5 replies to this topic

[quilty]

I already mentioned this in my Hyperion thread but like to ask this specially again

This is the Omegon Cronus Planetary 4 mm besides the Baader Hyperion 5 mm



I don't state that both are completely the same not even at number of elements. These Cronus' come differently branded but the general design reminds me very much to the Hypes.
The specs tell for all: 60°, 16 mm ER and 6 elements in 4 groups.
The view is really comfortable and considering the smaller eyelenses (22 mm) the 16 mm ER is quite enough and no kidney disease at all.
It must be some sweet spot at easily designing and producing them for they come as 2.5, 3.2, 4, 5, 6, 7, 8 and 9 mm, maybe differing only at their Smyth group

Like the Hypes you can screw off the Smyth lens to get a Plössl or Erfle like EP with the same field stop at 60°. Like the Hypes they grow longer the shorter the fl.
The strut diameter of the upper part is a little too wide to fit into the 1.25 but they seem to do good 15 or 20ish mm eyepieces.
Is this sort of design a general one for plantary eyepieces?

Edited by quilty, 28 May 2024 - 03:29 AM.

[Astrojensen]

The Omegon Cronus Planetary seem to be a clone of the old Burgess TMB Planetary eyepieces. 

 

The only similarity they share with the Hyperions is that both have a Smyth group (the Barlow in the 1.25" barrel), something they share with dozens and dozens, if not hundreds, of other eyepiece designs. 

 

 

Is this sort of design a general one for plantary eyepieces?

Not just for planetary eyepieces per se, but an easy way to build an eyepiece in general with long eye relief, even at very short focal length. Or to maintain a reasonably normal eye relief with very wide field eyepieces. Most of the modern eyepieces, the Naglers, the Ethos, etc., wouldn't be possible without the Smyth lens design.  

 

Televue were among the first to design a line of eyepieces incorporating this design, the Radians, that were specifically aimed at planetary observers. The Burgess TMB Planetary's are a clone of the Radians, more or less. 

 

 

Clear skies!

Thomas, Denmark

[SeattleScott]

“Planetary” is the marketing term for narrow AFOV.

[SeattleScott]

Fewer elements, less AFOV, less ER. I agree not very similar to Hyperions. Reasonably close in features/specs.

[CrazyPanda]

“Planetary” is the marketing term for narrow AFOV.

But it's funny when it's paired with "UWA" when 58 degrees is anything but ultra wide

 

https://agenaastro.c...epiece-4mm.html

 

I think the most "planetary" aspect of these eyepieces is the tight spacing of short focal lengths for better planetary magnification selection. But that assumes the focal lengths are precisely figured enough that there is in fact a difference between 4mm, 4.5mm, and 5mm. My guess is there isn't at the price point of this eyepiece line.
 

[SeattleScott]

But it's funny when it's paired with "UWA" when 58 degrees is anything but ultra wide

https://agenaastro.c...epiece-4mm.html

I think the most "planetary" aspect of these eyepieces is the tight spacing of short focal lengths for better planetary magnification selection. But that assumes the focal lengths are precisely figured enough that there is in fact a difference between 4mm, 4.5mm, and 5mm. My guess is there isn't at the price point of this eyepiece line.

As a matter of fact, sometimes the focal length is mislabeled and you don’t get the focal length you ordered.

It’s great that you can get wider AFOV and better ER than a Plossl for the price of a Plossl. But the trade off is the QC is non-existent.