better (less glass can be a good thing) and I can frame the object OK. On DSO tourism nights I prefer Panoptics and Delos since acquiring the object with a wide AFOV saves time.

    I do like a wider AFOV at times and on Dobs that becomes essential. So I will rarely use the ortho on a fast untracking scope. I've done it just to do the comparisons. Guiding was a bit of a pain when sharing the views.

    I have to make a comment about brands of Orthoscopics though. I have two sets of the Baader Classic Orthoscopics (one of which is actually a Plossl) because I use binoviewers. When I got them I gave my set of KK Orthoscopics to my daughter. Although the designs are identical I think the execution of the KKs are a tad better. I miss them just a little bit. I should have gotten a second set but at the time I was being cheap but wanted to make sure my daughter got a good set of eps. Ah, well....

    Kokusai Kohki 1.25" Fujiyama HD-OR Orthoscopic Eyepiece Set (Japan) - 8 Eyepieces

    Getting them is tough though.

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    Default Re: Ortho vs. DSO

    Thank you for your answers gentlemen.

    It is true that the AFOV is narrow and it is not very comfortable to look through, however I got used to it. It may be true that you can get similar perfect views from a specific green-labeled eyepiece, however for the time being the BCO is my shortcut to perfect and cheap planetary views. I think I will get them just to have them.. I will definitely find a proper usage for them


    @not_Fritz: Can you clarify what exactly do you mean by living up to its potential? I´ve read that in fast scopes only half of the FOV is sharp. Is this what you mean?
    Martin
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    Default Re: Ortho vs. DSO

    Despite its limited FOV (42 degrees) my 25mm Astro Hutech Japanese Ortho is by far my sharpest and best EP, bringing out stunning colour and contrast with my ED refractors. The Classic series is well known apparently for excellent contrast and bringing out subtle details in DSOs particularly galaxies - I haven't had much opportunity to use mine yet on DSOs
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    Default Re: Ortho vs. DSO

    Quote Originally Posted by matob View Post
    @not_Fritz: Can you clarify what exactly do you mean by living up to its potential? I´ve read that in fast scopes only half of the FOV is sharp. Is this what you mean?
    Half the FOV may be a little pessimistic, I think that 70% of the FOV is sharp. But if you use a good Barlow the whole field is sharp. For planetary views that doesn't matter to me. For DSOs I want the whole field sharp.

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    Default Re: Ortho vs. DSO

    Quote Originally Posted by Davesellars View Post
    Despite its limited FOV (42 degrees) my 25mm Astro Hutech Japanese Ortho is by far my sharpest and best EP, bringing out stunning colour and contrast with my ED refractors. The Classic series is well known apparently for excellent contrast and bringing out subtle details in DSOs particularly galaxies - I haven't had much opportunity to use mine yet on DSOs
    The Astro Hutech Orthoscopics are identical with the Kokusai Kohki and Kasai Trading Company Orthoscopics. They are all made by the same Japanese firm but marketed through different outlets.
    Davesellars likes this.

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    Default Re: Ortho vs. DSO

    Hi Martin,
    I've used my old 6mm Ortho eyepiece for some time. The views are good and sharp, but I finally got tired of the narrow field which requires a lot of nudging on my Dob. DSO's tend to benefit from wider fields, which is why I've recently purchased a 6.7mm 82 degree eyepiece. Hope that helps..
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    Default Re: Ortho vs. DSO

    I had several of the Baader Genuine Orthos and sold them all except the 9mm, which I thought was the best of the lot, to help finance the switch to the ES 82s and 68s. My scopes range from f/13.7 to f/4.7 and the ES eyepieces perform well in all. Glad I switched.

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