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paul

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paul last won the day on November 5

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    pharscape
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    Cambridge, UK

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  1. A great catch, I like them all. I always find comet images the most special, they are of that moment.
  2. Thanks. I'm the first to admit its noisy 😄 Its over stretched in the shadows and the saturation is a over the top! (Note to self,- don't post at 2am 😄). Thanks, I have used those guides and they are good. I've made crib sheets for processing sequences that have worked but when they don't its hard to see where I went wrong particularly if it was a poor decision I made in the early phases. More targets and practice will make the debugging easier and the need less.
  3. When imaging planets smaller pixels and high frame rate video capability are very desirable. The 224 is designed for that. The image of Mars is going to be small with either camera. Shooting planets is very different to DSOs. The A700 would be good for galaxies and clusters. I think the 130p is f5 (650mm) so you are going to need a good Barlow to get a reasonably sized planet and Mars is one of the small ones. Challenging but fun😊.
  4. Thanks, this is the first year I have had the right combination of gear to use all the fl of my scope and make the most of the mirror's quality. I'm still learning the ropes with NB. I just need the weather to cut me some slack!
  5. A second hand DLSR such as your old Canon 550d is an excellent starter, (I still use it - bought second hand). It has a good number of pixels and pretty good noise for a DSLR. It is one of the cheapest/oldest budget second hand cameras still available that supports live view and PC remote control. Features very useful for astrophotography. The 550d also supports a special crop mode useful I'm told for planetary imaging (I've never used that mode but its good to know its there). Its a low risk investment. Modding one is not very expensive. If you are shopping around https://astrophotography.app/ has a good list of supported cameras.
  6. I use a website like Telescopious : What's in the Sky Tonight? · Cambridge - Telescopius. Most planetarium software (e.g. Stellarium) will show you the fov of a telescope+camera.
  7. Lots of interesting structure revealed there 👍.
  8. My original lengthy dataset was too soft focus (when changing to lower gain I didn't up the exposure time in the autofocus routine - often resulting in a poor final focus). I started again using a longer auto-focus routine which gives me sharp stars but eats up my imaging time. After several patchy nights I've 3 hrs Ha and 1.5 hrs Oiii. That's not enough to reduce the noise to levels I'm happy with but the data is good so far. It's probably as much as I will do on this target for this year. I may have hit 11 on saturation.
  9. Thankfully, things are looking dry in the obs tent so should be good for a second attempt tonight 🤞. I'm designing my own automated dew heater-controller. I will now add the rain sensor and alarm capabilities too!
  10. Last nights forecast was for 8 hrs overall of clear sky with 1 hour of cloud in the middle. Sounded great and planned to image through the cloudy bit. 1hr in I had to run out and cover up as we had 20 minutes of heavy rain! I closed the session, dried off the optics with a hairdryer and then mopped out the observatory tent 🥵. Hoping things dried out overnight with the fan heater on - planning there is enough air flow to move the humid air out. Time to build a rain sensor!
  11. +1. But I guess it's not a bad price for a full frame scope if you're planning for that. Its no lighter than other 70mm solutions. In contrast the 51 is ultra compact and portable very wide-field and occupied a aperture slot not often sold. For either adding autofocus is comparatively expensive.
  12. I follow these HEQ5 threads with interest. I must have struck lucky. I stripped down, cleaned and re-greased my HEQ5 using the Astro-baby guide probably 7+ years ago but otherwise kept it stock. It did remove some swarf and I got to replace some production damaged grub screws. With a light load (under 10kg) it guides better than the resolving power of scope+camera and its very rare I reject a frame due to guiding issues. When I balanced my OO250mm on it that was a different story😀 (that combo was one of the reasons I lost interest for a few years).
  13. Some good deep detail, its the first pink one I've seen.🙂
  14. I don't believe we need to get obsessive about dark frames for DLSRs but they are important. You will notice that the number of hot pixels varies significantly by exposure length, ISO and temperature. There are a lot of hot pixels in a DLSR. You need to produce the dark frames at the temperature and duration and ISO your lights were produced at. The dark frames are themselves stacked and this noise floor is ultimately removed along with the hot pixels from your images. Similarly Bias frames (lots of short dark shots) provide a figure for the average read out noise. Personally I haven't been too scientific about my darks. I have one set for each exposure/ISO that I use for the winter months but if I use the camera in the mid year I tend to take darks for that session specifically as the sensor temp can be quite high (25- 30 degrees). If you want to get more scientific and build up a collection of darks note the temperature of your lights and if they differ by more than 5+ degrees from any other session then produce a new set of darks. Personally I won't worry about the difference between say 25 and 27 degrees. So a collection of darks at 5, 10, 15,20, 25, 30 and 35 degrees would cover all eventualities and could be reused multiple times. If you find that in subsequent sessions new hot pixels appear then a new set of darks is probably required once it get objectionable. I believe Bias frames are essentially independent of conditions if you take them soon after powering up the camera from cold. When guiding dithering is essential, the walking noise is significant and cant be removed otherwise. As soon as you begin to stretch your images the walking noise will be apparent. If I forget to dither I consider the session ruined.
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