Article – Causes of Reflections
Note: Originally investigated and written back in 2008, I wanted to capture the results of some hours playing around with lenses and lights at this site. Might be interesting for others as well.
I’ve seen quite a lot of discussions in different for a about reflections in pictures. The full range of comments and arguments ranged from “incredible” to “non-existent”. This seemingly impossible co-existence of views, triggered my curiosity. What is causing reflections? The architecture and construction of lenses are of course one important parameter, but my interest centered more around what I – as a photographer – could do to understand and limit this phenomenon in my images. What is increasing reflections, what is decreasing it in my image? I wanted to understand it more.
So, I started to spend some time looking into this and hundreds of photos later, my simple summary is listed below if the aim is to reduce reflections.
All images are available here in larger size, if you want to look deeper into the patterns displayed by the lenses.
1) Remove the filter
A filter, with its two air/glass transitions is constant source for more reflections. It is quite easy to take it off – Do it, if you need to.
AFS 24-70mm/2.8G (no filter)
AFS 24-70mm/2.8G (with filter)
2) Clear the lens
I was astonished, how well dirt and other material on the front lens is increasing reflections in direct (sun)light.
AFS 14-24mm, just returned from a trip in the mountains, with reasonable dirt on the huge front lens
AFS 14-24mm, cleaned
3) Which lens is used
Most discussions centered around this point, with sometimes very heated debates. There is a lot of variation in this section. Ranging from almost identical to clearly visible. Many rings, beautiful rings, laminar ones as well as colorful artifacts.
AF 14mm/2.8 D
AFS 14-24mm/2.8 G
4) Impact of the aperture used
This was a real surprise for me. Almost incredible, how the patterns of reflections change when the aperture is changed. The old saying “avoid an open aperture” does not hold every time true. It is rather the case at the other end (closed aperture), especially with wide lenses. As an example, I’ve used the AF 14mm lens, but the pattern basically repeats with all other wide lenses.
AF 14mm @ f2.8
AF 14mm @ f5.6
AF 14mm @ f11
AF 14mm @ f22
5) Position of the light source
Not always, but sometimes it is possible to position the light source in the image. This significant implications especially with wide angle lenses.
AFS 17-35mm/2.8 – The light source is at the edge of the image, but still within the visible area.
AFS 17-35mm/2.8 – The light source is at the edge of the image, just outside the visible area.
The light source was moved further by 4inch (10cm)
The light source was moved to about 3ft (1m) right of the camera. Right angle, a bit higher than the camera
If there is one factor which has the biggest impact, then the exposure should be taken care of. One f-stop more or less has a huge visible impact.
AFS 24-70mm/2.8G – one f-stop under exposure
AFS 24-70mm/2.8G – proper exposure
AFS 24-70mm/2.8G – one f-stop over exposure
AFS 24-70mm/2.8G – two f-stops over exposure
This should not be treated as exhaustive test, but it potentially serves as a good starting base to think and act about reflections in images. I’ve done some further analysis with different lenses, but this for another article.
Comparing 10 lenses
I’d like to conclude this article with a comparison of 10 lenses, how they display reflections in a somewhat similar and repeatable setup. Don’t take the level or artifacts in my pictures as indication how the lenses behave in every situation. As discussed above, many factors contribute to the visual impact. My setup and exposure was deliberately set up to visually amplify the inherent behavior and applying some care, those effects can be partially mitigated..
The tested lenses are:
- AFS 14-24mm/2.8G
- AFS 17-35mm/2.8
- AFS 17-55mm/2.8G (DX)
- AF 20-35mm/2.8
- AFS 24-70mm/2.8G
- AFS 28-70mm/2.8
- AFS 18-200mm/3.5-5.6G VR I (DX)
- AFS 70-200mm/2.8G Type I
- AiS 58mm/1.2 Noct
- Zeiss 100mm/2 Macro Planar
AF 17-55mm/2.8 DX
AFS 18-200mm/3.5-5.6G VR I
AFS 70-200mm/2.8G VR I
AiS 58mm/1.2 Noct
Zeiss ZF 100mm/2 Macro-Planar