What might be causing this??? Pentax K10 with manual lens

*8540tomg* · 09-19-2009, 01:57 PM

Hi all,

Below is a series of shots I took today. I was using my Pentax K10 and SMC Pentax M 400/5.6. The first image is fine but I'm getting a strange pair of vertical green bands in the last two shots. The images were taken moments apart. There was nothing in front of me and nothing behind the bird.

No green bands in the first shot.

ISO 100, shutter speed 100, f 11

It was overexposed so I stopped down a bit and got green bands from then on.

ISO 100, shutter speed 100, f16,

Any ideas what might have caused this problem?

I took a few images after I uploaded these pictures and I can't see any green bands in later shots. I'm puzzled.

Tom G

*heliphoto* · 09-19-2009, 02:21 PM

Reflections of reeds I'd guess...

*8540tomg* · 09-19-2009, 02:35 PM

That was my initial thought Josh but there were no reeds behind the bird. In the last shot the green band on the left seems to be passing over the duck.

Tom G

*heliphoto* · 09-19-2009, 02:56 PM

Originally Posted by 8540tomg

That was my initial thought Josh but there were no reeds behind the bird. In the last shot the green band on the left seems to be passing over the duck.

Tom G

I can see what you mean in the last photo, but I believe that's just an illusion - I'm convinced these are reflections of something in the background. Perhaps a Martian tripod-walker strode by and you missed it 'cause you were lookin' at a bird

...

Look at this crop from your second shot... notice how the band is affected by the ripples in the surface of the water?

*8540tomg* · 09-19-2009, 03:41 PM

Originally Posted by heliphoto

I can see what you mean in the last photo, but I believe that's just an illusion - I'm convinced these are reflections of something in the background. Perhaps a Martian tripod-walker strode by and you missed it 'cause you were lookin' at a bird ...

Look at this crop from your second shot... notice how the band is affected by the ripples in the surface of the water?

I follow your train of thought but there was nothing behind this duck but open water in the first shot. I'm sure this is not a by product of all those old football concussions. Shots 2 and 3 are from the same angle. I have no idea where these "phantom reeds" came from. There was no one around but myself at the time and the water is too shallow for anything but a canoe.

Hopefully it is just a one time aberration but I can't for the life of me explain it.

Tom G

ryan s · 09-19-2009, 03:44 PM

Sensor/lens reflections?

Does it only happen at f/16 or smaller? Have you ever seen it below f/11 in any other shots? Have you tried shooting something else as a test?

*8540tomg* · 09-19-2009, 04:40 PM

Originally Posted by ryan s

Sensor/lens reflections?

Does it only happen at f/16 or smaller? Have you ever seen it below f/11 in any other shots? Have you tried shooting something else as a test?

Possibly a sensor reflection or possibly I misjudged the angle and the position of the reed bed. I've never seen this at any f stop with any other lens. Very odd.

Tom G

*unkabin* · 09-19-2009, 04:43 PM

There's also a diagonal "reflection" or whatever anomaly, running from the upper right corner down to the lower left, that is not in the first pic.

*8540tomg* · 09-19-2009, 04:58 PM

I'm leaning towards sensor reflection as an explanation. It was a very bright afternoon. I was shooting against a reflective surface. This is a bit more plausable than Martian tripods marching by.

Thoughts?

Tom G

stevebrot · 09-19-2009, 05:35 PM

The first shot was taken from a different location than those that followed. Notice the vegetation in the water. It looks like you moved several feet to the right for the other shots. The "stripes" are the reflections in the water of something outside the frame (industrial chimneys...fence posts?). As Josh pointed out, the key is the ripples interrupting the stripes.

Steve

*8540tomg* · 09-19-2009, 05:56 PM

Originally Posted by stevebrot

The first shot was taken from a different location than those that followed. Notice the vegetation in the water. It looks like you moved several feet to the right for the other shots. The "stripes" are the reflections in the water of something outside the frame (industrial chimneys...fence posts?). As Josh pointed out, the key is the ripples interrupting the stripes.

Steve

I did move to the right but at the time of day in these latitudes the sun would have been almost over head. I could be wrong of couse.

Tom G