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Stub Mandrel

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Stub Mandrel last won the day on September 27 2019

Stub Mandrel had the most liked content!

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About Stub Mandrel

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    Bright Giant

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    Staffordshire UK
  1. Yep, plenty of detail to be found in those bands;
  2. No! It's meant to look like that, IMHO Nice pic, by the way!
  3. Silly question... but does anyone know if the Baader CCD filters are complemented by a set of CMOS ones?
  4. DPI for printing is much more complex than the 'use 300dpi' usually offered. 300dpi is the general rule for books and magazines etc. that will be viewed at a comfortable reading distance. At A4 that's an image about 3600 x 2400 pixels (~8Mp). This effectively gives you what Apple calls a 'retinal display' - that is the resolution is roughly that the eye can perceive so you don't see any artefacts and maximum usable detail is presented. In practice, we often interpolate images to get this resolution (one of my roles is a magazine editor) and it's surprising what you can get away with. Photographers are often astounded that 8 megapixels is plenty for the cover of a normal UK magazine (perhaps not Vogue or National Geographic...) For images to be viewed at greater distances lower DPI can be fine, for example a typical pullup display may be printed at 300dpi but the pre-interpolated image may well below 100dpi and still look fabulous at a normal viewing distance. On the other hand I have produced artwork for interpretation boards and used ~600dpi for the component images and downsampled to 300dpi for the final artwork, as it would be viewed close up. Ideally I would aim for about 150dpi multiplied by the viewing distance in metres, but you can go lower than this. For example, many desktop computer screens used to be 90 dpi but images looked fine on them at about 1 metre distance. The problem with most astro images is that they are often oversampled already with the finest detail being 2 or 3 pixels. They normally look fine as they are lightly blurred rather than pixellated, but it does mean they can look mushy and soft when blown up. One trick we often use in the magazine is to resample an image with interpolation and then apply a judicious amount of sharpening (usually just unsharp mask, but sometimes deconvolution) to bring definition to the sharp edges in the image which creates the illusion of higher resolution. This suits the sort of images we have which are typically machines etc. but may not work as well with 'organic' shapes like people or nebulas! Another tip is to view your image at 100% on your computer screen i.e. one pixel per screen pixel. This allows you to 'lean in' a bit and make a fair judgement of how sharp it really is.
  5. Very nice! Do you use WinJuPos to derotate video?
  6. Looks like spacex got scrubbed.
  7. Could be, I will try and find it. But at the time it had been guiding as well as 0.52", ticking away every 2 seconds then .... it just fell over, sometimes a minute or more before getting a frame, and some split frames.
  8. I'm using a 1.5m quality cable I've always had best results in Sharpcap allowing it to auto-set the USB speed. But PHD2 doesn't have such a feature.
  9. Couple from last night, and 20 mins each of RGB on Andromeda, after an hour each of SHO on a rather noisy Cave. Collimation wasn't too good...
  10. I use a ZWO ASI120MC for guiding with PHD2. I never have problems finding stars, but often have issues with poor connectivity with the camera. This seems to have got worse of late. What happens is that the time between frames gets longer, and longer and longer... Reconnecting the camera, in software or by unplugging it makes no difference. Restarting PHD2 makes no difference. Restarting the computer sometimes works. The only thing that works reliably is: Close PHD2 Open the camera in Sharpcap (where it invariably works) Close Sharpcap. Reopen PHD2 and reconnect the camera which will now work reliable for 'a period of time' which could be ten minutes or a few hours... The problem is somewhat intermittent and I have a suspicion it might be EQMOD related, not just PHD2. I am sure it isn't a camera/driver issue as it always works fine in Sharpcap. Note that 8 bit/16 bit mode doesn't seem to affect this.
  11. I'm having a go at the cave nebula tonight, first 130P-DS session for months. Hopefully the collimation isn't too bad...
  12. Definitely showing here on Sunday night's data. This has been 'Winjuposed' over about 20 minutes which I think must 'smear it out' a bit
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