mikeDnight

Sometimes I think the emphasis on cool down issues can be over exaggerated. The 127 is a small bodied scope and cools quickly. A few years ago a friend brought his 127 Mak round for me to play with. As he lifted the tube assembly out of its foam lined carry case, he told me he hadn't used the scope for about 18 months. I mounted it on a Vixen Porta mount, aimed it at Jupiter which was high in the sky, and was amazed at the immediate sharpness and definition in the image. It performed straight out of the box, so by keeping the scope in a coolish room you'll pretty much guarantee a good view from the start. To be honest, I'd suggest taking the tube into the house rather than keeping it in a shed where damp and fungal growth may damage the optics.

"Told You So"! Sorry, but you did prompt me Peter! ☺

Do TMB and LZOS never blacked their lens edges? There seems to be an awful lot of white edge on view.

If you keep the 127 Mak in a cool dry place it will give great views. Another alternative could be a second-hand 100mm ED which could also come within your budget. Both the above will be excellent double star scopes!

I agree! The amount of light that is redistributed to the first diffraction ring in a scope having a small central obstruction is likely to be so slight that it would be at the borderline of visual perception. Diffraction from spider veins however can be distracting on brighter stars, so a good Maksutov would be a great scope. IOptron produce a beautiful looking 6" Rumak that I hope someone will buy and review. It looks quite appealing!

If you have a psychological problem that's arisen due to some inadequacy, possibly a size or performance issue Paul, there are two doctors on this thread that will be happy to diagnose you. They may not have a clue about medicine but the're good enough for the NHS. 💉

Thanks for the explanation Peter. It's good to know I'm not as dumb as I look and I haven't lost it completely. I just couldn't remember where I'd read the info in the first place as it was so long ago. But that's what books are for, so I don't need to remember. That does look like me Jeremy, but all my astro friends look and dress like that too. My globe's aren't as large though! At just 5" pathetic in fact!!

And who wouldn't, he's a Doctor.

He did say that, which tells me he didn't observe much, or his telescopes/seeing conditions/skill as an observer wasn't upto much. W.F. Denning carries much more clout in my book as he was an undeniably excellent observer. Denning made many excellent quotes, one of which states " What one man sees through a 5" glass, another needs a 10"." In another he stated "There is little point in having a glass of great capacity at one end of a telescope and a man of little capacity at the other." 😆 Warmest regards, Mike

What's missing? You could do with the full set of Brandon eyepieces and gold diagonal. Then a full set of Zeiss Abbe Ortho's could be squeezed in I think. I'd buy either of these options off you Jeremy, cheap of course, if you didn't get along with them, or if you find yourself struggling for room.

Well its taught me a lesson, and I stil spend much of my time outside the headmasterz office!

It's the residual internal heat that I was referring to Andrew. It's a long time ago now and I could be wrong, but I think it was in Mackentosh's book on Optics. Cant remember the exact title! I've no doubt the accuracy of the optics needs to be unimaginably high with every component in any mirror system using such short focal length primary and amplifying secondary, including the corrector. I suppose the amplification of the secondary could also have an effect on how sensitive the scope would be to the seeing conditions, as it would amplify atmospheric error ( in the image produced by the primary ) compared to zero amplification in a Newtonian for example. At least thats how I understand it - I think!

Here goes: There's another thing to consider also and that's the amplification factor of the secondary mirror. I seem to remember from years back that an F2 primary with a 5X amplifying secondary, creating a F10 system, doesn't amplify the heat errors by 5X, but by 25X. (5X^2). So thermal equilibrium is much more difficult to achieve in a catadioptric system using an amplifying secondary, or even with an open Cassegrain design. What puzzles me though, is that a Maksutov always seems to perform better, presenting sharper stars and higher definition than a SCT. Why? I have no idea! Perhaps it's that awful Schmidt corrector plate that's responsible for those cotton wool star images and drunken planetary views?? I'm working on being more sensitive. How am I doing?👍 👎

Wow! I might be the only one who thinks telescope prices have never been better. The high quality of Synta/Skywatcher products make them a steal and a virtual guarantee of a top end scope at an unbelievably low price. Takahashi prices have stayed pretty much the same over the last 20 years, which I'm extremely grateful for. The vendors don't make a fortune on each sale, and the manufacturer's who invest massive amounts of money to be able to research and produce some of the best off the shelf optics ever available to the amateur, surely have the right to set their price. I really don't see price fixing but instead see great offers all round. There's so much high quality gear available today to suit any amateurs pocket, that everyone can play. Just don't go into debt and spend beyond your means.

When observing double stars the 1.6mm, which gives 500X on my 100mm F8 is really very nice, and can be used surprisingly often. It needs to be an excellent night for it to be used effectively on the Moon. Venus is something else when a thin crescent at 500X. The only other planet's that I think might benefit from it would be Mars when its below 5 arc seconds and Mercury. I did use it once with a 2X barlow giving 1000X while studying a close double. The view was very good but the limit of comfortable viewing, and the mount needs to be able to track. But the others in the range get much more use.

That's right Jeremy. As everybody knows, there is no bridge, O'Neill's or otherwise, and no roads leading directly to Burnley town centre. Burnley borough council put pay to that by diverting all traffic around the town centre via a ring road and out again. O'Neill's ring road! 😊

Arrived this morning direct from Greenwich Observatory. A Map of the Moon drawn by Percy Wilkins. Some people view Wilkins map as overly complex and containing errors. However, I think its a genius work representing a lifetime of lunar study, and containing detail you're unlikely to find anywhere else. I've used Wilkins drawings as reference for years as depicted in his book The Moon, but i didnt know his complete Map of the Moon was available until it came up secondhand a couple of weeks ago. Sadly it had been claimed, but a quick search revealed its still available from the Royal Observatory shop for around £12.

It was a 100mm F7.4 with a focal 1.6X extender-Q plus 2X barlow and a 5mm Pentax XW eyepiece, giving X473.6

I feel the Moon can take high powers well when its high in the sky and the atmosphere is steady. Although you are unlikely to see more at 300X than you will at 200X, high magnifications can present some really spectacular views and can be fun to use. And because there is plenty of light, you can push your scope until the seeing conditions put a limit to any improvement. I remember my stomach rolling as I drifted across the shear cliff face of the lunar Appenine mountains at 474X using my 100mm refractor a few years ago. The mountains looked almost 3D and because of the high mag I didn't see the sudden drop over the edge coming.

You must be the most inoffensive person on SGL John - after me of course. The worrying thing is that I'm actually starting to like the idea of an luminous pink refractor. For less than £5.00 I could respray my Tak, which would give me the reassurance that no-one would ever steal it.

I don't know John, pink used to be a boys colour before those bullying girls nabbed it for themselves. This might be one that catches Stu's eye, as its one refractor he hasn't yet got in his growing armoury.

Personally I'd wrap some lens cleaning fabric around a short stick and insert it through the draw tube, gently removing the particles on the rear face of the back element. Another way may be to attach a long tube or straw to a bulb blower and attempt to blow the particles off without touching the lens. I certainly wouldn't remove the lens from its cell but if the above fail, I may be inclined to remove the cell from the tube. You may be able to vac out the loose dust from inside the tube.

Thanks Andrew, I'm not being very scientific, but often I just get a feel for the kind of seeing a night will produce. But supposing the seeing is not particularly good, I might on occasion wait an hour or so to see if things improve. Some night's feel like they have some potential while others have a hopeless feel. I remember on many occasions being rewarded with some fantastic views after patiently waiting for an hour or more, but generally I've been with an observing buddy, which leads to mutual encouragement and so I'm more willing to stick it out than if I were on my own. Sometimes I can set up for observing and within 15mins get a feeling of hopelessness, but more often I can sense there could be spells of real steadiness and clarity, and when that happens, it makes the pain of freezing to death on cold winter nights worthwhile. I also find that having a purpose to my observing make it easier to stick it out and wait for those fleeting pristine moments. An example would be the Martian apparition of 2016. Even though the planet was so low that it was bouncing off the roof tops, I didn't presume the seeing would be too poor to observe. I'd set my sights on trying to see as much as I could of the northern hemisphere detail, and I was amazed by just how good the seeing often was low down after midnight. Not sure if any of this helps?

Wow, this could be an interesting thread! It's difficult to really pin exquisite seeing down but it probably happens fleetingly on most nights. The trick is being at the eyepiece when it happens. Seasonally, I find spring months to be most rewarding as regards exquisite seeing, but that could be due to the nights being milder and me being more willing to spend longer at the eyepiece. Also, with the Moon being high at a more sociable time, I find myself more absorbed by the superior definition the seeing allows. Bearing in mind that I generally use relatively small aperture scopes, which are perhaps not so seeing sensitive, I have seen some truly amazing things, plus I believe my observing site has above average steady air, ideal for lunar and planetary viewing. This could be because I'm low down in a valley with a river just a hop and a skip away, which can make things a little misty at times. In spring time I feel I can experience exquisite seeing for an hour or more, while winter seems to offer shorter periods in general, sometimes measured in seconds and occasionally 30mins or even longer. Transparent nights are rarer for me than super steady nights, hence my leaning towards lunar & planetary. As regards the finest detail - my scope of 100mm resolves to its limit as far as stellar resolution goes, but seems to go beyond its theoretical limit when it comes to fine linear features. For example, on most steady nights the central rille of the Alpine Valley is detectable when the lunation is right. The vortex nature of the GRS is often easily seen, as are not only the shadow transits but also the Galilean discs as they cross Jupiter's globe. Recognizable albedo features easily seen on a sub 5 arc second Mars. And recent observations of the linear crater Werner have revealed ultra fine rille like features crossing its floor and up its terracing out into the rough upland terrain. These are not easily visible in images and very difficult visually, but after searching for their existence in reality after I'd sketched them, I found that visually, only Percy Wilkins hinted at the existence of one, but only on the crater floor. Some but not all Orbiter images of Werner hint at them as positioned in my sketches. They appear to be collapsed larva tubes on images, and only one wonderful chap from the BAA sent me some images he'd taken confirming my sketches. As far as I'm aware, no-one else has seen them or they doubt their own eyes. Or they make excuses for their visibility as they seem to be beyond the resolution of a 100mm scope. Yet they are real, I saw them before knew of their existence, and they've been confirmed by the amateur who imaged them. Amazing!