Archive for April, 2010
Eyepiece first light, 16mm SWA, 7mm TMB Planetary
I got my hands on these two eyepieces yesterday, and I went cloud-dodging to get a first look through them.
With the work-in-progress briefcase dob, I got a look at a 13-day old moon and Saturn. Both were seen through a variable thin layer of cirrusstratus that was clearing up completely every now and then. Seeing wasn’t that good. The moon showed fast moving ripples over the surface.
The 16mm UWA (cost me €65) is a nicely built eyepiece, possibly a bit weighty. The images are clean and crisp in the scope, and it’s nice to get a good look at last in a premium eyepiece! The eye relief is just not enough to be comfortable with wearing the glasses but at an exit pupil of 2.8mm in my scope my astigmatism wasn’t *that* noticable. However the views were slightly improved with wearing the glasses at a cost of the outer 10 degrees of view. Using the meade #128 barlow with this eyepiece vignetted the outer 10 degrees but allowed the use without glasses for an effective FL of 5.3mm. At the native FL Saturn is crisp, easily showing the major moons. Very slight softness at the edge of field, and requiring a little bit of head movement to get the complete FOV.
The 7mm TMB Planetary (€45) is also very good but different. This is sharper to the field stop than the Meade is at the field stop, but it’s a narrower FOV at 58 degrees. The twist up eyecup is not as useful as the Meade’s. It is a little harder to find the sweet spot for the fully illuminated FOV, but this is reachable with wearing my glasses and I can still see the field stop. Just for fun, I put this eyepiece on the 3x barlow, for an FL of 2.3 and magnification around 580x. It focused to almost sharp, and it was odd seing the seeing shimmers over the globe of Saturn, and I was managing to keep Saturn in hte
The moon wasn’t being that interesting last night. I was looking at sunrise over Schiaparelli and I saw some details in the Aristarchus rilles that I never looked at before.
Saturn was not far from edge-on, with the gap between the rings and planet being difficult to see, and Cassini’s division was intermittently visible.The moons were resolving almost to points as it appeared that the high-altitude cirrus was getting in the way a bit.
My overall impression is that these eyepieces do make the telescope “get of the way” when looking through them. I’m looking forwards to adding a TV 2x barlow or powermate to the arsenal. The comfort difference that the wider FOV and longer eye relief gives is really quite a big one. The longer time between nudges is very useful too. MAkes me want to get that equatorial platform up and running.
Stuck in London
That unpronounceable volcano in Icelsnd has prevented me from being at home this weekend.
I can’t argue with the NATS decision to stop air flights, so I’ll have to consider a bus-ferry ticket this weekend as an alternative in case Ryanair decide to not fly again for a few days.
There is some hope about the restrictions being lifted by tomorrow, but the restrictions are looking likely to be back in place by Wednesday. The ash models are showing no real movement except to reach Canada..
Stargazing April 6th-7th
On this monday evening I had a nap when I returned to the house after work, but the nap went on a little longer than I had really wanted.. I woke up at midnight! On the plus side, I looked out the window to see a clear sky so I decided to go and take the scopes for an outing as it was going to take me another 2 or so hours to get sleepy again. It wasn’t that cold outside as well for a bonus.
I brought the ETX70 out of the car and set it up at the NW end of the house in Galway, attaching the 12v battery leads and easy-aligning. For a first target I chose M51, and seeing that there was actually fairly good transparency I went in and took out the 8″ dob-in-progress. As that cooled down I did a little bit of touring around the sky taking in some old friends, as I wanted to get a look at Saturn after the mirror had reached ambient.
As there is currently no finder on the Dob, I was re-learning star-hopping from bright stars again. First up was M51 – this was not that hard to locate, I think I could see hints of spiral structure but it wasn’t clear. I identified M104 through the high-level cloud to the south, then I swung up to M53 (quite a pleasant sight really) and on to M64 (couldn’t see the dark lane). I had a bit of trouble locating M97 but I located it in the end, it’s a little bit larger than I was expecting. I couldn’t locate M108 nearby. Over to Leo and M65/M66 were located, and I tried for M95/M96 without success. M13 was a spectacular sight in all my eyepieces, easily resolved in the 32mm. A quick look at the double-double, clear clean splits on both. Quickly scan over to M57 and using the UHC (thank you Sarah!) and OIII filters really helped to make the Ring surprisingly bright and visible. I slewed back over to Saturn, and it was crisp and mostly steady. Even though the rings are about 2 degrees from edge on, I could just make out the cassini division, and I could easily see through the ring-planet gap. There was an easily visible band across the planet’s surface, that I think was the ring system in silhouette. As I was looking at Saturn, there appeared a halo around the planet that got brighter as the minutes passed. This was seen in all of the eyepieces. Saturn got fainter and fainter and that put paid to my plans to go galaxy hunting in the Virgo cluster.
So at 02.30 in the morning I started to feel sleepy again, so off to bed I went, satisfied with a fairly productive 2 hours outside.