pipnina

So if I wanted the ground to be properly exposed, I should get a meter reading with the center of the frame pointed at the ground, then frame my shot? Works for me if that's the case, I was probably exposing for the sky.

I guess I can only give it a shot and see what happens! My first thought was that I'd try another Rollei-IR film shot but stick it on my guided HEQ5 and do some half hour to hour+ shots and see if they come out better. I think I'll try the Illford film though as you suggest as you have prior experience. What sort of exposure times might one manage there before over-exposing it? My skies are around mag 3-4.5 NELM depending on where I'm facing. Funny you should mention a modern mount and a film camera together, as that's what inspired me in the first place to give this a go: https://petapixel.com/2020/04/25/how-i-photograph-the-milky-way-with-medium-format-film/ This shot in particular!

I've done some reading about this Tech Pan but I'm not quite sure what it does differently to normal film, or if the benefit for astro is in the development and processing. Some local person is developing it, through a local shop dedicated to film photography. I presume that "pushing" helps to increase the brightness of the film, but is that just exaggerating the contrast already present in the film (can't boost the brightness of something that already has no signal) or is it bringing out chemical differences that otherwise would not affect the transparency? I'll have a look at this illford film and see if I can try it out on my next attempts, I'll also speak to the guy in the shop as he may stock it and have advice for shooting too Thanks!

A few months ago I figured I'd give my dad's Canon Æ-1 Program a dust off after I found out about a film photography shop in my town center. I looked at the data sheets for a few kinds of film and seemingly only Fujifilm Velvia (colour, the same film used to capture the famous windows xp desktop background) and Rollei Infrarot (Black and white) have spectral response at the hydrogen alpha emission line. I figured I'd pick up the rollei. I am definitely grateful that the cameras and lenses of the day had good focusing marks, or i would not have been able to focus on stars at all without hoping a bahtinov mask would be bright enough. The focusing prism definitely only works in daylight conditions and when hard edges are present... I stuck it on my star adventurer mount and took some photos. In my notes I took them of Andromeda, Cassiopeia and Cygnus. Either at 35mm or 105mm (my dad used a vivitar 35-105mm lens, so I opted to only use the extremes). Sadly the best I got from it was this... Not exactly what I hoped... Weirdly enough even normal photographs I took came out very poor, despite using the camera's inbuilt metering system (and setting the ISO on the camera body to the 400 declared on the film can). Maybe some film photographers here might know what's going on, but I am going to mention it to the guy in the store because he seems very knowledgeable (has in-repair cameras all over the store!) and could point me towards user error, dodgy processing, bad scans etc. So here we go: 6 minutes pointed at Cassiopeia yielded me this. Oh dear. And this was the best one! It doesn't help that the scans I got back were in jpeg format, and the scanner is not bias frame calibrated (those noise bands!) This was clearly one of my Cassiopeia attempts at 105mm, as the W takes up most of the frame. Not much going on here though. The rest of the astro snaps plain haven't been scanned (Only got a download of 26) which suggests they were blank and the guy didn't even bother scanning them. Although it's a bit odd, as other shots that were scanned also appear blank, despite also being based on the camera's metering... I plan on having another crack at this... But I definitely need to review my process! Some snaps to judge the film on, or my photographic prowess haha.

Astro equipment is very sensitive to the quality of USB ports too. I always run my mount on a cable straight from the PC to the mount, never through a hub. The only hub I truly trust is my Pegasus Power Box Advance, which is the first one I've used that has supported even the fussiest pieces of kit.

I really like false-colour images made from mono Ha! Yours looks very clean and tidy as well! I have only ever botched it without starless processing, but something potentially interesting that makes the nebula pop a bit is letting the Ha fade in saturation towards the highlights, if it's something you'd like the look of for your pics anyway. I do like the moody red-only look

I take it the EQ mount is providing you with extra necessary height then? In such a case, if you find in a few more weeks or months (depending on how often you manage to keep observing in that time, clouds and all) that you still very much enjoy observing but find this scope and its wobbly mount frustrating: You could consider doing what I did and upgrading to a 250mm or 200mm dob, which would have more height than the 130mm dob You can also in theory put a block of wood or somesuch underneath a dobsonian to boost the height. At the end of the day if you know a tripod mount is best, I won't ague with you, but I do personally quite like the dob format for its cost & rigidity. An astro society or club visit would be a good idea!

I had this exact setup when I started in 2014, I know exactly why it's frustrating you! Carrying it around led to being poked and prodded by all parts of the mount... I switched it up by moving to a dobsonian mounted scope, and I notice that if the AZ4 is on the table as a mount switch, you could buy a skywatcher heritage 130 dob for the same price, if not a little cheaper. Dobs I think are much more rigid against touching the ota and against wind, vibrations are less noticeable and settle faster. Even my chunky HEQ5 EQ mount wobbles when I touch the focuser of my frac. Hope you continue loving your scope!

Strictly speaking I think many of the new CMOS astrocams are the same as the astrocams sensor wise. Many astrocams literally use the same sensor as a consumer camera on shelves today. The difference comes from the amplifiers (don't see many consumer or even professional mirrorless/DSLR cameras with 16-bit ADC...), and the software in the onboard computer, plus the absence of ir-filtering sensor windows. For all intents and purposes, a new mirrorless camera from sony would perform the same as an uncooled ASI2600MC without the ir filter and dodgy processing done onboard, sadly the consumer cameras are insistant on things like raw file tampering (mistaking stars for hot pixels), so even if you modify them they still come out lesser than the 2600MC will. I think the difference between CCD/CMOS astrocams and DSLRs was more prominent however, back when these sensors suffered from much more noticable dark current and brighter hot pixels. Even if I don't cool my RisingCam 571, and it runs as +5 or even +10c, I don't notice any intrusive dark current like I did with my old Nikon D3200. Strong dark current in older sensors paired with a lack of cooling I think makes the bulk of the older DSLR's struggles with astro. Now of course, a lot of people are using these cheaper uncooled zwo cameras with a good deal of success and not seeing much dark noise at all. I do feel like traditional camera makers COULD demolish the current astro camera makers with simple changes if they wanted to, like having a pure-raw setting (zero software involvement or post processing) and having the IR filters cutoff point moved to say 680nm instead of 650, which as I understand is just a holdover from the film days where you needed to make the film insensitive to deep reds so you could see the film you were processing during development? Maybe the 533mc or 585 would be a good starting point for Astro74? Low noise, high QE, dark current is relatively low even in outdoor summer temps (around 20c at night in the uk?). And also very cheap (by new camera standards) https://www.firstlightoptics.com/zwo-cameras/zwo-asi-533mc-colour-usb-30-camera.html https://www.firstlightoptics.com/zwo-cameras/zwo-asi-585mc-usb-3-camera.html

I was skeptical about this the last time the topic was brought up but I feel like I am much more inclined to agree with you now. Many of the smaller sensor zwo cameras are actually very capable even without cooling, and can even be price competitive with modern mirror less cams that aside from sensor real estate will produce worse images... I can't remember the model numbers exactly but I think it is the ASI 533, 585 ETC that are uncooled, a bit small but don't break the bank and have good sensitivity and noise characteristics... Despite the idea of wasting imaging circle area by not being able to record it, after thinking about it, your simple statement of "4x sensor area doesn't mean much if it's four times as much rubbish" has pretty much won me over at least. As you say as well, astro cam costs have plummeted at the low end while quality has shot up. The only thing I'll say for you Astro74 though is that I can't recommend trying the zwo120 for deep sky, as it really is only geared up for guiding, has poor noise compared to other cams, and at a gain level where noise is not at CCD levels, the full well capacity is well below 1kev, whereas most of the other cams like I mention above I think have lower read noise and full wells around 10kev+ at those low noise gain settings. Much easier to get a clean picture without having to resort to super short exposures. Also, I can't seem to move the quote block on my phone, so I guess it lives there now haha. Sorry!

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.