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pipnina

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Everything posted by pipnina

  1. Looks good! The only advice I would give here is to pull the green curve down a little, and it should let those blues, yellows and browns in the galaxy shine!
  2. One thing I will add though is that the results at the eyepiece and or camera are the proof that's in the pudding: A flawed star test could help diagnose a problem, but if you are observing or imaging and the views seem good already, then performing a star test is just looking for an itch to scratch!
  3. You could just be seeing the effect of the spiders, which could give the airy disk a slightly boxy look compared to what you'd normally expect. this image from google suggests it could be affected
  4. Aside from the atmosphere attenuating light exceptionally fast as you move through the 400-300nm range, sensor sensitivity falls off too as a double whammy. And for most commercial amateur telescopes you have a triple-nail in the UV observing coffin where most mirrors are dichroic coated (not aluminium) and have very low reflectance outside the visible spectrum, as per this chart from a listing of the GSO 6" RC you can see that the reflectivity to UV light falls off to only 40% by the time you hit 388nm, and seems to fall very rapidly thereafter. These three factors are likely the reason why any UV image is faint. I suspect venus is only possible to image so readily in the near UV is because it is so very bright.
  5. You bringing up negative bananas, null bananas and programming reminds me of a joke. "The developer walks into the bar, orders a beer, orders 10 beers, orders -1 beers, orders fjedfjdiofjiowejfwe, and leaves. The QA tester walks into the bar, asks where the toilets are and the bar catches fire"
  6. Ektachrome 100 seems almost identical to Fuji Velvia when it comes to the spectral response and exposure compensation figures. It does seem they are two of very few films that don't clip out the Halpha line while also staying in a sensible wavelength range for the type of lens you could use (without spending silly money). Black and white films like Ilford SFX200 and Rollei Infrared are sensitive up to 750-800nm+ but they could suffer some focusing and or CA difficulties, potentially... Maybe I am overthinking how precice E6's temp needs to be haha. I was believing even a 1c change could be disastrous but if it's possible in a bath tub then small variations must be somewhat acceptable I guess...
  7. That sounds like some project. You'd need to find an adapter to convert the old lens mount to a telescope thread for one! As for the mirrors, it depends a bit in where the damage is I guess? If it's close enough to the center on either mirror then in theory you can just paint black over the marks without any I'll affect. On the primary you could get away with that anywhere possibily? Else it's a matter of a whole recoat!
  8. E6 process at home seems very complex to me! I have looked into development a little and seen that B&W is supposedly dead easy. C41 is much the same just with two extra steps, and E6 is yet more complex, with the added caveat that it must be performed with all the chemicals at 37.5c! Apparently getting that temp wrong leads to colour shift and all sorts 😬 I haven't looked into Portra yet but i have shot Delta 3200. I took this image as Orion was sinking earlier this year: This was shot on a Canon AE1-Program, Ilford Delta 3200 as said above, using a (crumby) vivitar 35-105mm lens set wide open at f3.5. Exposure time? 26 minutes! This shot was unguided on my star adventurer (original model in the white-green refresh colour). I am surprised there was no drift but as you can see, the film at that ISO is VERY VERY grainy and my wide-open and low quality zoom lens doesn't help matters either. I am still working on film astro, my latest attempt being on Fuji Velvia 100 which claims nearly no reciprocity failure by comparison. However I still underexposed by probably about 2-3 stops (exposure at 6 minutes f5.6 in shot below) so next time I plan on either using a faster lens or taking another set of shots between 20 and 40 minutes long. You have to look out with these films too, check the data sheet always! Most films lose all sensitivity just before 650nm, which cuts out our precious hydrogen line! It's like the infamous DSLR ir blocking filter but it blocks 100% instead of 75%!
  9. I am. The video i posted was for films shot in 2021. It might not be as popular, and is likely reserved for the films with budget to blow on millions of dollars worth of celluloid, but it's still being used. And they wouldn't use it if there wasn't SOME niche for it in filmmaking.
  10. I went to a Saturn when I was in Dusseldorf (big tech chain like Currys in the UK) and they had NEW polaroids in their camera section! Local London Camera Exchange near me stocks polaroid film too. Normal negative and slides are also having a resurgence, but maybe not quite to the same level. I also agree that digital sensors do allow for much more contortion of a scene, they're more scientific, easier to get results from, you get instant results etc etc. But big budget films to this day get shot on celluloid, and there has to be a reason for that! medium-format (60mm) Kodak cine film costs thousands of US dollars per 5 minute roll, the hollywood DPs wouldn't push to buy that equipment if they didn't see value in it!
  11. 2022 and 2023 were processed in pixinsight, with small tweaks in RawTherapee afterwards. I use RawTherapee for things like colour noise reduction (it has a good algorithm for it compared to pix) and tweaking certain colours. In the 2023 version for example, the pink hydrogen regions were too intense after the pixinsight colour boost, so I adjusted the image's colour in RawTherapee using the LAB colour mode to bring the nebula saturation down a bit. The big differences here come from the x suite improving the base data and a different approach to editing the image in the first place. I used spectrophotometric colour calibration, I used a fix i found for my overcorrecting flats and that improved DBE performance. I also used curves and stretches more effectively I think too.
  12. I am a fan of the laser collimator, however I also believe they must must must be used *with* the correcting lenses and other accessories on the focuser. All those joints between focuser and camera can have small mis-alignments which you want to take into account when collimating your scope, so just take the camera off and (if possible) screw the collimator on for the best possible result (use collimator with corrector/oag/filter wheel etc) You also will want a v-block or two supported bearings to collimate the laser, as it is unlikely to be perfectly collimated itself from the factory.
  13. When I took this image in 2022 (about 4 hours or so of data if I recall) I thought it was really good, and definitely the best I'd come out with to that point. Having tried the x suite, I went back to older images and figured I'd see what I could do with it on my 2022 M33 attempt. After using blur-x and noise-x and working with the resulting image (all before stretching) I wound up with an image that's almost impossible to believe came from the same data set. So here's my 2023 x suite process of my old triangulum data. Any suggestions and feedback welcome of course, but I am over the moon with the result this time around! And for comparison the original 2022 process:
  14. I can't share the horror at the mast's appearance, albeit I think they could put some effort in to make it look nicer, such as disguising them as trees (or even planting grown trees with the antennas near the top) Super fast phone internet is a bit silly to me, as what customers really want are *usable* speeds and broad coverage, which is typically offered by 4g and 5g in cities but can barely be found at all in more rural areas. Why do we need more than 5g? 5g already supposedly covers a very wide range of uses from insane speeds (millimeter wavelengths that are fast and high capacity but require totally uninterrupted line of sight, all the way to long microwaves that are able to penetrate deep into buildings) I would argue that while many of us are quite happy with our internet, I myself enjoy a cozy 300+mbps download and 25mbps upload, there are many many people who have connections too slow to be considered bearable if you have any use beyond browsing internet forums! I have a friend near Durham, who moved into a new house that was advertised as having fiber internet, only to discover that it is actually a very very BT-neglected ADSL line that can't manage sustained download speeds of more than 1MBps, and it is often slower. Add to that that their freeview TV mast was burned down for 2 years before it was repaired and they were quite unhappy. BT wanted £15'000 to run the fiber cable the next 30 meters down the street to them. Many in even more rural areas lack even ADSL internet, especially in larger countries like the US or australia, or poor/developing countries, or worse countries where internet is restricted like Cuba. For all these people, LEO satellite internet is a godsend even if it's not as cheap as cable in cities. I fully understand and see its importance and yet I despise that it must exist in such a way, and I also am very fearful for China, India, and possibly other countries or even private industries all wanting their own totally unique network! One good internationally supplied and protected LEO sat internet is enough... More networks is just pointless wastes of money, sky ruining, and likely the work of the worst aspects of human society: Regimes and Publicly listed corporations.
  15. I do find my HEQ5 a little variable. Some nights I am pulling RMS at 0.35 seconds, at its worst when there's any wind at all it'll end up around 0.6-0.7. Before tuning it was guiding above 1s. I do agree it punches above its weight class however. Mine is also "overburdened" to the point where the 2 5kg weights provided are nowhere near sufficient to balance it. Yet it still performs well most of the time? I think the big weakness as always is wind. My new refractor has a much smaller wind profile than my old 8-inch which was a lighter setup. Ultimately I think weight is a far less important factor with mounts (unless you're way way overburdening them!) than their rigidity against the wind... Which may correlate with their weight rating but probably won't be exact. Manufacturers probably aren't being super scientific with their method of working out the max weight anyway!
  16. And yet people still partake in horse races and take cart rides as a tourist and holiday activity, sometimes things are not done because they're practical but because we just enjoy them or are interested in the methodology! I personally quite like how tactile the film shots I've done have been, even though my attempts at astro film havent been so successful!
  17. If I've put that reciprocity failure equation into the desmos calculator correctly, the 0.7 reciprocity factor is very extreme! I believe I've set it up so the x axis regards to metered exposure, and y is the corrected exposure for said meter. In theory modern films might be a lot better for reciprocity failure than those of old if 0.7 was typical then. As the worst reciprocity film i've used so far has been Rollei infrared (line chart for such below) and the best one so far is velvia 100 which only has a table (also below) Fuji across II 100 claims only 1/2 stop correction between 120 and 1000 seconds, and no correction up to 120 seconds!
  18. I've received the scans for my Velvia shoot, the film itself should be with me this week at some point in the post. Sadly the space images are very dark, despite my attempts to meter it correctly! I suspect perhaps the meter in the Canon AE1-program cannot handle the dark conditions present and passed me a reading several stops brighter than I actually needed. This is the result of the image I took intentionally 1 stop over-exposing in Cygnus (deneb and sadr in left and upper center). The jpeg attached is heavily boosted so the stars can be seen clearly. This is under bortle 5 skies at a 6 min exposure, on velvia 100 and at f5.6. I note the stars are creating odd shadows too, I don't know if this is due to the film stock itself... or because I let the film sit at room temp for too long before getting it processed! None of the more normal photos I took had this issue. Will have to see what (if anything) is visible on the film itself when I receive it.
  19. Indeed higher ISO films are quite untasteful. See my orion image above which was captured on Illford Delta 3200! Even 400iso is a bit questionable, here's a (slightly underexposed) 400iso image i took on rollei infrared And here's a 200iso shot (A fuji colour stock I got in 2018, can't remember which type exactly), the grain is noticeable here too!
  20. You can buy 5x4 and larger sheets from various companies including kodak and Fujifilm as well Velvia 100 is available in 5x4 but you will be paying like 140 quid for a 20 sheet box! Then you have to pay for development...
  21. Most cities have one or more shops dedicated to just film photography! There's two in my small westcountry city, and I went to one in my Germany trip too which was sat right up against the Kölner Dom Your selection of films is limited however, and may shrink further as Fujifilm seems to be having various troubles getting raw material for their existing formulas, and some of their best stock (velvia 100) is actually banned in the USA for containing certain chemicals their agencies aren't happy with. You can still get film developed, scanned and printed at Boots pharmacies (only specific stores though) but by the sounds of things they aren't as good as many non-chain options.
  22. Cameras now have micro lenses, and now that you mention it I recall a special kind of camera that uses a similar trick to bypass the need for perfect focus by having the lens bring different sub-pixels underneath it to a different focal plane, allowing for software controlled focus in post-production. I recall as well a type of camera used in professional telescopes which might use EXACTLY what you describe, they act as per-pixel spectrometers but I think they only work at a narrow range of wavelengths near to the central wavelength observed or some other restriction. If they were perfect the pros would use them instead of dichroics!
  23. 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.
  24. 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..
  25. 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!
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