Nik271

Just a quick shout about the coming conjunction this weekend. The closest approach is at 19 UT on 30 April when the planets will be just 1/4 degree apart. In the UK the best naked eye visibility window is on the morning before and after, i.e. around 5:30am on either 30 April or 1 May. The UK forecast for Saturday morning looks particularly promising. I'm hoping to get both planets in the same field of view of my Mak 127. Clear skies, Nik

In practice it is rare to reach even x200 on the planets with any instrument except in rare conditions. But x200 is plenty magnification to see detail: belts and barges on Jupiter, markings on Mars, the Cassini division on Saturn. Easy calculation: Jupiter is 40'' in angular size. Times 200 gives 133' or more than two degrees apparent size in the EP, so it will look like the width of two of your fingers at arms length, big enough to see detail. At 150mm F8 the Bresser is a beast though: a heavy scope to move about and as other say as well it will need some CA control at high mags. You will be better off with a Cassegrain of some sort.

Such nights are truly special. There was a similar evening here last month in Oxford, we had a high pressure system over UK and no jet wind. I managed x400 with a Skymax 127 and still the stars were perfect. Felt I could go on increasing the mag forever. I could spot elongation in Dubhe. @Sunshine, did you look for the companion of Procyon? Looks like it was the perfect night for it, the separation is just under 5'' but the difference in magnitudes is 10, even worse than Sirius. I guess at x500 there could be some hope to see the dim secondary away from the glare of the primary.

Dear Matt, First: you should always refocus after attaching the camera, don't assume that the eyepiece and the camera attachment are parfocal, 99.9% of the time they won't be. In fact with a Maksutov you shoud check the focus now and then during shooting because the mirror moves slightly in a different position. I have the Skymax 127 and its focal length 1500mm is very demanding on the mount. So with EQ3-2 you are severely handicapped. I doubt it will track well even for a 30 second exposure. The other issue is that with focal ratio F/12 the Skymax is a very slow scope which is OK for bright objects like the Moon and planets but pretty poor choice for DSO. M51 will barely register after a 30 second exposure. It can be done: take many 30 second exposures and stack them but even then it will take an awful lot of time. For DSO you are better off with a fast Newtonian or a refractor.

Yes, I was pleasantly surprised how robust the collimation of these Maks is. I never touched the primary, just removed the corrector plate, inserted the flocking paper in baffle and then put the corrector back. This also answered my worry how to clean the mirror if ever dust goes in. But I don't think I will need it clean it for years: seems pretty well sealed.

Well done! Mercury is always a tricky one to see and the next 2 weeks are about as good as it gets. I believe the greatest elongation is on 29 April but the key is to have clear horizon in the northwest and no clouds of course. On 21-st I went out with my portable kit and could spot it about 30 mins after sunset, from about 8:45pm when it was still 10 degrees up. Worth having a look with a telescope from your clear spot if you have the chance. I could just about see the half-disc shape at x80.

I'm predominatly visual guy but just could not resist to image the current sunspot group. Skymax127 with Baader solar filter, Canon 250D (at native 1500mm F12). Recorded 4K video and then stacked best 15% of 5500 frames. The video compression ruins the fine detail but at least is pretty close to the view in the eyepiece.

Just spotted them too, right on the edge of the disc. Seem fairly big indeed. I'm looking forward to some sunspot viewing in the coming week!

I wanted to give a proper test to my Skymax 180 because I recently removed the corrector plate to flock the baffle. Collimation star test seemed OK but I'm never entirely sure because the in- and out- of focus patters in Maks are so different. The only test that matters is actually using the scope on difficult targets and last night the seeing seemed rasonable so here we go. I had made a short list of just four doubles in ascending order of difficulty, so at 9pm kicked off with Epsilon Hydrae. The secondary (component C) is 2.7'' away and 3 magnitudes dimmer. There were still some tube currents in the Mak and initually it looked very wobbly at x220. Half an hour later though the view steadied up and the secondary showed up nice and clear. Tick. 38 Lynx was a breeze (separation 2.6'' and 2 magnitudes difference). I was suprised how easy it seemed (perhaps since it was much higher in the sky). I was getting confident so next was Kappa Leonis (1 Leo). This is one of Burham's finds: 2'' separation and 5 magnitudes difference! Initially it was a no-show at x220. I inserted 8mm BST for a crazy x340 and voila: with averted vision I could see a dim spec just south of the primary. Thrilling! Finally - Omega Leonis (2 Leo). Separation is 0.9' and 1.5 magnitude difference. I'm not sure I got this one, it looked kind of elongated but the seeing was worse at the lower elevation , it was very wobbly at x340. At x220 there was no hint of separation whatsoever. As a consolation I looked at the nearby 6 Leo: widely separated unequal orange and blue. So there you have it - 3 and a half out of four. I think my Mak is in good shape 🙂 Clear skies! Nik

Is that a 6 inch Cassegrain? You should be able to split the Double Double using about x120 magnification in most conditions. Don't be disappointed about the other doubles you tried - these are very hard or impossible. Forget Capella and Arcturus, these are beyond amateur equipment (and Arcturus has only one observation from 2003 which has not been repeated). Vega has sevaral dim visual companions. The only one feasible with your scope is mag 9.5 about 80'' away, not easy in bright full Moon. Also it's a bit late for Sirius, by 9pm when it starts to get properly dark Sirius is too low in the west.

I also looked at the same night with no success. Surpising how hard it is considering it is showing big on most charts, even those from pre-satellite mapping era e.g: I will keep trying around the 11-12 day of the Moon cycle.

Just watched this Sky at Night program from 1982. It's interesting to compare the state of the art then and now and with the benefit of being 40 years ahead to know the answers to some of the questions discussed by the astronomers. Best of all there are close ups of many famous telescopes.

I came to the similar conclusions some time ago, faced with ever increasing local light pollution: 1. Invest in smaller and portable scopes which are to be taken to dark(er) sites as often as possible. 2. Thankfully the Moon, planets and a few of the bright double stars are still visible. 3. Longer term, I have planted some fast growing evergreens to block as much of my neighbours silly lights. and when all else fails: thick bath towel over head.

I had a look last evening (12.5 days old Moon) under so-so seeing with my 180mm Mak. I used x200 magnification and could easily see the first 50km of the south end of the rille, up to where it makes a bend around a craterlet. I think illumination and seeing is key, the southern end certainly looks doable in smaller scopes under good conditions.

I have used a Chinese manual 85mm F1.8 lens (Neewer, Andoer, they are very similar, well bullt, all metal) stopped down to F2.5 with good resuts. Don't expect miracles at the edge of the frame but decent overall. Here is one on ebay I just found by a quick search https://www.ebay.co.uk/itm/265636565119?_trkparms=ispr%3D1&hash=item3dd92c507f:g:v2sAAOSw89NiUbhS&amdata=enc%3AAQAGAAAA4KxiJOa4HNyEHn7wnVxyndUwR%2BEMYc5EByUzvwLPo3vsRqNgixHkGgtPd8IWI%2Fah4JltkY38A4PbV%2Fpc5qsp1Fq69%2BwGPjkwewy4ss1AIRUJbS%2BB0t5SiPOqQiKRW2JgMsExcUunCFVCYs%2F3b1wMlIF41ko1u7SDVAqrDY1PK%2FF1SxDK2awdb%2FehwAFVNbOvMdGYqcZoy3s6ZWghCYldIvvGVriGUOll67LhoEas7UYHh%2BP2dBWNEiiqzsuYzXd8XmN9aBIbJFo3uNPxVlJBY9YLbWYkLdngoHMYG9sd7VaM|tkp%3ABFBMpLjN84Jg

Even better - cooking with hydrogen! 🙂

Looks good! And it shows that even Polaris moves noticeably during the night. I assume it is the bright dash on the left of the celestial pole.

Looks good. 10 inches will show a lot of stuff out there, enjoy it!

Congratulations, Ags! First few times I looked for the Owl I couldnt see it, but eventually I managed it. The overall light pollution is the key. La Palma must be terrific. Shame about the local lights, try a thick bathroom towel over you head for some dark adaptation!

Sorry! my statement was not very precise, I meant to achieve the same SNR with the new F4 scope you need 64% of total integration time of the old F5 scope. So 100 hours total at F5 equals 64 hours at F4. This new camera looks very sensitive and with extremely low read noise so the length of the individual frames should not matter too much. With the F4 scope you will be saving 36% of the total time compared to the130PDS, to me this does not seem worth the extra hassle.

To answer your question, the difference of the speed of F4 vs F5 scope (using the same camera) is the square of their F-ratios. So the F4 scope will be 16/25= 64% faster: all other things being equal you will need only 64% of the total integration time with the F4 scope. If you use a dedicated astro camera it's slightly better to keep the same length of individual frames, but decrease their number. If you use DSLR which usually generate thermal noise in long exposures it might be better to decrease the length of the frames instead (only applies if you use frames of length several minutes). Most people find the difference in speed between F4 and F5 is not worth the extra need for manufacturing precision, collimation and corrections of aberrations the F4 mirror will require.

You don't need to bother with artificial star if you want to test chromatic aberration: focus on a distant tree branch or telegraph pole or TV antenna against a bright sky. Take a picture and look for purple fringing. You can repeat this with real stars, Polaris for example is white and ideal for testing purposes as it doesn't move, any chromatic aberration will show as a halo around it. Even if you spot chromatic aberration it's most likely to show only on the brightest stars. It's a bit unsightly but should not be a deal-breaker for the lens.

I will give it a try visually with the Mak next time the seeing and Moon phase allows. It's a nice challenge!

My modest experience from Bortle 5 sky is that in very long exposures the glow from the sky swamps the fine detail. Plus the longer the exposure the higher the risk of cloud/wind/satellite ruining the sub. 180 seconds may be about right. I had good results with just 30 second exposures and 150mm Newtonian at F/5 with an unmoddded Canon 250D but that was a bit on the short side.

Awsome detail! 28 panels, wow... time to upgrade to a full frame sensor then 🙂