mikeDnight

I managed a very nice, prolonged observation of Venus late this afternoon, 24/5/20. The sky began to clear and between the clouds I picked up Venus at 17.07UT in the 100DZ. I first found it in the 6X30 finder and quickly centred it in the field of the 35mm Eudiascopic at 23X. Clouds kept hindering the view initially but eventually I could increase the magnification, first to 64X with the 12.5mm Ultima, then 107X with the 7.5mm Ultima. The view was beautiful at 107X with the dark side of Venus globe standing out against a brighter blue background sky. As the Sun disappeared behind the trees the shimmering image settled somewhat, allowing me to increasing the power to 235X with the 3.4mm HR. The higher power and slightly darker sky background enhanced the ultra fine horns which extended past the meridian for some distance, more obviously along the southern limb than the north, but still evident on both. If you can keep the Sun at a safe distance its well worth hunting down in late afternoon daylight.

I made a complete turn around a few years ago, and although I've had many years using expensive wide field eyepieces, I have none in my collection today. An experience with a 26mm pseudo Masuyama around five or six years ago was like a breath of fresh air. Today I only use pseudo Masuyama's of various brands, along with four Vixen high resolution, high power eyepieces.

If I could change just one thing (possibly two), it would be the 4mm Ortho for either a 3.4mm Vixen HR or 4mm TOA. I know they are more expensive but its not my money, so it doesn't count. Plus, both would be much more comfortable to use at high power than the 4mm Ortho. I haven't used the TAO but the HR is stunning! Also, is the StellaMira diagonal good enough? I might be inclined to lean more towards the Baader BBHS mirror diagonal if you want to avoid prisms. Mrs S won't mind when you tell her it will be the last outfit you'll ever need. I've always found that a promise like that is good for at least two or three scopes!

I'm intrigued by this scope Mark, At F3.3 I'd always imagined it to be an imaging scope, but how does it perform on rich star fields, especially at the edge of the field?

The advert sounds a bit desperate, implying some apo's are optically unstable and fall out of colimation. I've yet to see any evidence of either. Other than that, I think they look like nice scopes, but that lens cell looks like plastic?

I thought that's what the Met office did!

Much depends on your mind set. I had one astronomer friend who when seeing a cloud on the horizon, would pack up and go home. Another who would sit out in 6" of snow on a cloudy winter night just waiting for a clear patch. I lean more towards the latter example, and because I'm generally optimistic by nature anyway, I've been rewarded with some very memorable night of observing. I think it pays to have a wide range of astronomical interests. If its clear and the Moon is on show then I observe the Moon. If there are planets observe, i'll observe planets. No planets or moon I'll sweep the skies hunting down anything of interest within my scopes range, and sometimes I will plan an observing session with specific targets in mind. I will nearly always sketch something during an observing session, as sketching helps me to see things in more detail and leaves me with a record to look back on. Some of the finest planetary views I've had have been on cloudy nights when suddenly a large sucker hole brings an unexpected half hour of perfection. Jaw dropping views often result, but the sad thing is that most people miss them because they look at the clouds and think it won't be worth the effort. It's nearly always worth the effort!

This reminds me of Leslie Peltier's observatory in his auto biography, Starlight Nights. He too used to open his dome early to let the heat of the day escape. His sister wrote a poem about him, which from memory went like this: Our hero felt the winds first dash, He saw the distant lightening flash. "My dear" he said "I shall return, some other night with lips that burn. Right now I have to dash for home, for I've forgot to close the dome."

Hi Rob, Being purely a visual observer, I don't have much in the way of electronics other than an RA/Dec drive on my equatorial mount, along with a few lights and an electric heater. When my wife gave me the go-ahead for an observatory in 2011, it was a question of a fiberglass dome or a run-off roof design. I'd seen others have issues with fiberglass domes and condensation, so I thought I'd build my own run-off roof observatory which would be condensation free as far as possible. The building was constructed from 3/4" ply screwed to a 3" by 2" frame, which I clad on the outside with double skinned white plastic cladding. This is brilliant for reflecting the Suns heat, and even on a hot day, the inside of the observatory remains at a comfortable temperature and never hot. There is a narrow air gap between the top of the walls and the roll off roof which is surrounded by a rubber skirt, but it still allows air flow and helps prevent condensation. The inside of the observatory is clad with black interlocking matting not only on the floor but on the walls also. This was done initially as a way of keeping my observing area as dark as possible and is very effective, but it also has the added advantage of acting as insulation, preventing condensation from ever forming. As regards the equipment, I never leave my refractor in the observatory when not in use, but the 10" reflector is quite happy and I've never had any issues with moisture affecting it or the mount. In fact, my observatory is so moisture free that I'm able to leave star atlases and charts in there without issue and have done for the last 9 years. The 240v electrics are protected with a circuit breaker but I've never had any issue with it. The only draw back is that batteries can drain in the cold winter months. The electric heater serves to warm the observatory when the roof is closed in winter, creating a nice little boys club for me and my observing buddies. I've never needed to use a dehumidifier! Below is an external view of the white clad 8' by 7' structure, and internal views showing the black rubber clad walls, along with wall charts etc. Even the steel pier is rubber clad to keep all surfaces warm to the touch and to keep cold surfaces where moisture may form to a minimum.

UPS pick up and deliver. Royal Mail for smaller items. I've bought and sold without any problems and without close contact with others throughout this lockdown.

Begining early with an observation of Venus before the Sun had set, then ending with two double star and a triple line of sight system in Cygnus.

The clouds miraculously cleared for a short while late in the afternoon, so it was an unmissable opportunity to catch up on my observations of Venus. I fault sight of the planet long before the Sun had set, and as it was set against a blue sky it was easy to see the whole globe suspended almost in 3D. The seeing was hit and miss with moments of steady air in amongst an otherwise agitated image due to some mild turbulence. This is a mirror reversed view as I was using a diagonal prism, and a 80A blue filter was used for part of the sketch. The fine horns extending around the darker globe were easy to see at 256X when the seeing was steady and appeared finer than in the sketch. It was difficult to see exactly where the fine horns actually ended and the dark limb began. Even the dark limb directly opposite the widest part of the crescent appeared at times to be illuminated, but that would have been merely due to contrast. Clouds moved in again bringing the observation to an end but I'd had my fix, so I felt much happier.

I'll second the Cambridge Double Star Atlas, available on Amazon and Book Depository I believe.

There's the jumbo pocket sky atlas you could consider. Then there's the Cambridge Star Atlas or Cambridge Double Star Atlas. And there's always a trusty Norton's Star Atlas. I've had three Sky Atlas's over the years and found them a bit too big to handle comfortably in the field. They are also rediculously expensive these days and really aren't worth the cost IMHO.

I think I've spent more on books since this lockdown began than I've spent in the last five years, and they keep coming!

That looks fantastic Alan. That refractor really makes my heart rate increase!

So because of UK seeing being rarely anything special, the true power of the smaller aperture really comes into play. Larger apertures are affected to a much greater degree by atmospheric turbulence than smaller apertures, so a small scope can show apparently perfect seeing while the larger aperture alongside it on the same night displays an image that is pure vomit. Couple that with the superb optics of many apo refractors (not just Tak!), and you have a formidable instrument that will often leave larger scopes standing when it comes to sharp high power views. If a scope can't form a sharp stable image because of the seeing conditions, there's little point in amplifying that already poor image. If on the otherhand the image is sharp at 200X, there is no reason why that image cannot be magnified still further, and the better the optics, the greater the potential power range. As for visual observations having "long been discredited as being too prone to observer expectations and therefore of no scientific value", well that comes from the micro minds both in our hobby and in science. Of course over-cooking the reality in the the endless barrage of taxidermied images we're relentlessly subjected to, is very scientific and totally trustworthy! Personally I'd rather trust the observational sketches of an experienced visual observer as giving a truthful representation of what can be seen through an eyepiece, than any image I've ever seen. After all, if you want to really observe something well, you really need to pick up a pencil!

I'm just trying to imagine the expressions on the faces of those happy apo customers, as the vendor takes their money and then informs them "Remember to use only 1X per mm then"! I'm sure they'ed laugh all the way home!

There will always be the doubters who doubt because they haven't experienced high powers successfully as yet. And there will always be the ridiculers, who have minds set in stone, - old fossils who will repeatedly voice outdated and inaccurate views, perpetuating old myths and wanting to stop those moving ahead from advancing any further. The best thing to do with the first group is to offer them encouragement or an opportunity to see for themselves. As for the latter, they are best ignored!

First of all I think the Equinox 80 is a fantastic scope. When I bought mine around six or seven years ago, I quickly found myself spending more time under the stars than I had done for years. At the time I was using the 31 Nagler as my lowest power eyepiece along with several other Naglers, Ethos and Pentax XW's. I used a binoviewer with a 2X barlow and a pair of cheap 16.8mm orthoscopics for observing the Moon and planets, and the views were amazing. It wasn't until I'd bought a 100mm Tak that paulastro loaned me a 26mm Meade plossl to try. I was insulted, first because it was a plossl and second because it was a Meade. What I saw that night though had a major impact on how I viewed eyepieces. I had all this high end and expensive kit, and here was a 26mm (5element super plossl) offering greater transparency and on axis sharpness than the worshipful Televue's and Pentax. The 26mm plossl gave roughly the same true field as my 20mm Pentax but it has a clarity about the image that wasn't quite as good in the XW. On axis the 26mm was every bit as sharp if not sharper than the XW, and although there was some edge of field distortion it was no worse than that shown in the XW. I couldn't get that experience out of my mind, and as the weeks went by I researched the eyepiece design that Meade used for their super plossl. It is commonly known as a pseudo Masuyama, made in the 1980's under various brands, and are no longer in production except the 35mm Eudiascopic sold by Baader, but they come up cheap regularly second hand. Today, all my eyepieces are pseudo Masuyama's with the exception of my high power planetary Vixen HR's, and they never fail to impress me with their clarity and sharpness. The problem with the plossl in an F6.2 scope, is that you'll get some edge distortion, and though it may not be too troublesom it will be present. But on axis they will give a great view. One way to overcome this would be to use a barlow giving you a F12.4 ratio and a better edge of field performance. But plossls vary so much in quality the cheap as chips Chinese ones can give the design a bad name. If I were you, I'd look to Japan and brands such as Celestron Ultima, Orion Ultrascopic and Parks Gold.

I think resolution limit and magnification limit can get confused. It may be true that 50X per inch is the resolution limit, but if the object being studied is small, it may require a higher magnification to be able to see it well. Much depends on the stability of the atmosphere, the quality of the optics, the object being studied and the stability of the mount. Jupiter and Saturn tend to be best observed between 150X and 250X as much beyond this and the intricate detail softens, and so definition suffers. Planet's that display albedo features such as Mercury, Venus and Mars can take significantly higher magnifications, but even then the power used should be tuned to the seeing. The Moon takes magnification well, but although the mountains and craters may look awesome, once the finer features such as rille's lose definition there's little advantage to going higher other than for fun. Stars are something else, as these can take extreme power. For example, in my 100mm refractor, which has a theoretical maximum power of 200X, I can happily and very effectively exceed that limit. Observing Izar only a couple of nights ago i was using 500X and the image was perfect. I regularly observe Venus at 335X and even well beyond this. Just recently I studied the north cusp of Venus at the rediculous power of 800X in my 100mm refractor and other than a little undulation of the atmosphere, the image remained sharp and contrasty. Was there any advantage to observing Venus at such high power? Not really, but it was fun, and I had to keep checking the eyepiece to make sure I wasn't mistaken, because the image was so good. The view at 400X showed all the same detail, but even at 400X my scope was well over its theoretical limit. Planet's do dim but they have plenty of light, so there's little to lose by experimenting. Stars are fantastic and just get better at high power. I think to keep a good scope restrained because of some theoretical limit is a shame. Only by really pushing your scope will you ever come to understand its full potential.

I strategically placed the DX mount in the porch and had all my gear ready for immediate action, a bit like Bat Man. Then went to bed and purposely wore a T-shirt knowing it would irritate the heck out of me and stop me falling asleep, which it did. So after a couple of hours getting all tangled up I threw the T-shirt to one side and fell fast asleep. I woke at 6am with the Sun blazing through my bedroom window. Next time I'll set my alarm!

The book Craters of the Near Side of the Moon, by John Moore, mentions that the floor of Albategnius may be fluidized eject from the Imbrium impact rather than lava flow. So it's highly likely then that the crater pit is a small impact crater, but the book does put (vent?) as a possibility. personally i believe it to be more likely an impact crater, but I've been wrong before!

Excellent! Thanks for that Paul. ☺

Its now the evening of May 14th, and Venus is getting closer to the Sun. Over the last few nights ive caught it before sundown while its still high and set against a blue sky. The phase is narrowing and when the seeing is stable, the horns of the cusps extends finely around the dark side of the globe at 178X. But the seeing degrades rapidly as Venus gets lower in the sky, so the early bird gets the worm, but well worth the effort!