145 replies to this topic

[ihf]

Like the Houdini 20, the Houdini 30 will have 42 mm diameter lenses in the top part, and that is too big for Dioptrix.

It might be possible to 3D print an adapter, I guess, the Houdini 20 has some 48 mm threading at the top that could be used for this.

The DioptRX eats eye relief and the adapter likely as well. There may not be much left. Maybe that is a stupid idea: Eye glasses are inexpensive to make. Most glasses are not quite as high quality as the DioptRX, but people cut their own and drop them into binoculars. So you might be able to offer a set of screw in cylinder corrections for your eyepieces. The financial margins should be there. (3D-print rotatable adapter frames, drop in prescription, offer an inventory of about 8 cylinder prescriptions from 0.5 to 4. The main thing is to keep as much eye relief as possible.)

Edited by ihf, 25 May 2025 - 10:08 AM.

[Starman1]

A few preliminary points:

1) Used the 20mm briefly in a 14" f/5 and discovered that the eyepiece is very sharp and has superb contrast.

2) Star images at the edge were not as small as the center, but not because of FC in the 1780mm FL scope (refocusing did not improve the image), but due to a tiny trace of astigmatism.

Coma was well controlled at that f/ratio and was not an issue.  Many highly-regarded eyepieces used in a Paracorr are no better.

3) It was usable with glasses on and the entire field was easy to see, and I have a large cornea-to-glasses vertex distance.

 

This is from only a few minutes with the eyepiece at f/5.  I have yet to use the eyepiece in a f/3.75 scope with a 1524mm focal length.

I will report more fully later.

[Neanderthal]

Thank you Don, was looking forward to your assessment! Mine sits in it's box with no chance to use it for perhaps another week.   

[Tangerman]

This is from only a few minutes with the eyepiece at f/5.  I have yet to use the eyepiece in a f/3.75 scope with a 1524mm focal length.

I really didn't think the field was any worse at f/3.5 than at f/5. I think you'll be pleased at f/3.75.

[TayM57]

I really didn't think the field was any worse at f/3.5 than at f/5. I think you'll be pleased at f/3.75.

The curve is steeper though. If I end up getting a H20, it will be for my f/3.17 and f/3.4 scopes. I need more reports from eyeglasses wearers though, before I buy.

[Tangerman]

The curve is steeper though. If I end up getting a H20, it will be for my f/3.17 and f/3.4 scopes. I need more reports from eyeglasses wearers though, before I buy.

All the spot diagrams I can find (there are a few for a 31mm 81° and a 24mm 86°, neither of which would necessarily be a final production design) do indeed show the stars are larger for faster focal ratios, but even at f/3 they should do very well. 

 

The eye relief was a huge selling point for me, as there aren't any other full lines of eyepieces with 86° AFOV or larger with 19+ mm eye relief. My current glasses are not optimized for astronomy, and with different frames I could get a smaller vertex distance, so I'll let others comment more on how well they work with astronomy-optimized glasses. Of course, if the eyecup changes, then it's possible the usability with glasses will also change — hopefully for the better.

[Houdini]

All the spot diagrams I can find (there are a few for a 31mm 81° and a 24mm 86°, neither of which would necessarily be a final production design) do indeed show the stars are larger for faster focal ratios, but even at f/3 they should do very well. 

If you're looking for the performance of the Houdini 20 at various focal ratios, see this post from the other thread.

Edited by Houdini, 25 May 2025 - 02:30 PM.

[jcastarz]

My Houdini 20mm should arrive from Agena Astro tomorrow.  My target instrument for this eyepiece is my 12.5" f/4.5 New Moon truss dob, and I have both a Nagler 22mm T4 and Paracorr 2 to contrast the Houdini with.

 

Per tradition with new astronomical equipment arrivals, my region is scheduled to be cloudy at best and rainy at worst, so my first test of the new eyepiece may be in an Orion 8" f/6 that can be more easily deployed during breaks in the weather.

[Tangerman]

Out of curiosity, where does the focal plane lie in relation to the eyepiece shoulder for the 20mm?

[CrazyPanda]

Out of curiosity, where does the focal plane lie in relation to the eyepiece shoulder for the 20mm?

2mm above the shoulder:

 

https://www.cloudyni...0th/?p=14118853
 

[Houdini]

You can also find all the product specifications on the product page: https://www.houdinit...ecting-eyepiece

[CrazyPanda]

Short observing report with the 20mm.

 

Weather has been so bad that this was the first clear dark night I've had since my last report with the 90mm F/6 a month ago.

 

I didn't spend too long with the Houdini since I wanted to be at higher magnifications, but I cruised through a bunch of Messier objects and got some glob season time in.

 

Every single glob I looked at, especially M5, showed very, very sharp little stars in the 20H that were every bit as sharp and defined as the 21E with or without the Paracorr. Contrast overall was excellent on every target. Very easy and comfortable to look through.

 

Axially, this is a great eyepiece that is easily as good as any of the other premium eyepieces on the market. I'll be interested in a test of the double cluster later this year, where whole field sharpness will matter.

 

I like the 20H enough that I definitely want the 12mm and 7mm, but with the threat of a 50% tariff on the EU this July, I might have to wait until things settle.

Edited by CrazyPanda, 27 May 2025 - 07:42 AM.

[Neanderthal]

Question for Robert...

 

The 20mm is listed as having 20mm of eye relief (15mm useful from edge of body).

The 12mm is listed as having 19mm of eye relief (15mm useful from edge of body).

 

Are all the future EP's going to maintain (or increase) that specification of 15mm useful from edge of body as well?

[Houdini]

Yes, the eye relief will be similar across the entire range: around 19-20 mm theoretically and 15 mm effectively.

The shorter FL eyepieces (7, 5.3 and 4 mm) become longer for this reason; it's the only way to maintain the eye relief.

[jcastarz]

On May 31, I tried out my 20mm Houdini for the first time.  I didn't set up my f/4.5 truss dob and used my 8" f/6 instead.  As the Naglers are outstanding in the 8" f/6, I didn't use a paracorr in the comparison with my Nagler 22mm T4 - which up to this time has always been my default eyepiece in the 8".  According to Astrospheric, skies were about average transparency, but with a heavy dose of forest-fire smoke.  The smoke wasn't visually detectable, but the sky had a dull look to it, and the 4-day-old crescent moon was not a clean white.

 

On the moon, the Houdini actually appeared to "out-sharp" the Nagler - if only by a smidgeon; it could be the extra magnification boost made the view more compelling.  I sort of forgot about the Nagler after that...  on M-13, the Houdini's view was very consistent across the field in terms of brightness and sharpness.  I won't go any further into optical details as others have already done so on this thread already, and with much better skies and faster scopes to boot.  Suffice it to say I'm looking forward to using the Houdini with my 12.5" f/4.5 at my first star party later in June to test out the "look Ma, no Paracorr !!" effect.

 

The one aspect of the whole Houdini experience for me that was unsat has also been mentioned in previous posts:  the rubber eyecup.  My experience with wide-field eyepieces is that I need to get close to the glass to take in the whole apparent field (FWIW: I do NOT wear eyeglasses while observing).  On my 28mm Asto-Tech UWA I can fold down the eyecup to do this; when I tried the same with the Houdini 20mm, the eyecup just rolled off and I had to go hunting for it on the ground.  The rubber appears to be too flexible and does not hold its shape well.

 

We all have different needs and preferences with respect to eye placement relative to the eyepiece lens.  Televue T4 Naglers handled this with the sliding eyecup.  Houdini might accommodate better eye placement using their current eyecup material to make eyecups in different lengths, so the user can select what works for them.  If these alternative-length eyecups are not shipped with the eyepiece, they could be offered as an after-market purchase, perhaps with a vial of rubber cement to better secure them in place.  Custom eyecup lengths for a custom eyepiece, and as a bonus the eyepiece cap would still fit.

[nkoiza]

Any more reports (or further review information on existing reports) on 20mm Houdini performance? Really interested to see how everyone is getting on with these! 

 

Also, interested to know if the 9mm form factor will be similar to the 12mm if it's not too early to enquire about this, Robert?

 

The 9mm Morpheus is a great eyepiece from the perspective of sharpness, contrast and transmission amongst other areas so I'm hoping the 9mm Houdini will fair well against this eyepiece once it arrives. 

[tommylee340]

I'll offer my perspective as someone who has considerably less experience observing with high end wide FOV EPs than others here who have already weighed in so consider my opinion with that in mind. (To use a baseball analogy, if the CN elite were major league all-stars, I would be a scrub grinding away in single A.) That said, I like to think I know what looks good through an EP when I see it and the H-20 provided some pretty impressive views to my eyes. I was fortunate to have really good viewing conditions in the mountains east of San Diego last week (new moon +1). No clouds, cool conditions, light wind and better than usual visibility. As a bonus, the marine layer came in off the ocean and completely covered the San Diego/Tijuana light dome making for some relatively dark skies in the area (Sunrise Hwy for those familiar). I was using the H-20 in my 13.1" f/4.5 scope.

 

This is pretty much my first in-depth foray using a wide FOV 2" EP (over 60 degrees) because of the associated coma that comes with them sans correction. I had not previously entered this realm because of the associated investment needed to do it right, although I was recently doing cursory research into Nagler, Ethos, Morpheus EPs and a Paracorr before the Houdini came on my radar. Given its price point and built in CC it made sense to try a Houdini out before continuing down that path.

 

So after a full night of observing I can say I was extremely happy with the H-20's performance. Nice crisp images of stars, galaxies and globulars, superb contrast, especially with nebula, and the edge to edge sharpness was as good or better than any of my narrow field EPs which consists of mostly Konigs, Plossls, and Orthoscopics, all which are pretty decent in their own right for what they are. After a couple brief rounds in the focuser for the sake of comparison, they spent the rest of the night in the EP case. Suffice it to say, I will be investing in the Houdini EP line going forward as they become available. I can understand why experienced observers with a substantial investment in high end EPs/Paracorr may not trade them out for Houdinis, but for someone like me who hasn't yet made that investment for their fast reflector(s), the Houdini is clearly the way to go given their price and high quality. Anyway, I thought a voice from the ranks of the astronomical unwashed masses might be appreciated by someone in similar circumstances.

 

Edit: Wanted to add that my interaction with Robert before and up to my purchase was nothing short of excellent. I dig his attitude and the enthusiasm he has for his product. It's pretty cool.

Edited by tommylee340, 03 June 2025 - 11:22 PM.

[Tangerman]

For anyone in the US who didn't order directly from Robert when it first came out, the 20mm is now listed on Agena Astro as In Stock. So if you're curious or you've been waiting to support a US vendor, now's your chance.

[nkoiza]

 

 

So after a full night of observing I can say I was extremely happy with the H-20's performance. Nice crisp images of stars, galaxies and globulars, superb contrast, especially with nebula, and the edge to edge sharpness was as good or better than any of my narrow field EPs which consists of mostly Konigs, Plossls, and Orthoscopics, all which are pretty decent in their own right for what they are. After a couple brief rounds in the focuser for the sake of comparison, they spent the rest of the night in the EP case. Suffice it to say, I will be investing in the Houdini EP line going forward as they become available. I can understand why experienced observers with a substantial investment in high end EPs/Paracorr may not trade them out for Houdinis, but for someone like me who hasn't yet made that investment for their fast reflector(s), the Houdini is clearly the way to go given their price and high quality. Anyway, I thought a voice from the ranks of the astronomical unwashed masses might be appreciated by someone in similar circumstances.

Thanks for your feedback. Sounds great!

[IslandPink]

I believe it's actually the *cube*.

 

F/3 has 8x the coma that F/6 does, so it's even worse.

 

Coma nomenclature is 'W _3,1 ' in wavefront. Hence the wavefront error is proportional to the cube of the aperture, if the FL is fixed ; however in terms of transverse errors ( ie. the coma in mm on the focal plane ) the dependence is quadratic , ie the square of the aperture, or the inverse square of the f/number . 

 

This is what allows these eyepieces to work quite well if you switch to a moderate to slow refractor - the coma effect decreases rapidly with f/number.

 

Thank you Robert for posting about your mirror recoating on the ATM forum ; I was just about to buy a Paracorr 2 on EBay .. now I think I will buy a 20mm Houdini.

One question - the designs you show on your website show designs with the intermediate image very close to a lens surface, or in some cases inside the glass. Have you have any problems with dust or cosmetic defects , yet ?

Edited by IslandPink, Yesterday, 05:20 PM.

[Houdini]

That's a very good question.

The designs on the Cruxis website are not production quality; the designs for the actual Houdini series are different.

One improvement to the production design was ensuring the focal plane was sufficiently far from the lenses, so that you don't have any issues with dust or cosmetic defects in the glass.