pipnina

Hubble Space Telescope: It is the source of all those pretty pictures whole generations have grown up seeing as THE bar for quality. Plus it allowed us to see back to near primordial times in a cosmological sense and continues its primary mission of observing and measuring extra galactic supernovae to this day, over 30 years later! Plus it was put into orbit in a space shuttle, one of the coolest things to ever fly. VLT: One of the first observatories to use a laser guide star system for adaptive optics, and THE best interferometer used for astronomical purposes. Besides being a technical marvel and living breathing science and technological development of the most impressive order, it also pinpointed the exact location of the black hole at the center of our galaxy and constructed an image of betelgeuse with surface detail! Arecibo: aside from simply being massive and cool (the dome was a 5 story tall building by itself!), the telescope's ability to perform active radar imaging of asteroids was pretty unique and cool. It also captured the minds of many.

Oops, when I said widefield camera I kinda meant the "main" camera. I guess I used that because the pixel6 pro has a telephoto periscope camera so the main cam is very widefield in comparison (I think about 6mm FL) To be honest from my experiments, the actual 0.7x widefield cam is even worse than the main cam. In low light performance the difference is honestly very dramatic.

I didn't realise the turbulence and astronomical objects could be at different focal positions! I guess I imagined it would all be at too high an altitude or that turbulence would affect the image whether it was in focus or not. I guess it does bring back an interesting tidbit: Apparently most of the turbulence on an average night comes from within 10 meters of the ground, I believe that was on some observatory's website but I cannot remember now.

Whoops, I got my mind muddled up and quoted you instead of Vlaiv, who actually did mention step-skipping (which is usually a result of insufficient motor torque) To that end, basically stronger motors would mean skipping fewer steps, which would mean better guiding/slewing if the mount is struggling on either.

I know this is a bit of a long gap for a reply, but I did some maths only a month or two ago to work out how much torque the heq5 can produce at the driven shaft. When run at 1/64 microstep I think it came out to around 0.24nm. about as much as I could apply to a 1/2" socket drive on my workplace's torque calibration machines with my finger and thumb. So all in all rather poor torque for a 705:1 gear reduction! You can increase torque by reducing the microstep ratio but it's not linear, maybe mods could improve the heq5/eq6 mounts with inexpensive higher torque motors hmmm

Working on my processing since my scope isn't in top shape right now. Having a fiddle with StarnetV2 in Pix. After many hours of headscratching trying to install the thing (turns out it won't even show up if you use an AMD CPU, unless you get an alternative tensorflow library that isn't compiled for Intel's AVX-compatible CPUs) So I try a recent image of the Pleiades, and at first it seems quite good, but when I look at the image a bit longer and the star map, it seems the brighter stars are... Not handled so well. At first this doesn't look so bad, but then... It seems like the bigger stars don't really get "saved" in the maps, and even in the starless version one of the big four stars is only mostly removed. Do I need to do some other work to these images before I can run star removal? Or tidy up the star-removed version and the star map to make it look good once re-combined? Second example, where it kinda worked a lot better: Obviously removing the stars from this image worked very well, the ABE+stretch-only version (left) looks way more crowded and it's harder to see the IFN in the background compared to the starless-processed version. The starless processed version looks cleaner, less busy, sharper even. But zooming in, it's not exactly perfect, so maybe I still need to clean it up a bit? I'd love to hear some tips abut using this tool, as I feel like mastering this new trend in astro processing is going to totally change the outcome of my images if I can get it right! Thanks and clear skies!

I've been thinking pretty much since I first saw the ZWO one in stores: What scopes can actually support these monster cameras? I imagine something like an RC in sizes above around 16" could do? I don't know of any newtonians that could cover a sensor of that size, or any coma correctors that advertise anything beyond 35mm. Maybe some premium triplets with very large flatteners can pull it off? But then I saw a post recently about the M82 sized riccardi flattener not correcting for one of these medium format sensors... Also, I'm slightly annoyed by manufacturers calling them medium format, when the last format to use that name (film) was *much* larger (60x60mm or 70x60mm even!) Large format is also taken by the film plates measuring 5*4 inches. I am quite excited to see these big sensors coming down in price however... Maybe when sony's next gen of sensors come out we'll see them come down again! (ha). Companies like Fujifilm have had these sensors in much much cheaper mirrorless formats for a while (think £3000)

My estimate for two way delivery was based on how much it cost to get it to me when I bought it: £57, plus some padding because when costs aren't 100% certain I tend to try and imagine it's more than is perhaps realistic. I realise now i made it seem like *you* quoted the postage price, when actually it's my own estimate, whoops... If parcelforce (seemingly Mr Reid's preferred courier) charges less than DHL then that's fine my me. I will be honest I had realised I did not clarify how long corrections can take (I worry a lot about mis-handling social requests, with the ASD and such). So I wasn't sure if I'd be paying for one hour or ten, for example. You, and others in this thread are most likely right, I am likely being a bit pessimistic, but not without having been worn down a bit first! I can only thank you guys at FLO for your help, as I've been directed to a fair few helpful pieces of advice and purchases via contacting you by email. Your service is why, the only times I've bought something astro related anywhere else- is because you don't stock it or I couldn't afford buying new. Thanks again for forwarding me to Mr Reid in this matter.

I believe the HEQ5 uses a lithium grease normally, I'm sure other greases will work as a substitute but I would probably choose to go with the manufacturer's choice myself, unless there's an obviously better alternative. Lithium grease is quite thick but of course that can be quite good for the slow, high torque and high load gearing being lubricated.

Sadly my idea didn't work 😕 I tried to reduce the larger detail levels int he galaxy so i could try and boost the areas where ha would be, but I couldn't isolate it much at all. Also looking at what you started with, I can see you really know your way around editing your photos! I was really struggling to get a background or colour anywhere as clean as yours.

Would you be able to share the unprocessed stacked tiff? I could have a fiddle and see if an idea I have could work out for you Your image looks very nice already though I must say!

I understand that line of thinking, and maybe I am stressing over it too much... But I also know at heart I am a pixel peeper and even if other people might look at my images and go "oh that looks nice!" I'll still know what's "wrong" with it and will struggle to be satisfied! As for diffraction spikes, I rather like them in all honesty in reflector images... But only so far as I could keep them sharp and defined, and they didn't encroach on the image or sit at angles other than increments of 45 degrees. It sort of gives a hubble-esque look to me and I think the mirrors scatter a little less light than lenses, leading to bright stars bloating a bit less in a reflector which makes up for it a bit in my mind. Still, at that point it's an artistic choice as much as anything! Coma in the field center and astigmatism at the edge isn't so easy to debate over. Like you say though, everyone has their tolerance and tolerances can change over time...

Best I was able to do when it came to star testing was this: Not easy to take pics with a phone down the eyepiece haha. Some also said I might not have been far enough away, although the 0.05mm star would have had a radius almost half that of the Rayleigh criterion for the scope at that distance so it might have been an ok test.

I have now been in contact with Es Reid, he says he can take the scope on if I send it late next week (was busy this week and into the next). I think I will send it after all, the only problem being that he is in Cambridge and I am in Plymouth! I trust parcel force (the courier he says he prefers, he said Post Office specifically but I think PF are the only courier through them that will take a telescope) to get it to him ok, but I don't know if I trust any courier to be delicate enough to bring a tuned and checked refractor back to me afterwards... A train trip to Cambridge and back might be in my future to feel safe here. He did say scopes like mine can lose collimation easily and are very sensitive to de-centering... Which does make me worried about holding onto the scope for too long after tuning... Might be reinforcing my purchase of a 365 cover and pier/permanent setup plans. Telescope can't lose collimation if I never take it off the mount, at least save for high winds.

Darks and bias frames will be fine Flats need to be retaken every time you move the camera or the dust bunnies shift around. I have heard that dark frames expire after a while, as the camera's dark pattern slowly changes over time. I don't know how true that is but I don't use darks personally.

Funny enough I also have those same flat/extraction issues, and given as it's happened on three different scopes I'm starting to think the problem lies elsewhere haha. Probably in my case I need to fully nail the calibration (flatdarks, bias, etc) Software updates have plagued me too, Kstars has had improvements but some releases have been broken and I've had to wrestle the ubuntu package manager to get the old one back! The seller used a much smaller sensor camera, and I suspect this is a big part of why they didn't notice. I did speak to them about it but they seemed fairly sure it worked when they had it, and the pics they sent taken with the scope before I bought it looked ok, in the end maybe it was bad when they sold it, maybe it wasn't! In likelihood it probably was in at least some of the ways described, but it's a bit far gone now to go and complain haha. Thanks for your best wishes also.

2022 was a year of some decent highs and painful lows when it came to my astrophotography ventures. I made the dive from an unmodded DSLR on a handset-only HEQ5 with a 130-PDS, to modding the DSLR, then replacing it with an astrocam and using my laptop to control the setup. Then I broke my PDS (cut the focuser abrrel too short when trying to prevent it from intruding the light path), and replaced it with the horrible TS-PHOTON. That plagued me for 2022's summer and set me back over £900 once I dealt with dovetail bar upgrades and coma corrector upgrades on top of it. Then when I was at peak distress with the PHOTON that would not hold even secondary collimation at this point (took the secondary out to blacken the edges, when it went back in, it wouldn't stay in one spot...) an ad came up in the classifieds here. 130mm f6.6 carbon tube triplet. For 1500 including a 0.79x corrector. In theory that's not just a good deal, but ideal timing for me. Some discussion with the seller and I wind up buying it, and it goes via DHL and turns up at my house a few days later. First night I get to try it, I can't get the corrector to work, massive astigmatism at the edges (later turned out it was my fault, backfocus went down by 6.5mm due to no longer using a M48-T2 adapter). I took the corrector off and realised the focuser was tilted, and not in a small way. And on top of that, the focuser slipped when my ZWO EAF moved back and forth, and even slowly slid out during the night... It needed changing. After bribing the machinist at work with a box of Celebrations and cutting the rear flange off of the telescope to make it accommodate ANY alternative focuser, I was now down £2050 minimum, but I had a 3" R&P with tilt adjustment instead of a rubbish 2" crayford instead. But the images still weren't right. Even dialing in the corrector's backfocus more accurately I realised there was astigmatism on one side and coma on the other, and a bit of coma in the center of the image. The front cell was mis-collimated. After googling and researching and buying an artificial star testing kit, I used my highest power EP to study the center of field star pattern for an afternoon in daylight. I thought then that there was a little astigmatism in the middle still, but hopefully it was improved as the tilt of the cell had now eliminated the off-center rings. Yet the next time I went to image, it was unchanged. Something more drastic is wrong and it's beyond my capacity to correct. If I want to fix it now, I need to send it to a specialist. I contacted the people at FLO and they have forwarded me to Es Reid, who I will be contacting shortly. But they warned me that the *minimum* I would be charged would be £75 per hour, plus the (based on my estimates) £150 needed to post it to and back. Now I am torn. Is it still worth me going through and spending yet more money on this refractor... Or am I just getting trapped in a sunk cost fallacy, and this scope will just cost me more and more money, never being as good as it could have been if I just splashed £3500 on a 120 or 130 triplet straight from FLO which was already checked by Es Reid as part of their running agreements... And saved myself months of stress and DIY and most importantly, NOT IMAGING. I feel like I need this off my chest, just because at this point it's genuinely eating into my life because of the sheer emotional, financial, and time investment I have sunk these last 12 months. Hope all of you are having a better time!

I have been tuning the spacing but since the star shapes are different in each corner it's been hard to get it exact. I will have the chance to test it tonight so hopefully I will know if the tilt is now correct and will be able to dial the spacing in a bit better. A good shout. I have been keeping it outside for a while now as the weather is ok and it is protected from prying eyes. So it should remain decently acclimated to the temperature

The biggest issue as mentioned will be creating the threads. There are a few things that all need to be parallel or concentric in a filter wheel so it might not be easy to print. Given as a good LRGB filter set will set you back at least £400, and a single quality 3 or 5nm narrowband filter will set you back 300-500 (thinking about 36mm size here), I think it's probably not a great place to look for savings sadly. Still, maybe money isn't the point- perhaps it's the challenge and seeing if it's possible regardless. In such a case: off-the-shelf bearings and bright steel rod could make a decently sturdy center for your filter wheel's rotating part with minimum run out. Might be a good starting point?

I've done some fiddling with it in daylight and I think I've solved the coma issue in the center. But now that that's solved I think I've introduced astigmatism... or worse, it's there when the cell is properly tilt collimated, meaning the problem lies within the arrangement of the triplet of lenses within... Far beyond my ability. Hopefully this makes it better when imaging however, will report back if it is or isn't 😬

I have my artificial star torch (5 holes, 50 micron, up to 250 micron) and I'm looking at the smallest one in my 6mm eyepiece at a distance of about 13 meters (800mm focal length, 130mm triplet of unknown make and design). As I adjust my focus from intra to extra, I notice that when it's focused it actually looks quite good, intra focal it looks like two strong rings concentric with the white dot in the middle... but the middle isn't well defined. it looks strong, but it also almost looks like three dots split up. Not sure if that's pinching or if it's miscolimation or something else! When I'm extra-focal, I see rings moving into one corner of the outermost ring, which seems like coma (cell misalignment) to me. Should I be basing my adjustments of the tilt of the main cell on the extra focal value? Thanks Here's the best pic I could get down the eyepiece extra-focal, sadly intra focal wasn't possible as getting the phone into position was very hard indeed and the stars were a white-out! And this is what I'm seeing in images (albeit with corrector, but it shows that star shapes are not uniform across the field) I have performed the paper-with-crosshair check over the front of the scope to align the focuser with a laser. And because I have tightened the grub screws holding the focuser that is now rock solid (can't use the rotation feature though now) Should I adjust my cell with this artificial star setup, do I need more magnification, am I reading things right (that extra focal view is showing me the coma error?) Many thanks!

It does produce a cleaner image for sure, but it also does cause some artifacts on stars (they tend to go odd colours) and it means you need to sit there with the phone hitting the shutter button every 4 minutes- deep sky camera lets you take about 30-40 mins worth at a time. That said, I did find a way of controlling my phone from my pc indoors so it might be tolerable if I tried it again. In the end these phones are impressive for jack-of-all-trades devices but I think you'll agree that we mostly image with them from curiosity or necessity and not because we expect greatness!

I have gone down this route, and sadly even if you go through the effort it's not worth it: The camera in the pixel6 (at least the wide angle one, I only have the normal version not the pro) has terrible coma and concentric rings of distortion. It also suffers from internal reflections and has very strong dark noise and hot pixels. Mind this was when I attempted it when night time temps were still 15c, not freezing! The end result is that you hit a brick wall fast, I'll find my attempt that took a lot of working out to get right, and even then it's not as good as I would have liked for I believe 2 hours of data! Edit: Here's what I achieved using the p6 by itself and a star tracker, using deepskycamera app and pixinsight. This used several hundred gigabytes of hard drive space and hours if processing so I think the result is a bit disappointing. Best to stick to the inbuilt 4 minute timer I guess!

It's the wrong time of year right now, as the milky way core is more of a summer-autumn object. I know that usually people refer to the core when they say "Milky Way", but of course everything our human eyes can see without assistance is the milky way (except for the megallanic clouds and andromeda) so really the core would be best specified as the outer milky way is also visible under suitable skies! Based on your location however, visual observations of the milky way structure could be challenging. This is because the brightest part (the core) appears in the south, where you will be staring at london's light pollution! The outer sections of the milky way structure are fainter, and so harder to detect. The outer milky way runs through Cassiopeia down just to the left of Orion. It's not easy to spot but if you can it's quite incredible! In your case I would think you need to drive somewhere dark, but maybe someone more local to you will have better tips and experience to let you know how practical your aims are! I live in deepest darkest devon so the lack of life down here has made astronomical observations a bit easier. I have seen all parts of the milky way visible from the north only a short drive away from my host city. I appreciate I am raletively lucky in this way however. Happy hunting! If you have a modern or higher end phone you might catch the core of the milky way in the summer via the long exposure camera mode? Even when I can't see it directly, the phone seems to be able to with a bit of teasing.

In my case it meant tightening the flathead grubscrews that held the focuser onto the scope. These have always been external screws for me so I could just take a screwdriver to them and tighten them to remove the slop. Only my current focuser is tilt-adjustable though.