pipnina

Same here. I look in mine and see rust and during operation it sometimes stops and needs to be off-on cycled so I fear repair could be in its future... Or the crashes are purely software based...

The film cost was that high!?!? Was Kodak tech pan that dear or are we talking about some sort of scientific glass plate that's hypered, high speed but fine grain, and comes in sizes of 4x5 inches at the smallest and requires cooling and gases to store? A normal colour roll of 35mm or 120 was quite affordable until only very recently when the costs rocketed up.

The sky at my home has an Exposure Value (EV) of about -5.5 or so, and it's already dark enough that the ground is very hard to see even once I'm adjusted. However a place near me is much darker, dark enough to see the MW core and even sometimes the outer spirals, which means it's probably closer to EV-7 or even EV-8, I can see the ground at this level but not clearly. I would guess if it were just the MW core in the sky and no sky glow at all, I'd struggle to see any ground at all as you say. The milky way just isn't that bright!

It may be different up north where you are, but in devon I can manage about 1.5-2 hours of imaging during the astro dark holiday if weather permits, and with narrowband imaging I can get away with a bit more. The brightest sky I see from that period here is when the moon is out, which means a moonless night in that time window is still better than normal full moon conditions, under which I'd either image a target at opposite sides of the sky to the moon, or use narrowband, and my results are usually somewhat decent as the last few years the summer period has had a good number of clear nights so I can make one target a multi-night project (relative to UK average...)

Wait noise adds with the square root?? How does this work?

I want to improve the speed of my setup. I worked out that if shooting only RGB then the ASI 2400MC would afford me effectively the same resolution image as my RisingCam 571 (6000x4000) but with a wider FOV due to the larger pixels, since I am speeding up my imaging with a normal camera lens I expect that would be best for star shapes anyway, while affording me a 1 stop boost to my speed (so 6.2x faster than my RisingCam+ f5 scope) However it means narrowband (My main interest turned out to be Halpha only really, not worried about the loss of SII and OIII) becomes much less efficient as only one subpixel gathers data for it. If I got the ASI 6200MM I can keep my narrowband capacity but with the 3.76 micron pixel size, the same as my RisingCam, I won't gain the speed increase as I would with the 2400MC. Unless, I binned. A 3200x4800 image might be a little small for me but could be servicable. However this increases the effective read noise by a factor of four even though in theory is gives me a 2 stop light sampling boost right? So am I worse off with the 6200MM and should stick to RGB imaging with the 2400MC if I want speed, and simply forgoe narrowband for now? Interested to hear thoughts. Thanks

I only have a cursory knowledge of electrics in motors in general, but I think as a motor spins faster the magnetic back force increases which means you need yet higher voltage to move the motor. I'd guess if voltage correlates to max speed it's because of that. Holding torque I'd guess would be current based as the strength of the magnetic field is proportional to current and not voltage.

The number of bars on the rotor shows you the step angle. A 1.8 degree motor will have 100 bars on the stator and 98(IIRC) on the rotor. A 0.9 deg motor will have twice as many. Yours certainly looks like an 1.8 to me

I bought one of these and it seems to be quite good Of course it will be most effective once the sun goes down. You can position it some distance away while your camera is on a tripod, focus on it and the picture will show you the sharpness you can expect from stars. Just adjust the camera's orientation to position the fake star at different parts of the frame: https://www.firstlightoptics.com/other-collimation-tools/hubble-optics-5-star-artificial-star.html For smaller camera lenses (nifty fifties?) I'd guess the larger holes will be suitable and nice and bright once more than 10m away. For bigger lenses ideally you want as much distance as possible. Most lenses will decrease in quality as you focus closer.

This lens does have a built in motor, and given it was designed in 1987 that's definitely way ahead of its time as Nikon would use the in-camera motor until I think the 2000s. I suspect the need for the motor to be insanely fast to track sports and wildlife led to this design choice. The lens from reviews I've seen almost literally snaps into position on subjects, and this lens is big, so moving it (and quickly too) would put a lot of strain on a wimpy in-camera motor I think. Regardless, all manufacturers use in-lens motors now and only pro tier nikon DSLRs have the built in motor for legacy lens support (Nikon D850, D7500 and similar). The bit that irks me is not being able to manually focus the lens AT ALL without it being powered. But then the lens wasn't designed for people who would care about that I assume...

Ah yes you're right there is only the original lens (the one I got, from 1987 https://global.canon/en/c-museum/product/ef270.html) Which is not IS but does have the ultrasonic motor. Then the subsequent 2 versions are simply IS USM and IS USM II. I just re-checked the ebay listing and they don't mention broken motors. I suspect I got it uncontested because of the very minor damage to the front element (two small chips, noticable but I suspect not ruinous to the image, won't know for sure until I can test it though!) I still have my fingers crossed (now that I've been re-injected with hope due to this adapter) that it'll prove a very suitable replacement for my telescope.

Sergey from Astromechanics replied to me earlier, managed to work out a way for me to pay and that the UK does not impose the same restrictions as the EU so they can deliver it to me directly. They suggested 12-20 days on average until it should arrive, I await it patiently and thank you guys for letting me know of its existence! Feels a bit wrong to buy from russia at this time but alas it seems they are the only ones who have made the exact part I need.

My goodness! If I can get my hands on one of those it'd be just the ticket! It would solve the challenge of autofocusing as well which requires some jury rigging on manual focus lenses. I've sent them an email as their website seems to suggest the UK doesn't impose the same level of sanctions as the EU... I await their response. I'll hold onto the lens for a bit to see if I can get hold of the adapter. If I can it might just push me over the edge to buying an asi full frame camera haha. It's been my plan to downsize from my big scope to something faster and more portable so if this lens and adapter work... I'll be over the moon! Thanks for the links both of you!

I thought I scored a real deal when I won the bid for a Canon 300mm f2.8 L (non is non usm) for only £600. Given the lens was originally over 4000 I felt pretty good about it. Until I got my hands on it today. And learned that it WILL NOT manually focus and cannot be focused AT ALL unless a canon DSLR is attached to it. So it may as well be a brick as far as my astrocam is concerned! I am beyond disappointed and to make matters worse, my normal DSLR is a Nikon so I can't even use it on that. I guess I can only hope that I can return the lens to the ebay seller and find another set of optics to try for compact and fast astro imaging unless anyone knows a way to hack it lol

Captured back in January on my 130mm f5 triplet. Forgot to post here at the time but quite pleased with the result- just wish I got another night or two to add data to it.

I have tried to do astro with my Pixel 6 in a similar way with the same app. I also ran into the same flat calibration issue. I suspect the lens suffers too greatly from internal reflections. I also noted that despite the images supposedly being RAW, it appeared as though the camera was still imparting a white balance into the image which may affect matters. I also struggled a LOT with hot pixels. Did you succeed at removing or handling them in your phone? In my case I was shooting in summer so it was 15c outside. I also did not have BlurX or NoiseX. Certainly however many differences in technique (or hardware from P6 to P7) your result is miles ahead of what I achieved!

I think Alan has created a more pleasing level of contrast and balance of colour than the photo editors of the hubble project. However one cannot deny how impossibly detailed and sharp the hubble image is (and always will be) in comparison to our meak sub-meter telescopes! Hubble images often have an almost greeny tint to them and sometimes squander the red colours. Alan has captured a beautiful blue hue in the galaxy with maybe a slight magenta lean and has produced incredibly vibrantly scarlet hydrogen. That's my take at least.

I think if this image were any better it might make Hubble blush!

Just got my first roll of Kodak Ektar developed in 35mm format. I took some astro shots and while i can't get them quite right I feel they're still worth sharing! First is this star trail shot from a local beach. 24mm lens so pretty wide angle. I can't get the shadows to stop looking red though. I don't have a proper negative scanning software so I am just trying to fix it manually. All I did here was colour balance and some contrast enhance. Was about a 40-50m exposure. This was a tracked shot of orion with my 50mm lens. My scanning job again seems less than perfect with it being a bit out of focus. Nonetheless barnard's loop, M42, flame, horsehead, rosette, and SH2-264. I dare say either my brain is wishfully thinking or the witch head is in there too! I provide it here both with only contrast and colour balance improvements and with a pixinsight gradient removal, to show how the film natively recorded the scene as well as what I was able to extract from it easily. Even the new pix gradient tool didn't tackle this image perfectly, I am not experienced enough with it yet to get perfect results. Finally I have one with the very nice 135mm f3.5 canon FD lens. Aside from a bit of blue fringing this lens handles astro very nicely. Nice detail starting to show up in M42 and the horse's head itself becomes visible as well as some veins in the flame. I couldn't get the image to look neutral in pix so I had to settle for it either looking blue or orange... Not sure why! I intend to try shots like this again but with my medium format kit. Ektar proves to be a very capable film stock for astro and the raw sensitivity to h-alpha puts any unmodified DSLR or mirrorless to shame. My RisingCam 571 is still the much more sensible choice of course. But I am having a lot of fun with film anyway!

I noticed a strange vignette on my halpha filter during the last imaging session, and shon a torch down the tube to see if it were a spider or some such. Horrifyingly I saw spiderweb like fungus had grown to cover a sizable portion of the filter. I images RGB that night but the other day I opened the filter wheel to see Multiple filters affected, red in particular but none as severely as the halpha. On chroma's website they say acetone or pure alcohol is suitable but while my acetone did remove fungus from one filter, it left a misty haze behind and so I stopped in case the impurities caused further issues! During this operation multiple filters seemed to have snapped or cracked retainer rings. I have to admit they looked cheap rubbish when I installed them from the zwo kit but I didn't expect to find £3000 worth of chroma filters held in by the screws alone... I don't seem to have any spare clips so if they're available I will have to find replacements I suppose, as I will need to remove the filters properly to give them the thorough delicate clean they need to avoid damage but I can't reasonably put them back with broken retaining clips. My next idea was to use distilled water from my film development station, which is very good stuff and leaves my negatives in pristine conditions of cleanliness as the final rinse. Pipetting it onto the filters to cause remaining dirt or residue to rinse off. Maybe using the acetone or a more pure acetone or alcohol would be better? At the same time I have to find a way to remove dried super glue from a panic repair to my EAF bracket that spilled onto the filter wheel. Acetone seems to dissolve it but so slowly I'd be there all year. I am terrified of damaging the paintwork and am trying to avoid scraping or sandpaper... Oh dear oh dear. I've often cursed myself for buying chromas instead of far cheaper but nearly identical Baader or Astronomik but now with fungus issues I'd really really rather have cheaper filters that would be less stressful to clean! Thanks in advance for advice! James

To what extent do you process a mosaic like this? I would need to do complex things like background extraction for wide field work like this normally. I assume this was with your dual pentax 67 rig, what lenses and aperture did you use, and if you stopped down did you use special stop rings instead of the in-lens blades? It's certainly better than a lot of DSLR images I've taken, albeit those were on an old camera at APS-C format so about 9x less capturing area per exposure. If I had skies as dark as yours presumably are I'd be most pleased too haha.

Impressive nonetheless Sort of surprised if you'd shoot so many rolls in one go that you didn't end up with a camera that had one of these bad boy backs on it haha

I'm not so sure about this horseless carriage business either, sounds like a fad to me! 🤣 I've just had a proper look through your Flickr and I have to say your collection of BW film images, not to mention the astro ones, are simply inspiring. I am still early on in my film astro attempts (despite working on it for a year now, cursed weather!) but having poured over datasheets it seems either Ilford Delta 400 or Fomapan 400 would be the best choices for astro work despite their high reciprocity failure, simply because they are the rare black and white films that have the deeper red sensitivity for Halpha. I can imagine Acros/Acros II being pretty good in that it's fine grain and has no reciprocity failure up to 120s and only 1/2 a stop is lost afterwards, but if we factor in the removal of reciprocity from your 60 minute image (45min?) and then take into account the improved sensitivity of Foma400, meaning it would need about 20-ish minutes of exposure, and then factor in my estimate for Foma400's reciprocity failure factor (roughly MT^1.454) we come to about 15 minutes saved in exposure time, at the cost of some grain, but in doing so we also gain a lot of hydrogen sensitivity which Acros lacks entirely. The difference would be even more stark (I intend to verify once weather improves) with Delta400 as it can reach 500 iso in microphen vs Foma400's 320, and has a lower reciprocity factor of 1.41 while (if the datasheet is accurate) still having Ha sensitivity. Not intended as a lecture, but I am curious at your process and reasoning, maybe you leave out hydrogen purely for artistic purposes? Thanks for your time. Here's a negative (Foma400) I am not yet ready to scan properly and as such can only provide a simple phone scan. But I have high hopes for it. Foma400 in microphen, 16m at f3.5, Bronica ETRS with Zenzanon 150mm pe.

I shot a roll of Velvia 100 last year and although I butchered the exposure on most of the images I have to agree with your assessment 100% Looking at one of the good slides I have placed on my flat panel is pretty magical. No manipulation required besides that which was baked into the emulsion at the factory. I think when HDR tech catches up we'll be able to make a similar effect on a digital screen. I think velvia has a contract ratio of something like 3/4k:1 whereas a very good SDR digital screen has 1.2k:1, and looks washed out in comparison. I tried viewing my astro photos on the OLED TV but the peak brightness isn't there to make it pop, and the TV has a not-exactly-calibrated contrast curve which made my deep grey sky background black clipped which looked quite ugly. A bit like how it took LCD screens a long time to truly surpass CRTs on all fronts, I think we still have a bit left to go before digital displays beat the last edge case holdouts of slide quality.

Is that a large format sheet? I'd love to know what your setup is!