68 replies to this topic

[CaribbeanCruiser]

OK, am I dreaming?  After spending the last, several, rainy nights reading through a few of the “The joy of a small refractor” posts and the countless replies, I find myself wondering if there’s a reasonably priced (sub $200US) 4mm eyepiece that has an equally reasonable exit pupil. 

 

I bought my Z73 mainly for AP, but almost every time I take it out, my family wants to look through it, this is great!  The trouble is,  I only have a decent 12mm (Celstron X-Cel) and an OK 9mm Plossl that came with a cheap scope.  Both throw up some nice views of our moon and the moons of Jupiter, but I’d really like to show them some detail on Jupiter and the rings of Saturn. 

 

4mm, roughly 100x, would seem to be more than enough.  Maybe 80x, roughly 5mm is enough and a little more comfortable?

[NOLAMusEd]

A 73mm scope should have no issue with 100x or even more. Consider a 2x barlow lens or telecentric focal extender to take the 12mm to 6 mm and the 9mm to 4.5mm. If you're set on an eyepiece, a used Radian of 4mm should give nice views on bright objects like Saturn, Jupter, luna and not be too expensive. The drift time shouldn't be too bad either since it won't be very high magnification, and it should be plenty comfortable with its long eye relief. You could also pair it with the barlow for 200x which would be starting to push the limits of the scope, but should still be workable with bright objects when seeing permits.

[MrsM75]

A small Refractor so I'm guessing it fast f/5 scope, it will not be forgiving in eyepiece than a f/15, plus eyepiece of 4mm is not a magnification that a cheap eyepiece can achieve good view with a fast scope.

 

I really can't recommend any cheap 4mm eyepiece with a fast Refractor. 

 

I think you should get a 4mm Delite Televue, or a 4mm Vixen SLV Lanthanium glass. Or the 4.5mm Delos Televue.

 

Delos is 72 degrees. And it Televue, who doesn't love it.

[havasman]

If that's the William Optics scope a 4mm eyepiece yields a 0.7mm exit pupil and that can be difficult for relatively inexperienced observers. Consider an Astro-Tech 7mm UWA, a very good eyepiece that will be much more user friendly. It will also make enough magnification to show what you want if you'll take the time to build observing skill and patiently ferret out all that combo will show you.

[Matthew Trail]

A Celestron Xcel LX 5mm (apparently really 4.5)? I have one on the way but haven’t viewed through one. I like my 4mm Radian in my TV 85 and you could find one used in that price range. 5mm Paradigm gets good reviews and is well within that price range too. My TMB planetary II clone (Svbony brand) is also a great value. It’s labeled 4.5 but I suspect it’s closer to 4mm—perhaps even mislabeled.

You’ll probably want an eyepiece with good eye relief for family viewing, and all of the above would do.

[Mike W]

Televue radian

[Jay_Reynolds_Freeman]

Before you spend piles of money on more modern types, look for used orthoscopics. They will likely do reasonably well at f/5. Perhaps you won't want anything fancier.

 

Clear sky ...

[Ernest_SPB]

Consider also TMB Planetary

[Jon Isaacs]

Consider also TMB Planetary

 

The WO ZS73 is a ~72 mm F/6 FPL-53 Doublet.  

 

I had a real 4 mm TMB Planetary, it was decent at F/6.  The 4 mm Astro-Tech UWA is a pretty good eyepiece and I believe it's $120.  I use the 5 mm Paradigm quite a bit. It's quite good at F/6 as well.

 

Jon

[MisterDan]

I agree with Ryan.  One 2x Barlow or telecentric amplifier => two "new" eyepieces.

 

Best wishes and luck.

Dan

[T1R2]

Shoot for 146x-ish+, and another EP that gives about 20-30x over that, the formula for finding any telescopes highest theoretical max power is its "aperture in mm's x2" ,  so 73mm scope is 146x, if you can only find an EP that gives 150x thats fine also. but don't expect magic in a 70mm scope seeing details in Saturn's rings requires at least 5" (maybe a 4" scope)  and 250x+ and with that you can just start to see Saturn shadow etched across the backside of the rings, Cassini's Division will be visible in a small scope but the sky has to be really steady. 

 

But don't expect much since Saturn's rings are edge on for the next 3 yrs at least until they start opening up real good again. 

Edited by T1R2, 11 May 2025 - 11:44 PM.

[MrsM75]

I would still get a $200ish range 4mm brand name ep OP, your Williams Optics is too precious for a cheap eyepiece.

[triplemon]

Before you spend piles of money on more modern types, look for used orthoscopics. They will likely do reasonably well at f/5. Perhaps you won't want anything fancier.

A 4mm ortho ? I call those contact lenses ... barely 2mm eye relief. That is REALLY for hardcore folks only and not a family-have-a-look thing.

 

If you like the 12mm X-Cel LX, get the 7mm version. Maybe plus a 2x barlow. As that easily fits your budget and you know exactly what to expect. The 5mm in that series has a poor reputation, so I'd have some reservations. With the 7mm + barlow, you get 65x and 130x, which both make sense with that telescope. Plus the barlow might make the 9mm Plossl a lot more useable as a 100x eyepiece, as the barlow will increase its eye relief notably.

Edited by triplemon, 12 May 2025 - 01:08 AM.

[izar187]

Consider perhaps a 4mm Siebert SS4

68º fov with 17mm eye relief, less than 1mm recessed.

Call and talk to the man who makes the ep before ordering.

https://www.sieberto...rtho page).html

Edited by izar187, 12 May 2025 - 08:51 AM.

[SeattleScott]

For sharp views on a budget, a vintage 3.8mm Parks Gold/Orion Ultrascopic. However only 7mm or so ER and vintage 50 AFOV.

The 4mm Radian might just be the ticket, long ER, decent AFOV and under $200 (probably around $150).

New, I would say the 4mm AT UWA. Fast, before tariffs double the price. Or a Vixen 4 SLV if you can find one around $100.

[MrsM75]

The Vixen 4mm Lanthanium glass it everywhere it just it retail price of $146.95 (Explorer Scientific) and other sites all has them.

 

You could have get them for $105 at Amazon Japan, but starting midnight of May 1st Amazon Japan has taking down  telescopes to eyepieces that 'Made in China'.  No more $100 Vixen SLV at Amazon Japan anymore.

 

The thing is 4mm is hard to get sharpness to the edge unless it a premium eyepiece, or if you have like f/20 scope.

 

And for OP "William Optics" brand Refractor, it too precious to get $50 range eyepiece anyways. I go for Televue.

 

Sorry No to 4mm Orthos or 4mm Plossl, no please, it literally like a peep hole so tiny to look through, I salute all those who can look through those in 4mm magnification.

Edited by MrsM75, 12 May 2025 - 01:17 AM.

[MrsM75]

I am sorry this is  4mm Ortho, am I missing something? Are there like a 100 degree Ortho for bigger hole? 4mm Plossl it like this too, how can anyone look into a tiny tiny hole like this?

 

 

[Tropobob]

I suggest buying an economically priced 2x barlow and using it with both the 9mm & 12mm eyepieces.  Barlows work pretty well these days, providing its not a cheapie that was packaged with a beginner's scope. 

 

 

[Jay_Reynolds_Freeman]

I am sorry this is  4mm Ortho, am I missing something? Are there like a 100 degree Ortho for bigger hole? 4mm Plossl it like this too, how can anyone look into a tiny tiny hole like this?

The eye relief is very small, but many of us have been using them for years with no difficulty, they are inexpensive used, and they do work reasonably well at fast focal ratios. Notwithstanding, "Try before you buy" is always good advice.

 

Clear sky ...

Edited by Jay_Reynolds_Freeman, 12 May 2025 - 03:27 AM.

[Procyon]

4mm Takahashi TOE

The board below is claiming Pentax XO performance in a more comfy and larger AFOV setting.

Also: 4mm Radian or 4.5mm Delos.

Edited by Procyon, 12 May 2025 - 06:47 AM.

[davidgmd]

For occasional, inexperienced observers (family members taking a peek now and then): 4 mm DeLite for ease of acquiring and maintaining the exit pupil. 

[ABQJeff]

Best bang for buck and under $200: AT/APM/Stellarvue/Meade (pick your label, they are the same eyepiece just in different jackets) 4mm 82 degree. Nice wide field of view if you choose to go manual.


Over $200….

Best no compromise high mag performance, Takahashi TOE 4mm. Narrower FOV but some of best on axis/high mag performance.

Next best with a little more eye relief and field of view: TV Delite 4mm.

[rgk901]

4mm AT UWA

5mm AT paradigm

xcell 7 (6.5)

+ 2x/1.5x Barlow for versatility

or

svbony 6 element 7-21 zoom plus the barlow

or

svbony 3-8 zoom

or

used 4.5 (4.8) Morpheus

*the exit pupil size is measured by focal ratio / eyepiece focal lenght so a 4mm/f6 = .66

Edited by rgk901, 12 May 2025 - 03:40 PM.

[GGK]

WO Z73, f/5.9. 430mm focal length -- My closest similar scope is an AT60ED, which is 60mm / 360mm at f/6.  For a 4mm eyepiece for guests at 90X, I select the 4mm TV Delite.  I fully extend the adjustable eyecup, tell them to find the image first, then push down on the eye cup until the field stop is visible and twist to lock in place.  It's easy for them to use every time with or without glasses. A used 4mm Delite is likely around $200.

 

For some guests, though, the 0.67mm exit pupil in the AT60ED is getting a bit dim (will be brighter with your 73mm aperture),  so I keep a 5mm available too, which is just as easy to use.  I'll also note that many guests prefer the larger diameter eye cup and eye lens of the 4.5mm Delos as well as its wider field of view.  The process to adjust the eye cup for easy observing is the same as the Delite, but the Delos will be more than $200 used.

 

Gary

[MisterDan]

I am sorry this is  4mm Ortho, am I missing something? Are there like a 100 degree Ortho for bigger hole? 4mm Plossl it like this too, how can anyone look into a tiny tiny hole like this?

 

 

Yes - lots of us can and do use 4mm & 5mm Abbes & symmetricals.

Cheers.

Dan