Down the Rabbit Hole with the 72ED

[Nightspore]

I’m pretty certain that I have sorted the three essential eyepieces for the Titchy Sixty. These combine a light weight with maximum versatility for such a small scope. I wondered about similar oculars for the 72mm, f/5.8 Evostar. For at least three years I have taken out a 19mm Panoptic for low power and a couple of TMB clones (4mm, 3.2mm) for high magnification. Sometimes other EP’s were included. As this is essentially a grab & go rig you will appreciate that a simple eyepiece approach is needed. Not only does it make the rig overall lighter to transport, the simplification just makes the whole session easier. Any eyepiece would be 1.25” as 2” diagonals were a tad difficult for me to manipulate and may be prone to fall out of the non-rotating visual back. The less shagging about with gear, the more observing right? So, I wondered just how far down the rabbit hole I could take this.

 

 

The 24mm Tele Vue Panoptic was a no-brainer (I’d regularly used the ES equivalent with the 72 even though I’d owned the Panoptic for years longer). Then there was the possibility of the 35mm Baader Eudiascopic, which would give 12x as opposed to the 17.5x of the Panoptic. The Baader has a bright, well defined, exquisite and satisfyingly flat image, but only has an aFOV of around forty six (45.6°) degrees. After doing some sums I didn’t need to ‘ask Alice when she’s ten feet tall’ or bother the ‘hookah smoking caterpillar’ as the 24mm Panoptic had a very slightly bigger field of three arc degrees, fifty three minutes and six seconds of FOV. Furthermore the 24mm Pan’ becomes 12mm with a TV Barlow, giving a 2mm exit pupil with negligible vignetting.

 

 

I was still chasing rabbits and the men on the chessboard about a planetary eyepiece choice though. I didn’t really want to have some kind of mushroom either (except maybe on a pizza). I did consider a 7mm Nagler for 60x, as: (a) I own one, (b) it’s a Nagler and (c) I actually bought it originally for the 72ED. By this time logic and proportion had fallen sloppy dead, the white knight was talking backwards and the red queen recommended it was off with the Nagler’s head. So I listened to the dormouse and fed my head with a 6mm TMB clone. This gives me 70x at 58° FOV, 140x with a TV 2x Barlow. Which are more or less 1mm and 0.5mm exit pupils. Plus, if I also take the BCO 2.25x Barlow which, let’s face it, weighs less than the caterpillar, it will give me a trippy but sharp 157.5x (0.45mm exit pupil). The 72 is certainly quite capable of that magnification. Technically only 13.5x above the supposed maximum power.

 

 

On 3/11/23 at about 23:00 most of the seasonal pyrotechnics had ceased and I got about an hour in the great outdoors. At least I thought it was 23:00, but my ‘Official Swiss Railways’ pocket watch claimed it was midnight. It took me a few seconds to realise this wasn’t some weird time dilation caused by the fae, the Army of the 12 Monkeys, Zeta Reticulan warp engines or any other form of weird science and I had just forgotten to reset the watch to GMT. Temporal existential panic over I looked up at the night sky.The jet-stream had come back with a vengeance, even though it looked as if the seeing would be good. I saw a fair amount of stars … and clouds. I set-up the 72ED and the first target was naturally a near-transit Jupiter. The 6mm TMB clone gave me 70x and the big 'J' was looking pretty sharp. I could just see the GRS, and the Galilean moons were all easily observed.

 

 

I reckoned the TV 2x would be fine, but at 140x a lot of definition had disappeared and I realised the seeing just wasn’t up to it. At 112x (Barlow element threaded directly into the EP) Jupiter was fairly decently defined, the GRS was easier to see at least. After a while I decided to look at a few open clusters with the 24mm Panoptic.

 

 

The great Subaru in the sky was probably the best thing I observed on this night. The Orion’s Belt Serpent Cluster was cool as well.

 

 

The rapidly rising 62.8% illuminated Moon (Gemini) began to cause problems, so I basically switched my attention to that. I swapped the Everbrite for a GSO Amici for another 112x with the TMB/Barlow element combination. I didn’t think there was anything super interesting to see. The Aristoteles and Eudoxus craters in the north were quite well detailed, as were Maurolycus and Clavius in the south. Although that was about it, nothing else really grabbed my attention, not even a white rabbit …

 

 

[Nightspore]

Just realised, when I observed Jupiter it was at opposition.

 

 

Too many raves in the 90's for me, my brain's gone a bit Trumpton.