GazOC

Not much chance of forgetting it, John. You can pretty much guarantee that someone will make that comment every time a thread is started about glass types

I've had my ED120 and ED100 on an AZ4 with stainless steel legs and an extension tube. The damping down time on the 120 was borderline what I'm willing to put up with but the ED100 was fine. I think upgrading the Skywatcher ally tripod is very worthwhile even with the bit of weight the steel tripod adds

Hi all, I was looking at dipping my toes back into a bit of lunar/ planetary imaging and was dead set on getting a ZWO ASI 290MC camera but then saw this from QHY. Does anyone have any experience or views on it? https://www.modernastronomy.com/shop/cameras/lunar-planetary/qhy-lunar-planetary/qhy5iii462c-planetary-and-nir-imaging-camera/ It seems an attractive option with the far IR sensitivity as I definitely want to go down the OSC route for planetary but would also like the advantages mono gives for lunar imaging.

It was the achromat. I didn't have them both side by side but I'm pretty sure I had them at the same Jupiter opposition (it was ~15 years ago so I can't be sure). The 127 gave clearly better views of Jupiter than the 120 and I've always regarded the planet as the acid test for refractors. Ironically, given the question, I sold the 127 when I bought an ED120 which rendered the achromat a bit redundant

I've owned a Skywatcher 120 and a clone of the Bresser 127, the latter was by far the better scope.

Result!

I'd upgrade the Celestron, I'd prefer to have the thinner 80mm tube over the 100mm that the ED80 uses

I'd go for the ST102 for the reasons mentioned above, it would be the perfect compliment to the 127 Mak. The ED80 is undoubtedly optically superior to the ST102 (as it should be given the relative prices) there's no beating the extra aperture for DSO observing.

The reason I've read is that, while in an ideal world there's no reason a Mak/Cass should outperform a SCT, it's easier to accurately mass produce the Mak corrector than it is the SCT corrector so the customer is more likely to get better quality optics. (Disclaimer: I am not a telescope manufacturer)

@John I tried to find one but couldn't but if you can locate a similar diagram for an ED doublet or an achromat it may show the idea more clearly Depending on how the designer has chosen to set up scope the focus point for the wavelength at the blue end of spectrum will be further apart from the on the vertical scale from where the red/ green wavelengths come to focus than it is the example above. This is the CA you see at the eyepiece

It's sounds like you're sold on the refractor and planets despite the pros and cons probably weighing in favour of the Cass being the more versatile scope overall? If that's the case then go with the 'frac

I've used a HEQ5 for lunar/ planetary imaging with a 180mm Mak and it's more than capable.

I like the look of that, John

Ouch! It's worth 3 times more than the scope

Does anyone make a 1.25" only Crayford or R&P focuser? I'm guessing not but it could be an option for people who wanted to move away from the stock focuser without wanting the extra weight of a 2" focuser on the back of the scope?