Seelive

'That'll do' ...

What about trying again at either +/- 300mm? 🤔 Found exactly the same thing when I tried planting some new shrubs in my garden a few years ago. Not sure that all the effort with a bolster and a lump hammer was worth it! Must admit, a beautifully edged hole, your lawn edges must be so much better than mine 😆

That was used to allow a proper nights astrophotography to be undertaken without the worry of constantly looking at a computer screen and wondering why you are getting more than 1" RMS guiding error 😆

That takes me back to my early years trying to follow my 1st edition of Texereau's 'How to make a telescope'. Saw the light in the end a bought the mirrors (although it was fun trying) 😊

For just 2 mirrors and a corrector, I wonder what the cost of the HST was per sq mm? 😉

I have a Canon 200D that shows as 6000 x 4000 pixels in properties because that is what is reported in the EXIF data but in reality the the RAW image is larger. The older versions of DSS using DCRAW give images of 6024 x 4022 whereas the later versions using LIBRAW give an image of 6024 x 4020 pixels (so incompatibIle with the earlier versions). My old copy of IRIS opens them as 6288 x 4056 (although their is a large black border and the actual useable image size is only 6024 x 4020). The Adobe DNG converter gives 6024 x 4020 in both the old version of DSS and IRIS. To be honest, different plate solvers giving a focal length variation of only 0.33% wouldn't worry me too much.

I believe it will be a 1/4-20 UNC which is a US imperial size rather than a 1/4-20 Whitworth which is an old UK imperial size (and which would probably fit but it's not a good idea to mix as it has a different thread form).

I've always thought that the risk of condensation only occurs when a cold item is exposed to a warmer moist environment? (Hence the need for dew heaters, so unless you took it outside from an AC room on a hot summers evening, that ruins that idea 😊)

Try scrolling to the bottom of a page and clicking on Themes. I use the 'Default Simple' which is black on white (the other option always crashes on my phone!)

Definitely not! I want to enjoy my time on this forum 😊

I don't disagree. If observable or measurable facts do not form any part of a theory, then I would guess that the theory is suspect.

Their's theory and theirs's opinion and I suppose their lies the problem

I suppose their will always be both acceptable and optium methods for anything.

And here's a full frame Canon 200D image of the pair with a 400 mm lens!

'Normal' stretching generally tends to loose colour. I believe Siril has an Arcsinh stretching function which will help retain the colour whilst still bringing out the fainter details.

What stacking method did you use? A lot of the brighter stars appear to have a fainter companion so it's hard to say whether it's a problem with the individual images or with the stacking software or both. If you've not already, try a Kappa-Sigma stacking method to see if that reduces the effect of the 'doubles'?

I bet the DSS processing was also significantly quicker as well! You only get any advantage from using drizzle if your images are undersampled, there is movement between the images (dithering) and there are lots of images.

If I remember correctly, many years ago, a 3" Frac or a 6" Newt were considered to be the minimum mainly because at the time they used to be about the same price and gave about the same visual performance? Whilst I suspect Fracs have come on leaps and bounds in terms of optical performance since those days, I'm not so sure thay the performance of Newts will have changed that much (other reflector types are a different matter as back then you mainly only had a choice of a Newt or a Cass). But the 'mass production' out of Asia has certainly cut prices and made decent quality scopes much more affordable.

A 32 bit file would only be twice as big so only about 280Mbyte. @JemTaylor When you load the TIFF image into your processing software, what is the image size in pixels that the software reports? For a 24Mbit camera it should be about 6000 x 4000 pixels.

The 16 bit TIFF from a 24Mpixel camera should be about 140Mbyte. Have you enabled the Drizzle option when stacking?

Good job that plates and 120 roll film are virtually a thing of the past then 😉

Surely a 400mm FL camera lens has a FL of 400mm? It might be physically shorter in length because of the optical train, but then a telescope may be only 500mm long but if a barlow lens is placed in the optical train would have a focal length much longer.

LED lighting seems to have such a wide bandwidth that I believe anything other than narrow band filters will let most of it through. If you are surrounded by LED lighting I have the impression that any of todays so-called LP filters will just give a minor improvement in the background sky pollution level but at the expense of a reduction in the image colour range. (Bring back LP sodium lighting, these days it's surely easy to filter out the two D lines whilst leaving the rest of the spectrum intact?)

It's quoted in my Synscan manual (under 'Tips for improving alignment accuracy - Mechanical backlash')

Had a look at the needle.tif (gave up with the other 2, the data seemed well over to the right). Although their were hints of colour in the background noise the main image artefacts just appeared to be greyscale.