PIX 2015
Andy C Knight

Andy C Knight

Lives in United Kingdom United Kingdom
Joined on Jun 30, 2008

Andy C Knight's recent activity

  • Correct - Much easier with a Refractor, no central obstruction and the big 2" focuser really helps with the Max FOV! I keep looking at a 90-100mm APO Refractor... But I need to resist :-D Correct. ...
  • Yes Hmm not quite sure about the above line... Perhaps something like... but during afocal photography to avoid the secondary shadow, clearance for the Eyepieces exit pupil and expanding light cone ...
  • Here we are only considering the minimum 'clear aperture' required to pass all the light from the eyepiece to the sensor focal plane. Since your adapter tubes are bigger than the light cone coming ...
  • You need to be careful here, as it's also very dependent on how deep the Iris is buried inside the zoom lens. Best bet is to try out the setup. Only your eyes will have this restriction. (i.e. not ...
  • Visually, the dark spot is caused due to the exit pupil of the 32mm and 40mm eyepieces, which are much larger (at f6.3) than the size of the Iris in your eye. In the day time your eye probably ...
  • That's not really the way that I would look at it with regards to light pollution... The idea of the filter is to increase the contrast between the wanted signal and the unwanted skyglow. Despite ...
  • Ahh... Now I understand what you are getting at. Poor seeing means the bigger pixels have no real disadvantage... and the 'tendency' of bigger pixel cameras having a deeper well size helps with ...
  • I'm puzzled...Why do you think that larger pixels may be ideal for areas of high light pollution? (Are you referring to a deeper well size?) It's one measure of DR which defines the number of ...
  • I could not agree more! At little while back I had the hard drive in my main PC fail. Good Job I had multiple backups using different media!! My backup hard drive failed about half way through ...
  • Correct when binning 4 pixels, it doubles the DR / SNR. (Technically the full well capacity is quadrupled - but the noise is also doubled - hence it's only double the SNR) Note: I need to be ...
  • Yes I was having grief with that reply - There should have been a red line on the left, where I quoted your question!! (But I don't need to click anything to see the whole reply) I'm a bit rusty ...
  • Yes I normally use a M42 thread Barlow. I have a x2 and a x3. You are correct: Increasing the separation increases the Barlow's Magnification. Doubling the distance between the Barlow and the CCD ...
  • alexisgreat wrote: Something called the full well capacity is 23,000 on the color sensor and 50,000 on the mono sensor.
  • I found a useful article on the web (about using DSLR's for Astrophotography) which you may find interesting... http://www.covingtoninnovations.com/dslr/newdslr/ Regards Andy.
  • Should be fine (for mirror vibrations) at 10 seconds. (my GP Mount damps out in 2-3 seconds) Simple Test: Tap the scope, when looking through it with a high power eyepiece and see how long it takes ...
  • Yes - I was shooting the Moon at f10 and f20 on the C8 using a 400D. At shutter speeds below ~1/400 it became quite noticeable, but I think I needed around 1/80 and it was really bad (8 pixels!). ...
  • Nope - I got it wrong!! - I mixed up the diagonal and the horizontal measurements when I looked up the spec :-( I've corrected the mail You would need to download the manufactures datasheets - ...
  • This may or may not be an issue depending on the focal length. Best bet is to try it out. I'm not that familiar with the E-520. (maybe someone else can help out here) Failing that... It's better ...
  • 3fps Should be fine. Sure faster would be nice, but all you need to do is shoot for a bit longer. However a 1/2.8" sensor at 640x480, works out at about 8um pixels. For this large size of pixel, I ...
  • My opinion is that web cams can be much better for the Planets. I've seen some really sharp images using webcams. Their tiny pixels automatically give the correct image scale, without playing with ...
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Total messages 703
Threads started 6
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Last post 1 month ago
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Photos uploaded 31
Last upload 9 months ago