283 replies to this topic

[Houdini]

Santa came early this year – ten days ago I received the following package:

 

 

This is a prototype of the Houdini 20 mm 86° coma-correcting eyepiece using my optical design.
We've been discussing coma-correcting eyepieces on Cloudy Nights, most recently in the thread I started 4 months ago. 
I never expected that this dream would become a reality so quickly!

 

 

I've been testing the Houdini 20 with my 1100 mm (43") f/3.6 and 25" f/5 Newtonian telescopes, and with a 6" f/8 refractor binoscope for the past week.

 

 

I spent a first night with the 1100 mm f/3.6 constantly switching between the Houdini 20 and the Ethos 21 with Paracorr in (200X with 86° field of view, and 220X with 100° field of view, respectively).
Among others, Saturn, Jupiter, M33 (the nova was not visible), NGC 7789, M35 + NGC 2157, M1, M42, Mars, and Sirius B passed in review.
The two protagonists can be seen in the image below.

 

 

Almost a kilogram difference in weight (570 grams versus 1400 grams), but little difference in performance - sharp and nice images with both solutions.

It's impressive to see how well the Houdini 20 removes the parabolic coma, even at f/3.6, and rivals the Ethos 21 + Paracorr in image quality.

 

The second night I followed about the same program in the 25" f/5 where the eyepieces give 160X (Houdini 20) and 175X (Ethos 21 + Paracorr).

 

 

Both solutions gave nearly perfect images at f/5, with all stars in the field sharp (slightly worse at the edges, but still very good).

 

The third night I used the 6" f/8 binoscope. My interpupillary distance is large enough for binoviewing with the Houdini 20 (64 mm in diameter), but it's a challenge to squeeze my nose between the eyepieces. With some squirming and discomfort, I managed to see the 86° field with both eyes (the edge peripherally, of course).

 

 

 

The Houdini 20 offers 60X and almost 1.5° field in this setup. I got some great views of many large objects including M45 (Pleiades), M42 (Orion Nebula), M31 (Andromeda), M81 + M82, NGC 2344 (Rosette Nebula), M33, NGC 891, NGC 7789.
The eyepiece shows a sharp, flat image with some inverted coma at the edge, but not much. The edge sharpness is actually about the same as the Panoptic 24. This confirms that the Houdini 20 works well at f/8 in any type of telescope.

 

After the three nights, I could conclude that what I saw in the eyepiece agreed well with the optical design calculations. My "theoretical" predictions about the quality and flaws of the eyepiece (e.g. the visibility of inverted coma in an f/8 refractor, or the amount of lateral color near the edge of the field) were confirmed. In retrospect this may seem obvious, but ten days ago I wasn't sure .

 

I was able to use the Houdini 20 mm 86° with the 1100 mm f/3.6 for two more nights, while the Ethos 21 remained in the eyepiece case. I would have no problem making this switch permanent. The Houdini 20 is a much lighter and handier eyepiece, and the field of view you lose is more than compensated for by the improved ergonomics. The 86° field of view is sharp, flat, and distortion-free, with a comfortable eye relief - it's a near-perfect window to the universe.

 

As some may have guessed from the look of the eyepiece, the Houdini 20 is manufactured by Kunming United Optics - known for many other eyepieces including the XWA and UFF series.
The idea is to launch the Houdini 20 eyepiece in about 3 months. Over time, we intend to create a complete line of 28, 20, 12, 9 and 7 mm coma-correcting eyepieces.

 

This also means that my status on Cloudy Nights has changed to "Vendor"; it will take some getting used to .

 

Thanks for reading,
Robert

Edited by Houdini, 06 December 2024 - 09:27 AM.

[vkhastro1]

Congratulation !

Your “Houdini” 20mm eyepiece will be a game changer.

Please let us known the effective eye relief (very important info for eyeglass wearing observers).

Looking forward to further updates.

Edited by vkhastro1, 06 December 2024 - 09:27 AM.

[TOMDEY]

Now that's got my attention! Indeed, coma-corrected eyepiece(s) dedicated specifically to fastish Newtonians makes a lot of sense. I can see that it would be more compact than the Nagler or Ethos + Paracorr and still perform well... because the correction is fully-optimized for that exact application and focal length, as the entire design, rather than two disjoint modules in series. My big scope is 36" F/3.75. I also am attracted to the 86^o field. I like Naglers and Ethos... but find the 100^o field of the Ethos "too much of a good thing" for me. Where will we see these advertised, when and how to order, etc? I'm in the U.S.A. Thanks!

 

PS: Your 20mm and 12mm (and maybe the 9mm) would probably be my most used. For many decades I've been using 20mm and 13mm Naglers on my (other) 29-inch F/4.5 scope.   Tom

[AstroPotamus]

All I see are dollar signs.

[Houdini]

Congratulation !

Your “Houdini” 20mm eyepiece will be a game changer.

Please let us known the effective eye relief (very important info for eyeglass wearing observers).

Looking forward to further updates.

Thank you.

Nominal eye relief for the center of the field is 19.7 mm, measured from the glass. 

The eye lens center is recessed about 3.5 mm from the upper metal surface of the eyepiece (if you remove the eye guard), so the effective eye relief should be about 16 mm.

 

If you look at the pictures above, the eye guard on the prototype was too short. It will be 4 mm longer in the production run.

 

 

Now that's got my attention! Indeed, coma-corrected eyepiece(s) dedicated specifically to fastish Newtonians makes a lot of sense. I can see that it would be more compact than the Nagler or Ethos + Paracorr and still perform well... because the correction is fully-optimized for that exact application and focal length, as the entire design, rather than two disjoint modules in series. My big scope is 36" F/3.75. I also am attracted to the 86^o field. I like Naglers and Ethos... but find the 100^o field of the Ethos "too much of a good thing" for me. Where will we see these advertised, when and how to order, etc? I'm in the U.S.A. Thanks!

 

PS: Your 20mm and 12mm (and maybe the 9mm) would probably be my most used. For many decades I've been using 20mm and 13mm Naglers on my (other) 29-inch F/4.5 scope.   Tom

The 20 mm will be available in about 3 months (March 2025). There will be a dedicated web site and shop.

I'm living in Europe, so I may have to find a US dealer to make the shipping costs more reasonable for American customers.

 

I have the designs ready for the 12, 9, 7 and 28 mm eyepieces. I expect that they will be launched in that order in the coming 18 months.

Edited by Houdini, 06 December 2024 - 10:41 AM.

[Astrojensen]

WOW! Now THAT is interesting!!!! 

 

 

Clear skies!

Thomas, Denmark

[Mike Q]

Ok, i will take one for the team and be a guinea pig lol

[Neanderthal]

Thank you.

Nominal eye relief for the center of the field is 19.7 mm, measured from the glass. 

The eye lens center is recessed about 3.5 mm from the upper metal surface of the eyepiece (if you remove the eye guard), so the effective eye relief should be about 16 mm.

 

If you look at the pictures above, the eye guard on the prototype was too short. It will be 4 mm longer in the production run.

 

 

The 20 mm will be available in about 3 months (March 2025). There will be a dedicated web site and shop.

I'm living in Europe, so I may have to find a US dealer to make the shipping costs more reasonable for American customers.

 

I have the designs ready for the 12, 9, 7 and 28 mm eyepieces. I expect that they will be launched in that order in the coming 18 months.

I'm a little confused by the eye relief specs, hope these are going to be eyeglass-friendly. Any ball-park idea on the cost?

[Houdini]

The pricing of the eyepieces is not yet decided; we'll announce it as soon as possible. (this is all quite new for us, and we want to take the time to do this right).

 

For the eye relief, I hope the following diagram will help. It shows a cross section of the upper part of the eyepiece.

The green light rays come from the left and converge in point A.

You are looking right to left with your eye at point A, so that you can see the whole field.

 

 

 

The distance A-C is the nominal eye relief, measured between the eye in A and the glass element in C.

 

The distance A-B is the effective eye relief, measured between the eye in A and the upper part of the eyepiece in B against which you will press your eyeglasses.

Edited by Houdini, 06 December 2024 - 01:09 PM.

[TOMDEY]

Heh... I might as well get this out of my system while you're still in the prototyping/finalizing phase >>> I hope your finalized opto-mechanical design/build insertion barrels are "smoothies" or an option for that. I can imagine ways to offer either/or as a ~slip on~ outer skin to an undersized inner barrel, or some other approach. Televue is staunchly entrenched on the fancy undercuts side of the fence. Your prototype up there looks like an interesting nifty smoothish approach.     Tom

[Houdini]

Hello Tom, the Houdini eyepieces will have a barrel with kerfs, like the Baader Morpheus.

This is a far better solution than an undercut or a tapered barrel.

Edited by Houdini, 06 December 2024 - 02:38 PM.

[TOMDEY]

Hello Tom, the Houdini eyepieces will have a barrel with kerfs, like the Baader Morpheus.

This is a far better solution than an undercut or a tapered barrel.

Yippee! --- That will be wonderful.    Tom

[Olimad]

Impressive... Félicitations. 

[Starman1]

Thank you.

Nominal eye relief for the center of the field is 19.7 mm, measured from the glass. 

The eye lens center is recessed about 3.5 mm from the upper metal surface of the eyepiece (if you remove the eye guard), so the effective eye relief should be about 16 mm.

 

If you look at the pictures above, the eye guard on the prototype was too short. It will be 4 mm longer in the production run.

 

 

The 20 mm will be available in about 3 months (March 2025). There will be a dedicated web site and shop.

I'm living in Europe, so I may have to find a US dealer to make the shipping costs more reasonable for American customers.

 

I have the designs ready for the 12, 9, 7 and 28 mm eyepieces. I expect that they will be launched in that order in the coming 18 months.

Careful!  If the eyecup is taller, when it folds down it will stick up quite a bit above the top surface of the aluminum.

That would reduce the effective eye relief of the eyepiece and might make it unusable by glasses wearers.

As it is, your effective eye relief of 19.7-3.5=16.2mm is OK for most glasses wearers, but, you forgot the rubber above the aluminum surface, likely a mm.

That makes the glasses user's eye relief 15.2mm, which is about the same as the Pentax XW and  some other eyepieces that are glasses-compatible.

If you make the eyecup 2mm taller, it will stick up above the aluminum surface more than the one that is there, and might make the eyepiece a non-viable candidate for glasses use.

[Tangerman]

Very exciting! And with impressive eye relief for such wide apparent fields of view, I might have to try one out sometime.

[ihf]

This is awesome. I am in line for one.

[Houdini]

Careful!  If the eyecup is taller, when it folds down it will stick up quite a bit above the top surface of the aluminum.

That would reduce the effective eye relief of the eyepiece and might make it unusable by glasses wearers.

As it is, your effective eye relief of 19.7-3.5=16.2mm is OK for most glasses wearers, but, you forgot the rubber above the aluminum surface, likely a mm.

That makes the glasses user's eye relief 15.2mm, which is about the same as the Pentax XW and  some other eyepieces that are glasses-compatible.

If you make the eyecup 2mm taller, it will stick up above the aluminum surface more than the one that is there, and might make the eyepiece a non-viable candidate for glasses use.

Thanks for the very useful comment, Don. I'll make sure to follow this up, but I'm not too worried.

 

My point of comparison is the eye guard of the 30 mm UFF (also made by KUO) which is 2 mm taller than the production eye guard of the Houdini 20 (this matches the specified eye relief, which is 22 mm for the UFF 30 and 20 mm for the Houdini 20).

 

I can fold that eye guard as flat as the shorter eye guard on the Houdini 20 prototype, so I would not really expect any issues.

[vkhastro1]

Thank you.

Nominal eye relief for the center of the field is 19.7 mm, measured from the glass. 

The eye lens center is recessed about 3.5 mm from the upper metal surface of the eyepiece (if you remove the eye guard), so the effective eye relief should be about 16 mm.

 

If you look at the pictures above, the eye guard on the prototype was too short. It will be 4 mm longer in the production run.

 

 

The 20 mm will be available in about 3 months (March 2025). There will be a dedicated web site and shop.

I'm living in Europe, so I may have to find a US dealer to make the shipping costs more reasonable for American customers.

 

I have the designs ready for the 12, 9, 7 and 28 mm eyepieces. I expect that they will be launched in that order in the coming 18 months.

A North American dealer(s) would be a definite plus - one for Canada and one for the USA !

[eyeoftexas]

Looking forward to this.  I for one like long eyecups.  Will this design in any way restrict the eyepiece to only fast scopes?  I have a 20” f/4.3 Starmaster but also a Mewlon 180 f/12.

[Houdini]

The eyepiece will work well with any telescope with longer focal ratio, f/8 and above are fine. At long focal ratios the parabolic coma correction is not visible.

The Houdini 20 will behave like an excellent "normal" eyepiece in your Mewlon 180 f/12.

[Astrojensen]

The eyepiece will work well with any telescope with longer focal ratio, f/8 and above are fine. At long focal ratios the parabolic coma correction is not visible.

The Houdini 20 will behave like an excellent "normal" eyepiece in your Mewlon 180 f/12.

This is amazing. Many of us have a big, fast dob, plus some smaller, much slower scopes. A wide-field eyepiece that can work well in both, without the need of additional expense and hassle of a coma corrector, is going to be a major breakthrough and become hugely popular (depending on the final price). 

 

Pleasepleaseplease consider making a 24mm ~65° version for smaller telescopes with 1.25" only focusers. 

 

 

Clear skies!

Thomas, Denmark

Edited by Astrojensen, 07 December 2024 - 07:20 AM.

[eyeoftexas]

 

If you make the eyecup 2mm taller, it will stick up above the aluminum surface more than the one that is there, and might make the eyepiece a non-viable candidate for glasses use.

It would be best to have two eyecups come with it, one for each crowd.  For me, short eyecups (or even no eyecups) are difficult to use because it makes finding and holding eye placement more difficult and allows more stray light in.  

[PEterW]

… and we wondered whether we’d see any more innovations in eyepiece design… well done on finding a missing product that can unlock the short focal lengths of fast fins without needing additional optics.
Any more new product ideas in the works?

Peter

Edited by PEterW, 07 December 2024 - 10:13 AM.

[GeraJensen]

I would definitely have a lookout for your 28mm.
Large field stop eyepiece + coma corrector is a clear winner.

Best regards
Thomas

Edited by GeraJensen, 08 December 2024 - 04:47 AM.

[CHASLX200]

I hate coma and at speeds faster than F/6 is see it.