MalcolmP

Well done, you are telepathic (** see below) Yes alt-az do need to, and alt-az-goto (as per eg. the S50) do it to track the object gone to There was once upon a time on the web a well researched paper(pdf) plotting for many latitudes the acceptable(for defined limits) field rotation at all manner of pointings in the sky. (I can no longer find it on the web or the safe place I put it on my HD !!lol) The best being due east and due west where the az tracking is minimum and most of the motion required to keep track is vertical-ish such that 30sec exp were reasonable. For south at 45deg el I think was worst at 10sec or a bit less. Certainly the altaz of the S50 smart is keeping folks happy with 10sec for field rot. But having said all that I thank you for the Star Adventurer suggestion/options. I have often hovered my finger over offerings in the for sale section but never done the deed, always meaning to look up which model/pack/addons does what So I think from what you have listed a mini would be enough for me. Lots are posted on the forum about getting polar aligned accurately, but never anything about **^ needed accuracy, so that was going to be one of my future posts ^** especially as I cant see polaris from my fav spot in my garden. If plumbob and compass-line-on-ground was going to be good enough for my humble needs to get beyond 2 and 5sec that would be a good start. Re darks, I'll come back on that later [ if you are game for more (!!) ] suffice to say for now that I have been using lights and just a hundred bias in a master bias.

I agree, no contest, hardly an effort IF that is required to keep the forum safe

I am wild because (maurice) I remember eet well (chevalier) it has taken 'us' this long to get back on the job. And at this rate I probably wont live to see people back on it let alone get there myself !! I 'liked' your post then changed it to a 'smile' (we cant do both |??) thinking that conspiracies are better played out by something going wrong, like falling over. Whereas 50y ago nothing ,,, oh hang on ,,, one guy did actually fall over on the moon 50y ago. Now what was his name ummm google >>

Because you specify "generally" "rule" etc I would answer Yes ! One particular case springs to mind : if you are checking out a variable star (photometry) then data will be lost if the star is overexposed in any of the sequence. Sometimes special measures can be put in place to partially recover the situation, never-the-less it is not ideal, stricto sensu, information has been lost. Usually eg. stacking for pretty and/or special effect pictures, it is not a worry. So another answer would have been "it depends"

If it was a (well known) part of the original (or time of signing up) T&C then yes fair doos.

Yes, it threw me to begin with "how on earth did he-she appear to do required astro posts yet still make obvious non-astro blunders in the ads. " until I re-read Grant's orig. In this case it was a lapsed user , but was that an essential part of the hack, or could the nerd have hacked any account.?

also saves having to argue with ones speelchucker,, optional ' not included

Unless I am horribly confused, I dont think that would have helped in this as it was a case of a hacked account. Ie a genuine account with valid astro posts but it got hijacked by a nerdowell ? EDIT a few moments later ,, from Grant's post QUOTE "we have banned a potential scammer using an old, unused members account to post potentially fake adverts"

Just thinking aloud and because I feel like explaining, some may be wondering, why I raised my 2 original questions : There was recently elsewhere a very long post about the effects of various noise sources on the quality (ie.SNR) of an image obtained with many stacked subs. Also posts raising the question of total integration time, you know " are a few long subs better than lots of short subs " are very common and often end up very long with much theory ! In my case I am well aware that the more subs the better, regardless of their individual length without worrying too much about the contribution of read noise (rn), (one does with what one has to and soldiers on) but realising that it was probably significant in my case of very short subs (2sec and 5 sec) and that I should probably take steps to mitigate that, like an az goto or a full eq setup. However I do like to be able to 'do astro' quickly between clouds or worse ! So to be able to plonk a camera on a tripod and capture a passing supernova in galaxy far far away while also preparing roast ducks and entertaining guests at the same time was very satisfying https://stargazerslounge.com/topic/419292-caught-another-sn-with-my-simple-dslrlens-fixed-on-a-tripod/ Knowing that recent DSLRs are reported to be very noise free and not needing darks to be used, (allegedly ! which also often generates long topics ), yes, I know, that is not related to rn but hear me onwards , , and because in that topic I refed above there was mentioned millisecond exposures, I got to wondering if read noise was now also less of a problem for exposures of many seconds than had previously been thought, you see. So, I decided steps to find out my practical individual noise levels might be interesting to do ! Hence the op. It is (has turned out to be) quite an involved process and I may throw up my hands in horror and wait till I obtain a new computer with which to run SharpCap and give up on this quaint Victorian notion of educating myself There is an alternative :- I could use 'her' computer, but you know - - - "It was ok until you did ,,, " Ok, we can all go back to sleep now thanks for reading.

Thanks, yes already checked them out, NINA only supports win10&11. APT does run and may be useful in the future after I buy a bigger monitor to read its screen ! Meanwhile I have found a YTube vid describing a method to measure rn with Siril which also runs on my win7. So I'll go play with that for a while

Yes. But you may have missed, in my first post, why I wished to evaluate rn and lp :- "Up until now I have been entertaining myself ,,,using the 60d ,,, fixed on a tripod. ,,, but now I am wondering if I should progress to an alt-az goto for 10sec subs or to a polar aligned device for even longer subs?" So yes I would if I could but I cannot yet do as you suggest. Thus far I have determined that 2 and 5 sec exp at iso800 work best for me at 135 and 50mm fl without tracking &/or guiding.

Or even something similar to a 60d would be a ball-park for starters, Just an intervalometer (camera on a pan/tilt fixed on a tripod) followed by DeepSkyStacker and Gimp. Turns out Gimp can do something like that if I import the raw CR2 in 16bit, else it defaults to 8bit, thanks for the prompt.

Thanks Ah! good question, iso800, I should have included that. Also I should have said this was taken early evening 12 Feb, I have been playing with it in Gimp since then! Yes! But back in the day they cost a substantial fraction of a months wage OK on axis but some are quite peculiar round the edges. Thanks, ( I am practicing for when Beetlejuice pops LOL ) Soligor f2.8 135mm, from about 1967-8 I suppose that makes it more antique than vintage ?! > Goes off to google Askar FMA180 >>>

After my surprise find https://stargazerslounge.com/topic/418346-supernova-sn-2024gy-comet-62p-using-just-a-dslr-on-a-tripod/ with a 50mm lens this time I was better prepared with a 135mm vintage telephoto, so my stars were not as blobby in the big crop needed. This is SN2024any about m13.5 in NGC1222 650 x 2sec @ f2.8

Thanks Alan, I thought I was probably not near swamping the read noise with my skies, until Vlaiv mentioned millisecond exposures in a recent topic So I began to wonder since I had no feel for it. 20sqm is the best I have seen (in my rural back garden, nearest street light a few miles away) since I have had the capability of measuring it with ASTAP,, but not the best skies I have seen historically by MK1 eyeball. Sadly Sharpcap will not run on my old window7 machine it objects that I do not have a required instruction set in my cpu ! Lots of rainy day reading to be had in that link but I fear it has lost me already in the second post - I know not how to measure my median ADU though I understand it is common practice amongst real APers with dedicated cameras

Re-posted in the right ? forum ! Questions :- (1) How can I measure my read noise? * (2) Given a lp level **(of eg. 20mag/sqarcsec) how long does my sub exposure need to be for my rn to be 5x *** lower than the lp The rest is by way of chat and can be discarded ! Discussion! :- * I have googled and found generic specs in the region of 3e per somethingorother at iso800, but how typical is that of 'most' 60d ? ** lp is often given in terms of (not very useful bortle units or) SQM units of mag/arcsec^2 So how do we convert that to electrons in the sensor. I can measure lp SQM using ASTAP ***5x is often quoted to reduce read noise to insignificance when evaluating total integration times Why? :- Up until now I have been entertaining myself chasing supernovae and other dim objects like asteroids and variable stars using the 60d + 50 or 135mm lens fixed on a tripod. Several hundred subs have been interesting but now I am wondering if I should progress to an alt-az goto for 10sec subs or to a polar aligned device for even longer subs? Is 10sec going to be long enough to suppress read noise @ typically 20m/as^2 , maybe I am already suppressing read noise with 100 or 1000subs of 5sec or 2sec ? I have of course googled, but most of it rapidly goes over my head or is not relevant to a specific dslr Sorry for the long post, I blame too much thinking time on my hands waiting on the weather thanks for reading !

Or a modest lens and a big stack in DSS ! My limit at the mo is 13.5 going on 14, with a 135mm vintage lens so I was getting all excited until I saw the declination !

approx mag16, but sadly not from the UK ! Gaia cat DR3 4805630493655815040 RA 82.3159 Dec -43.8645, mag=BP16.91 RP15.69 my Cartes du Ciel is still on DR2 must update it soon

The more important time scale to consider is how many hundreds, or hundreds of thousands, of years are these clouds going to remain and if she does blow will it be visible through them ? >I'll get my coat >>

It is spring time, two filters go missing, no surprise there, wait a while and they will re-appear with lots of little ones - which you will need to re-home with your chums on SGL

For too long now the Metofice has been accurate Would I be a sucker to hope that they may continue to be right tonight into the wee small hours ? !

A member of this parish

Discovered 19Jan @m17.6 just now popped up at the top of the Rochester listing with a latest m12.7 report , , ,2024any.... another one that would be in range of my modest dslr+lens if it wasn't for these persistent clouds In Eridanus, nicely positioned for early evening obs. https://www.rochesterastronomy.org/snimages/index.html https://www.rochesterastronomy.org/sn2024/sn2024any.html

typo = awol decimal point "through all 3 filters, 25 hours each filter and 7.5 in total," should be 2.5 hours each then it all works out and 50x3 = 150 150/60=2.5h

Starting with when I ordered it the Metoffice has reported and is continuing like this for the next week at least. What I want to know is : how did the cloudgods know that a humble usb cable was going to be used for Astro? I blame them for dabbling in AI ??!