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Everything posted by ollypenrice

  1. Firstly, see what you think of the image. This is a crop to close in on the galaxy - or galaxies. There are lots! Personally I love it. I can say that because all I did here was the post-processing of the data collected by Julian Shaw from his New Zealand observatory. This was from a six inch refractor and Atik 460 mono. I'd say that was darned good going from a 6 inch scope. (TMB LZOS 152 apo. A good six inch scope! ) His sky was also excellent, SQM 21.95 to 21.98. Mount was a Mesu 200, guided by small guidescope. Now for the big surprise. This was taken at F15 using an Astro-Physics Advanced Barlow. It does rather knock some popular assumptions about F ratio on the head, no? So the focal length was 2280mm and the pixel scale 0.41"PP. The image also shows what an incredibly versatile photographic scope a large refractor is. It can close in like this on a pretty small galaxy using a small pixel camera or it can do the whole of M42 and the Running Man with a full frame chip. While I don't know the total integration time (Julian will doubtless come in on this), here's another surprise. Determined not to blow the core, he shot this in three minute subs. So that's F15 and 3 minute subs. Shouldn't be possible, should it? I have never enjoyed a data set more than this one. Many thanks to Julian for bringing it along. Olly
  2. ollypenrice

    Spaghetti anyone?

    If you use Ps I'd begin by adding Ha to red in blend mode lighten. Then you could apply a little as Luminance. When I do this I usually stop at 15% or less but some go higher. Olly
  3. ollypenrice

    Spaghetti anyone?

    Superb image. Tiny, tight little stars and lots going on besides the pasta-fest! I think (being honest) you could get it even better. For me too much of the Ha has found its way into the luminance channel. Sure, you haven't shot a luminance layer but it is still effectively there in an OSC dataset. If you could concentrate more of the Ha into red then I think you'd get better colour in the nebula and smaller blue stars. But what a great result on a very large, very faint target. This is not a beginner image!!!!! Olly
  4. ollypenrice

    Color CCD + HA

    Fine, then you have two answers both of which will work. I watch new methods of Ha combining appear on the scene, notably Pixinsight's and APP's, but I still prefer Photoshop and the application of Ha to red in Blend Mode Lighten. Once you get into the swing of it you can experiment with processing the Ha specifically to be used in this way. This means it doesn't have to be processed to look good on its own. Some of my Ha layers look horrible when processed to go into red in blend mode lighten. However, you don't have to worry about noise in Ha where it is less bright than the red layer quite simply because it won't be applied in 'Lighten' mode. I also tend to process Ha with ultra-hard contrasts for adding to red because the red layer will soften and blur them anyway. Olly
  5. ollypenrice

    Color CCD + HA

    Simple but out of your control, perhaps? This is not for everyone. The method described by Adam gives full control to the imager with lots of room for weighting and adjustment along the way. In the event of the Ha being too prevalent or creating artefacts in places it can be placed over the original OSC as a layer and reduced in opacity or any artefacts selectively erased. Are we actually answering Wayne76's intended question here? Wayne, are you asking how to combine an Ha image with an OSC or how to contstruct an Ha image when using an Ha filter on an OSC chip? Olly
  6. Good effort but I agree that focus looks out. Be aware that at 300mm your system is working at 2.56 arcseconds per pixel. This is a thoroughly 'telescopic' resolution and certainly in 'serious mount with autoguiding' territory. For comparison, it's a considerably higher resolution than our Takahashi FSQ106/CCD rig which works at 3.5"PP. In reality this means that tracking error will probably not allow you to get anywhere near to resolving detail at that scale. By bringing the focal length down by a long way your level of real captured detail would be unaffected and you'd have a far wider field of view. I'd be thinking of working at maybe 5"PP or more on the Star Adventurer to start with. I used this calculator which you might find helpful: http://www.12dstring.me.uk/fovcalc.php Olly
  7. Cropping included? This seems odd to me. Mind you I don't know the routine at all but I'd have thought that stacked image borders had unique artefacts of their own. Olly
  8. ollypenrice

    Fill a focal length gap??

    F ratio myth? Life is full of surprises: Olly
  9. I entirely agree. I'm at a bit of a loss to know where pixel size comes into the story but will be happy to read an explanation. Olly
  10. Sorry, I can't see how to contact you on the new forum so I'll ask here. I host an instrument on behalf of its owner. It could be collected from me but isn't mine and I have no financial interest in it whatever. Could I put it up for sale on here? I can personally vouch for both the instrument and the vendor since I know both of them well but I thought this came into a grey area so I wanted to ask first. Thanks, Olly
  11. ollypenrice

    Question for moderatorss, please.

    Thanks. I think the restriction does apply, really. Olly
  12. I think you need to clarify your use of 'drift.' What exactly is the effect you are seeing? The candidates are - differential flexure, meaning the guide scope and the main scope moving relative to each other so that the guide scope tracks properly but the imaging scope moves relative to that correct guiding to produce trailed stars. - field rotation due to polar misalignment. In this scenario the main image will slowly rotate around the guide star. If the guide star is in the middle of the image that will be the centre of rotation but if the guide star is off the imaging scope's axis then that will be the centre. It is always best to guide a reflector with an off axis guider because the guider uses the same light cone as the imaging scope. Mirrors are always susceptible to 'flop' which is an overstatement of what is usually a very small movement in the primary mirror. A separate guidescope cannot 'see' this movement so cannot correct for it. An off axis guider can see it and will correct it. There is also an enormous difference in resolution between the little Quad and the big SCT. Even without flexure I would expect your resolution to be below what is needed to guide the SCT. The SCT is a big scope with large diameter tube rings. I would always worry that these would flex so I'd favour a side by side arrangement on this one. But I would go for an OAG for the C11. Olly
  13. ollypenrice

    First astrophotography setup

    The 'modding' bit refers to the removal of the camera's stock daytime filter which cuts off the reds at wavelengths a tad shorter than those of the H alpha line. Older cameras in particular are almost entirely blind to Ha which is disastrous for emission nebulae. Once removed the camera will need its white balance setting manually for normal use. If you insert an Ha filter you will not be shooting on all your pixels but you'll still get a result and this opens up the nights with a significant amount of moonlight. Some do the mod themselves but it's tricky. There are people doing it professionally too. Olly
  14. ollypenrice

    band running along image

    You could download a free copy of AstroArt and try stacking in that. It won't save unless you buy the program but it would be a good test. Olly
  15. In this thread a beginner is asking if not removing the card when downloading to a PC might have produced a horizontal banding artefact. This rings a bell with me but I can't remember the story. Can anyone help?
  16. ollypenrice

    band running along image

    I'd certainly try that. Olly
  17. ollypenrice

    band running along image

    I don't use a DSLR but this card-removal thing rings a bell. I think Carole wrote something about it. I've put a link to this thread on the cameras section. Since the bands are colour-specific and the colours are read separately it might indeed have something to do with reading and saving. Olly
  18. ollypenrice

    iOptron CEM60-EC First thoughts

    If you have a rig which works and you still have an itch to change it then you are in a very unusual position. A private psychoanalyst will actually cost you less than changing your kit. Hardly anything costs more than a course of psychotherapy but one of the few things that does is buying a new astrophotographic setup and getting it to work. The cheapest though not necessarily the most enticing option might be a cold shower. lly
  19. Not a clue, but how do the scopes perform? I use two fine old fluorites and have seen enough new EDs giving hassle here to know that I don't want one. Spent quite a lot of this afternoon trying to analyze problem subs from one which I host. The new Capstan wheel (now abandoned) is another issue. At least they were right to abandon it. It's a prime source of tilt. Refractors should just work. Too many new Tak FSQs just don't. They need a kick in the behind and that's what they're getting from me. Olly
  20. Wild horses wouldn't drag me from my old style fluorite Takahashi FSQ to the modern ED 'equivalent.' Olly
  21. ollypenrice

    The Birds revisited.

    Eagle and Swan: I was never really happy with the processing of this data and couldn't put my finger on what was wrong so I had another go. It also got me thinkiing about the summer skies which was no bad thing in the dead of winter! I hope the stars are now better and the emission nebulosity deeper. HaOIIILRGB. Atik 11000 mono/Tak FSQ106N. High res data for the Eagle added from ODK14/SXVH36 and for the Swan from TEC140/Atik 11000. Olly
  22. ollypenrice

    The Birds revisited.

    There's a lot of star reduction going on in this image so some artefacts are going to get in. Without the reduction it is just 'starred out.' This certainly isn't processed to be pixel peeped, though: I accept in this processing that it's a widefield image trying to feature nebulosity over stars and high resolution. I think it's important to have a final presentation size in mind and in this case I'd settle for 66%. Olly
  23. Try Registar or even try it by hand? Just seen this. Given the focal length the resolution is incredible and the seeing hasn't tended to be good here recently. Olly
  24. ollypenrice

    The Birds revisited.

    Heh heh, now that's not daft!!! Olly
  25. ollypenrice

    The Birds revisited.

    Thanks, I'll have a go with that. Olly

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