Infrared Conversion: 4/3 micro vs. Crop vs. FF sensor?

Started 3 months ago | Questions thread
nkistrup
OP nkistrup Senior Member • Posts: 2,497
Re: Hot spots: Function of DoF? Or fstop value?

robgendreau wrote:

nkistrup wrote:

Only occurred to me this morning. For a given lens on a 1.5x crop, it has same DoF as a full frame camera, a full stop higher. Example: f5.6 on a 1.5x crop is the same DoF as f8 on full frame. So if a hot spot shows at f16 on full frame testing, it will show up at f11 on a 1.5 crop?

Or are hot spots a function of the aperture blades of the lens, which are constant for a given fstop value? Curious.

Tough question. See https://kolarivision.com/the-science-of-infrared-hotspots/ eg.

Thanks robgendreau!  Didn't answer my question, but learned three things:

  1. Sensor DO MAKE a difference.  Really big take away, since I always ASSUMED that hot spots were strictly a lens issue.
  2. Testing is dependent on the focus point.
  3. Gave my Zeiss 50mm f2 a failing grade, when I tested it for hot spots.  Wondering if my test procedures were suspect?
 nkistrup's gear list:nkistrup's gear list
Olympus XZ-1 Nikon D7100 Sony a7 III Sony a6400 Nikon AF-S DX Nikkor 17-55mm f/2.8G ED-IF +10 more
Post (hide subjects) Posted by
Keyboard shortcuts:
FForum PPrevious NNext WNext unread UUpvote SSubscribe RReply QQuote BBookmark MMy threads
Color scheme? Blue / Yellow