Captain Scarlet

Fascinating. I wonder how many other fundamental constants are out there awaiting discovery...

Do you have EOS Utility? If so, an alternative method is to set up the camera connected to the computer via EOS Utility/computer control with the lens pointed at something high-contrast in the distance, and use the computer screen at max zoom to estimate infinity focus. Then tape the position down on the lens, like this on my Samyang 14/2.8

Just had a look. They seem to be more expensive than when I got mine. I see you’re in the US, where I think they may be marketed under a different brand name; try also Rokinon, Bower, Opteka, Vivitar, Phoenix and Quantaray

I have the Samsung 24mm/1.4 and the 14mm/2.8 both frequently recommended for wide MW shots. I really like them both.

cheers Magnus

these were both done using them, the 24 for both I think

3 hours ago, Stu said:

I told Lorna to remember her old Dad when she sees the next one in 2080!!

2040 shouldn't be too bad, although it'll be at the wrong end of the day: 6am ish 30-31/10/2040 should be viewable, although only an unimpressive 1.1 degrees minimum separation. But it will have the benefit of a quite close-by Mercury. You'll still be a spring chicken. It's in my diary anyway.

M

I very recently had an identical experience with my new paracorr. It totally transformed my view of star-fields, especially open clusters and especially with my panoptic 35 which I decided to not sell as a result.

My understanding is that for Newtonian coma it’s not the eyepiece fov that chiefly matters, but how far from the centre of the Newtonian’s image circle you are. So the longer the eyepiece FL you are using, the more of that image you are looking at, further away from Its centre. High mag eyepieces won’t show much of the coma as they’re looking at the very centre of that field where there’s less coma.

I too regard it as an essential part of the system.

cheers, Magnus

I had a reasonably full rig out yesterday, 150mm Intes and Pan 24 on my Ayoii+NexusDSC giving 70-odd magnification. Totally mesmerising. Today was looking to be a wash-out with violent squalls passing through and big banks of black cloud in the requisite direction. So I was taken by surprise when I went out to collect a delivery to see two fine pinpoint jewels and a cloud-gap worth at least 10 minutes. I grabbed my Kowa spotting-scope and was rewarded with a lovely view at 60x mag, 3 Jovian Moons more or less underlining Saturn. Such beauty!

Magnus

All the above. Can you just buy body-only? Then perhaps as a first lens a 50mm/1.8? I’ve seen some amazing astro shots with it, and it’s useful as a regular terrestrial lens too of course. 
 

Cheers, Magnus

I’m a big fan of APM based on my small sample of their products (an 8x50 finder - really superb) and an LZOS 4” refractor (also obviously superb).

So I’m not at all surprised their branded eyepieces are also really good.

An unexpected patch of clearness in the right direction, so I grabbed my Kowa 88mm spotting scope and used it first-time-ever on a celestial object. I mounted it on my Stellarvue M2 alt-Az and I think I’ve found my “grab and go” set-up. Fully waterproof too which was just as well!

Anyway, back to the point, the two planets were both on view at max zoom, 60x, and remarkably clear. All 4 Jovian moons unless there was an interloping star, two main equatorial belts, Saturn’s rings very clear. And just off stage right and down (this is a correct-image scope) a huge looming crescent New Moon.

Im glad to be able to say at least I have seen the conjunction-ish now, hopefully I’ll get some gaps on 20-21-22.

Magnus

Skywatcher 200p gets my recommendation. It's useable for any target, not too small (aperture) for dark sites, and not too big for light-pollluted sites. I myself have one. People refer to it as a "Goldilocks" scope. The eyepieces (lenses) that are supplied with it aren't very good but that's no different from almost any new scope, even some very expensive ones. It is likely to come with a 25mm and 10mm eyepiece. The 25mm is not too bad, the 10mm is poor. It would be worth improving those by getting BST Starguider eyepieces at similar focal lengths, at a modest extra cost but huge optical improvement.

Good luck, Magnus

As a fairly recent newbie myself I can totally relate to your enthusiasm and relive the experiences. And the scope you have is very capable. I only recently used the same scope  to see the Veil for the very first time, by all accounts a rather difficult target! But I was (am) at a dark site, in Ireland as it happens.

Whereabouts in Ireland are you? I’m near Baltimore West Cork. If you say you’re 20 minutes from bortle 3 ... that’s a total luxury for most of Europe and UK!

cheers, Magnus

58 minutes ago, Jiggy 67 said:

That’s quite scary. Can permanent damage be done to the mirror??

No, no damage at all, just the figure changing in response to different cooling rates in different parts of the mirror. I was lucky to be able to observe two extremes on consecutive nights, first terrible, thinking I’d been supplied a dud; then with previous night still fresh-in-memory, a beautiful experience indicating a near-perfect mirror.

Just another thing to add to the list of unlikely things that need to be “just right” all together to be able to take full advantage of a good mirror: good seeing, good transparency and now as I’ve discovered, stable temperature.

I believe @GavStar has a serious contender in this category ... ?

I’ve toyed with the idea of a cooling fan but don’t have one yet. The mirror was cooling naturally but I’d say the temperature had dropped from around 4-5 degs C to about -2 in the space of an hour.

I’d heard of the cooling effect on mirrors by reading some of Mike Lockwood’s writings.

M

13 hours ago, Deadlake said:

I  have an APM reticle EP, but to me the cross hairs are a little fuzzy compared with the Vixen finder scope.

That is actually a feature not a bug. That rubber ring allows you independently to focus the eyepiece onto the reticule, then adjust the focus of the objective until the stars are sharp. That way the stars and the reticule are at focus in the same focal plane. If the stars are sharp and the reticule fuzzy, they are in different focal planes and you’ll get parallax, ie the cross-hair point moves around the star-field as you move your eye. I have an APM finder/ eyepiece and it’s very good. The SW-style ones that come with many scopes don’t easily allow one to make those adjustments.

Cheers Magnus

Well. Out again tonight and as forecast, the early part of the evening has been lovely and clear.

Filled with anxiety, that after my Star Test of the scope last night I'd paid big money for a dog from OO, imagine my relief when tonight the scope delivered a text-book and identical inside- and outside-focus star test. Thanks be to. Last night was, incidentally, First Light for the outside 3/4 inch of this new mirror. The inside part of the mirror got its FL a few weeks ago when I just plonked it into the SW cell replacing the extant mirror without regard to the different focal length, which required some surgery to the tube to place the secondary further away.

Unfortunately, as forecast, early cloud has now rolled in so the heavens are teasing me! "Yes you have a good mirror, we'll just about allow you enough time to discover that, but sorry no you can't play tonight."

Anyway, I'm pretty relieved. I've learned something fascinating though: a rapidly-cooling mirror, losing heat from its periphery well before its middle, thereby changes its shape and becomes "over-corrected": thinner at the edges than it should be, but still fat in the middle. I saw this first hand last night with that appalling star test. Temperature tonight was stable, and no dew (frightened away by my hair dryer close at hand no doubt).

Cheers, Magnus

Yes very good. Over here in the West of Ireland there are similarly dark skies to protect. Much of Kerry somehow has managed to make a Dark Sky reserve of itself, and now that I find myself with some time to spare I'll have to see how West Cork can be persuaded to do the same.

Magnus

I too had a disappointing night for slightly different but by no means uncommon reasons. I’ve started a separate thread rather than hijack John’s.

My problems were dew, and rapid temperature change.

tonight should be better though, hairdryer assisted...

Magnus

On 04/12/2020 at 20:37, Astrofriend said:

Earlier when I tested my Canon 300 mm L f/4 lens mounted on my Star Adventurer I found the load on the mount too high. Now I 'm adapting it to fit my EQ6 mount and include an auto guiding camera too.

Here are drawings and photos of my rainy day project:
http://www.astrofriend.eu/astronomy/projects/project-300mm-setup/01-300mm-setup.html

Have anyone seen a power regulator to USB heating bands ?

 

/Lars

Really? A 300mm f/4.0 is essentially a 75mm refractor, they don’t come much smaller than that. I’m surprised it overwhelms a star adventurer unless seriously unbalanced. I have one by the way, a lovely lens.

M

I think thicker vanes won't affect the diffraction spikes, the spikes are all about the total length of edges in the light-path (including the edge of the aperture). Thicker vanes will just result in a little more total obstruction. But shiny surfaces parallel to the light-path, especially those actually inside the llght-path, my instinct tells me will result in disproportionate glare around bright objects.

A reflective inside of the tube itself will also be glare-inducing-contrast-reducing, but because it's outside the main light-tube-cone its effect should be reduced. But then again the sheer area of the inside of the OTA will offset that (i.e. make it worse).

I plan to test the vane-reflectivity effect by introducing a long wide shiny blade into the light-path when next observing. Actually flocking the vanes may be the next step.

Such fascinating fun, these thoughts fill my mind when going to bed and send me to sleep!

... on reflection, pun intended, I decided to reorientate the side-support grubs in the mirror cell so there is no chance of the mirror getting “jammed” between two nylon tips at the bottom. Rather have it resting not-quite vertically on a single one.

that involved rotating the whole tube in its cell by 60 degrees.

while I was at it, and this is the reflection part, I removed the spider again and the secondary to paint the spider-vanes cardboard black. They were actually very reflective, and the last thing one wants is a parallel reflective surface in the light-path. Before and after pics...

On 02/12/2020 at 22:41, Ships and Stars said:

 JB Weld is excellent if you need to epoxy anything on. You can even drill and tap it for threads. Extremely strong bond. I use it on just about everything ...

Ive always plumped for Araldite, I’ll get some JB weld on your recommendation, thanks

Lightpollutionmap.info is a very good resource (how I hate that word apols). The way to use it is to set the overlay to Atlas 2015. It’s a simulation of how the darkness will appear at zenith at best to an observer on the ground. I’ve calibrated it to two very different places, one 19.0 and one 21.8, and they’re both spot on with that overlay.

The other overlays are views of how bright it looks from the satellite, a different thing.

Cheers Magnus