Why can flare appear in a DSLR viewfinder but not in the final photo?
Asked 2/23/2019
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2 answers
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Using a Canon 2000D with a 55-250mm lens, I saw what looked like sunlight reflections/flare in the optical viewfinder while aiming near the sun (with the sun outside the frame). But the captured image looked normal and showed no visible flare. Why can flare be visible through the viewfinder but not appear in the final photo?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
7y ago
2 Answers
5
Without having more information on how exactly you took your image, and without the possibility to reproduce this effect, one can only guess. I see three possible causes for a sun reflection that is visible in the view finder, but does not appear in the image that is taken by the image sensor:
Automatic aperture control
Possibly you took your picture with the aperture not fully open. When looking through the view finder, the aperture is fully open, and the sun is reflected inside the lens barrel. During the exposure, the aperture is closed to the chosen value, and the paths of the reflected sun rays are blocked.
Reflection through ocular
A reflection of the sun may have entered light from behind through the ocular.
View finder penta prism
The last odd possibility would be sun rays that are reflected in the view finder's penta prism.
Originally by user48887. Source · Licensed CC BY-SA 4.0
user48887
7y ago
0
Generated from our catalog & community — verify before relying on it.
This can happen on a DSLR because what you see in the optical viewfinder is not always identical to what reaches the sensor during the exposure.
Likely explanations:
- Aperture behavior: In the viewfinder, the lens is typically held wide open for a bright view. When you take the shot, the aperture stops down to the selected f-number, which can block some stray reflected rays that were visible before exposure.
- Eyepiece/ocular reflections: Strong sunlight can enter or reflect around the viewfinder eyepiece, creating glare you see while composing, but that light never reaches the sensor.
- Viewfinder optics reflections: The mirror/pentamirror/pentaprism path can show internal reflections that are specific to the viewing system, not the recorded image path.
So yes, a lens hood can still help reduce off-axis stray light entering the lens, but flare seen only in the viewfinder does not necessarily mean the photo will show it. If you want to test, try the same scene in live view: if the flare appears there, it’s in the imaging path; if not, it’s likely just in the optical viewfinder path.
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AI7y ago
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