Houdini eyepieces

[Don Pensack]

I'll bring your attention to a new line of coma-corrected eyepieces that work well in all newtonians and SCTs and refractors of f/6.5 and longer.
The reason why they work in refractors is that the reverse coma is no worse than coma in a newtonian of the same f/ratio.
Currently, 20mm 86° is available and 12mm imminently.
7mm late in the year.
Other FLs designed: 4mm, 5.3mm, 9mm, 30mm

Here is the website:
https://www.houdinitelescopes.com/
and long threads describing the eyepiece(s) and how they work:
https://www.cloudynights.com/topic/9...ing-eyepieces/
https://www.cloudynights.com/topic/9...ing-a-reality/
https://www.cloudynights.com/topic/9...ng-april-10th/
https://www.cloudynights.com/topic/9...-reports-here/

My test of the 20mm in f/4.5 dobs and f/7 apo:
Paracorr setting not applicable
spherical aberration seen? none
coma seen? none
lateral astigmatism? none
field curvature none seen
Distortion type not obvious
Distortion visible? no
Chromatic aberration axial none
chromatic aberration lateral: none seen though I didn't view 1st or 2nd mag. stars at the edge of the field.
Glasses allow full field to be seen? yes
Eye relief comment? had to press against the rubber eyecup to see the edge.
light scatter control, bright object outside field excellent
light scatter control, bright object in field DSOs good, no test with Moon or planets yet
SAEP none noticed.
CAEP did not see any in daylight except when looking through glasses at a sharp angle.
tint did not test
vignetting? none seen
transmission emphasize any color? did not test
field stop focus OK
EOFB? none seen
Apparent transmission (no lab test done) OK
sharpness on axis excellent
sharpness mid field excellent
sharpness at edge excellent
field presentation(close/medium/distant) close (resembles 100°)
presentation of field when panning (concave/flat/convex toward user) flat
impression of contrast in star fields superb. Resembles 21mm Ethos except sharper in outer 20% of the field.

A tour de force. Star images as close to perfect as I've seen in an eyepiece of this focal length or close to.
Better than the 22mm Nagler in the Paracorr. Shocking.
No reverse coma seen in the f/7 apo. (don't notice coma at f/7 in a newtonian, either)
loose rubber eyecup
110g lighter than 22mm Nagler, ignoring the Paracorr weight.
if storing it with eyecup folded down, you'll need a 55mm eyepiece cap.

[EpickCrom (Joe)]

Originally Posted by Don Pensack

I'll bring your attention to a new line of coma-corrected eyepieces that work well in all newtonians and SCTs and refractors of f/6.5 and longer.
The reason why they work in refractors is that the reverse coma is no worse than coma in a newtonian of the same f/ratio.
Currently, 20mm 86° is available and 12mm imminently.
7mm late in the year.
Other FLs designed: 4mm, 5.3mm, 9mm, 30mm

Here is the website:
https://www.houdinitelescopes.com/
and long threads describing the eyepiece(s) and how they work:
https://www.cloudynights.com/topic/9...ing-eyepieces/
https://www.cloudynights.com/topic/9...ing-a-reality/
https://www.cloudynights.com/topic/9...ng-april-10th/
https://www.cloudynights.com/topic/9...-reports-here/

My test of the 20mm in f/4.5 dobs and f/7 apo:
Paracorr setting not applicable
spherical aberration seen? none
coma seen? none
lateral astigmatism? none
field curvature none seen
Distortion type not obvious
Distortion visible? no
Chromatic aberration axial none
chromatic aberration lateral: none seen though I didn't view 1st or 2nd mag. stars at the edge of the field.
Glasses allow full field to be seen? yes
Eye relief comment? had to press against the rubber eyecup to see the edge.
light scatter control, bright object outside field excellent
light scatter control, bright object in field DSOs good, no test with Moon or planets yet
SAEP none noticed.
CAEP did not see any in daylight except when looking through glasses at a sharp angle.
tint did not test
vignetting? none seen
transmission emphasize any color? did not test
field stop focus OK
EOFB? none seen
Apparent transmission (no lab test done) OK
sharpness on axis excellent
sharpness mid field excellent
sharpness at edge excellent
field presentation(close/medium/distant) close (resembles 100°)
presentation of field when panning (concave/flat/convex toward user) flat
impression of contrast in star fields superb. Resembles 21mm Ethos except sharper in outer 20% of the field.

A tour de force. Star images as close to perfect as I've seen in an eyepiece of this focal length or close to.
Better than the 22mm Nagler in the Paracorr. Shocking.
No reverse coma seen in the f/7 apo. (don't notice coma at f/7 in a newtonian, either)
loose rubber eyecup
110g lighter than 22mm Nagler, ignoring the Paracorr weight.
if storing it with eyecup folded down, you'll need a 35mm eyepiece cap.

Hi Don.

Thanks for your review of the new Houdini 20mm coma correcting eyepiece. Sounds like a fantastic piece of kit, your stellar review has me second guessing my planned ethos/paracor 2 upgrade long term plan!

The only issue for me would be the AFOV, I just love 100°. If the Houdini's were 100° I would be on them in a heartbeat.

Clear Skies
Joe

[Don Pensack]

The main difference with 100° eyepieces is that they are glasses-compatible, which, alas, no 100° eyepiece is.

I corrected my post: folded down rubber eyecup takes a 55mm eyepiece cap, not 35mm.

[AG Hybrid (Adrian)]

That 20mm is looking mighty attractive! Useful in all my scopes and will pair beautifully with my 12mm ES92 for a minimalist travel setup with comfortable LER eyepieces. Using a Paracorr T2 for low-mid powered eyepieces in my dob is annoying.

Other FLs designed: 4mm, 5.3mm, 9mm, 30mm. These are filling in were Explore Scientific couldnt be bothered continuing from their 12mm and 17mm.

Also, a 30mm 86 degree with 20mm eye relief? Thats going to be a 2Kg eyepiece unless the designer knows witchcraft.

[gaseous (Patrick)]

Great review, thanks Don. They sound amazing. It'll be interesting to hear a comparison between the Houdini 30mm and the Nagler 31T5.

[sn1987a (Barry)]

I tested my new Houdini 20mm vs 20mm type 2 Nagler and Paracorr type 1 setting 1. The Houdini feels about 1/3 the weight of the Nagler/Paracorr combo. I'm not savvy enough to make meaningful eyepiece telescope optical assessments but I know what I like. Stars appear slightly tighter in my 18" and 20" in the Houdini to my aging eyes and the Houdini is way lighter. I'll be ordering a couple of the 12mm and any others he decides to make. I think the prices are very reasonable. I hope he's charging enough to make money. Would be happy to pay more.