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Regardless of theoretical reasons not to, I haven't had any issues reusing flats with my QHY filter wheel. I always take new flats if the camera rotation changes, otherwise it seems to work fine between sessions. I actually find flats quite time consuming, as I tend to do them indoors the day after. Practically, it'd be very hard for me to take a flat before every rotation of the filter wheel.

For the price, it may well be a solid starter kit, in the same that a £100 telescope might not satisfy the needs of people here, but will amaze a lot of other people. But it's ALT-AZ and I can't imagine it will work well on anything other than a few select targets.

Mine melted due to a short and I couldn't find one nearer so I ended up ordering from Cyclops optics in Hong Kong. The cable was cheap but postage will almost certainly make it more than the one you found. In the interim, I just used a normal cable with tape.

Friday was my first attempt at a dark nebula, from Bortle 5 too. Should have gone for one final galaxy for the year! Over-processed and the color isn't right, but the data isn't there to create anything I'm happy with!

Doesn't PHD2 have a way of analyzing if there's significant periodicity to the noise? Humans are very good at spotting patterns that doesn't exist in noise - so it's worth confirming if it is periodic or not. If you can attach the log, it's a pretty easy thing to in R or Python.

Almost certainly a hair - it's very plausible that a hair fell in, but very difficult to imagine how it could get scratched. But in many ways it doesn't matter - it won't affect views, and few people keep their Newt's long enough to need to clean the mirror (which isn't to say people don't clean them - just that it's rarely necessary!)

For only £600, this seems like it could be a bargain - although if that's without VAT and import duty, which would be my guess, far less so.

Without wishing to rekindle the debate.... - I imagine what we all have in common is that when we look on astrobin, we can people who've beaten our images with both technologies! - the ASI 1600 is probably the last generation of CMOS where there's a real debate to be had - after that (e.g. 2600) I think any rational debate lands on the CMOS side - the specs simply do not lie.

I've always assumed the 67% rule applied to things that are current or don't get superseded over time? Eventually technology will move on and all the cameras mentioned here will be worthless, much like the early starlight express CCDs are now. So the rule has clearly got a time limit!

Out of curiosity, did you settle on a reducer? I have this scope and would love to get a reducer, but the one that altair supply is out of stock and they appear not to reply to emails, so would like to source something for the autumn. In other news, I too probably see a hint of red fringing with this scope - I saw a similar result to the one above. I can't be 100% sure as I've tended to capture LRGB on different nights, and on at least a couple of sessions, the R had worse seeing conditions. I've got a backlog of data to process so I'll post back with any conclusions. I haven't had a refractor very long - I have a chesire - but don't really understand how to use it to check for tilt

The Moravian might be a better example of the KAF 8300 CCD, but I think I saw an Atik version for <£600 on ABS a while ago. This must be close to the best value 2nd hand camera available - although the ZWO 1600MM or QHY163M are probably to be had for the same price - and I'd guess that choice is down to personal preference.

One thing to add to @vlaiv's list is that the astro cameras almost always double up as a guide camera and can also be used for planetary, lunar or solar photography. So for example, I used to use a DSLR for nebula and galaxies, with a ZWO camera for guiding, and then it could also be used for lucky imaging. My personal view of a fan cooled astro camera is that it can only be a good thing to have a cooler chip - but I wouldn't pay much for fan cooling over the cost of one with no cooling.

Older modded Canons (e.g. 450D, 550D) regularly come up second hand for <£200. But it's worth noting they make a real difference on emission nebula - less of a benefit on broadband targets like galaxies. Lots of good advice above - but my take is: - the DSLR will always be noisy, so it's not really fair to compare them to a cooled CMOS - the DSLR wins on price by a large factor - the noise can be combated with more subs - generally, avoid worrying about darks on any camera that doesn't have set point cooling - just dither a large amount instead

Thanks - I hadn't really thought to google that, but the idea had crossed my mind.

I'm down to just a 115mm Altair wave triplet at the moment. The lunt wedge has a pretty clear warning about only being able to dissipate the heat up to a 100mm scope for the 1.25" version. Does anyone have experience otherwise?

Interesting thread. I have a 1.25" lunt wedge and a 1.25" continuum filter but no longer have a refractor with an aperture <=100mm so I was probably going to buy something for this summer (gotta get the astro fix somehow!). I'd settled on a 72mm apo as this would also fill a gap in my current focal range, but looks like a cheap Startravel 102 would be worth considering too.

I don't think there's a simple answer. It depends on your mount and what you're hoping to achieve. But if you have 0.3" RMS guiding then that's very good - beyond the limit of most EQ6 class mounts, so probably only routinely possible with mounts costing many thousands of pounds. Alternatively, if that's 0.3 pixels and you're using a standard type of guide camera, it's probably not amazing. But mainly came here to say that round stars are not a cast iron guarantee of good guiding. It's entirely possible to have round starts and terrible guiding, as long as both axis are equally terrible. Much better to measure FWHM of your starts - which is in DSS.

I keep my mount outside year round, under a mass produced heavy duty, large outdoor furniture cover from Amazon. I wouldn't recommend the cheapest ones, but I've found the premium ones to work well, and are much cheaper than anything dedicated to telescopes. I've left my OTA out under one of these in the summer for a few days whilst the weather is good, but tend to bring it in if the forecast is bad.

I wasn't aware that the skywatcher you link to could be computer controlled. As I recall, you'd at least be soldering wires on to the PCB. Most people use the Hitec Astro DC controller for that purpose. I've used the Skywatcher + Hitec, ZWO EAF, Sesto Senso 2 and Lakeside focusers with astroberry and all work fine. If I was choosing based on price/performance, the ZWO EAF is hard to beat.

Opinion may vary, but I'd vote no. The pros are it has better quantum efficiency than your Canon and is cooled, but that's all. It's 20 years old, has rectangular pixels, no set point cooling, and a tiny sensor. I tried a slightly newer (~2005) but similar SXV camera and it didn't produce better results than my Canon 450D. If the SXV were £100 or less I might buy it to try, but I don't think it's worth any more. Is you Canon 450D broken or you're just unhappy with the results?

I heard a few similar stories about QHY's early offerings, but I've not had any issues with their newer gear at all.

I once saw something similar, and it turned out to be caused by a Baader Mark 2 coma corrector paired with the FW + filters spacing I had. In that instance, it was solved by moving to a mark 3, which has better coating.

I've had an EQ6 outside for 1.5 years now with a similarly priced cover from Amazon. I serviced it to add a belt mod recently and there was no sign of any damage from water or heat. From what I've seen, the mount ends up just as wet from dew on an overnight imaging session as it does on the rainiest/dampest of days under cover. I may think twice before putting a £3K mount outside permanently, but from what I've seen, most concerns (and expensive covers) seem unnecessary.

Been meaning to ask this elsewhere, but it seems relevant here..... Is the correct advice not to over sample, or is the advice to bin to the appropriate level? I ask this because: - it's not like there's a massive range of pixel sizes available in the mainstream cameras - if I stick to 4 of the most recommended ZWO cameras (1600, 2600, 553 at 3.7 microns, 183 at 2.4) the pixel sizes are similar when compared to the older CCDs - The low read noise on these cameras makes binning less of an issue, and they tend to have higher QE than older CCDS, so without doing the maths, I'd imagine one achieves a better SNR with these cameras + binning over an older CCD with larger pixels? - Startools (and probably other tools) offers fractional binning, so I can bin to the exact level needed, even adapting to seeing if needed If the guide is primarily telling people what camera to buy/use - it's important to know if a newer, efficient CMOS camera with small pixels + binning is going to outperform a choice that has the optimal native pixel size.

Afraid not. I do know that RVO offer this service, but I was a bit too far from them to have them take a look.