bomberbaz

Apart from the big star bottom right which looks like it's in the middle of an Einstein's cross 😃. Need to remember how to create a star mask now, lol.

You prompted me to have another look at PyAstro tools for gimp, took a while to get my install right but now I have and so I had a play with this mornings image using them. I used it to round the stars, add a little colour and smooth the image out in general. Top one before. New effort below using the tools.. It definitely a little tidier and that's without really learning it properly. Certainly the star rounder could come in handy down the line.

That gives us 2 pixels at 7.5/(15x0.9) = 0.555 or 555 milliseconds, even lower than mine, extraordinary. Although remember this is for calibration only and only done at the start of your session. Assuming you redo it at the start of every session, something a few videos I have watched seem to say should be done every time.

you need your guide scope and guide cam pixel scale lee, half your problem right there, haha 😄

I have been having a few problems with my tracking, I think I am getting the hang of things a bit better but trying to get to the bottom of some figures is a little confusing at times. These figures being the amount of time for calibration steps in the mount. Before I drone on I found an article that covered it quite well: Remember that the "Calibration steps" is in terms of the duration (milliseconds) of a calibration pulse at the Guide Rate. So, the same Calibration steps duration will move the mount by twice as much (in terms of arc seconds in the sky) if you use a Guide rate of 1x sidereal instead of 0.5x sidereal rate, for example. 1x sidereal rate moves at 15 arc-seconds per 1000 milliseconds of time. At 0.5x guide rate, the mount will move by 37.5 arc-seconds in 5000 milliseconds. You want each calibration pulse to move a star by about 2 pixels on your sensor. PHD2 will try to move the star by 25 pixels during calibration; so the 2 pixels per calibration pulse will finish calibration in 12 or 13 steps. You can use this tool to determine the pixel scale (arc-seconds per pixel) for your guide scope: https://astronomy.tools/calculators/field_of_view/ Select Imaging Mode, and select any Messier object (M1 will do; the tool won't produce a result unless you have chosen an object first). Enter the focal length of your guide scope and the guide camera that you use. Then look at the result for the "Resolution". It will be in arc-seconds per pixel. From what I mentioned earlier, you want to scope to move about 2 pixels per calibration pulse. The plate scale will convert that to arc-seconds per calibration pulse. For example, if the plate scale is 6" per pixel, and you want 2 pixels, then you want to move 12 arc-seconds per pulse. If you use 0.5x sidereal rate as the guide rate, this 12 arc-seconds corresponds to 12/(15*0.5) = 1.6 seconds. So,for this example, you will want to use a Calibration Pulse of 1600 milliseconds. Ok so I had to read it a couple of times before I got my head around it but here is my equation: Guide scope / camera combo gives Pixel arc second 6.45, sidereal rate being used 0.75 so it's 12.9/(15x0.75) = 1.146 or 1146 milliseconds. Yet there are some articles giving what appears to be a rule of thumb type guide for a 30MM F4 guide of 8000-10000 Have I missed something here as my calc is either rather low or the rule rule of thumb guide seems amazingly high. (FWIW I prefer the scientific method)

What app did you use for removal of halo's please Lee?

My efforts, only 27 minutes of data before i got too tired and fed up of cloud causing issues. There is a bit of star trail I know, I will go through the subs again and try to remove the culprit(s) then stack again but just sticking this up as a foretaste. Much more data needed to get a decent image but it's a start. On the blown out image I have placed a small arrow on to show IC1296, a 15th magnitude galaxy, pretty amazing from 27 minutes. The tracking issue was the RA & DEC Aggr settings in tracking in the ASI Air app, they were set to 100%, once I dropped them it started tracking again. I found the best to be 35% for both and was tracking at about 1.5, sometimes less. Happy enough with that but I know there is some fine tuning to do on my guiding (exp, possibly focus, exp time and so on)

In colne, do you ever do visual or you strictly imaging?

I questioned Sw as the blurb on FLO website isn't clear, so I put chinese with a question mark. I also caveated my post with a statement in that it is only an opinion. I have owned and still do SW scopes. The gear is decent but the current 200p needs bringing up to speed IMHO. A statement which was echo'd by at least one other in this thread.

Finally watched this, very interesting stuff and I get more now the rationale behind flat darks. think I will make a similar flat panel to @AstroNebulee has below and then I can set my flats/flat darks to always run at a set level, makes sense. Thanks Gentlemen.

A guide scope cozy and two focus masks. Both very practical and also themed to the setup. Made from 2 sheets of 2mm playfoam, uhu glue and some mesh I had knocking around. These mesh focus mask are easily as good as a bahtinov mask but cost pennies. The guide sock fits the 30mm guide full length with I have a 20mm overhang

Bit of a different animal the Starsense 8", not really apples to apples comparing with the others but it looks a nice idea. I will read it up a little later. Celestron StarSense Explorer 8” Dobsonian | First Light Optics

Some love gone into that, nice looking piece of work.

See below I think @johninderby encapsulates what I was referring too, it's not that they are bad, just that others in the market have overtaken them and of course this is "IMHO". So if someone came onto the forum asking for advice on a DOB in the range of the 8", I would be considering all options before I put my two penneth forward, but SW need to up their game or risk not being in the short list of myself and possibly of others. I stick with my opinion that StellaLyra currently lead the way, but only just.

I suppose you make a call on where to balance it based upon your eyepiece weight, focuser etc then use a small adjustable weight as aluded to earlier. It's all personal taste in the end.

Ah yes a definite improvement there John. ......................... I was giving things a little more thought after my last post and came up with some interesting pioints. I used to have an Orion xti 10" and this had a single compression type Alt fixing similar to the stellalyra however there was just the one. This made it a little sticky with tendencies to be jerky but in fairness when I slapped on the Nikon 17mm and 2x powermate it was heavily loaded with glass (2lb 6oz). Also it was not very well balanced which didn't do it any favours either. The SLyra has clamps on either side so may be a little more forgiving. A simple magnetic strip mod at the bottom of the dob tube with a metaliic weight to slide up and down is far easier to adjust. (Here I am, don't even own one and already modding it 😅) Seems no one of the above is perfect out of the box given this. However good to hear you are still happy even with the Bresser even with the above points. Would be interesting to hear if @cajen2 has any input regarding the StellaLyra 8", particularly on the Alt bearing. Steve

Yes never noticed the 6 point mirror fixing to be honest John, another plus point to be sure. I also though did fail to point out the stellalyra roller bearing in the dob base. I know what the SW Alt bearings look like, I would like to see up close the stellalyra bearing. The Bresser and Ursa Major bearings are on full display but you only have a description for the SLyra. I didn't know about the replacement shoe for the Bresser, much better to have a standard type. Add a RACI and Telrad and away you go. I hate those Bresser shoe fixings that come attached. I think with hindsight I would have to see both the Bresser and StellaLyra side by side to make a final decision if I were buying. I think the Alt bearing would be the deciding factor.

What specs is it sporting out of interest?

wow, thats "BIG" whatever it is. What do we have there and is that mount a goto, looks it?

seems my optimism was misguided, the clouds arrived suddenly and quickly, whiteout now. Incidentally, whereabouts you at then?

snap

So I had some spare time and decided to do a basic side by side of 8 inch dobs currently available from FLO (Other dobs are available elsewhere). The information is as given from the website so anyone with more accurate info on stats etc, fire away. The (subjective) results which form my opinion are given below. The Bresser has a lot going for it, I really like that big Alt bearing, the upgradeable focuser a nice touch (pity it's not std) and the glass seems decent quality. If your a W/L solar fan then that is also a worthwhile extra. What I am not so keen on is the adjustable tube ring design, over complicates a beginners scope whilst adding to the price I would guess, might have been better spent on the focuser. I hate those finders, they are cheap and yuk. But that's only my opinion! (prepare for repeats of the last phrase) Skywatcher need to, in my opinion up their game. Firstly I think I was generous giving them 4 from 5. The focuser is pretty basic at best, finder the same, couldn't find detailed spec for glass, weight etc and, wellll they are just falling way behind even at the lowish cost. Note lowish, better options imho are available at a lower price. StellaLyra is the pick of the bunch in my opinion (told you it would be repeated). Just great all round, excellent glass, cooling, dual speed focuser with compression fittings and a base fan. To top it off they have thrown it a very useable 2" 30mm eyepiece. A first time buyer could do a whole lot worse than stump up the cash on this package. Ursa Major are new to me, until recently they were just a bunch of stars but this is the surprise package. Good glass again, only basic finder and single speed focuser although the latter looks a nice piece of kit, better than dare i say the SW? Nice they have added the base fan, would again have preferred a dual speed focuser over that but hey, the cheapest in price of the lot and if on a tight budget, easily the pick of the bunch. (IMHO) So who is the winner? (kop out statement) it's the consumer because competition in a tight market can only be to the benefit we would hope of the end user. Feel free to correct me and/or add your own thoughts. Steve

Looking clear here guys, hopefully going to get a few subs of M13 with new OTA on mount, tracking will be restored and can compare my M13 result with the old 50mm OTA results.

Sorted 0one of these for the main OTA, thanks. Good idea Mike, I actually have a sheet of kits playfoam, very malleable. I will make a foam sock as it were out of it as a permanent sock 😄

Looking for other peoples solutions for dew control for their imaging rigs and suggestions for mine. First here are my scopes that need protecting, the rvo horizen 60ed (built on shield about same length as aperture) and astro essentials 30mm mini guide. Similar dew sheild to horizen. First question is will a simple extention to existing dew shield suffice on these modest apertures. I ask because that what I use for visual and I have never experienced any moisture issues when doing so. If not, I think I would be looking for a simple USB powered solution, much easier transportation and less clunky. I have numerous power banks too. I have looked on FLO but sadly they are without USB type tapes. TIA everyone Steve.