6mm EPs: TV Radian, S/W Planetary Compared

[cloudsweeper]

I bought the now-discontinued Radian to replace the S/W when I spotted it on an auction site.

The TV has seven elements, 20mm eye relief, and 60deg of AFOV, while the S/W has respectively five, 16mm, and 58deg.  The TV's eye lens is slightly larger, and its rubber eyecup is in an adjustable clickstop housing which I have not encountered before.

In the ST120, these EPs give x100 at 0.60 and 0.58deg of TFOV.

Nine days ago I compared the two using the waxing gibbous Moon, putting the terminator right across the centre of the FOV, and almost reaching the edge of field.  The Radian showed sharp detail right to the edges, while the S/W gave a very slight loss of sharpness there.  Targeting a crater in centre-field, the fine detail appeared slightly sharper with the TV.  (Or did I just want it to?!)

And so to the present - looking out at 1.30am the sky was very clear, so I set the ST120 up again and got M45 in view.  Before using the 6mm EPs, I admired the cluster at x14/4.55deg.  It is truly beautiful when seen in its entirety like that, a spectacle the long FL 'scopes can't match.

M45 looked somewhat sharper in general, and right to the edges of view with the Radian.  The stars looked a little brighter somehow, which I would put down to better contrast.

While my comparisons have not exactly been exhaustive, I reckon I can safely say that the Radian is the better EP, which is of course to be expected, but the differences are subtle rather than dramatic. 

As a further conclusion, the S/W Planetary is a perfectly good EP, and unless an EP gives a really poor view, upgrading is perhaps a luxury rather than a necessity, and might be best reserved to improve properties such as eye relief and AFOV.

Doug.

 

 

[MarsG76]

I'm a fan of Televue EPs... in my kit the TV EPs are definitely the most used, sharpest and best of all....

 

[RT65CB-SWL]

The Radian 6mm is my favourite... along with the Nagler 3-6mm zoom. 

[michael.h.f.wilkinson]

Very nice report. I had a couple of Radians in the past. Very nice EPs, and indeed a clear notch above the Skywatchers, but not a huge amount. I replaced them only when a couple of second-hand Pentax XWs came along. In sharpness the improvement is subtle, but transmission and colour neutrality of the XWs is definitely better (again, not a huge amount, but noticeable. What with some TV fans replacing Radians with Delos or Delite EPs, you can get some Radians second hand for a very reasonable price.

[John]

Good report Doug

"...the differences are subtle rather than dramatic..."

This is almost always the case I've found when comparing eyepieces that are decent vs the premium alternatives.

So if you are on a budget you can get good performance for not a huge outlay and if and when you decide to "splash the cash" at least you can have realistic expectations on what the additional £'s will buy

My problem is that once I've noticed small differences, I tend to find it hard to be content with the "lesser" performance. Must be some form of OCD I guess  

 

[paul mc c]

I used to have a 7mm TS planetary, and the view of Saturn was the best i have ever had with all my eyepieces.....although i dont have any TV.

[michael.h.f.wilkinson]

21 minutes ago, John said:

Good report Doug

"...the differences are subtle rather than dramatic..."

This is almost always the case I've found when comparing eyepieces that are decent vs the premium alternatives.

So if you are on a budget you can get good performance for not a huge outlay and if and when you decide to "splash the cash" at least you can have realistic expectations on what the additional £'s will buy

My problem is that once I've noticed small differences, I tend to find it hard to be content with the "lesser" performance. Must be some form of OCD I guess  

 

Very true: once I spot shortcomings, even slight ones in my EPs, I just have to replace them. After I got my first premium EP in a collection of very respectable Vixen-made Plossls, and a couple of LVs, I just wasn't satisfied with the older EPs, because I could see the (small) differences between premium and decent ones. It is very like audio equipment. After being content with a set for years, and then getting a better set, you often suddenly wonder how you missed all the shortcomings of the old set, and it becomes very hard finding contentment with the old stuff ever again. This is why I looked through Olly's Leica 8x42 binoculars with some trepidation, as I feared being overwhelmed by the quality difference with my Helios Apollo 15x70s. The Leica was indeed a touch sharper, but the Helios made up for that with sheer light grasp

[25585]

Interesting comparison. I have a 6mm Vixen LV & 5mm Radian. LV is only 50 deg AFOV while Radian is 60. Both seem equal when looking at the moon, the LV as good contrast as needed for my aging eyes. 

My Radian is better for DSOs, but as slightly higher magnification the TFOV is not that much larger. I like it in my TV Genesis as it gives 100x mag and it's the one I use with an OIII filter or UHC.