CraigT82

There’s a nice diagram on Wikipedia showing where the diff spikes come from, it’s actually not that complicated when you see it laid out like this:

Wow what a fab project and product. I can see them dotted around the grounds of high end luxury hotels! I like that the structural components are metals whilst the those parts at the user interface are hardwood. Nice touch that (pun intended).

I wouldn't jump to conclusions on global warming by just looking at the prevalence of summer heatwaves in one single country. There is no doubt that the world is warming up, note this graph only goes back to the 1850s which is the period we have actually temperature measurements for. There are graphs that go further back (and that further reinforce the recent increases) but they are constructed using temperature proxy data and so have rather large error bars. Now, what has been going on since around about the 1800s? The scientific consensus is that the world is indeed warming and that the cause is anthropological. Generally speaking, any doubt about that anthropological cause mainly comes from industry/media/political figures, rather than scientists. It's just a shame that the general public are exposed to these media/political figures a lot more that they are to the scientists, and so there is a fashion for climate change denial now amongst those who see themselves as 'free thinkers'. Personally, there is no doubt in my mind that the observed warming of the globe is being driven by accumulation of greenhouse gases in the atmosphere. Cn we do anything about it? I doubt it, there's just not enough will - political or individual - to make the changes necessary to avert further warming. I think we all will need to learn to live with our new hotter planet. Scottish wine anyone?

What mount is it? If you’re not getting correct stars in the alignment procedure than your location info and/or time date info is probably incorrect, did you double check the info you entered into the handset?

Didn’t you have a 200p newt Neil or have I made that up? I think any of the CATs will do well for you so it comes down to personal preference. I’ve never had a classical cass so can’t comment on those but I did have a skymax 150 and I absolutely loved it, hits a real sweet spot of size/portability and capability (both visual and imaging). Downsides is that you will most definitely need some kind of dew management.

Nice shot, the hydrogen filaments are really showing up nicely

It was a primary from a 12” dob which had been kept outside in a shed for 20-25 years, so it’d had a good innings. Pic was taken using one of those little clip on macro lenses on a phone. This pic gives a bit more perspective (believe it or not the views with this mirror were actually pretty good)

I wouldn’t say that TBH, the protective coating is still incredibly thin and even a tiny of grit pulled across the surface will scratch through it. It’s probably best to consider it a protection from atmospheric elements rather than mechanical attack. Eventually tiny holes form in the overcoat which allows the aluminium beneath to be exposed and that eventually leads to holes right through the coating…. That looks like this:

I’ll second that… the QHY462c is a fantastic planetary camera. I captured the Jupiter and Saturn images in my signature with one. Well worth considering.

Both the 120 and 224 are very decent cameras to be getting started with. They have the same sized pixels and same sized sensor but the 224 is more sensitive and has less read noise, so I’d go with that one if your funds will allow. When using a colour camera you will also need to budget for a UV/IR cut filter to go on the nose. If you do decide on the 120 try and get the 120MC-S which is the USB3 version and is capable of faster frame rates than the older USB2 version.

Modern mirrors have an overcoat of silicon dioxide (i.e quartz - very hard) on top of the aluminium. This top coat is protects the reflective surface for many years. Not sure about modern mirrors being kept sealed after coating but I think older mirrors without a protective overcoat were advised to be kept sealed up for a couple months after coating to allow the aluminium to develop and oxide layer. OOUKs hilux coatings is a silicon dioxide overcoat which has some trickery in the application process which increases the reflectivity (and also the longevity apparently).

Maybe you’re thinking about moving mirror cassegrains here. With this scope the mirrors are fixed and so the focal plane is also fixed at 255mm behind the scope, and the focuser just serves to move the cam/ep to coincide with the focal plane. With a normal SCT or mak the mirror moves and so does the focal plane. In this design the focuser actually moves the focal plane to coincide with the position of the cam/ep which is fixed. There is an ideal ‘spot’ for the focal plane which corresponds to the point of best correction (spherical) I.e the proper distance between corrector plate and primary).

This site really helped me get my head around involute gear teeth. https://www.tec-science.com/mechanical-power-transmission/involute-gear/geometry-of-involute-gears/ I use Civil 3D and haven’t really found a satisfactory but quick way of drawing gears yet, so have to draw one tooth manually and polar array it. I found a few tutorials on YouTube where they seem to use random arcs to create the involutes but this site helped me to come up with my own way of drawing those curves with proper geometry.

Nice session by the sounds of it. Absolutely love my H130p, maybe I should get an Oiii filter 🤔

I think the point you’re trying to make is that linear features can be resolved much at a smaller size than the theoretical resolution limit of the objective? That’s pretty well accepted I think. People are free to express different views on this site and many do just that, but the general tone and language that are used whilst expressing those views plays a big part in the response they will generate and whether or not they are taken seriously and with respect. If you find your posts to be ignored, dismissed or considered inflammatory on a regular basis then perhaps it’s not what you’re trying to say but the way you’re saying it.

Base arrive today, perhaps a little flimsy with 2mm wall thickness but I’ll give it a whirl and see how I get on. At £13 for the print I’m not too fussed if I have to draw and order a stronger mk2 version.

Could try a simple arrangement like this, add in three 'guylines' made with steel rope and turnbuckles and it should be nice and stiff whilst very low cost?

The double image is probably resulting from an internal reflection somewhere inside the scope or eyepiece, have a look inside both for any shiny reflective surfaces. If you do find any you could try 'flocking' it (using a black velvety self adhesive fabric which absorbs light) or even just painting it with blackboard paint or something similar. If you could post up some pictures of the insides of your scope and eyepieces it could help us to diagnose the issue.

Trust one manager to name a scientific instrument after another manager 🙄

Yeah it’s incredible isn’t it, the best I’ve seen.

Haven’t tried it myself but have seen some fantastic ISS images on twitter by a chap using it with his 400p auto dob

Magnus wrote an excellent tear down thread not long ago, I can’t find it now. IIRC he found his Skymax 180 mirror was indeed oversized at 200mm but it was the baffle design that clipped the light cone.

Ah I see, apparently GSO spec a smaller secondary to improve planetary performance. Bit cheeky of them to claim it’s 203mm

7”? Isn’t it a 203mm aperture?