pipnina

Back in the 90s it was seemingly the only way to produce colour digital cameras and camcorders that had any quality to them, albeit they used 1/3 sized sensors and the units still cost $3000 in the case of this sony camcorder: This is a revised model from 2003 which seems to have used the same 3CCD system but likely lower noise / higher efficiency sensors. It seems reasonably well corrected. The limited information I have found suggests it can result in reflections and it limits the system to a slower f-ratio due to the light path length, but us astrophotographers often have telescopes of f5+ which most "normal" photographers would consider quite slow these days. Technicolour used a two-beam prism for their 3-colour camera in the 30s to the 50s (the camera that shot the now infamous wizard of oz film), so the idea goes back some ways although in this case it was not to maximise light use, but to allow for colour cinematography to exist at all: I do note that it seems to be that the JWST NIRCAM instrument uses a dichroic beamsplitter (so a two-channel prism most likely? exact details are a bit vague) to allow the instrument to observe one filter of longer wavelengths, and another filter of shorter wavelengths at the same time. Why they didn't extend it to 3, 4, or even further simulaneously acting cameras is anyone's guess... But being a space telescope I would have to bet it comes down to launch payload weight, and following that cost. But quite frankly with 10.5 billion dollars you can probably make almost any idea work so perhaps this isn't too indicative of the tech's feasability haha.

The extra focusers are not necessarily a problem as a helical one similar to those used for OAGs can be used for 2/3 of the cameras, which can be accurate if used in conjunction with a bahtinov mask for initial setup. All focusing after that can be carried out with just the main focuser as the 3 cameras would be appropriately spaced to the 3 focal planes and thermal expansion would be minimal in that area relative to the that of the main objective to the main focuser. As for cost, in theory this is cheaper than dual or triple mounting telescopes to a single mount or having three separate setups, and was clearly cheap enough to use in pro-sumer equipment back in the 90s, so I feel like it could be quite viable in theory! Backfocus could be an issue though yes, it would probably either have to be used in place of, or as part of an OAG-prism combined unit..

I don't know about historic interest but I have been trying to capture stuff on my dad's old Canon AE1-program and various films. I made an attempt on Rollei Infrared 400iso but despite 6 minute+ exposures there was little to see as the reciprocity failure of the film is very high. I then made an attempt on Illford 3200 Delta which promised less reciprocity failure and ok sensitivity for h-alpha but the extreme grain proved unworkable I am waiting for my roll of Fujifilm Velvia 100 to be developed now, which only has 2/3 of a stop reciprocity failure at 8 minute as per spec sheet and SHOULD have high sensitivity to halpha. However, the film also was used to take my germany holiday snaps and I wasn't able to stop the people at various airports from running it through their xray machines 😕. Velvia is expensive stuff too at 22 quid for the roll and then another 20 for development! More than a pound per snap! To top it all off nowhere I can find will give me anything better than an 8-bit tiff scan (and these images are as I was provided them... in processes jpeg form 🤮) To say film astro is challenging would be an understatement!

OIII and Ha alone on the trunk should produce a nice image Many go further and add SII but HOO is still very nice on many targets like the trunk neb. By and large I think you can expect similar to other nebulae imaged in HOO, where the hydrogen looks red-pinky and the oxygen adds a blue and pale hue to certain regions. I am not very good at HOO processing as I think for some people there is some wizardry involved to give it that extra edge but I think you'll probably be pleased with your results if you go for HOO here!

I personally used water and cotton balls Rinse with water to remove the worst of the dirt non-abrasively. Then I use wet cotton balls to wipe once on each side of the ball in one direction to remove the last of the dust Any blobs of water left will leave minerals behind so take dry cotton balls and gently touch them to any drops to soak them up. Cleaned up my newt mirrors nicely at least. Your cleaning method seems to have worked really well! I love seeing a nice quality and clean mirror

Yes this should work! I have used home versions of windows since xp and afaik all have been able to remote into eachother with the microsoft inbuilt tool I haven't used windows for a few years now though (for more than a few minutes or for more than using a web browser) and whenever I do I am filled with rage so sadly I can't be too much more help haha.

https://en.wikipedia.org/wiki/Dichroic_prism I read about the Technicolour 3-colour process and how it used 3 black and white films running through the camera at once, splitting the light into purple and green with a prism and capturing green on one film, then blue and red on two films that ran sandwiched against eachother and where one film had a filter in its backing to create red and blue. I saw this and realised my old obsessive thoughts about minimising telescope photon waste could be compatible. As we know, if we shoot RGB images we must lose 2/3 of the light entering our scope. Either to bayer filters (which knock red and blue down to 1/4 efficiency and green to 1/2) or to our RGB dichroic filters in mono cam systems... But what if we could use 3 sensors and a prism to get closer to 90%+ utilisation in this range? Well it seems at the slower speeds (f5+?) we tend to see in our typical astro scope this could work. Back in the early days of digital sensors, this setup (3CCD cameras) was done to maximise resolution and quality in the earliest DSLRs and camcorders, to results that looked fine colour wise but were seriously held back by the noisy low efficiency sensors. But now our sensors are super efficient, our ability to make these prisms hasn't disappeared and astro seems like the perfect modern use for the technology! Instead of buying 3 mono cams and three telescopes and (potentially) three mounts, we could get the same result with three cameras, ONE telescope and ONE mount! In theory you could even expand on this by having not just an RGB prism but a SHO prism too, and capture narrowband images at insane speed for your preferred telescope type. Who knows, maybe with some design tweaking it would even be possible to create a very complex prism to allow the simulaneous capture of all 6 common astro bands at once haha. Does anyone know more about these? I have become a little fascinated...

This sounds similar to a video by an optics youtuber (very impressive videos) who tried to use the same principle to make a variable shape mirror I like the ingenuity of the design principle!

I had not noticed this in winter, but now that I am doing shorter narrowband imaging stints during twilight months I have seen my focus slipping through the night. Due to the good weather I have kept my scope outside, and I suspect as it is a carbon-reinforced plastic construction of some thickness, it is absorbing a great deal of heat from the sun during the day. At night, I will autofocus at the start of my session, however I have noticed that my focus is quite poor by night's end. Last night I set it up to refocus every 45 minutes (3 focuses total, as I forgot to ask it to focus at the start, oops!) This resulted in a total change of 55 ZWO EAF steps between first focus and last focus. A rather considerable change. And since this is on a R&P focuser I don't believe the focuser itself is moving between focuses. Could it just be that the tube is getting very hot in the day and slowly cooling off at night, leading to dramatic thermal contraction? Curious if others experience this issue, or if there is a remedy to this that doesn't involve air conditioning the scope during the day to match the forecast night's temps haha.

My anecdotal evidence would suggest that better PA usually results in better guiding. But only to a point. Sub-minute is what i aim for and often get 0.4 to 0.6 total RMS on my belt mod HEQ5 with an overweight (unbalanced) load. I sometimes forget to polar align... And it ends up 2-3 degrees out. I might still get sorta-ok guiding but not for the 1.2s/pix scale i image at (about 1-1.2RMS common here, plus likely to see some rotation through the night)

As for the animal assistance mentioned in this thread: Whenever I go out to the garden to observe or image, I get a little fluffy assistant (bengal cat called Winston) who sits by the apple tree and watches me. Whenever I go to walk back inside he pounces on my feet

Since pumpkins are not native to Europe (an American veg) it actually was traditional to celebrate All Saints Day (IIRC four days of Halloween back then) by giving out food to the poor (sweet cakes, or apples and pears if you didn't have those) and by putting candles (at the time, very expensive) into hollowed out turnips to "keep the bad spirits away". So actually you were practicing the original British tradition

I got an email from the kstars bugtracker system as I added to another person's report on this bug, a developer has marked it as fixed in git, and the fix should be released in 3.6.5 which is great!

The thing is, these kstars-bleeding packages give me 3.6.4 which reports itself as a stable release in the about tab. 😕

With so many equipment (mostly software) bugs recently I needed a win of some sort. A big mosaic might not have been the best idea as I have never made one successfully before, yet somehow both the images captured properly, AND I wrangled PixInsight to produce the images correctly the next day! I thought I'd need to spend ages wrestling the images to be the same brightness, but the merge mosaic feature (once tuned a bit) seems to have pulled it off without me having to bash my head against a wall using linear fit. Well chuffed, now I wish I had more imaging time to make it look clean when you zoom in haha. Captured with HEQ5, 130/650mm triplet, RisingCam571 mono, 3nm Chroma Ha filter, processed in Pix and then tweaked in RawTherapee. 10 panels, and one single sub of 10 minute exposure per panel.

Kstars generally worked quite well when I picked it up early last year, and there's been a few cool features since. But when they started adding the optical train system (as good as it could be for multi-scope control) it started getting very dodgy. On my laptop a while back the optical trains would get a mind of their own. Deciding that my scope in fact did not have a reducer and refusing to let me save changes to 0.8x, crashing during autofocus capture, and now trying to even edit the optical trains that I MUST use on current kstars versions crashes the program, making it impossible to use at all. This happens on my EndeavourOS (Arch) computer, as well as my Ubuntu 20.04 laptop and my Lenovo ThinkCentre with Ubuntu MATE 22.04. I get my Kstars and indi from the following commands: sudo apt-add-repository ppa:mutlaqja/ppa sudo apt-get update sudo apt-get install indi-full kstars-bleeding And on Endeavour I used just "yay -S kstars" Meanwhile the indi driver seems to have updated for my RisingCam 571 and now Kstars and Indi cannot control the offset used, it is always 0 resulting in very suboptimal results in narrowband images (a lot of 0 ADU pixels in 2 minute Ha subs last night for the brief time I had it working, the Lenovo had Kstars working very briefly...) Is this a known issue with the most recent branches, should I be seeking to go back to the previous version packaged with ubuntu 22.04? And is there any way at all to solve this Touptek driver issue, because of all the problems I have had to deal with I was not expecting this one 😕 Many thanks to anyone who can help

if the sensor is moving, then that implies the collimation is being thrown off at the focuser via slopping perhaps? If that's rigid, I dunno why your flats would be unbalanced... It is possible though that the flat panel being close to the aperture is allowing light into the focuser, this could potentially cause a visible issue... However the only other possible cause might be that the flats are overcorrecting. If your flats and lights are collected with an offset, try calibrating with input pedestal set to match the ADU value of the offset (the median pixel value in a bias frame)

Is this on the 200P? I didn't have any issues with my 130-PDS in this reagard, however I struggled endlessly to get my mirrors to stay put on my TS-PHOTON 8" My conclusion has been that smaller mirrors can be held securely far more easily, and even the simple step up to 8" can make a world of difference to the rigidity required. Out of interest, have you tried using a laser collimator, and turning the scope in the mount and seeing if the return point of the laser moves as the scope flips around? This revealed a lot of things in my photon.

I just noticed you process in Pix, is your SPCC still not working as per the other thread? I have found once that has been done I basically need not touch the colour besides some saturation tweaking.

Some cameras have multiple filters, some only have one. Dichroic coatings can be used to make a single glass surface allow 400-650nm to pass to the sensor while blocking both the UV and IR that the sensor is otherwise sensitive to, so multiple pieces of glass is sort of unnecessary. My Nikon only had one filter, but the canon I modded had two. interestingly both filtered the light from my NIR optical mouse! (light I can see with my eyes, faintly) I wonder what target is best for this type of camera... Perhaps a dusty region like the iris nebula or ghost nebula? As those IFN clouds seem to be visible at many many wavelengths.

I think planetary imagers often use IR to get higher contrast in some situations, but for deep sky there is limited use. You can use it to capture stars through dust clouds, as well as more distant galaxies that would otherwise be invisible at optical lengths, but your sensitivity is going to be much lower and most of the "interesting" stuff is going to be gone with the optical information!

I picked up a £400 3" R&P by TS. I figured for visual I might like a super-smooth and high quality focuser, but for imaging I could cut the corner a bit as smooth feeling when focusing wouldn't matter when it's only moved by stepper motor! Unfortunately the 3" TS R&P is a little floppy, and unless the brass screws are done up TOO tightly to allow it to rotate, it flops position in an optically detrimental way as the telescope slews... Maybe there's a middle ground here but it's very frustrating! I have thought since, if the extra spend on the FT equivalent would have been worth it...

It says 500+ sources found, yet claims to have no stars... Hmm Might be a good idea to share an image that is failing, I (and others here) will likely have a try at it ourselves and see if we have the same issue, or if we can find good settings for it.

Looking good! I dare say as well, that I think despite the short exposure you have detected a little IFN! I recognise this very faint 'M' shape, barely visible. But it is part of the IFN around M81! Not bad for only 1.5 hours of RGB To take it a little further, I could recommend tweaking the colour balance to make the image a bit warmer, as it seems a bit cool at present. Happy imaging!

I've attempted something similar. My focuser has a built in rotation feature but sadly it slops when not done up so tight, that it won't rotate any more 😕 (3 brass screws allow rotation, another one thumbscrew locks and unlocks rotation, the brass ones need to be done up every time it's moved for some reason) Glad yours is working however! That looks like roughly what I wanted to achieve with mine!