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mvas

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About mvas

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    Vacuum

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    NE Ohio USA
  1. I see no reason to increase the ISO, which decreases your Dynamic Range and only slightly decreases Read Noise. Check the peak on your Histogram You need to expose long enough to get a clean separation of the Histogram from the left wall The peak can be between 20% to 33% This will determine your exposure time, under light-polluted skies. Finally, you will need many exposures to reduce the noise from the Sky Glow. Here is link to M31, from Bortle 6, notice it took John Rista 7.5 HOURS at ISO 400 using Canon 5D Mk-III ... M31-Bortle-6
  2. Are you imaging from a very Dark Site or a Light Polluted Site? In your stacked image, what percentage of your "Overall Noise" actually comes from "Read Noise" ? If Read Noise is not a significant percentage of your Overall Noise, then why increase ISO, which reduces your Dynamic Range? Have you calculated how many more exposures are required, to restore your lost Dynamic Range, each time you double the ISO? When you double your ISO, and you don't shorten the exposure, then you risk clipping the bright areas to pure white <= not good! More than 50% of the stars in the typical astro-photo should be yellow, orange or red, not pure white. Objects like galaxies with bright cores and the Orion Nebula have a huge Dynamic Range. One guideline suggests that Read Noise should be 5% or less of the Overall Noise ...
  3. DSLR = Good / lowest cost Cooled OSC CCD = Better Cooled LRGB CCD = Best / highest cost Look for "modified DSLR" or "full spectrum DSLR" in astrobin. You can see the images that others have produced with a Modified DLSR + Filter. DSLR's have disadvantages vs Cooled LRGB CCD... DSLR = Higher Noise DSLR = Lower QE DSLR = Bayer Blurring which makes creating great images that much more difficult.
  4. With most DLSR's, they don't report he temperature of the Image Sensor. The Canon temperature probe is embedded in the Canon Digic Processor Chip, not the Image Sensor. Subtracting Darks that have a "higher temperature" than your lights, can cause black holes.
  5. A half a dozen dark frames will add a significant amount of noise into your lights (image). And that noise is visible to the eye. See the visible noise in actual Bias Frames in Reply #3 of this PixInsight thread ... BiasFrames The noise in your Bias Frames, Dark Frames and Flat Frames adds, in quadrature, with the noise in your Lights
  6. OK, I attached a Canon 6D in BULB Mode to my computer via a single USB Cable & switched ON. The Canon EOS Utility started automatically. I shut down, not shrink, but shutdown Canon EOS Utility - it will conflict. I started Nebulosity 4. I selected "Canon DSLR" from the pull down in the "Capture Control" window I entered the following parameters ... [Duration] field = 60 seconds [# Exposures] field = 3 [Time Lapse] field = 5 seconds I clicked "Capture Series" and it worked! Verify this Nebulosity Menu Option ... Main Menu => Edit => Preferences => DSLR Long Exposure Adapter => Digic III+ onboard
  7. Do you have just a USB connection to the DSLR? I think you might need a Shutter Release Cable for > 30 seconds ? USB SHUTTER DIAGRAM
  8. Yes, Deep Cycle batteries are a good choice. Typically, I only plan on using 50% of the battery's AH capacity. I use a single 110AH Deep Cycle battery, but it weighs 50 lbs / 25 kg +/-. A 110AH battery will give you 6 amps for 8 hours and will discharge 50%. For your AC Powered equipment - purchase a $20 Kill-a-Watt and actually measure the watts consumed. For DC equipment - measure the DC Amps using a $10 volt-ohm meter. You need to KNOW your power requirements, we can only guess-timate. I think , a 75AH battery (from your LINK) , fully loaded with ALL of your gear, will not last 8 hours. I suggest running everything directly from 12 Volts, no inverter for best efficiency. Mount = 1 amp Computer = 2 amps Dew Band = 1 amp EACH QHY8L Camera = 2 amps (4 max) AutoGuider = 1 amp Focuser = 0 amps USB Hub = 1/2 amp ================= I guess-timate 7.5 amps already 75AH battery x 50% / 7.5 amps = 5 Hours +/- 110AH battery x 50% / 7.5 amps = 7 hours +/- If weight is an issue then purchase two 75AH batteries and split the loads. Batteries with built-in handles or batteries-in-a-box are great to store and carry. And the charger must be configured properly for your battery type. How to kill a battery in less than one year ... 1) Chronic over-charging 2) Chronic under-charging 3) Discharging too deeply, too many times
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