MercianDabbler

It's worth stretching the contrast of some of your individual exposures to figure out where the issue is coming from - lights, darks, flats etc. Most 'regular' image manipulation tools will do it but best to use one that will work on raw files. Darktable for example will let you do non destructive editing on your individual raws... or perhaps use the Canon raw editing software. If you use Darktable then you will probably need to clone whichever stretching module that you use (levels, curves etc), maybe using 2 or 3 copies to achieve enough stretch. Having done one file you can then copy/paste the edits (aka 'history stack') to other images to apply the exact same changes.

Thanks all. I think the main message is to stick to one brand or else check carefully that clamp A will fit dovetail B. I don't have a big problem with mixed brands - everything I have is either ADM or home made. Just a pity that I did not realise that there was variation in the angle before I cut metal... but it still works.

One would hope that Vixen is the standard... but I think everything I have found so far has been for 'Vixen style' dovetails from other manufacturers. I hadn't realised there were so many variations. Having some narrower seems particularly problematic.

Thanks. Kinda comforting to know that it's not just me then. I think this was the page that I was using as my original source - it does seem to have been measured by someone who recognises the difficulty of measuring a dovetail so hopefully they did it right. I also just found a drawing of the Stella Mira bar on the FLO site. That drawing gives an angle of 76 degrees. I think ADM are probably consistent between their bars and clamps and between clamps bought on different occasions... so it's puzzling that their web site says 75 degrees. Oh well.

Online sources (including ADM) give 75 degrees as the angle of the Vixen style mini dovetail. I milled my own with a 75 degree angle and it doesn't quite match. I've checked mine and I'm as sure as I can be that I hit the angle correctly. Measuring an actual piece of ADM dovetail and doing some trig I got an answer of 77 degrees... which would explain why my ADM clamps grip the fat side of the dovetail and have a small gap where the clamp jaw ends. The clamps grip OK and I doubt I will do anything about it now because my putting metal back on cutter seems to have gone astray... but thought I'd ask. It would be interesting to know how a proper Vixen one measures up too.

Did that... Checking the settings I didn't find anything that was obviously losing colour info. I exported the image with the adjustments embedded (i.e. not applied). I then applied the history stack from the previous image in Darktable. I had to alter the stretching because the TIFF was not stretched by DSS. This produced a similar result but with an obvious yellow cast. I then tried a different debayer algorithm - superpixel. This reduced the image size because the debayering combines multiple pixels into one. The result of this is below. There is definitely colour in it but it's mostly either an overall cast or else noise. The star diffraction patterns also seem to look oddly banded at some degrees of zoom. I don't think it is an improvement. I still think that the lack of colour in the earlier stack happens because of the short exposure time rather than being something wrong in DSS. I think DSS is applying a colour balance on output with adjustments applied because the histogram shown by DSS has the red peak shifted to the right. With the adjustments embedded there is no colour manipulation by DSS and the differing position of the histogram peaks shows through as a colour cast. Whether the colour adjustment done by DSS is a good thing or not... I am undecided. I shall revisit NGC 7000 when another opportunity arises and hopefully get a good deal more data. Before that I plan to do some more tests with the Sonnar lens to see how the star diffraction patterns change with aperture - it shouldn't need a major stacking exercise to figure that out.

Thanks. My astro focus is in about the same place as yours. Better to have it slightly short of the stop than slightly beyond it I suppose. I have some more checking to do and I really need to practice again with my tablet controlling the camera over WiFi, I have had it working indoors in daylight but so far have not had it connected out in the dark. No particular issues but it's always easier to stick to what I've done before when I'm at the scope. I'm usually somewhat dubious about the value of the various calibration frames but that may be because I rarely end up with as much exposure time as other folks. TBH the darks are not too much of a pain to get - I usually take them while I am packing up so I usually do them 'just in case'. After this photo I have now seen the value of flat frames. I'll have another play with DSS. It does have multiple debayering options and I have messed with it in the past but I think it is currently set to something 'sane'. ... but mainly I need to reduce the amount of hardware needed to get the camera to track. In the short term sorting out the mounting direct to the SP102 should be very little effort but I think it would be even better to attach the ST80 direct to the SP mount so that I can avoid carting the SP102 in and out if I am doing wide field AP. The ST80 is a better 'finder' than the 102.

Thanks. Lens aperture ring was on f5.6... Conveniently positioned at the bottom when mounted on my camera I guess that's a problem with non bayonet mount lenses.

I picked up this lens for not much money a couple of weeks ago and last night was just about good enough to tempt me out to try it out on my EOS 70D. The camera was piggybacked on my SP102 so that I could use the SP mount and drive for tracking. Actually my ST80 was also piggybacked because that has the camera mount. Rather cumbersome (and now on the 'to do' list for improvement) but it worked. I was out for a couple of hours but clarity aroud Cygnus was in very short supply. Only Jupiter and Saturn were clear for the first hour or so. In the end I got just 6 and a half minutes of usable light frames - selected manually by losing the cloud affected frames from a bigger set. All were 10s exposure at ISO3200 with the lens set to f5.6. Focussing was done using live view (with 10x magnification) using Jupiter as the target. The 39 light frames were stacked in DSS along with 14 darks, 26 flats and 11 dark flats. The 32 bit TIFF was then edited in Darktable. It's the first time I've tried Darktable for AP (it is not an AP tool) but I use it a lot for more 'grounded' images and love the non destructive nature of the editing. Changes were confined to stretching the contrast, cropping (down to a little under 50% of the original frame) plus the haze removal and local contrast modules. I initially stacked without any flats but there was a big splodge of dust which turned the 'Yucatan Peninsula' into a black patch so this evening I got the camera out again (I had not touched the lens) and took some flats. The flats seem to have fixed this but I suspect there will still be some loss in that area. So what do I think? Firstly I'm impressed by the overall sharpness of the image for such a small financial outlay on the glass. There is pretty much no colour in the image (not quite none but almost). I think this is down to the lack of exposure time. Hazy sky glow probably didn't help either. There was so much 'stuff' in the frame and the camera was at an odd angle (the scope was almost vertical) so it took me over an hour to find my bearings around the image. I was even doubting that the bright star was Deneb for a while, even though I knew where the camera was pointing. The diffraction spikes around Deneb are pretty spectacular. For the less bright stars I dont find them too unattractive. I'm not sure if using wider or narrower apertures would help to tone these down in future?

I'll tag these words onto the end of this thread because at the moment they are looking like an isolated spell of clear skies. Clear Outside was looking decidedly amber but the skies were pretty clear before dark and the clarity continued after the 10 O'clock News so I headed out. First target was M23 on which I'd not been successful last time. I sturggled a bit more to find my bearings initially but eventually managed to identify the top two stars of the teapot handle and hop upwards from there. I managed to lose my way at the first attempt and had to go back to the beginning but finally managed to alight at the crescent of stars just west of M23. The Meade S4000 26mm was showing just one star in the right place (which I had seen last time too) with a suspicion of a smudge but I was not convinced. I scanned around the surrounding stars to confirm that I really was in the correct spot and then upped the magnification. The 15mm SLV and 9mm DeLite both showed the smudge with some averted vision so I was finally happy that this was indeed M23 but it was hardly an easy spot. Next target was M26 in Scutum. For this I scanned back across to the Small Sagittarius Star Cloud and M25 and then up to find the west edge of Scutum. I moved up the west edge to alpha and then east to find the stars near M26. Finding the spot went quite smootly but again it took me a while and a few eyepiece changes to convince myself that I had picked up the cluster. Now I decided to shift the scope and explore some different parts of the sky. I dont have a record of having seen M103 in Casseopeia so I gave that one a go. It was very refreshing to be looking at a higher altitude and having no difficulty seeing stars by naked eye or navigating my way around. Finding the spot for M103 was no problem at all and I couls see several stars in the area but I gather they are foreground stars and not part of the cluster. I think another visit will be needed. I'd also promised myself a visit to M81 and M82 having not been there for some time. They are an easy enough hop from Dubhe but are in the worst part of the sky for light pollution for me. The sky was also starting to brighten as the Moon was coming into play. I eventually picked up M81 but it was a pretty indistinct view and I managed to suspect M82 so eventually decided to move on. I keep trying to split Epsilon Lyrae with the ST80 so I had another try. It was a pretty folorn hope. I'm not sure whether the sky conditions were good or bad but the main challenge was the altitude and with either a 9mm or 6mm eyepiece I could not keep things steady enough to reliably get focus. I decided to finish off with M57. I put the 26mm eyepiece back on, got the bottom end of Lyra into view and M57 was easily visible... but only if you knew which spot it was. The 9mm DeLite showed it better but again stability was a problem so I plugged in the 15mm SLV which was a better compromise between being able to see that it wasn't a point source and having a view that would actually sit still for long enough. By now it was getting near to 00:30 and the Moon was now peeping over the nearby houses and the sky was very much washed out. I did not need the head torch while packing up. Having locked up I looked out of the window before turning in and saw a big sheet of cloud advancing across the whole sky and just about to cover the Moon so I think that packing up was the right move.

Nice report, good to see you braving the haze. It's hard to know how much it will affect things but it seems that it's not a total write-off.

I went out again last night with the ST80 just before midnight. It was still very hazy. A passing plane part way through the session confirmed this, its lights making a visible beam through the sky ahead of it. It was also very warm - I'd donned long trousers and long sleeves to try to protect against the insects which I could hear whining around me from time to time. It's an odd experience to be out with the scope and feeling too hot. The only comfort was that I knew I would be even hotter if I was indoors. Once again I could make out very little by eye anywhere near the horizon so it was a matter of figuring out where I was by comparing with Stellarium. From memory (and a local tree) I managed to find myself in the handle of the teapot straight away. I'd hoped to have a crack at M54 but it was in the said local tree. I had another attempt at it later in the evening but the haze was too overpowering at this low altitude. Next on the list was M25, stopping by M22 on the way up. M25 was straightforward enough to find but it still took a bit of peering before I was confident that I was seeing anything like a cluster in the relevant spot. Trying to fill a gap from the target list from previous nights, I tried M23 next. I can't record this one as a success in spite of being sure that I was seeing the nearby open ended loop of stars. Looking at Stellarium now it seems pretty spread out so that in combination with the haze would probably explain why I could not pick it up. My next move was to pan further to the right and head over to Ophiucus. The initial objective was simply not to lose track of where I was. NGC6536 was pretty much at the same altitude so that became my first target. I found the spot but could not see the cluster. Nearby M9 is listed as even fainter so was rejected as a target and instead I decided to aim for M10 and M12. I panned over and slightly upwards by guesstimation to reach Saik. From there to M12 the stars are not very distinctive but it's not far off a vertical pan so that's what I tried. I got distracted by a satellite that appeared on Stellarium and then in the eyepiece so slightly lost my way in the star field. Trying to find my position again I spotted a rectangular pattern of 5 stars that looked like the '6' on a dice with one middle spot missing. Only four of the five were shown by Stellarium on the tablet but it was clear enough to see that I was close to the cluster. Following one diagonal of the rectangle brought me to the cluster which was visible in the 26mm eyepiece and also in the 15mm and 9mm ones. From there it was a straightforward hop to M10 which again was an easy enough spot. I rounded the evening off by shifting the scope closer to the house and enjoying some nice views of Jupiter and Saturn. I was back indoors by 1:30. Sure enough it was hotter!

Good luck with it. The Eagle and Swan are higher than the others so should be a good bet. The Lagoon was also pretty clear when I looked. I do think there is an extra attraction for objects that only pop up over the horizon for a few months, particularly Sagittarius... and I also got quite a kick out of finding M104 from my garden earlier in the year. In the past my efforts in Sagittarius have been confined to trying to take a nice Milky Way photo but that involves making a trip to somewhere where the landscape to the south will make a nice picture. Lockdown has forced me to re-acquaint myself with the possibilities of my own garden and that has been a good thing. Sagittarius from the garden is something I have not tried before. My 'window' to the south is quite restricted and the foreground would certainly not make for a good landscape photo. It is also limited time-wise for any given object so I won't be making any 6 hour exposures in that direction but it is better than nothing. Using a lightweight setup also helps both with finding the best 'angle' and also allowing me to set up and pack away quickly when time is short or conditions are changeable.

Thanks. Looks somewhat similar to what I saw. I will give search strategy a try in future. Cloudy here. Still... I could use some sleep. Cheers, I will check those out.

Thanks. It wasn't just me then. I'm never very sure whether my assessment of conditions (good or bad) are accurate or whether it is just me trying to find excuses. Thanks, I completely agree. That is one of the good things about this part of the forum. It's good to know the boundaries of what might be doable with a given setup and find out from others what is easy and what is not. I also regularly use it to steal ideas for my next target list. One thing that I would like to find is a set of images of DSOs that show what they look like visually through a small scope... knowing how Hubble sees them is very interesting but does not always help with nailing the identification.

Clear Outside was showing green last night and the moon set around midnight so I decided to head out again with the ST80. My initial impression when I saw the glow in the sky was that it was cloudy but looking at the sky there were no clouds so I pressed on. Once again it was a matter of pointing in the general direction of Sagittarius and then trying to figure out what I was looking at, helped somewhat by it being fresh in my mind from the previous night. I'd written a longer list of targets beforehand, partly helped by the post by @SuburbanMak . The first target was M28 starting from Al Thalimain. I think I had spotted this the previous night but had not noted it. On the second attempt I really struggled to find it with the 26mm eyepiece, I think because of the glow. Plugging in the 15mm SLV and 9mm DeLite I was eventually convinced that I'd seen it but it took some time. My main targets were the Eagle (M16) and Swan/Omega (M17) Nebulas. After the difficulty of finding M28 I was not optimistic but I pressed on and found Polis and then M24 where I'd been the previous night. From there it was straightforward to hop upwards to the location of M17. I suspected a smudge so decided to try the UHC filter. I was quite impressed on this occasion by how much clearer it made the nebula. It still wasnt stunning but at least there was no doubt that I was seeing it. I upped the magnification by using the 15mm SLV and 9mm DeLite, swapping the filter each time. Not wanting to faff further with the filter I then tried to hop up to M16 with the 9mm DeLite fitted. I locked the azimuth on the tripod almost directly upwards and found the Eagle nebula easily. I finished of by removing the filter and looking for the nearby NGC 6604 and NGC 6605. I certainly found the locations of both but I'd need to recheck what they are supposed to look like and how big they are - neither location looked particularly distinctive to me. The sky was still looking very hazy and I still could not reliably make out the main stars of Sagittarius so I decided to pack up by around 00:35 rather than pressing on with more targets. While carrying the gear back to the house I was rewarded with the sight of a bright meteor arcing across the sky. It seemed to come from the general direction of Casseopeia. Jupiter was also hanging in the sky so I couldn't resist a quick look at it and Saturn with the 10x50s before locking up and heading for bed.

I took the precaution of donning a pair of long cotton trousers and a long sleeved shirt to avoid putting myself on the menu. Glad you had a good night too.

I've been keeping an eye on the weather over the new moon period hoping to point the scope at Sagittarius but it's been pretty much wall to wall cloud... until last night. I had a wander around the garden about 10:30PM to scout for a good spot. A couple of spots that I'd used earlier in the year are now more obscured by foliage or in one case by some squash plants that have spread a couple of yards into the surrounding grass. One previous spot also now seems to be in direct line of sight of a street lamp, presumably because some neighbouring trees have been cut. Eventually I found a small patch of grass at the very end of the garden which offered a view to the south which was relatively free of trees and houses. It's definitely a grab and go spot - I dont think there would be enough space there for the big tripod and me. I dug out the ST80 and went out just after 11:30PM. The sky was still visibly bright but Antares was visible but very flickery. I could not see the main stars of Sagittarius by naked eye so it was largely a matter of fitting a longish eypiece (I went for the 26mm Meade S4000 because I like it), pointing the scope in the general direction, and trying to figure things out by comparing with Stellarium on the tablet. Not ideal but I quickly happened on an area busy with stars. A hint of nebulosity was visible in spite of the lack of proper darkness. Checking Stellarium showed this to be the Lagoon Nebula (M8). The 15mm SLV and 9mm DeLite both provided good views. I also had a try with a UHC filter on the 26mm and this also made a nice view but in general I'm still not a huge fan of the filtered view. An short move upwards from the Lagoon Nebula took me to the stars in the Trifid Nebula (M20). I can't honestly say that I could see any nebulosity there. Stellarium showed a couple of globulars nearby - NGC 6544 and 6533. I thought the second might be within reach. Finding the spot was easy enough but I could not see the cluster. Looking again now I think I may have misread the magnitude as 6.3 instead of 8.3. By now I could just about make out some of the main stars of the 'teapot' but it was not high enough to discern the full shape or figure out which star was which. I pointed the ST80 at one and figured out that it was Nunki. From there I hopped to Namalsadirah and then over to Al Thalimain at the top of the 'lid'. From here it was easy to find M22 with the nearby tight grouping of 4 stars including 24 Sgr helping with the identification. The next move was up to Polis ... more by trial and error rather than hopping because the stars in between are pretty dim. From here it was easy to get to the Small Sagittarius Star Cloud (M24). I packed up just after 12:30 so only an hour of observing time and I probably missed a bunch of good stuff but most enjoyable to be out again.

Proper job! I bought mine new (BC&F in Farringdon... 2 Nov 1991 I think) on the basis that it looked like a proper telescope. It still does. A terrible way to choose a telescope but it worked for me.

Mostly overcast here but with occasional breaks in the cloud. I set the ST80 up on the tripod ready for the event along with its no-expense-spared Napolina Pizza box shade (not new I hasten to add - reused from a previous projection occasion). I left the patio doors open and nipped out whenever it looked like there were some visible shadows. I haven't tried projecting with the ST80 before and found that the focuser tube isn't long enough to get focus with 'straight through' projection so I had to put the diagonal on and project sideways - not ideal but it worked. The SP102 has no such issue but is more hassle to drag out. I must figure out some sort of focusser extension for future occasions. This photo was about 5 minutes before the max. I could have used a cleaner piece of paper but now you can have some extra fun and work out which recycled target list I was projecting onto

I just pop the 32mm TeleVue or 26mm Meade S4000 onto the scope, point at a naked eye star and go from there. I've never found the bundled finders much use. I could buy a better finder but the ST80 seems to do just fine as its own finder. When the SP102 comes out to play the ST80 gets piggybacked as a finder for that too, usually with the 26mm EP. I also use the Rigel finder on the SP102 for initial pointing but have never really felt a need for it when using the ST80 on its own. I don't find myself liking the view through my (Jenoptem) 10x50s much. I'm not sure they are in great shape but having googled the subject... they seem a bit non straightforward to mess with.

Last night was forecast clear and warm with the moon not rising until about 1AM so I decided to head out with the ST80 and see what could be seen despite the lack of proper darkness. There was plenty of time beforehand to have a poke around on Stellarium and see what likely targets presented themselves, concentrating on globulars again since they seemed to work out OK last time. I wasnt particularly methodical, just scannning around the south and east aspects to see what caught my eye. The list started M10, M12, M71 then C6 and M4. There were more but that's as much as I got through with the scope. I headed out a little before 11PM and it definitely wasn't properly dark but it's still interesting to see how much more the scope reveals. Vega was pretty obvious so I went there first to get focus and also visited the double double again with various eyepieces and even less success at splitting either pair than last time. For M10 and M12 I decided that I could just about see Rasalhague so started there. It was a fairly lengthy star hop along the top of Ophiucus and M12 was on the way so I did M12 first. I found the spot without too much difficulty but I can't say that I was conviced that I could see it through the 32mm TeleVue Plossl. The 15mm SLV and 9mm DeLite both showed it but it needed a bit of AV and scope wobbling to really spot it. A short hop from there to M10 which was much easier to spot. For M71 I started from Altair and hopped over to Sagitta. To cut a long story short... I could not see it through any eyepiece. After spending a good deal of time on M71 I moved on to C6. I've not tried any Caldwell objects before and the ST80 was probably not at the forefront of Patrick Moore's thinking but anyway... It was a bit of a stretch to reach it because it was pretty near the zenith but I extended the extra column on the tripod to achieve a not completely unbearable eyepiece position when sitting in a chair. I started from Rastaban and Eltanin. Again it was a none too short star hop with some fairly thin start fields in places but I got to the right spot. Could I see C6? I could see something in the right place and the tablet version of Stellarium didn't show anything else there but checking again today on the PC I think it was more likely a faint star. Maybe it's possible or maybe it isn't but I'd certainly need to do a bit more homework to be sure if I was seeing it or not. By now it was past midnight and Antares was visible above the neighbouring gardens to the south which has been quite a productive spot for me but I need to be quick because there are plenty of nearby trees for things to disappear behind. I had to reconfigure the tripod to its full height to see over the vegetation. Antares was still very low and very twinkly in the ST80. The correct spot for M4 was not at all hard to find but I could not see anything there - I think it was just too low and that part of the sky was not dark enough. I even tried the 10x50s but no joy. Stellarium showed that I wasn't far from M80 so I hopped up to that and spotted it without much difficulty. I spent a bit more time just sweeping around that part of the sky and then decided to look for Sagittarius which was just peeping into view on Stellarium. At the moment that part of the sky is behind the houses in the street behind us so not well positioned. It will be better positioned for me in a month or two... shame about the lack of darkness. I retired to bed at about 1AM. All in all well worth heading out even without any astro darkness. The ability to observe without first donning 15 layers of clothing on was also a big bonus.

I must take a closer look using the SP102 but the lack of darkness and plentiful clouds at the moment mean that it's grab and go or not at all.

It's been weeks since I've been out with the scope. I'm pleased to see that some folks managed to get some time during the waning moon a couple of weeks ago but every favourable forecast for me turned into a cloudy night. Last night there was a green hour showing on Clear Outside. It was forecast for 9-10PM and not dark enough but it did at least encourage me to keep an eye on the clouds. The sky was about 50% clear at 10:30 when I was doing a few chores so I rounded up the ST80, tripod, eyepieces and other bits ready to go out. Naturally as soon as I was ready the cloud cover was 100% so I decided to watch a YouTube 'how to' for 30 mins and take another look. Once that was finished there seemed to be enough clear sky to be worth a try so I headed out. My list of targets was pretty straightforward, being globular clusters around Hercules and Bootes. The first quarter moon combined with some wispy misty cloud at high altitude was washing the sky out somewhat so I could not make out the shape of Hercules reliably. I decided to start with M13, star hopping from Vega... which I could definitely see reliably. Not a short star hop and I was a bit rusty having not been out for a while but I managed to get M13 into view with the 26mm Meade S4000. The 15mm SLV and 9mm DeLite both provided more magnification. Next up was M3, starting from Arcturus. I repositioned the scope to access this area of sky. While doing so I was completely gobsmacked by what I saw (and not in a good way) - a stream of Starlink satellites making an ugly slash across the sky below Bootes. Pretty soon after this had faded, the ISS trundled across the sky looking very bright indeed. I had a quick look at the ISS through the ST90 but could only see a very bright blob. Once that was gone I headed back to Arcturus and took in M3 and then M5. M5 turned out to be down in a tree. Fortunately with the grab and go setup I could reposition the scope without losing my place too badly. The final target on my list was M92. By now the sky was a bit less washed out and I could use Arcturus and Alphecca to identify zeta Herculii with the naked eye and hop from there... revisiting M13 on the way (I can't say my planning was very efficient). All of the GCs were reasonably straightforward to find despite the washed out skies, either with the 26mm S4000 or 32mm TeleVue Plossl on the ST80. None showed any detail with extra magnification. As I'd started the session at Vega I decided to finish off with M57. This was tricky to spot with any confidence in the 32mm Plossl but easier in the 15mm SLV and 9mm DeLite. I tried the 6mm BST Starguider too but I don't think it added much. I could not do more than suspect the hole in the middle with any eyepiece and the ST80. I didn't quite finish there. Finally I popped over to the double double to see how the ST80 performed on this. The best I could do was a sort of sausage shape on one pair through the 6mm Starguider. I packed up around 01:25. All in all a short but enjoyable session and plenty more clouds forecast to allow me to make up for any loss of sleep.

Nice report. Looks like you had some good results there. Glad you found my efforts to be of some use