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narrowbandpaul

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Everything posted by narrowbandpaul

  1. As others have said there is no formula. The ideal number is an infinite amount of all frames. If you get near this you will have done well. I like combining a ton of bias frames. It can show sub electron fixed pattern noise. I once used >1000 which was interesting. Using the subframe feature in maxim kept download times and file size down. Paul
  2. Nice strong colours there. Lots to like. That's a good andromeda you got there
  3. Nice images Stuart, Why do you advise to increase ISO and shorten exposure time? There is a big myth surrounding ISO and that is increasing the ISO somehow gets you more data just because the image looks bright. If you point as scope and open the [removed word] for identical times you will get the same number of photons. That is a fact. I wouldn't advise shortening subs to get more of them. I advise using 15 mins where possible and getting more of them, along with the extra calibration that I was referring to. Yes you need to have sufficient quantities for a good sigma reject but not at the ex
  4. It's a reasonable assertion that when RGB imaging (or true colour) the colour of the object should represent how it actually appears. That's kind of the point in RGB. Yes you have liberty to process certain features if you want, but overall it should be a faithful representation. More or less all bets are off for emission line, where transitions in atoms are represented by colour. This is a false colour if you like as if viewed by the eye it would not appear this colour. Any narrowband image will have weird colours compared to RGB. There is more scope of artistic licence. There is a rather hea
  5. 5 darks aren't really enough. You need to reduce the random component of the darks (which you do by taking a bunch and "averaging") so you will end up injecting the random component in to your corrected image. To really maximise your DSLR you will need a very good calibration. A very good set of darks and flats and bias frames to remove all the possible noise sources. Kudos for the use of 15min subs, this is helping a lot. Overall it's a very nice image, but your calibration frames could certainly be improved. You need more flats and bias frames. I know getting darks with a DSLR is very tough
  6. Thanks guys. Narrowband makes stuff colourful, its part of its charm, at least for me. The HDR was a pain as the software is meant for daytime dslr images. I had to make 3 separate colour images rather than an HDR on a per filter basis. Still it did a good job with just 30mins per filter. Olly, definitely need more subs, the longest was just 6 mins and theres only 5 of them. Im thinking 15mins at least and about 6 of them. That will help the SNR in the faint dust. I will also take a few maybe 30s shots to really keep the core tight. Paul PS image is a collaborative effort between myself and a
  7. I don't know if there is any benefit in making a pseudo luminance from Ha+S2+O3. Rather than a 1:1:1 weighting you could say 0.5Ha+2O3+2S2....or something like that. Thought should help emphasize the weaker lines, but I'm not sure if it would look daft. Might give it a look. Paul
  8. I would like to grab more data on this of course. Some trees have blown down allowing for more time during the evening to image. The longest subs were just 6 mins..... not bad considering. Paul
  9. Hi All Data taken with QSI583 and TMB130 The first image is a fairly standard, though slightly overcooked image of M42, using the shorter subs. The second is a colourful image focussing on the core And the third is an HDR composite I made using Luminance HDR (I dont have PS). About 30mins per filter. I quite like this effect.... Enjoy Paul
  10. Even still, it would have the same spatial distribution. It wouldn't be able to highlight the compression areas. It's ok for Hbeta as it will have the same distribution as Ha only at a reduced intensity (in the absence of dust). Agreed with Orion, the bar near the centre shows up well in the S2 image. As an experiment why not take an Ha image and make it look like the S2 image that you have for the same object. Not just the same brightness but the brightness in the same places. I'll bet it is extraordinarily difficult to make the Ha look virtually identical to the Ha. To get this right withou
  11. Thanks all. This was my 5th version. With no clear skies up here I have taken to messing about, trying different methods and techniques. I think I am getting better even without using any photoshop. Just maxim and ImagesPlus 2.8...well behind the times now! My normal method for NB is to stretch each channel individually and then combine and adjust. Normally I process Ha first but this leads to me maxing the HA data and in response murdering the SII and OIII. In this case I processed them first then the Ha to match. It stops the Weak channel from being blown out by the much stronger Ha. Tim, I
  12. Hi All, The Christmas favourite of the rosette nebula. Borg 71 at f/4. 4x15 Ha 8x15 OIII 8x15 SII Enjoy Paul
  13. Wasn't asking for help processing it. More an opinion on the image itself.
  14. Three hours! Wow, that is long! Have you a link to some of these long subs? Looks like the biggest effect then comes from the read noise limited area. The long sub trumping the combination of many. Paul
  15. Very nice Tim. I believe you are a fan of the very long sub. What your record so far? Happy new year Paul
  16. Is it pretty pictures you are after or are you trying to do some science. I ask as the leader of the club is a physics teacher. Is it LRGB imaging you want to do? This is fine for galaxies but emission nebula also respond well to emission line imaging. As far as cameras go, I would suggest that you consider other cameras than just SBIG. QSI are of similar quality and FLI are in general one of the best. Buying these though you will get hit on the exchange rate and import tax. Buying from the states usually means you pay the same value in £. Atik and Starlight Xpress are both European. As are Mo
  17. I was really rushed in that last post. Let me complete it. Captured back in early Dec with TMB130, QSI583, Astrodon 3nm filters. Taken on EQ6 guided by MGEM. The Oxygen data was a stack of 3x2mins and the sulphur is 5x6mins. Let me explain the timings. The regular SII OIII and Ha data was captured as a HDR image. With 2 min subs used for the core. I was playing about with just the short subs except I pinched the trapezium from the short SII subs and placed them in the longer subs. This didn't work for the oxygen data. Hence the 3x2 for OIII but the longer SII data. If that makes sense. This w
  18. Hi All Just messing around with data really, but combine some short subs of orion using only the SII and OIII. SII is red and OIII is blue. No green at all. This should highlight the diifferent areas within the nebula, with blue representing all the hot stuff and the reds showing compression of the gas. Its quite a gaudy image but hey ho, its a bit different. Opinions welcomed Might take a look at other data with no Ha! Enjoy, Paul
  19. I would set it up in daylight and try to focus on something as far away as possible. Check that when you turn the focuser knobs the focuser actually moves in and out. I would always start with the longest focal length eyepiece as it will give the widest view and make finding things easier. Good luck Paul
  20. The full frame sensor will be more demanding of the corrector. I'm not sure if the Baader or skywatchers will correct over more than APS C. You may need to look at ASA to correct over the full frame
  21. Very good point Sara. How are you storing the equipment? If you take it down after each session then ease of use is important. If it's got its own building then once it's set up it stays that way. 10k sounds like a really generous budget, but when add up everything involved suddenly it looks quite tight. You need to be doubly sure that you buy the right things. What a crazy game this is!
  22. As others have said your choices depend on what you want to image. Things like mount, telescope, camera, filter wheel, filters, guide scope and guide camera and software need to be thought about. Also whether you want just pretty pictures or whether you want to attempt to do science with your images needs contemplated. Deep sky, planetary, photometry, spectroscopy, emission line imaging:all these have differing requirements. Once you know what you want to achieve the you can discuss exactly what you need to achieve it. As for cameras, consider all the various choices. Atik, Starlight Xpress, M
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