Aramcheck

From the 5th & 6th May... near full moon & sky Bortle 6 here in lockdown Leeds. A couple of (very) late night/early morning sessions with the SW200dps & Canon 600d. The main aim was to get the guidescope (a converted 50mm finderscope) working. On the first night I couldn't get PHD2 to calibrate, so pressed ahead un-guided. Focus was also a little off, as I couldn't find a star bright enough to use with the camera 'Live View' & Bahtinov mask. After tweaking the software settings, the second night went more smoothly, with the guiding working for the most part. I lost some subs due to moonlight shining on the scope & ended up hastily duck-taping a plywood board to a pole and holding that for an hour-or-so to block out the direct moonlight... Towards the end the guidescope had also dewed up a little. Nevertheless, the FWHM (Full Width Half Max.) / Eccentricity & Signal-to-noise plots showed a marked improvement between the Un-guided & Guided nights. In total I used 122 (NGC3180) & 136 (M51) x 60 second subs. I stuck with 60 sec's so I could stack the best frames from both nights in one go, but hopefully will be able to take 2-3 min subs in future. NGC3180 - "The Little Pinwheel" didn't come out too well, but I'll no doubt try again. Processing was a little tricky but then it is approx. 40 million light years away... (I'm not sure whether it should be NGC3184... Stellarium lists it as "3180".) M51 - For some reason the image is flipped L-R compared to the picture I obtained from the OU COAST scope. Not as good quality as COAST, but at least it's home-grown. Both images heavily cropped! Cheers, Ivor PS: clear tonight but too knackered to have another later night... Eccentricity.pdf FWHM.pdf

Was it "Dr. Maggie's Grand Tour of the Solar System" by Maggie Aderin-Pocock (Buster Books £12.99), from the Dec 2019 edition?

With HDR Multiscale Transform (& also Local Histogram Equalisation) it's best to take a clone of the image beforehand & then use Pixelmath to combine the before & after images, so the result doesn't look over processed. Pixinsight is a very versatile bit of kit... Cheers Ivor

The 130M only has a small motor, so works happily for a couple of nights viewing with ordinary rechargeable batteries.

I found a Telrad in conjunction with a right-angled erecting finderscope much easier to use than the Red Dot Finder which came with our 130M. (Though the extra weight did put the mount on about it's limit for balancing) I'd also suggest a ND filter for viewing the moon and depending on your location a light pollution filter. Cheers Ivor

When we started out with an EQ2 it took me a couple of frustrating nights, wondering why the DEC wouldn't move any more... As @DaveL59 says - check that it isn't moved to either end of it's travel. I felt a right numpty when I figured that out! Cheers Ivor

Might be an idea to check whether your camera is set to automatically alter the picture orientation between portrait & landscape. I don't use DSS, but there's a good video on manual calibration with Pixinsight:- https://youtu.be/zU5jJgjKuQQ Good question about whether the orientation of the Bias matters, I'd guess it does because otherwise how would the software know to rotate it 90 deg clockwise or anti-clockwise in order to match the top and bottom with the light frames? Cheers Ivor

I could be completely wrong here, but it looks like the Master bias hasn't been applied correctly (Either that or no noise reduction has been applied?). Try applying the Superbias procedure to the Master Bias & use that & the Master Dark when calibrating the Light frames. It's also worth taking flats, so that a Master Flat can be included too. Pixinsight has some Procedures to help reduce noise, both in the Linear an Non-Linear phases of the workflow. More subs will increase the Signal to Noise ratio, but I would expect that you'd be able to get something pretty decent with 80 x 90 secs. The Star Alignment procedure will cope with images taken in different orientations, but it's likely that you'll need to crop more as a result. (Worth looking into Astro Photography Tool, which has plate-solving and Framing masks to help align scope to precisely the same bit of sky / orientation on successive nights). Did you use the Debayer process after image calibration? Once ABE or DBE has been applied, the Colour Calibration steps (Background Neutralisation + Colour Calibration or Photometric Colour Calibration) seem so have a large bearing on the final colour in the image. BTW There's a very good book on Pixinsight by Warren A. Keller. ("Inside Pixinsight" - 2nd edition), which is well worth getting & is a handy reference. Cheers Ivor PS: Worth looking at using Masks as well, to apply different processing to the Galaxies. eg to enhance the colour saturation (Curves Transformation) & structure (HDR Multiscale Transform & Local Histogram Equalization)... Likewise Curves Transformation applied to the background to make it darker. PPS: Welcome to the SGL!

I'm not sure which scope the "AZ-GTi / Heritage 130p" description refers to. If the tube length is 650mm then I would have thought it should be possible to achieve focus, but the draw tube will have to extend into the OTA by several cm. I use a "130pds" with a DLSR & that requires winding the drawtube into the OTA by a long way in order to get focus. Try getting the camera to focus in the daytime on a distant object on the horizon. If the OTA tube length is longer - i.e. 900mm then, I don't think it will be possible to do prime focus photography. Also - if the scope is this one: https://www.firstlightoptics.com/sky-watcher-az-gti-wifi/sky-watcher-explorer-130ps-az-gti.html then the mount won't be suitable for DSO's which require long exposures, and you should also check that it is capable of carrying the extra weight of the DLSR. Cheers Ivor

There's a good talk about various noise sources & optimising exposure time on youtube by Dr. Robin Glover from Sharpcap: https://youtu.be/3RH93UvP358?t=61 Cheers Ivor

117 x 60 sec subs from last night. SW200pds + Cannon 600D (astromodified) & Bortle 6 sky. Rough processing in Pixinsight... Cheers Ivor PS: I need to work on the Colour Calibration, I think.

From last night - think I have some Coma despite using a Baader CC. 109 x 60 sec's with a Canon 600D (astromodified) of NGC7635 - The Bubble Nebula + M52 (Cassiopeia Salt & Pepper Cluster) + NGC7538 (Northern Lagoon Nebula). Bortle 6 skies... Roughly processed in Pixinsight. Cheers Ivor

I'm using Astro Photography Tool (APT) + a version of Stellarium which supports ASCOM. I also have ASCOM/EQMOD installed & use an EQDIR cable to connect the laptop directly to the mount. I can use APT to help initially align & focus the scope, control the camera & move the mount. It's still early days for me though & I'm just getting to grips with plate-solving images. (Haven't attempted guiding yet!) Cheers Ivor

You can do it in PI by using Dynamic Alignment to align one image to another & then either Pixel Math to combine into a new image, or HDRComposition. (HDRComposition is more for combining different exposures) To combine images in Pixel Math you'd just need an expression like:- (0.6*first_image)+(0.4*sec_image) To blend the images with 60% of the first and 40% of the second. Remember to select Create New Image though... as the default is to overwrite. Cheers Ivor

In EQ Mode, there's a procedure in the Synscan manual (p.37 - '11.3 Polar Alignment without Polar Scope') where having done an initial 2 or 3 star alignment, you can refine the alignment by pressing "Menu -> Alignment\Polar Alignment" & following the steps to adjust the Altitude & Azimuth bolts. That will get much more accurate alignment. I used to get errors of around 45 min initially, which would drop to about 10 min by this process. I've also had similar problems where from the parked position, the first slew is 90 deg out. Recently I've been using an iOptron iPolar to take the pain out out Polar Alignment & only keep the Synscan handset for visual use. As per @MarkAR I've not experienced any problems when controlling the mount direct from a PC. Cheers Ivor

In ColourCalibration have you tried just setting a preview on the background & leaving the White defaulted to the whole image (with structure detection ticked)? I think that's what I ended up doing when I had a go at M81/82 last week. Later on in the processing I found that I had to use different masks for either Galaxy as HDRMultiscaleTransform & LocalHistogramEqualisation needed different settings for each of them. Cheers Ivor

I filed down the ring lock a little bit (on the thread side), so that it's now about 10.6mm in depth. That seems to have worked ok, as I can now get focus. Thanks for your help! Ivor

Well done! BTW I've found the Inside Pixinsight book very useful... Cheers Ivor

Excellent talk! Thanks!!

I've tried that as per @eikie's thread but it didn't work, i.e. the objective lens couldn't be screwed in as far, but thanks for the suggestion. Maybe there's a large tolerance variation in the length of these finder-scopes? I'll know I'll need to use a guidescope that can be attached to the OTA rings at some point, as I can't get balance with the 130dps and DLSR+9x50, though the 200dps is fine. Cheers Ivor

As @knobby and @fozzybear suggested, removing the locking ring did allow me to get focus. Without the ring however the star position is very sensitive to any movement in the objective. I'll have to look to see if the locking ring depth can be reduced. Had hoped to do an imaging run tonight, as skies here are nice and clear.... but nearby neighbour has a garden fire going & I don't think it'd be sensible to proceed with the wood-ash fallout. I've ordered a USB hub and active extension lead too. Cheers Ivor

Yes - it looks exactly as per the picture. Going to have another try tonight... Cheers Ivor

I recently bought a ZWO ASI 120MM Mini and a C adapter so that I could convert a spare SW 9x50 finderscope, to have a go at guiding, but I think I'm having trouble getting it to focus. I've looked at @eikie's earlier thread: https://stargazerslounge.com/topic/347996-focussing-guidescope but I can't get it to focus on a distant object & when I try to view a star I'm not sure if the result is good enough or not. (See attached image from ASICAP with Capella enlarged & at original resolution. The star looked ok through the main scope & I couldn't see any high cloud). Also, at present, I'm running a 5m USB lead from my DLSR to laptop & similarly using a 5m EQDIR cable to control the mount. The USB lead that came with the camera is 2m, so am I better off getting a hub or a USB extension cable? (I usually leave the laptop in a storage area under our house & just bring it near to the mount during initial set-up) I think longer term I'll be opting for a different guidescope, which I can mount on the OTA rings, but was hoping the finderscope would be a way to get started... Any advice would be much appreciated! Cheers Ivor

From last Saturday night. Only managed 104 x 60 sec subs (200dps + EQ6 + Canon 600d) as had a few hiccups including narrowly avoiding the scope hitting the tripod & getting used to controlling the mount via APT/Stellarium on a laptop. One image shows the light gradient of the stacked image, with just the initial colour cast from the DLSR removed. I find it difficult to get an even background level from this data, which I guess would need longer exposure time to improve on? I'm processing in Pixinsight & after DBE found the Masked Stretch process worked better than the STF + HT combination. Cheers Ivor

Or ditch the Synscan handset & use an EQDIR cable to connect laptop direct to mount. Then install the version of Stellarium here: https://www.cloudynights.com/topic/679620-stellarium-direct-ascom-support-testers-wanted/ which includes support for ASCOM. I'm rather a newb to this - but when I tried it for the first time the other night it worked like a treat with both APT & Stellarium. Cheers Ivor