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Showing content with the highest reputation since 10/10/19 in all areas

  1. 19 points
    The middle of September brought with it many clear nights to Berkshire (as usual starting with the full moon) and during it I captured 3hrs per channel RGB, 19hrs Ha, 7.5hrs Oiii and 5hrs Sii (total 41 hrs) on the Elephants Trunk Nebula (quite a lot of whilst asleep). Equipment used was my Esprit 150/SX-46 with piggybacked Esprit100/ASI1600mm on a Mesu 200 all controlled through SGPro. Guiding was by OAG with dithering on the Esprit 150 every 3 or 2 frames depending on whether it was taking RGB (10min subs) or Ha (20 min subs). Exposures on the ASI1600 were 5mins and about 15% were lost to dithering and autofocus on the Esprit 150. Processing was done in Pixinsight and Photoshop with the StarNet star removal tool in Pixinsight used to remove the stars from the narrowband images. Starless and starry narrowband images for each filter were then blended in PS to produce images suitable for combining with the RGB as HaR_OiiiG_OiiiB or on their own as SHO. Ha was then used as luminance over both. StarNet was then applied to these images, PS heal brush used to remove artefacts, channels split and combined with lightly stretched and split RGB (Photoshop blend mode lighten) for tight stars. These new images were then blended with Ha as luminance and the non star removed HaLum_HaR_OiiiG_OiiiB and SHO for the final result. The Elephant's Trunk Nebula is a concentration of interstellar gas and dust within the much larger ionized gas region IC 1396 located in the constellation Cepheus about 2,400 light years away from Earth. Thanks for looking, c and c welcome Dave
  2. 18 points
    Surprisingly it stayed clear all night so I got almost 14 hours from my dual Esprit rig on this enigmatic planetary nebula. There was a full mon of course but I still took the chance of collecting some RGB with the Esprit 100 and ASI071. I only expected that I at best could use it for star colour but the data turned out to be virtually without gradients. It probably helped that the scope was pointing away from the moon. I also decided to go for rather short subs so I ended up waiting for my computer to stack 263 x 90s of RGB data. On the Esprit 150 the ASI 1600MM was collecting 2 hours of Ha (Baader 3.5 nm) and 5 hours of Oiii, (Baader 8.5 nm) yielding another 200 or so subs. I also shot some 10s and 30s subs to save the very bright core of this nebula - the actual eye. The result of shooting the sky with the Esprit 100 was a quite wide field with a rather small nebula, so I post it from wide to narrow here. Suggestions and comments most welcome! Cheers Göran
  3. 15 points
    The new Ikarus Imaging website is built and populated The paint is still a little wet in places but the products and brands from Ian King Imaging have been moved to the new website and the man himself is sat by his phone taking calls and responding to emails, just like always. Email. info@ikarusimaging.com Tel. 01392 791001‬ Why have we (Ian and I) done this? A few have asked us this question and a number of rumours are circulating so I want to take this opportunity to explain: Ian and I have known each other for over a decade. We have of course routinely discussed business and astro retail. In particular we recognised and understood the difference between our two companies, FLO and IKI, and the customers they serve. FLO focuses on a mix of products for astronomy (visual and imaging) and communicates via email and SGL. At Ian King Imaging, Ian focused exclusively on high-end equipment for astrophotography, communicated largely by phone and attended events. Over the years we, both of us, worked to maintain this difference. We believe doing so has contributed to our individual business success. FLO grew to become the UK's largest astronomy retailer and Ian King Imaging the most trusted source for high end equipment for astrophotography. Then, about three years ago, Ian mentioned how he missed being part of a team (prior to FLO & IKI he worked at Telescope House). Running a business single-handed is especially challenging. It can be a lonely experience! Needless to say I offered him a place at FLO whenever he wanted it. Earlier this year he accepted and we began making plans. The challenge, we agreed, was how to integrate Ian's business with FLO's without it adversely affecting the customers we individually serve. I was confident FLO's customers would welcome the change but was concerned some of Ian's might not. They might, I feared, think we would dilute Ian's high-end product range and make it difficult for them to speak with him via phone. After several conversations (always at Ian's favourite curry house!) we concluded we would build a new website (Ian King Imaging was due an update anyway) fill it with the same high-end astrophotography products and change as little as possible. So here we are... Like Ian King Imaging, Ikarus Imaging focuses entirely on astrophotography. It has a layout similar to FLO's because it is plugged into FLO's inventory system (FLO handles IT & logistics). Otherwise it is a standalone website managed by Ian King. From Ian and I, a huge thank-you to all the IKI customers who have already made the move to Ikarus Imaging and trusted us with their orders. Thank-you also to our manufacturers and suppliers who, without exception, welcomed this change and have worked with us to ensure continuity of supply. Best wishes, Annette, Grant, Ian, James, Katie, Lisa, Martin, Rob & Steve
  4. 10 points
    M27 - Dumbell Nebula in Vulpecula Here's an image I took back in 2013 using Ian King's remote telescope when it was located at 'Astrocamp' in Nerpio, Albacete, Spain. Telescope: Ikharus 10" R/C @ F/8 - Paramount MX Camera: QSI 583wsg - Cooler -15C - OAG with Lodestar Exposure: LRGB= Only one frame of 600sec and 3x 600sec averaged darks Taken: Astrocamp, Nerpio 23/06/2013
  5. 10 points
    TS130 f6.6 G3-16300 Riccardi APO Reducer und Korrektor 0,75x SkyEye Observatory 70x300 L 40x300 R 40x300 G 40x300 B
  6. 9 points
    A friend tipped me off that some clear skies were advancing in my direction so at 7pm I ventured out with the big 12" Dob' for its second outing since buying it second hand a few weeks ago. The 12 dob just fits through the door frame and settles nicely on a concrete patch in the patio and on went the tube. I used a laser collimater to align the scope having attempted to collimate the collimater earlier in the week (it was way off). Connected up the battery and started to align. The sky was looking very grey with the rising moon, streetlights and damp in the air from rain during the day so I wasn't sure what I would be able to see and as this was an unexpected outing I hadn't prepared any particular targets to vue either. For some reason the suggested alignment stars always seem to below the fence or behind a house. I settled on Altair and Mizar. Mizar making a nice double to start the evening. Taking my tour around anticlockwise to start with I slewed to M13 as a nice easy target. The cluster showed up clearly against the grey sky with a 15mm EP and a number of outlying stars could be resolved, the centre starting to look a little grainy The next target was M57, the ring nebula. This landed in the right half of my 25mm EP fov so I guess my alignment was a bit hurried. The ring was unmistakeable and it was nice to be able to look at it directly and then see even more with averted vision. My CLS filter and the 15mm ep helped to subdue a bit of the grey background. Then came M27, the dumbell nebula, which was also nearly overhead. Ive seen it clearer than this night, but it was again an obvious misty patch looking a slightly rectangular in shape. The CLS filter helping a little bit to subdue the background again. At this point I noticed that my stars were looking a little astigmatic so I checked the collimation. I dont know if the scope had just settled a bit or I had jogged the flextube, but it wasnt quite right. I also noticed that the standard skywatcher EP adapter tilted the collimater when the screws were tightened. Returning indoors for a rummage in a box of bits, I returned with a Baader 2"-1.25" adapter and the collimater sat nice and squarely in it. The collimation needed a slight adjustment and was rewarded by some nice dark circles right in the middle of any out of focus star images. The moon was now advancing and blanking out most of the sky so I switched to some star clusters. M103 came first which revealed its lovely triangular shape with the red giant star showing clearly near the centre M29 came next, slewing back over towards the west now away from the moon, which is a new addition to my Messier collection. The small triangle and rectangle were quite clear and reminded me of the Pleaides (which were still behind the tree near the moon). M39 was another addition to my Messier collection and appeared as a rather loose collection of stars. In spite of the large number of stars in this region the open cluster was clearly a cluster of stars although I couldn't pick out any memorable shapes. M34 was the final cluster of the night. The cluster was clearly visible in a 25mm EP even though the moon was now quite high. The drop in temperature seemed to have cleared some of the mistyness from the air - and deposited the water all over my scope. To close the evening I toured the western edge of the moon. This is an area I haven't explored in much detail and there were a number of significant craters with central peaks casting long shadows onto the walls. I must learn what some of these are. The air must have steadied since I was able to use an 8mm EP on the 1500mm fl dob to get some nice close-in views. The dew was falling heavily by 11pm, my secondary had started to mist up and thin cloud was drifting back across the sky so I called it a night. A very pleasant and un-expect night out and all tucked up by midnight. I must get my pencils and pad ready next time for some sketches. PS - loving the posts on here for some great ideas of things to look at.
  7. 9 points
    Three hours of Ha (3nm) and one hour each of RGB. All Astrodon filters HaRGB with 1x1 binning. Samyang 135mm lens with G2-8300 camera, guided. Everything five minute exposures. Processed with Pixinmsght to the RGB and Ha Masters and then Photoshop. Blended Ha and RGB with tone mapping RGB Ha (3nm)
  8. 8 points
    Well--I think this is it. I removed some of the purple patches and gave the dark structures a more smokey, charcoalish appearance.
  9. 8 points
    Another one from an enjoyable fortnight with our guest Paul Kummer, though this uses a previous dataset as well. The increase in data does allow some little advantages to be teased out even though the first set was pretty good. Here we have around 7 hours of luminance and three hours per colour. There's no NB in this. It's full size here with the 0.9"PP of the TEC/Atik 460 used for luminance and cropped heavily. Dual TEC140, Mesu 200, Atik 460, Moravian 8300. Rig co-owned by myself, Tom O'Donoghue and Mr and Mrs Gnomus. Olly
  10. 6 points
    Following other posts, I am reprinting the image of Uranus that I made artificially colored, along with another that I tried to make as natural as possible (bottom left). In this IR 610 nanometer image I just piled on AS! 2 and gave the wavelets a slight tug with a 200% resize. Of course the original image was red and I converted it to black and white to make it more aesthetically pleasing. In this less processed image we can actually perceive what Uranus looks like, none of those artificial colors that are impossible to exist and with nuances of things that do not know what is real or artifact. Most experts agree that nowadays Uranus presents itself with almost no noteworthy activity, and that the only thing right is the lighter polar region relative to the rest of the planet, which can easily be seen in the black and white image. White. We then deduced that it would be virtually impossible to take anything large as it appears in the color image and that as such, most of those "nuances" are really just noise caused by over processing. https://www.astrobin.com/vrop86/
  11. 6 points
    Swan Nebula (M17) in bi-colour HOO. I took this in the summer, but it's taken me a while to process it - various other hobbies and a nasty bout of flu got in the way ! Please click through for hi-res And an upsampled detail in Ha monochrome: 17 each x 10min Ha and OIII, darks, flats and bias, equipment as per sig, processed in Pixinsight, taken in a dark sky sight in Spain. The Swan Nebula, also known as the Omega Nebula or the Horseshoe Nebula (M17) is an H II region in the constellation Sagittarius. It is located in the rich starfields of the Sagittarius area of the Milky Way. The Swan Nebula is between 5,000 and 6,000 light-years from Earth and it spans some 15 light-years in diameter. The cloud of interstellar matter of which this nebula is a part is roughly 40 light-years in diameter and has a mass of 30,000 solar masses. The total mass of the Swan Nebula is an estimated 800 solar masses. It is considered one of the brightest and most massive star-forming regions of our galaxy. Its local geometry is similar to the Orion Nebula except that it is viewed edge-on rather than face-on. The open cluster NGC 6618 lies embedded in the nebulosity and causes the gases of the nebula to shine due to radiation from these hot, young stars. It is also one of the youngest clusters known, with an age of just 1 million years. For comparison, here's my previous attempt, taken with a modded DSLR: Hope you like it, comments and CC welcome ! Stuart
  12. 5 points
    Hi, A short announcement for those using SGP and wishes to more closely follow/analyse the autofocus routine after a nights worth of imaging. Since a few months I've been publishing a Autofocus Logviewer that opens SGP logfiles and presents graphics of the AF runs logged in the file. The program can also extract temperature shifts of the focus position from the logfile. If you are interested, here is the SGP forum thread: http://forum.mainsequencesoftware.com/t/sgp-autofocus-logviewer/ The latest software version can be found here: https://sourceforge.net/projects/sgp-autofocus-logviewer/ Having read and learned a lot from this forum during the years, I hope to make a small contribution. Cheers, Mikael
  13. 5 points
    Thanks all for the feedback... I have added a bit more saturation and slightly increased the contrast as you all recommend. I didn't want to overdo it so what do you think now? Maybe I should try to reprocess again in Pixinsight with star masks to make the Nebula's stand out more??
  14. 5 points
    Yes, yes, yes a Baader Steeltrack refractor focuser does fit. I borrowed the Baader Steeltrack from Big Red and test fitted it. With the stock focuser using the 2” spacer is recommended but as the Steeltrack has nearly twice the focus travel only the 1” spacer would be needed. The Baader refractor adapter has the same 90mm x 0.1 thread so was a straight screw on. Without the spacer the drawtube was just a few mm too long. The stock focuser is certainly adequate but doesn’t compare with the Steeltrack. Think I will be looking round for a second hand.Steeltrack. Don’t you wish a refractor focuser would fit you mak or sct.
  15. 4 points
    I just received a new focuser for my APM 80 mm triplet, to replace the standard Crayford. The Crayford was OK, but a bit too long to let my cameras come to focus with the 0.6x focal reducer. The new one can handle a much larger load (5 kg), and is 25 mm shorter. It really feels better made than the old one. It also allows easy attachment of a motor focus unit. My filter-switch diagonal should now also reach focus with the new set-up. I will now see if I can adapt the old one to the ST80. As expected, clouds, wind, and rain accompany the arrival of the focuser.
  16. 4 points
    Hi all, This is my third Uranus capture this season. I am much happier with this result. The seeing helped a lot and the sky quality was favorable. This image is the result of 5 de-rotated videos on Winjupos, all captured with IR742 filter. The result was used as luminance in the composition. RGB came from a normal color capture. Following the images of other friends, we can notice the atmospheric activity on the planet. It seems to be changing every week. Many changes can still happen until the opposition. Lucas Magalhaes
  17. 4 points
    I'm likely most relaxed with my 4" Tak. Does that count as a serious scope? I don't know, seriously enjoyable I guess. Any scope with good optical quality is a serious scope as far as I'm concerned. I had just as much fun with my 72mm apo as with my 350mm dob when down in Wales and felt the observations were of equal value, giving different perspectives of the same objects.
  18. 3 points
    All change for this one - new 61EDPH scope with flattener (I couldn't get a flat field with the TS72) new ZWO Mk 2 NB filters ( I got fed up with the huge haloes on the Mk1 version) and new software - AstroPixel Processor (I got fed up with the smeary effects I keep getting on DSS, (though to be fair it is free and seems to work well on everything under the sun (any sun) apart from the Veil)) I'd like to do a proper review of the 61EDPH, but I'll save that for another thread when I've had a proper chance to check it in more detail. One thing for sure is the field is pretty flat. I did this over several nights from the 1st-20th September - initially I anted to keep it simple and work in LRGB but was quite disappointed with that result, and so went with Hubble palette. I couldn't get DSS to deal with the processing - theres something about the veil that really throws it. I tried reducing the star count, change the flats, changing the stack settings - nothing seemed to work. So I'm on a free trial of APP - seems to work well, pretty intuitive, and stacks all channels from multi session much easier than DSS. Still trying to get the finer points sorted, one of which is how much to stretch it during the stack process. I went with the default and is seems pretty good, though the channels didn't seem very equal - tons of Ha which I guess it to be expected. Also I think my flats still aren't right so the corners have some odd colouration which I had to fiddle with in PS. So - I stacked in APP, and just used PS to equalise the channels best I could. I tried reducing noise in the background, and also sharpening the detail a bit but the result didn't looks natural so this is just stretched and colour adjusted. The stars are a bit big - guiding wasn't 100% mostly because I forgot to rebalance East heavy after the meridian flip (Doh) - but I like the star shapes. I tried limiting the star numbers with a median filter in PS, but the result wasn't so nice - to my eye anyhow. HEQ5, 61EDPH + flattener, ASI1600MM Cool, ZWO Mk2 NB filters (unmasked), Subs 300s with Hi gain (300) -15degC, 57xHa, 35xOIII, 26x SII. (No reason for the odd numbers - just the way it worked out!) Seen better, but quite pleased with this so hope you like it - always happy to receive criticism!
  19. 3 points
  20. 3 points
    Haha. Not sure of the obby name yet, I am expected to form an astronomy club and need to be careful not to upset my neighbours... When ordered, the difference between the Pulsar and Scopedome was around a thousand pounds, but it all depends on the exchange rate. Plus, being in Europe already, carriage costs were better - it really hurts costs to cover the channel crossing so my advantage would become a disadvantage in the UK... I also get torrential rain here and not a single drop of water gets into the dome, so happy with the weather proofing. I have no axe to grind with the Pulsar, it was actually a close call between the two but the shutter width was the winning feature for me. Having purchased the Scopedomes, for sure, they are very well engineered and pre-assembly in the factory before shipping makes sure they will fit together quickly and easily on site. The only thing to be aware of is the flat and level base requirement. Less than 1mm on flatness and 0.5 degrees on level. The brick construction was done slowly and levelled carefully as we go and the occasional use of a grinder to take out any high spots made assembly easy. I am sure the same care and attention applied to a Pulsar would also pay dividends. (Please don't hate me, Pulsar owners !!) Gordon.
  21. 3 points
    More tree pruning today by next door neighbour, southern horizon looking better, having spent the last few months trying to catch Jupiter and Saturn between gaps in the trees. Dave
  22. 3 points
    I managed to see Triton last night with Neptune just a few degrees away from the nearly full moon. I hadn't really set out to see it, I was mainly observing Jupiter and Saturn, but as they were disappearing behind the trees to the west Neptune was clearing the tree tops above my head so I thought I'd have a look. I used the Baader zoom to centre Neptune in the EP and then put in my new TV 3-6mm zoom. First on 6mm (250x) with no sign of Triton I took it right up to 3mm (500x) and there it was! Very, very faint, almost at the limit of my 12 inch SW Dob, but very definitely there just at 2o'clock to the grey/green planet and mostly with averted vision. Amazing really, as there was considerable glare from the adjacent moon, I think in a dark sky I could aee it fairly easily on a good night. Go away Moon!
  23. 3 points
    Keep the scope and learn to do everything manually. Its worth the effort. Rob
  24. 3 points
    I can now reveal Star B is 2MASS J19095965+0437597, a previously unknown variable, co-discovered with Adam Nowak https://www.aavso.org/vsx/index.php?view=detail.top&oid=1498835 Note the brightness of this star at ~mag 19 g which would make it by far the faintest object recorded spectroscopically using amateur equipment. This is a bit of a cheat though as my spectrum mainly covers the R and I bands where the star is significantly brighter (This is an M6 star, further reddened significantly by the interstellar medium, which explains its presence in the 2MASS catalogue of objects detectable in the IR at 2 microns. Cheers Robin
  25. 3 points
    You are very welcome to come back anytime, just remember to bring your work clothes too !!! (haha) But a serious thank you for coming over to help. Marvin brought his petrol driven auger to cut the holes for the fence posts.. Didn't touch the hard clay and stones that counts for "soil" here. Luckily he also brought his big concrete breaker and every hole was dug out the hard way. Should have only needed one day, but took two. Since then, I have filled in the perimeter with more gravel, around a tonne down and still a lot more to do.... My two sons are visiting next week and if all goes well, hoping for first light if the clouds (and moon) don't mess everything up... Gordon.
  26. 3 points
    Thank-you Also, we have learned the encoders will be made available separately so those who purchase an AZ100 mount-only (without encoders) can later add encoders. However, at this stage Rowan recommend they are fitted by Rob in our workshop or by themselves at theirs to ensure they are properly fitted and working 100%. We will post details at our website soon.
  27. 3 points
    The 732-member WBL catalogue of galaxy groupings tend to have relatively sparsely-distributed members and differ in this sense from the more compact groups such as the Hicksons (although some Hicksons are also members of the WBL catalogue, I think). Armed with nothing more than RA/Dec, I often like to dip in to the WBLs just to see what is there, as these are under-appreciated objects and don't appear on (m)any charts. The results can be quite varied, but typically consist of 3-7 galaxies that fit on my small sensor. Here are 4 from last night. WBL 676 is very close to the bright star o AQR and consists of 5 main galaxies, though a sixth mag 18.6 galaxy is also visible as a fuzzy blob just N of a star. The lowest galaxy is NGC 7182. I'd say this is a fairly typical (not particularly exciting) WBL object type, with the galaxies strung out across the field. Seeing was quite good through most of the session but seems to have deteriorated for this object. Nearby is Shakhbazian 81, a very challenging compact group of about 11 faint galaxies. Also in Aquarius is WBL 669, a 3-member group. Again, nothing particularly spectacular. Aquila contains just one WBL group, again a triplet. I enjoy looking for WBLs in star-rich constellations as the combination of a dense star field with galaxies in the distance is appealing and unusual. The 3 galaxies form a near equilateral triangle with the base composed of mag 14.2 Sc type UGC 11524 and mag 14.7 SBc UGC 11522 which are at a distance of around 250 M Lyrs and may well be interacting. Finally, back to Aquarius for WBL 666, one of the six WBLs in that constellation. This is a real beauty, with 7 individually-interesting galaxies in the field, and it is finding configurations like this that motivates me to explore the WBLs. I reckon this would make a good AP target. Interestingly, these galaxies are all at a similar distance of 180-200 M Lyrs so may be a physical grouping. On the inverted shot I've marked the 5 NGC galaxies and a couple of quasars. Q1 is mag 19.5 with a redshift of 2.06 (8-9 billion LYs?), while Q2 is mag 19.6 but much closer, with a redshift of 0.18 (around 2 billion). The non-inverted shot is an LRGB as I decided to add a little colour (although it is mainly luminosity so the effect is subtle). Thanks for looking Martin
  28. 3 points
    I have a triple pulley block hoist to lift my 7" refractor onto its mounting. Does that count?
  29. 3 points
    AG Optical Convergent FA14 Moravian G3-16200 Mount:10 Micron GM2000 HPS II Astrodon B 50mm: 10x600" bin 1x1 Astrodon G 50mm: 10x600" bin 1x1 Astrodon L 50mm: 39x600" bin 1x1 Astrodon R 50mm: 10x600" bin 1x1 SkyEye Obsevatory
  30. 3 points
    The reason it works is based on 3D geometry. If you platesolve images which are separated by a move of the mount's RA axis only (i.e. no move in Dec between images), you can work out exactly where on the celestial sphere your RA axis is pointing, because it is the centre of rotation between the platesolved images. It works best if you take 3 images because this gives three points to work with and any 3 non-colinear points in space define the circumference of a circle. The centre of that circle gives the pointing coordinates of the mount's RA axis. It can also work with 2 images, because it's a reasonable approximation to use the midpoint of the 2 images as the third point for calculating the circle. I have used this method myself using an Excel spreadsheet to calculate the PAE, and then using APT's GOTO++ function to point to a position offset from a suitable alignment star by the amount of Polar Alignment Error. It is then a matter of adjusting Alt-Az bolts to centre the alignment star. On my last test, this gave me a calculated PAE (using my spreadsheet) of <2 arcminutes. This was confirmed by running the Guiding Assistant in PHD2, which also reported <2 arcminutes error. My reason for developing the spreadsheet for this approach is that I use an OAG on my Edge HD8, and I image with a DSLR. Sharpcap's polar alignment tool needs a larger FOV than I get on my guide camera, and it doesn't work with DSLR live view. I'd be happy to share my spreadsheet if it's of interest to anyone. Graeme
  31. 3 points
    A serious scope? I have never met a serious or otherwise telescope to date In a serious (get it) note. A scope that you are happy to use on a mount you are happy to use, is a serious scope. Be it a 60/80mm or an 8", it does not matter. And as @Peter Drew noted, the astronomer provides the seriousness or not.
  32. 3 points
    Yes it is very important that the calibration passes through zero at the zero order otherwise you cannot use it to calibrate other stars where the wavelength of the lines will not generally be known. This may be at the expense of precise alignment of other lines but this is less important Cheers Robin
  33. 2 points
    Yes. I must learn to read posts thoroughly. When I replied I missed that @Andy R wrote he used StarTools. I didn't mean to imply it wasn't good software.
  34. 2 points
    I can't not comment on the fact that the Johns are very helpful here !
  35. 2 points
    Hi folks, From time to time get asked what kind of astrophotography camera should I buy on the (social) media accounts where i upload my images. There are many technical discussions (which is helpful of course) but in my opinion it often also depends on the interests of the person itself en his/her skill level... For example, I wouldn't recommend a CCD mono camera >$3K to a person who is starting his/her hobby :-). Anyhow, I attempted to capture that in a video and put it on my personal YouTube channel, here's the link: https://youtu.be/HhIAEnVMzHU Feedback is highly appreciated, and I know I have a (Dutch) accent...being a non native speaker... I'll keep at it and hopefully it will improve over time :-). Clear skies, Wido.
  36. 2 points
  37. 2 points
    Well I enjoyed that, great to be so broad a question base. I did feel some of the questions failed to be fully answered though. Sorry should add, Thank you to @DaveS for pointing it out.
  38. 2 points
    Ok, here is sort of as simple as it can get explanation of binning, and related CMOS vs CCD thing. - Binning increases SNR in the same way stacking does (or rather very similarly, there are small differences not important to this discussion). When you stack 4 images - you are adding / averaging pixel values between those images. Binning is adding / averaging 4 pixel values in 2x2 matrix - in principle same thing. So binning is always increasing SNR of recorded data predictably - bin 2x2 you increase SNR by factor of 2 (same as stacking 4 subs). Bin 3x3 - you increase SNR by 3 (same as stacking 9 subs, as you are adding/averaging 9 pixels) - Difference between hardware binning (CCD) and software binning (CMOS) is what recorded data is being binned. With CMOS you are binning completely read out data, while with CCD you are binning electrons prior to them being read out. There is subtle difference between the two - CMOS binning is after each value had read noise added to it, while CCD binning is done prior to analog-digital conversion and read noise is added to binned value. Difference between the two is - hardware binned pixel (or group of 2x2 pixels) has regular level of read noise - same as single pixel. Software binned pixel has twice higher read noise than single pixel. In another words - if CCD camera has read noise of 5e, when you bin 2x2 and get sub with less pixels (and higher SNR) it will also have read noise of 5e. On the other hand if CMOS sensor has read noise of let's say 1.7e (like ASI1600), after you bin it - it will behave as camera with larger pixels but each pixel having 3.4e read noise. That is the only difference between software and hardware binning (if we bin in "regular" way, software binning can have certain advantage related to pixel blur, but that is "advanced" topic). - as for resampling, binning is a sort of resampling, but it is not only way to resample image. There are couple of things that resampling or rather downsampling does to your data: it creates less pixels covering same FOV - hence it reduces sampling rate, it changes SNR of your data and has some effect on pixel blur and possibly introduces correlation between pixels (last two have small impact on sharpness of the image). Different resampling methods give different results in all of these except producing same sampling rate. Binning is predictable - it creates larger pixel so SNR increase is known, and it adds pixel blur. It does not add correlation between pixel values. Other forms of resampling can add less of pixel blur so image will be slightly sharper, but SNR increase is less (sometimes even more, at expense of noise statistics because of correlation) and there will be correlation between pixels (that has to do with noise statistics of the image). I regularly bin my data in software when I record it with 8" RC (1624mm FL) and ASI1600. Native sampling rate is around 0.5"/px and that is of course way too much. Sometimes I bin it 2x2 and sometimes 3x3 - depending on conditions of the session. Here is an example of binned image vs unbinned image that clearly shows improvement in SNR: This is single 60s uncalibrated sub of M51 taken with above gear. I created a copy of that sub, and with first copy I did software bin 2x2, while with other one I did "downsample" in particular way - one that really does nothing to the image except change sampling rate - so no correlation between pixels, no pixel blur and no SNR change (I simply took every other pixel in X and Y and formed image out of those - no addition, no interpolation, just x2 lower sampling rate to match the scale of binned image). Then I pasted part of second copy over first copy and did basic linear stretch to show result in such way that can be easily compared. One simply cannot not notice improvement in SNR (it is x2 improvement in SNR). Btw, above image is 50% scaled down, but here is the same image at 1:1 zoom: (notice that scaling down for display, which also uses downsampling, improves SNR a bit, so scaled down version above does look smoother than this one at 1:1, but in order to really compare results - we need to measure resulting noise in different approaches to determine how each one behaves - I can do that for you as well if you want - make composite image of 4 different approaches - bin x2, above splitting of pixels, simple resample, and advanced resample technique and do some measurements of noise - as well as star FWHM so you can see the impact on resolution).
  39. 2 points
    Looks like I might have a name for the observatory now... Mind if I use the name?
  40. 2 points
    My God!!! you are scary at the best of times Tich, I wasn't expecting that when I opened the thread. Still can't find the cat... I'm still hoping to attend Tich, depends if Cath's sister is still about.
  41. 2 points
    A good 4" apo is just such a useable and enjoyable scope which does most things well. White light solar with a wedge can be amazing when skies are steady. Double stars are beautiful and clean to view, I prefer the views over the slightly fuzzy stars you tend to get with a mak. You may lose a little resolution for lunar and a bit of reach for deep sky eg clusters would open up a little better in the mak perhaps. I've tried a few maks and keep coming back to my 4".
  42. 2 points
    Scope choice fatigue, what a great name, love it as it is so true. As to scope churn to find an all rounder, good luck with that Doug, I like so many others have tried and still chasing the one allrounder. Apochromats do give a super view, but at a cost, even though reduced these days. My favoured scope these days are Newtonian for value, ease of use so I can sit comfortably using them. My less favoured scope is my wonderful Vixen ED103s, super sharp views and very crisp stars, but not comfortable for my back or knees now, so used far less than I should. So in conclusion, the scope you use most and most comfort is my driver. Really not sure if that’s any answer to the original post though, but good luck Doug.
  43. 2 points
    Thanks for all the replies so far. Interesting replys which have firmed up my thinking. I would be using it mainly for visual and the odd bit of dabbling with imaging. I may do some more serious imaging when time allows and I am not wreck on the sofa after work or chasing around after the family. I am not even going to go down the doublet/triplet rabbit hole. Does anyone think there is just too much choice with everything these days these days? Buying Astro equipment is bad enough but buying buying a light bulb is like a punishment from the Greek gods.
  44. 2 points
    Thanks Mick--don't sell yourself short. Many docents at museums can't paint or draw if their life depended on it--but they make excellent reviewers. Just because someone can't do a better job at whatever they are critiquing does not invalidate their critique. Music is a good example. Someone might not be able to play an instrument, but they can tell when a musician makes a mistake. Rodd
  45. 2 points
    Hi all, Onward and upward, please find attached BASS project for Alpheratz and Vega. Hopefully getting to grips with it. Please comment, thanks. P. S. Just noticed my Cal02 line on Vega is slightly out, humph.
  46. 2 points
    I share the same attitude and concluded that buy quality and cry once is the best policy. Just save for a bit longer and buy the better ones.
  47. 2 points
    A focal reducer would widen your field of view and reduce your pixel scale. More sky will land on each pixel. In a perfect world this would reduce the level of detail in your image but in the real world your image scale in a C9.25 is almost certain to be unreachable because tracking errors and atmospheric seeing will be the factors which limit your real captured detail. The reducer will be a big help. Many will assert that the reducer would also reduce exposure times but this is not as simple as it seems. Beware of the Hyperstar website which is misleading. 'Exposures that take an hour at F10 take mere seconds with the Hyperstar lens.' In my opinion this sentence implies that they are the same exposures - that is exposures of the same target - but they are not because a galaxy which fills the frame at F10 will be a tiny thing surrounded by stars and sky with the Hyperstar. If that's what you want, fine, but there is no free lunch. The F6.2 reducers are widely available second hand. And the idea that an F2 system can ever be 'easy' will find few takers in imaging circles. I'm agonizing over whether or not to say this but... you are about to devote a fair amount of cash to set up the C9.25 for deep sky imaging. If you later regretted this you wouldn't be the first and I've had the same regrets over a similar SCT. Modern cameras are getting smaller and smaller pixels which means that longer focal lengths are becoming unnecessary and even counter-productive in some cases. And they do make life difficult. Olly PS The reducer does not work with the Hyperstar. They are alternatives.
  48. 2 points
    Please read the full description. This is a duplicate of the advert posted on Astro Buy Sell. For sale is my Takahashi TOA 150 refractor, fitted with the large (70 mm) illuminated finder, and Parallax Rings (not shown). Images taken with this telescope can be found on my Flickr astronomy album: https://flic.kr/s/aHsk148DDF Additional images *of* the telescope can be found in this Flickr album: https://flic.kr/s/aHsmHA1Cik As shown in some of the photos, the coating on the objective shows small spots, usually not obvious but they show up clearly under sunlight/daylight, which is when the close-up image of the lens was taken (ignore the BIG blue spots in lines - these are the reflection of my observatory lights!) The small spots have been caused by pollen grains being allowed to settle on the lens for an extended period of time - they break down releasing enzymes which etch the coating. It's a known issue, to which Taks seem particularly susceptible (search the web), especially if like me, you tend not to clean optics until "absolutely necessary". The spots are very small and though they look silvery in one of the images, they're transparent - it's reflection at the different refractive index boundary which makes them look the way they do. The total area occupied by the spots is tiny, and so the effect on image quality is very small indeed. The objective has been thoroughly and carefully cleaned with Baader Fluid and Purosol to ensure that there are no traces of the particles left, so this issue is not progressive. There are a couple of minor marks on the tube; the focuser is the A-type, and the shortcomings of that are well documented. I used it successfully for visual work, and then fitted a Lakeside focuser to it for imaging, at which point the shortcomings of the focuser design become largely irrelevant. The images on my web page were taken in this state, with the stock focuser and Lakeside autofocus. The Lakeside motor mounting bracket is included in the sale in case the next owner wants to go down the same route, but note that I'm not selling the motor or controller. I'm trying to price the 'scope realistically - a significant reduction on the typical used prices for this telescope to reflect the issue. The telescope will produce the classic Takahashi image quality now, and the future owner may choose to simply to use it as it stands. Of course, the cell can be returned to Takahashi for re-coating if desired, to restore it to an as-new objective. That doesn't come cheap - though adding the cost to the sale price still results in a total cost far below the price tag of a new TOA 150. The Parallax rings will need to be fixed to a dovetail plate (not included), and then it's ready to go. Metal aperture cover included as shown. There's also a cover for the 70 mm finder, though it is a very loose fit. I've been as open and honest in this listing as I can be - I'm trying to hide nothing, and questions are welcome. Price £4000, collection only from Braunston, Rutland (LE15 8QX). UPDATE - SOLD.
  49. 2 points
    Thanks for all input guys I had a session in my obsy starting over from scratch. 1. measuring the spider vanes, got the secondary holder centered to 1-2/10th of a millimeter. 2. Insert cheshire and got the rotation of the secondary correct, however, i recognized that the focuser was not centered to the secondary (or so i thought) - it turned out that the secondary was not glued to the holder as precise it could be, it was off by a couple of millimeters. I hope that this not will cause any issues (70mm minor axis) 3. changed the cheshire to the hotech laser collimator and checked everything and indeed the error between the cheshire and laser was much lesser than before. 4. with the laser turned on, i corrected the tilt of the focuser so that the laser beam hit the center mark of my primary. 5. adjust primary to hit the center mark of the laser collimator. 6. repeat cheshire procedure, even more fine tuning of the secondary (because of my adjusted focuser) 7. insert laser collimator and yet again adjust tilt on the focuser tuning in the laser dot to the primary center mark. 8. adjust primary mirror again (we are now in the region of just tenths of millimeters... 9. Put back camera, adjust focus and got it down to 3" fwhm with alot of humid in the air and a primary mirror not even close to ambient temp (looks promising) 10. Clouds rolled in. 11. put a "snus" under my lip and wait out the clouds. 12. found a gap in the clouds, shot apr. 20 images and measured them with ccd... aprox. 2% tilt, just a couple on arc seconds collimation off. Conclusion - as a newbe on newtonians (have been photographing with APOs for almost ten years) i might have found a workflow that actually gets me somewhere. And this was done with a diy cheshire (drilled a hole in a 1,25" cap) I have now ordered a concenter eyepiece.
  50. 2 points
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