weihaowang

Lives in Taiwan Taipei, Taiwan
Works as a astronomer
Joined on Jan 11, 2009

weihaowang's recent activity

  • Not a joke. In Finland, you won't need a cooled DSLR for astrophotography. The electronics in the camera does generate additional heat, which typically brings the sensor temperature to 10-15 degC...

  • There is a random component associated with the dark. The dark subtraction procedure removes the fixed pattern in the dark, not the random component. To casual eyes, the fixed pattern (especially...

  • Interesting that XEEN's website doesn't even reveal the numbers of lenses/groups of this 135/T2.2. If they are the same as the 135/F2, then there is a high probability that they are based on the...

  • I also feel the main limit of the 645z line is lenses.  I am an astrophotographer, so the only thing I care is center+corner sharpness at larger apertures, including color fringing.  I have to ...
  • Does it have bulb exposure?

  • Replied in IT2
    Hi, I just checked the LED.  It's behavior is consistent between M and B, and it's off during exposure.  So this doesn't seem to be the cause of what I saw. Cheers, Wei-Hao
  • Replied in IT2
    I can verify that all NR options in the camera menu are disabled.  So no, the weaker ampglow at high ISO is not caused by any in-camera NR.  It must be something more fundamental in the camera. Per ...
  • Replied in IT2
    I did try Light room tether for 645z.  Unfortunately the Bulb mode there is not timed.  One has to push the button manually to start the bulb exposure and push again to stop it.  This is not ...
  • Replied in IT2
    Hi, Unfortunately, it looks like IT2 is not a free software.  It doesn't come with my 645z too.  The Ricoh website only provides the update file for download, which still requires the original ...
  • I will let you know once I try the IT2.  Based on my experience with some 10-year-old cameras, ampglow doesn't quite change its intensity with temperature, unlike dark current.  However, I can't ...
  • Nikon used to apply a filter to remove hot pixels in Bulb mode images.  As a result, many stars are also filtered out.  This is very notorious in astrophotography, and is one of the reason why many ...
  • Yes, I have some files taken by unconverted 645z.  They show the same behavior.  So it is not IR leakage. Could you tell me more about the IT2 software?  I don't know what it is.  I am willing to ...
  • Replied in more tests
    Thanks for all your suggestions. I made more tests, and found something interesting. Please see the images below. First, as previously stated, the ampglow-like feature does not change its ...
  • No, since they are not useful for astrophotography. 1/16 is the shortest I can reach in bulb mode, and the results are the same. 2 sec, yes, but not longer. The reason is, again, long exposure ...
  • It's done by a local company in Taiwan, who specialized in IR conversion.  I work with them in the process, to make sure the conversion is suitable for astronomical work.
  • Replied in Wow
    On earlier DSLRs from Nikon and Canon, the amplifier is always on.  Thus the ampglow always appears and its intensity goes up with exposure time.  Then later the camera companies realized this is ...
  • Hi, I don't quite understand this.  How can light leakage from eyepiece have equal brightness no matter the exposure time (M mode) is 1/4000 or 1 sec?  (The example pictures I attached in the first ...
  • Interesting.  Thank you.  I did not notice this in my Bulb exposures of 5 minute length.  I guess this is because I took all my images at night when the surrounding is very dark.  But now I saw ...
  • Hi everyone, Thank you for the comments, and thanks to those who helped to answer some of the questions. The band of light doesn't seem to be light leakage from the eyepiece. It's not there in Bulb ...
  • Created discussion thread 645z astrophotography, and ampglow
    Hi, Want to share with you a few of my astronomical pictures taken with my new 645z: https://www.flickr.com/photos/weihaowang/24532290754 https://www.flickr.com/photos/weihaowang/24795271809 https: ...
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Total messages 39
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Last post 6 months ago
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Last post 2 months ago
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Last entry Oct 9, 2011
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Last upload Oct 9, 2011