Having fun at the eyepiece

[mikeDnight]

It seems to have been raining or cloudy nearly every night for months, and when it has been clear I've had to be elsewhere. Life gets in the way!  This afternoon however, the Moon was high in a clear blue sky and the Sun, though still above the horizon, had set behind a small wooded hill across from my house. I rushed to set my refractor up on its mount in the observatory, rolled back the roof and aimed the scope at the Moon.  

 Earlier this week I'd bought a nice second hand 8mm Burgess TMB eyepiece and wanted to try it out. The Moon, being set against a blue sky lacked some contrast, yet the 8mm gave a very pleasing view, and I could imagine how good it would be as the sky background darkened. So to pass the time, I aimed the scope at Venus. The 8mm gave me 93X in my 100mm F7.4, so I used a 2X Celestron Ultima Barlow to increase the image scale to something I could work with. Now that Venus was larger in the eyepiece, I made a sketch. Then I was required to go back into the house for tea, so I capped the scope and closed the roof. It's a good job I did, as soon after it began to rain again.

I decided to spend a few minutes after tea turning my rough eyepiece sketch of Venus into a finished drawing in my observing book. Then as luck would have it, the rain stopped again and the sky cleared, revealing a beautiful Moon against a dark sky. And on returning to the telescope I was pleased to see the seeing was really quite steady. The Moon was beautiful in the 8mm Burgess TMB now that the contrast was higher. Using the Ultima barlow gave some highly detailed views which confirmed to me just how nice these eyepieces are.  

 Now to make things just a little more interesting, I thought I'd compare the 8mm with my existing 7.5mm Ultima. Its good to remember that the Burgess TMB were designed for use in the superlative TMB triplet Apochromats, while my Ultima eyepieces are around 30 year old and were themselves state of the art in their time. How would these two eyepieces compare when used in a top class apo?    Well the 8mm Burgess TMB was a joy to use. It's relatively wide field and long eye relief made it very comfortable to use. There's something glorious about seeing the whole moon in the field of view at over 90X with space around it, while at the same time being able to see highly detailed views of its cratered surface. I liked this eyepiece very much, it is sharp to the very edge, though it does suffer from noticeable field curvature. It also barlows beautifully in the 2X Ultima.

 The 7.5mm Celestron Ultima by comparison, and which was state of the art in its day, is still state of the art. After studying a complex region along the terminator using the 8mm, I quickly swapped the 8mm for the 7.5mm and the difference was immediately obvious. The difference in magnification was only 6X, so really quite negligible, yet the image quality was definitely in favour of the Ultima, which despite its narrower field and shorter eye relief, revealed finer, sharper detail with increased clarity. I was really quite surprised at just how much sharper the Ultima was.

 Now, all enthused by the image quality of the Ultima, I rushed back into the house to bring out my little box set of Vixen HR eyepieces. And again I carefully studied the same complex region on the lunar terminator using the 7.5mm Ultima. Then swapping the 7.5mm for the 3.4mm Vixen HR I expected the seeing to begin to have an effect on the view, but it didn't. The 3.4mm HR was jaw droppingly sharp, even sharper than the already wonderfully sharp Ultima despite the power increase from 99X to 218X. The 3.4mm HR was so comfortable to use, having great eye relief and an amazingly bright sharp field.   I decided to play for a while looking at a few stars starting with Betelgeuse, which was the most textbook perfect star image imaginable. At this point I swapped the 3.4mm HR for the 1.6mm HR, and still looking at Betelgeuse I imagined this would push even a 100mm Takahashi over the edge. It didn't!  The star was perfection, so leaving the 1.6mm in the diagonal, I aimed at Alnitak, which along with its companion was embedded in nebulosity. The scope was now working at 463X and seemed to be indestructible, that is until I aimed it at Sirius, which boiled in the increasingly turbulent atmosphere as I got lower in the sky.  So it was back to the Moon for a last look, but this time at 463X. The HR eyepieces are really something else. The views were still surprisingly sharp and gave me an almost 3D feeling to the view. The comfort, brightness and sharp full field effortless views, even in the 1.6mm left me in awe of the eyepiece. But its equally a testement to the telescope and its prism diagonal.

The clouds were once again beginning to move in, so I again capped the scope, closed the observatory roof, turned on the electric heater and just contemplated what I'd just witnessed. Sometimes it's good to just play with our gear for no other reason than to have fun, and refamiliarize ourselves with the tools we have at out disposal.

   

Edited March 1, 2020 by mikeDnight

[Stu]

48 minutes ago, mikeDnight said:

Sometimes it's good to just play with our gear for no other reason than to have fun

Totally agree with that Mike! Sounds like you had a fun session. I did likewise today, observing the moon whilst still full daylight, looked great.

[laudropb]

Very nice report Mike. I have been doing something similar using coloured filters on Venus. I have never been a great fan of these, but I purchased a few filters to try on Mars later in the year. To my surprise I have found that the #47 violet and #80 blue filters have improved the views of the clouds. Quite a subtle difference requiring prolonged views to get my eyes in so to speak, but definitely worth the effort.

[JeremyS]

12 hours ago, mikeDnight said:

The scope was now working at 463X and seemed to be indestructible, that is until I aimed it at Sirius,

After that build up, I was just so hoping you'd say that you'd pulled out the Pup with your Tak, Mike 🙂

 

[mikeDnight]

3 hours ago, JeremyS said:

After that build up, I was just so hoping you'd say that you'd pulled out the Pup with your Tak, Mike 🙂

 

Sorry Jeremy!  There was a brief moment when I thought I'd glimpsed it, but it was fleeting and it didn't occur again, so I think I'd be deluding myself if I believed I'd seen it.  Perhaps if I'd lowered the magnification quite a bit I might have stood a better chance, as the atmosphere at the Sirius level was becoming a bit rough to be honest.

[mikeDnight]

3 hours ago, laudropb said:

Very nice report Mike. I have been doing something similar using coloured filters on Venus. I have never been a great fan of these, but I purchased a few filters to try on Mars later in the year. To my surprise I have found that the #47 violet and #80 blue filters have improved the views of the clouds. Quite a subtle difference requiring prolonged views to get my eyes in so to speak, but definitely worth the effort.

I used a couple of blue 80A filters in my binoviewer a couple of years ago while observing Mercury. It really did seem to draw out subtle detail, but it also seemed to have the effect of steadying the image somehow. I'm not sure why that would be, but if it works I'm happy using it. The same with your minus violet filter. Whatever works is worth using. I've had pleasing results in the past using a neodymium filter and even an OIII and UHC filter on Mars. Not playing by the rules can be liberating sometimes! 

[cotterless45]

Sounds very much like one of my tinkering about under the Moon sessions. The old school Ultima 7.5mm is a gem and one I always reach for , just pure clean views. On occasion it even works in an old school triplet x2 Vixen silverside Barlow.

Its always worth swapping eyepieces around and quite a good adventure !

Nick.