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ZEISS DTI thermal imaging cameras. For more discoveries at night, and during the day.

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  1. S

    New but probably wrong insight about lowlight

    I don't understand from where you get the idea that higher magnification concentrates the incoming light more. The objective gathers the light and the gathered light is proportional to the area of the objective. The magnification determines how big area the light is spread out over. If you...
  2. S

    New but probably wrong insight about lowlight

    This picture mixes up relative brightness with light amount. The brightness is always primary based on the effective exit pupil. With 4,2mm(or smaller) eye pupil, 8x42 and 10x42 provide equally bright image. As soon as eye pupil is larger than 4,2mm, 8x42 becomes brighter than 10x42. But when...
  3. S

    New but probably wrong insight about lowlight

    I mean that is not correct. Photons per area are already included in the exit pupil, which is based on the relation of aperture and magnification. All configurations with same exit pupil have same brightness providing equal light transmission. Otherwise 20x80 would be brighter than 10x40. It is...
  4. S

    New but probably wrong insight about lowlight

    I like this topic. I will give my try to complement. Total light gathering power is linear to surface area of the objective. Brightness is determined by exit pupil. Brightness is not to be confused with light amount/light gathering power. For example: if you compare following configurations...
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