eyepopping Stratus mod: 80+ degree ultra-wide

[janoskiss (Steve H)]

Attention all Stratus owners! I know there are at least three of you because you bought my EPs. Here is something I discovered under the stars at Falls Creek this week: how to turn your Stratus super-wide into an ultra-wide.

Unscrew the 1.25" barrel at put it away. This is the barlow bit. Now you have a longer focal length eyepiece (not quite double the original) with bad edge performance, but a very wide field of view. At least 80 degrees, but probably more. You need to fold down the eyecup to see all of it. Stick the eyepiece in a good quality 2" barlow, and you get a very usable ultra-wide angle eyepiece with a focal length a bit (10-20%) under the marked focal length of the original eyepiece.

I tried this with the 13mm in a Japanese (University Optics equiv) 2" barlow in an f6 Dob, but it should work with the other focal length Stratus EPs too.

They are not exactly Naglers, but edge performance of the barlowed half-Stratus is not at all unpleasant in my f6. There is no seagulls, i.e. stars are not elongated tangentially, turning into concentric circular arcs like in the Superview. Instead they are elongated radially from the centre out. For some reason this aberration I find a lot less distracting than the seagulling, and I cannot even detect it when looking at or near the centre of the field of view. (Seagulling I can see even in the periphery and find it very annoying.) On clusters and nebulae I found the ultra wide Stratus+barlow combo awesome. Tuc47 and Orion neb looked absolutely fantastic. The centre of the view in the combopiece is very sharp; sharper than in the original eyepiece, easily as sharp as a Panoptic.

PS. This might not work the same with the similar Hyperion EPs, since they are promoted as a dual focal length eyepiece (i.e., the manufacturer expects you to take the barlow bit off). So they probably have a smaller field stop for the unbarlowed half of the EP.

[janoskiss (Steve H)]

Much belated edit: my final comment about Hyperions is incorrect. They'll work the same way.

[MortonH]

Originally Posted by janoskiss

Much belated edit: my final comment about Hyperions is incorrect. They'll work the same way.

About bl**dy time! Ten years I've been waiting for that!

[janoskiss (Steve H)]

I'm glad the wait is finally over. :-P

Like I said in the other thread, you end up with a ridiculously huge 2" EP this way with the size of a small refractor. It's basically the Speers-Waler ultra-wide design but in 2" instead of 1.25".

Real shame I did not have a digital camera at the time to take photos of it. The setup looked quite comical but I was excited about my discovery at the time. One really needs those tensioning and focus-lock screws on the Crayford.

[bytor666]

Originally Posted by janoskiss

Attention all Stratus owners! I know there are at least three of you because you bought my EPs. Here is something I discovered under the stars at Falls Creek this week: how to turn your Stratus super-wide into an ultra-wide.

Unscrew the 1.25" barrel at put it away. This is the barlow bit. Now you have a longer focal length eyepiece (not quite double the original) with bad edge performance, but a very wide field of view. At least 80 degrees, but probably more. You need to fold down the eyecup to see all of it. Stick the eyepiece in a good quality 2" barlow, and you get a very usable ultra-wide angle eyepiece with a focal length a bit (10-20%) under the marked focal length of the original eyepiece.

I tried this with the 13mm in a Japanese (University Optics equiv) 2" barlow in an f6 Dob, but it should work with the other focal length Stratus EPs too.

They are not exactly Naglers, but edge performance of the barlowed half-Stratus is not at all unpleasant in my f6. There is no seagulls, i.e. stars are not elongated tangentially, turning into concentric circular arcs like in the Superview. Instead they are elongated radially from the centre out. For some reason this aberration I find a lot less distracting than the seagulling, and I cannot even detect it when looking at or near the centre of the field of view. (Seagulling I can see even in the periphery and find it very annoying.) On clusters and nebulae I found the ultra wide Stratus+barlow combo awesome. Tuc47 and Orion neb looked absolutely fantastic. The centre of the view in the combopiece is very sharp; sharper than in the original eyepiece, easily as sharp as a Panoptic.

PS. This might not work the same with the similar Hyperion EPs, since they are promoted as a dual focal length eyepiece (i.e., the manufacturer expects you to take the barlow bit off). So they probably have a smaller field stop for the unbarlowed half of the EP.

Will the same work with an Orion / Vixen LVW? or will the glass fall out?

[janoskiss (Steve H)]

That was the Orion.

I wouldn't want to butcher any LVWs this way. They are very nice EPs as they are. I have tried a few of them and used to own the 22mm, which is probably the best of the lot. I'm certain they are very well thought out and optimally designed by some of the best Japanese optics engineers Vixen money could buy. Anything one could do to mod them (beyond simply barlowing them in the regular fashion) is likely to only stuff them up.

The Orion Stratus and other similar clones are just approximate copies of the LVWs. They use cheaper glass for example (no Lanthanum glass in Stratus and the like). I'm pretty sure I recall seeing lens arrangement drawings of both LVWs and clones, and while they are similar, they are not identical. That makes sense because the clones would have to account for the use of different glasses and at least change the lens shapes to match up the focal lengths of individual elements.

So the clones are fair game for tinkering but the LVWs are a case of don't fix what ain't broke.

[bytor666]

Originally Posted by janoskiss

That was the Orion.

I wouldn't want to butcher any LVWs this way. They are very nice EPs as they are. I have tried a few of them and used to own the 22mm, which is probably the best of the lot. I'm certain they are very well thought out and optimally designed by some of the best Japanese optics engineers Vixen money could buy. Anything one could do to mod them (beyond simply barlowing them in the regular fashion) is likely to only stuff them up.

The Orion Stratus and other similar clones are just approximate copies of the LVWs. They use cheaper glass for example (no Lanthanum glass in Stratus and the like). I'm pretty sure I recall seeing lens arrangement drawings of both LVWs and clones, and while they are similar, they are not identical. That makes sense because the clones would have to account for the use of different glasses and at least change the lens shapes to match up the focal lengths of individual elements.

So the clones are fair game for tinkering but the LVWs are a case of don't fix what ain't broke.

Thanks mate!

Cheers!