A Light Leak in my D300?

In summer 2009,  some 18 months after switching to the Nikon D300 body, I noted a strange artifact on some of my photos. Here's a sample shot that highlights the problem:

18 - 200 mm super zoom @ ISO 200, 27 mm, f/11, 1/320"

Initially, I didn't even notice the defect which was most conspicuous when it fell onto a clear sky or other monotonous area. I just thought "strange!" — and patched it away in Aperture. My primary suspicion was that this may be a reflection caused by the skylight filter that I used to protect the front lens of my 18 - 200 mm VR super zoom lens: sun light (the artifact seemed to be linked to pictures taken in bright sunshine) can be reflected from the filter in front of the sensor, then reflected back on the backside of the UV or Skylight filter, producing an extra reflex / artifact — this is a known phenomenon. However, if this was the problem, why then would the artifact always appear in the same location??

My next thought was that it might be some object / dust particle towards the back end of the zoom lens, which might explain why the artifact looked like a diffraction pattern (with dust on the sensor I would expect well-defined, dark spots). So, I was hoping that better lenses would cure the problem. Wrong.

In spring 2010 I switched from the super zoom to professional (full frame) quality 70 - 200 mm f/2.8 and 16 - 35 mm f/4 lenses; I did not use an extra UV filter, just to make sure this does not cause extra headaches. The lenses produced very good, high quality, clear images — but sure enough, the problem was still there! Sometimes it took while to realize the issue was present, like here:

70 - 200 mm f/2.8 @ ISO 200, 105 mm, f/10, 1/400

But once I realized that it was at a given location in the raw image, it became hard to ignore it:

One some background it wasn't easy to make it disappear — sometimes I needed to use Photoshop, or at least very careful patching in Aperture. Here's a close-up look at the artifact in the above shot:

Now I was more worried about my camera body. But — if it wasn't the lens(es), could it still be some strange kind of dust particle on the sensor filter? I took a series of blank, defocused shots of a uniform surface, at various lighting conditions — nothing at all, not the tiniest sign of sensor dust anywhere, let alone such (not so) funny circles!

So, I continued investigating and noted that the artifact only showed up when I had direct sunlight on the camera body — and particularly when the sun was almost or directly in the picture. My hypothesis then was that only a tiny light leak at some distance from the sensor plane would explain the circle-like diffraction pattern on photos, and why it would only appear when direct sunlight fell onto the front part of the camera body. In October 2010, I sent the body to Nikon for repair, along with pictures highlighting the issue. The warranty had expired, but the repair was done at no cost; the repair sheet spelled out some warning about not letting dust enter the body — but I'm sure this was not the issue! I took some shots with the sun in the picture — and I'm glad to report that the problem is gone and has since not reappeared:

24 - 120 mm f/4 @ ISO 200, 36 mm, f/10, 1/400"

24 - 120 mm f/4 @ ISO 200, 36 mm, f/14, 1/800"

Airshow Photo Attempts

On June 25th, 2011, the Swiss army air defense troops celebrated their 75th anniversary, and on this occasion they organized an air show in Dübendorf, just about 6 km from the place where we live. The setting was an old, venerable military airport (formerly also Zurich's civilian airport) that is in the process of being dissolved: it is located within the agglomeration of Zurich, in a relatively densely populated area — we all (even 4 - 6 km away!) still remember the very disruptive, rumbling noise caused by the Mirage IIIS jet fighters starting with afterburner!

Lea and I had been at the Air '04 in Payerne 7 years ago (2004-09-04, in tropical heat and totally blue sky) — I then took pictures with my Nikon Coolpix 5700, with mixed success: for good pictures that camera was simply too slow, the electronic viewfinder too limited. This time I wanted to do better, and so I took my Nikon D300, the tripod, 70 - 200 mm and 24 - 120 mm zoom lenses (only used the former in the end), as well as the 2x teleconverter into my slingbag and was curious to see how things would go. The weather was so-so: mostly covered sky, but at least enough visibility for the event to take place. That part worked out OK, though the contrast was limited with all that gray background. Once it began raining a few drops, but that was just minutes.

So, how did I do? Well, let's start with the downside: we arrived by train, what we thought was "just in time" — but we did not anticipate the extended foot walk due to the route which they assigned to pedestrian visitors! Once we were on site, we spent some time trying to find a good viewing spot: the initial location was not good enough, so we had to walk a while to find a suitable, central location. This was merely minutes before the event would start; needless to say that front row spots were all taken, though that was a minor issue, as things would mostly happen in the air. I had enough time to install my tripod, mount the 70 - 200 mm zoom on the tripod (with the teleconverter), to attach the camera body, and to adjust the tripod height — and (too) soon the event started! In the aftermath I should have taken more time to think about optimum camera settings: most of the shots were taken with "P", I must confess! That alone wasn't too bad, though — but I should have switched to a higher ISO setting: in lieu of ISO 200, I should have used ISO 400 or 800, maybe (above that, the D300 starts to be a bit noisy), in order to shorten the shutter speeds for sharper pictures. Of course I used the VR — but with moving objects this is of limited value.

Some general remarks: most of the pictures were taken from the tripod, though I kept the ball head loose, so just used the tripod as stabilizing support, which worked out OK. I never used the 24 - 120 mm zoom, all pictures shown here are from the 70 - 200 mm zoom, with teleconverter, using the resulting range of 140 - 400 mm focal length (210 - 600 mm equivalent @ 35 mm frame size). In the aftermath, this turned out to be adequate: with a stronger zoom it is hard to capture some of the fast moving actions, and at wider angles (e.g., 70 - 200 mm without teleconverter, or with the same lens setting, but a full frame body) I would end up doing more cropping back home — and then I might need a higher pixel count. A camera with higher ISO range would have helped, though! Note that all pictures are taken with horizontal camera position — with cropping back home, as necessary. On to the show — all focal lengths mentioned are for 35 mm frame size; click on the images to enlarge:

The event started with the PC-7 team (currently still located in Dübendorf), showing off its power in precision formation flight — the selection of a central viewing spot paid off:

D300, 70 - 200mm f/2.8 zoom + TC-20E III @ 480 mm, f/14, 1/250"

D300, 70 - 200mm f/2.8 zoom + TC-20E III @ 600 mm, f/14, 1/160"

D300, 70 - 200mm f/2.8 zoom + TC-20E III @ 600 mm, f/14, 1/160"

Next in the program was a F/A-18 "Hornet" fighter plane:

D300, 70 - 200mm f/2.8 zoom + TC-20E III @ 600 mm, f/14, 1/160"

D300, 70 - 200mm f/2.8 zoom + TC-20E III @ 600 mm, f/10, 1/400"

Paratroopers showed off a precision landing. When you see these guys sitting in their ropes, that looks rather comfortable — not really comforting, though, considering that international war convention explicitly allows shooting at paratroopers during their descent!

D300, 70 - 200mm f/2.8 zoom + TC-20E III @ 210 mm, f/10, 1/400"

D300, 70 - 200mm f/2.8 zoom + TC-20E III @ 420 mm, f/10, 1/400"

This was followed by a Super Puma helicopter presenting some amazing maneuvers: military pilots call this a "truck" — yet it can almost do loopings!

D300, 70 - 200mm f/2.8 zoom + TC-20E III @ 210 m, f/10, 1/400"

D300, 70 - 200mm f/2.8 zoom + TC-20E III @ 210 mm, f/10, 1/400"

This being the 75th anniversary of the Swiss air defense, they had to show some live shooting at real airplanes — using self-decaying plastic ammunition, of course:

D300, 70 - 200mm f/2.8 zoom + TC-20E III @ 480 mm, f/8, 1/250"

The highlight of every airshow in Switzerland is the Patrouille Suisse, showing some spectacular acrobatics & precision formation flights on their six F-5E "Tiger":

D300, 70 - 200mm f/2.8 zoom + TC-20E III @ 300 mm, f/11, 1/500"

D300, 70 - 200mm f/2.8 zoom + TC-20E III @ 300 mm, f/11, 1/500"

D300, 70 - 200mm f/2.8 zoom + TC-20E III @ 300 mm, f/10, 1/400"

D300, 70 - 200mm f/2.8 zoom + TC-20E III @ 210 mm, f/10, 1/400"

D300, 70 - 200mm f/2.8 zoom + TC-20E III @ 600 mm, f/11, 1/400"

D300, 70 - 200mm f/2.8 zoom + TC-20E III @ 600 mm, f/11, 1/500"

D300, 70 - 200mm f/2.8 zoom + TC-20E III @ 315 mm, f/11, 1/400"

 ... and their final bouquet before finishing the show with flares:

D300, 70 - 200mm f/2.8 zoom + TC-20E III @ 210 mm, f/10, 1/400"

D300, 70 - 200mm f/2.8 zoom + TC-20E III @ 210 mm, f/10, 1/400"

D300, 70 - 200mm f/2.8 zoom + TC-20E III @ 210 mm, f/10, 1/400"

D300, 70 - 200mm f/2.8 zoom + TC-20E III @ 210 mm, f/10, 1/400"

I missed the most spectacular piece where five Tigers are forming a tunnel, and the sixth machine is flying against them at near speed-of-sound, through the tunnel: exactly at that moment a guy in front of me decided to lift his daughter onto his shoulders, right into my view! Well, even with serial shots this is hard to capture anyway.

Given my lack of experience with photography at such events, I was quite satisfied: after processing and selecting I retained  almost 100 pictures out of 160 taken (could probably trash a couple more, though).