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Old 17-08-2017, 02:19 PM
TonySize (Tony)
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Questions about Baader Hyperions and Projection Astro photography

Hi All,

I'm interested in Baader Hyperion's to use for projection photography with my Canon EOS camera along with my t adapter and get an M43 to T adapter. After playing with the http://astronomy.tools/ FOV calculator i was curious. With the following, would the images be projected into the centre of the sensor like a camera lens with heavy vignetting depending on exit pupil or are all focal lengths projected out at 72 or 68deg which should cover the sensor.

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Old 22-08-2017, 08:32 AM
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mental4astro (Alexander)
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Tony,

You are headed for a world of pain with the Hyperions in your Newtonian. These eyepieces are not designed for Newts, but for refractors, SCT's and Maks. It comes to the shape of the focal plane each scope produces: Newts produce a concave focal plane, refractors, SCT's and Maks a convex. Of the entire Hyperion line, only the 5mm works well in Newts. All the others will be affected by field curvature (some focal lengths more than others), pin cushion and even astigmatism. This is not a design flaw in the eyepieces. Instead, Newts and Hyperions are not an optical match.

If you are wanting to do eyepiece projection with them, you may get away with it if you keep the planets really tight in the centre of the FOV. As for vignetting, it really is not a concern as you will be using EP projection for the planets, and the background sky will all be black - you won't see the edge of the FOV. For lunar photography, there I cannot say, but vignetting will be the least of your problems here. But eyepiece projection is the least that you do with eyepieces - you mainly look through them.

I too had bought several of the Hyperion line for use in my Newts, thinking 68° would be brilliant. What I was not aware of was as oils ain't oils, eyepieces and scopes ain't eyepieces and scopes. Optics is a bit more complicated, and unfortunately there is a steep learning curve involved - as with everything else...

When I kept seeing that the image was so poor with each Hyperion I used, and how the aberrations changed in appearance between them, I started to think that not that there was something wrong with the eyepieces (you just won't get 4 lemons straight), but that I was missing something from my understanding of the relationship between scopes and eyepieces. When I mentioned what I was seeing to a friend of mine who has a phenomenal knowledge of optics, he straight away recognised the problem of optical mismatching, and explained how scopes produce a focal plane and that it is curved, and some curves are concave and others convex, and how the radius of this curve also varies according to the f/ratio and focal length of the scope!

I have used Hyperions in refractors, SCTs and Maks since, and they are just fine in these scopes. Just not in Newts. But I do have a 5mm Hyperion which throws up a pretty good image in my 8" f/4 Newt. And the 5mm is good in Newts because the lens design is different from the others.

Note also that many people think that the Hyperion line is a "copy" or "clone" of the Vixen LVW line. They are not. They are only similar in size and the use of colour bands that are used to distinguish the different focal lengths (pretty dumb in the dark when you are using red light... they all look the same ), but other than that internally they use different lens arrangements and glass types. What Hyperions are exactly the same as are the Saxon SWA, Celestron Duo, and a couple others.

It is important to know that there are actually only a handful of eyepiece manufacturers, and that nearly ALL brands have their eyepieces manufactured by these manufacturers. Many eyepiece lens designs are actually exactly the same from brand to brand, and the only difference is the outer casing's appearance.

I know I've written more than your question asked for, but I felt it is important to know that there is more involved than just what your question alone asked about.

Alex.
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Old 23-08-2017, 01:21 PM
TonySize (Tony)
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Quote:
Originally Posted by mental4astro View Post
Tony,

You are headed for a world of pain with the Hyperions in your Newtonian. These eyepieces are not designed for Newts, but for refractors, SCT's and Maks. It comes to the shape of the focal plane each scope produces: Newts produce a concave focal plane, refractors, SCT's and Maks a convex. Of the entire Hyperion line, only the 5mm works well in Newts. All the others will be affected by field curvature (some focal lengths more than others), pin cushion and even astigmatism. This is not a design flaw in the eyepieces. Instead, Newts and Hyperions are not an optical match.

If you are wanting to do eyepiece projection with them, you may get away with it if you keep the planets really tight in the centre of the FOV. As for vignetting, it really is not a concern as you will be using EP projection for the planets, and the background sky will all be black - you won't see the edge of the FOV. For lunar photography, there I cannot say, but vignetting will be the least of your problems here. But eyepiece projection is the least that you do with eyepieces - you mainly look through them.

I too had bought several of the Hyperion line for use in my Newts, thinking 68° would be brilliant. What I was not aware of was as oils ain't oils, eyepieces and scopes ain't eyepieces and scopes. Optics is a bit more complicated, and unfortunately there is a steep learning curve involved - as with everything else...

When I kept seeing that the image was so poor with each Hyperion I used, and how the aberrations changed in appearance between them, I started to think that not that there was something wrong with the eyepieces (you just won't get 4 lemons straight), but that I was missing something from my understanding of the relationship between scopes and eyepieces. When I mentioned what I was seeing to a friend of mine who has a phenomenal knowledge of optics, he straight away recognised the problem of optical mismatching, and explained how scopes produce a focal plane and that it is curved, and some curves are concave and others convex, and how the radius of this curve also varies according to the f/ratio and focal length of the scope!

I have used Hyperions in refractors, SCTs and Maks since, and they are just fine in these scopes. Just not in Newts. But I do have a 5mm Hyperion which throws up a pretty good image in my 8" f/4 Newt. And the 5mm is good in Newts because the lens design is different from the others.

Note also that many people think that the Hyperion line is a "copy" or "clone" of the Vixen LVW line. They are not. They are only similar in size and the use of colour bands that are used to distinguish the different focal lengths (pretty dumb in the dark when you are using red light... they all look the same ), but other than that internally they use different lens arrangements and glass types. What Hyperions are exactly the same as are the Saxon SWA, Celestron Duo, and a couple others.

It is important to know that there are actually only a handful of eyepiece manufacturers, and that nearly ALL brands have their eyepieces manufactured by these manufacturers. Many eyepiece lens designs are actually exactly the same from brand to brand, and the only difference is the outer casing's appearance.

I know I've written more than your question asked for, but I felt it is important to know that there is more involved than just what your question alone asked about.

Alex.
Thank you so much. Incredibly useful, a shame but useful. So a guess there aren't any adaptors to correct this it's just the design, otherwise you would have mentioned it?

I'll probably stick to prime for the DSLR for a bit then and i'll think about the 5mm for planetary and small objects though. Did you take the front lens group off your 5mm and try it as 22.5mm? I'd better start saving looks like an APO in my future.
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Old 23-08-2017, 03:08 PM
Wavytone
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Tony,

For eyepiece projection, from an optical design perspective there's an awful lot of merit in using an eyepiece that is more or less symmetrical front-to-back, and which is also suited to the field curvature of a Newtonian. The simple Plossl is the obvious and almost perfect candidate as it's just two Plano-convex doublets with the crowns facing.

In some respects a 20-50 mm camera lens - reversed - may also work if you have the rings and adapters to fit one backwards as camera lenses in that range are usually Gaussian designs.
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Old 23-08-2017, 03:38 PM
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mental4astro (Alexander)
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No, there are no adapters to correct for this. The only correctors are for the scopes themselves. Recall that I mentioned that the focal plane produced by scopes is curved? The shape is somewhat like a bowl. But, the CCDs in our cameras are flat. Without some type of gizmo that can alter the shape of the incoming light from the scope onto the chip, if the centre of the image is sharply focused, the outer edge will not be. These gizmos are called field flattners for refractors and SCTs, and coma correctors for Newtonians. And they are not interchangeable either. Plus, with field flattners you need to get the right one exactly for your scope - diameter, focal length and focal ratio. AND these are only made for apochromatic refractors, not achromatic ones.

Wavy' mentioned that plossl eyepieces are ideal for eyepiece projection for Newtonians. GSO has a line of plossl eyepieces exactly for this purpose, complete with a threaded jacket to accept adapters . Look at the Andrews Communications or Bintel websites for these. I have one of these 32mm plossls with the threaded jacket.

Alex.
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Old 23-08-2017, 10:47 PM
TonySize (Tony)
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Wavytone and Mental4astro thank you. I'll look at the GSO's and a variable projection adapter to use my current plossls in.
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