• Posted on: 14 February 2019
  • By: tihomiry

HDR stands from High Dynamic Range. In short it is the number of tones that compose the image. The larger it is, the best capability we have to see details in the bright and dark regions of a scene. We mostly use it to prevent burning out bright objects and stars. Best way to do it is to take different exposure shots and stack them with DeepSkyStacker or similar software. Most high-end cameras has a build in function to do that. The disadvantage is that the resulting image is JPEG. This is also a quite power consuming process as using the camera image processor.
Below are single frame of Andromeda Galaxy with HDR OFF and ON. It is shot with Pnetax k-5. ISO 51200 and 30 seconds of exposure, untouched frame. You can easily see the greatest challenge of this object – bright core and faint outline. The core burn out is suppressed with the HDR function on.



http://www.deepskywatch.com/deep-sky-hunter-atlas.html This is an amazing resource. Detailed atlas of all the sky with NGC and IC objects.

Reading a new product that claims to be 100x time more powerful then conventional telescope, I realise that this is just an astrograph with a digital camera that is doing stacked images and show them trought eyepiece or App.

I am so impressed with the K5 ability to quickly gather signal from nebulas (Quantum efficiency) and galaxies, so I decide to take one more K5 and to remove the IR-cut Filter of the old one.

Recently I got one very good lens the Asahi Takumar 135mm 1:2.5. This is fast telephoto lens and from my point of view a good lens should be with aperture from 1:1,2 to 1:2,8.

Moon at 45% illumination and 70x magnification. With aperture of 200mm,14,1 stops dynamic range, color depth of 23.7 bits at this image there are slight color variation on the moon surface that reveals it’s structure.