I went for a walk this morning, and I decided to play with sun stars — that’s the effect you get when you get the sun, or part of the sun, in the image at a small aperture. The sun’s rays striking the diaphragm leaves cause radial spikes of light. If you’re going for part of the sun’s disk, it’s something that is hit-and-miss with an SLR; first, because your finger gets tired holding the DOF preview button down all the time, and second because the sensor and your eyes see bright light differently. Without a lot of luck, it’s impossible with a rangefinder camera; the difference in location between the finder and the lens means that they see the sun very differently, and, besides, there are no diaphragm blades in the finder’s optical system.
With an EVF camera, particularly one with a great finder like the a7R, it’s a piece of cake. I used the Leica 24mm f/3.8 Elmar, set to f/11 at ISO 1000. Here’s an unmanipulated sample with just the tiniest part of the sun not occluded:
After these heroic adjustments in Lightroom:
The image looks like this:
The JPEG compression and reducing the size for the web just ruins the star. Here it is at 1:1:
The center (shown here at 1:1) is pretty sharp, but diffraction has taken its toll:
What really impresses are the corners, which are shown here at 1:1 with 1 2/3 EV exposure push so you can see the details:
There’s a fair amount of noise — ISO 1000, big shadow move, and extra + 1.67 EV for visibility — ans some corner smear is evident, but the image isn’t half bad. I’ve not corrected for either falloff or color shading towards the corners.