Jump to content

Narrowband

ollypenrice

Members
  • Posts

    37,879
  • Joined

  • Last visited

  • Days Won

    302

Everything posted by ollypenrice

  1. It's a total non-issue if you have a decent number of subs and a good outlier-rejection algorithm, as others have said. Now that I'm working with CMOS in 3 minute subs, rather than CCD with up to 30 minute subs, sat trails no longer exist, despite the increase in the wretched things. Olly
  2. Super resolution in the galaxies but is the black point slightly clipped? It's very flat and black. I wonder if you could trade a bit of noise for a bit more faint stuff? Olly
  3. I'd put it on a Skywatcher AZ EQ6. AZ (Alt Az) is much nicer for visual because eyepiece position and orientation are more consistent and this is OK for planetary imaging, too. It's quick to set up, with no polar alignment. But... when you want EQ orientation, you have it. Finally, you will not be under-mounted, which is just so nice. For Ha viewing I would just buy a dedicated Ha scope at whatever budget suits your pocket. Olly
  4. For focus, your capture software should give you a Full Width Half Max reading on either a chosen star or an average across the chip. https://en.wikipedia.org/wiki/Full_width_at_half_maximum This means that it looks at the bell curve of brightness going from one side of the star, through the middle, to the other side and it measures the stellar width half way up the curve. It can't accurately measure from one side of the full stellar image to the other because the faintness of the edge of the star makes it impossible to be sure just where it starts and ends. If using this FWHM facility in your software, the star must not be saturated. If it is, the top will be chopped off top of the curve and this will then have a flat top. To avoid saturated stars you can choose fainter ones or shorten the exposures, but 3 second-plus exposures average out the seeing and give you more stable FWHM readings. Do expect them to vary, though, at each reading and keep the lowest reading in mind. In practice, I would use the B-Mask in live view on your bright alignment star, frame up the image and then check FWHM just before starting the run. The thing about FWHM is that you'll find a focus star without having to leave the target whereas, with a B mask, there might not be a suitable one in the frame. So... initial bright star focus with B mask and then FWHM on the target region after that. Check focus regularly - as ever. Olly
  5. For me, way better. We can now trace spiral detail much further into the core. Olly
  6. I'm not sure I agree. Not destroying information in processing is as much scientific as artistic and going from unsaturated to saturated does destroy information. Olly
  7. I agree with Elp. This would be great with the colour balance eased away from red in the bright parts. Olly
  8. An attractive nebula, nicely done. Things I might look at would be 1) noise - StarXterminator is so effective. 2) Colour noise in the background sky. It's quite 'colour busy' and just selecting the background and reducing saturation might make a difference. Olly
  9. I wonder if the active ingredient here is the exit pupil? Olly
  10. I'm not a fan of mini-computers on the scope. I host six remote instruments and have replaced a lot of them for their owners. For long term reliability I like an observatory desktop with a lot of USB ports and I gather the cables at the dovetail and at the top of the counterweight bar and let them hang from there. Clearly this isn't a portable solution. Olly
  11. Yes, lovely. I'm going to see if I can find my old linear TEC140 data and see what difference modern processing tools make. Olly
  12. I'm surprised this hasn't piqued more interest. It certainly doesn't look like near IR in your data. Olly
  13. That green glow... I bet you could be persuaded... These are great galaxies. Olly
  14. It's very good and the colour is far more accurate than the bright blue spirals which we often see with M101. The core is saturated in the first one and still saturated, though less so, in the second. The first thing I'd want to do is look at the core in the linear data. Is that saturated? If it isn't, there is no need for it to become saturated during the stretch. You just need a better stretch, or a blending of two stretches. Maybe just a hand-shaped stretch in Curves would do it. What does the linear core look like? Olly
  15. For me, this image didn't seem exceptional until I clicked for the largest size - and then I found that the central bulge and dust lane were absolutely stunning. Unfortunately the last one seems to have been posted at lower resolution, or am I giving it the wrong clicks? It needs to be seen in large format to show its class. What I do think is that the fainter outer regions are noisy, with a pronounced grain. I'm sure Russ Croman's Noise Xterminator would fix that easily and might allow you to give the lower brightnesses a bit more of a stretch. I wouldn't apply it to the brighter parts or dust lane. Those are superb. Olly
  16. Interesting. This is the blue channel from our OSC camera. I'd probably vote for reflection, but who knows? Olly
  17. The answer is 'yes.' This is a mosaic combining 42 individual images. I can't tell you how to do it in five minutes, though! lly
  18. Very hard for imagers to capture the globular sparkle but you have it for sure. Great image. Olly
  19. Ah yes, perhaps the OP is talking about a field de-rotator for long exposure alt-az imaging? I would just say 'Don't.' Don't throw money at de-rotators or wedges, just buy a proper equatorial mount. I'm not sure that there is any guiding sytem for alt-az de-rotated mounts, at least for amateurs. Olly
  20. Preprocessing, APP. Post processing, a bit in Pixinsight and a lot in Photoshop. I also use Registar, particularly for composite (multi-scope) images. I consider StarXterminator and NoiseXterminator to be absolutely essential. Olly
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.