Is my XT dying?

[Fadia]

My XT is at about 25,000 pics. It has served me well. I have had no problems other than a few misfocused shots. Usually user error.

Tonight I was trying to capture some action shots of my daughter with my new 85 f1.8. I was shooting in very low light. She was running around our house. I was putting the lens to the test. Didn't get too many keepers as I was trying to figure out what the limits of this lens was.

When I loaded up the pics, I saw something that disturbed me. I got maybe one keeper. But what was troubling was a consistent pattern in each of the pics. I was shooting RAW and wide open.



Here is a 100% crop:



The banding lines seem to be on only the lower 50% of the picture. Most of the other pictures I took this evening exhibit the same pattern. This is about the most pronounced of the pics. Others are less and there are a handful that I took that I don't see any banding at all.

My 50 f1.8 did the same thing. So I am convinced it is a sensor issue. I can't bear the thought of having to send my XT away for repair. How long would that take?

We are going to the circus tomorrow night. I am going to see what happens. Hopefully this was just a fluke thing.

 

[sparkey2]

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It looks more like moire to me. Banding has a different look. Kind of like you monitor is on 256 colors rather than 10 bazillion. I think moire involves the filter over the sensor. Did you possibly use the wrong type of cleaning fluid and damage your anti aliasing filter?

Google moire for better diagnosis and and possible solutions. I don't know any more about it.

Good luck, hope my XT don't start that.

 

[highpriest]

When I loaded up the pics, I saw something that disturbed me. I got
maybe one keeper. But what was troubling was a consistent pattern in
each of the pics. I was shooting RAW and wide open.

Some sort of electrical interference maybe? What ISO was this shot at?

Cheers
HighPriest

 

[Fadia]

No cleaning fluid. I have never used anything except a rocket blower to clean the sensor. And that I have not done for some time.

I tried to replicate this today, but it doesn't seem to be doing again.

 

[Fadia]

Shot at ISO 1600.

I thought about some type of interference. WiFi? Cordless phone? Cell phone? We live in a rural area so I am not sure if we would be picking up something that would interfere from outside our home.

 

[imqqmi]

I've tried it with my xt/350D (around 50K shots) and I don't see any banding like yours does. I've used the same settings you've used (looking at the exif info) and same lens.

I have seen banding with this camera at times though, most notably in fluorescence or sodium vapor light. Could this be the case with your shots?

--
Kind regards
Imqqmi



http://www.pbase.com/imqqmi

 

[Fadia]

We have energy efficient, soft white fluorescent bulbs. White balance has been a little tricky since we began using these lights.

I didn't associate the occurrence with lighting - but maybe.

 

[imqqmi]

If lighting is not like daylight 5500K some of the colors of the sensor is pushed more to produce proper colors which can introduce more noise and banding. But Fluorescence pulses in different colors and intensity over time too, I think the period time is around 100-120Hz or a multiple of that. That might show as banding, sometimes a color shift along the axis the shutter moves (only in speeds about 1/200ss).

If AI Servo mode is used it might be the motor giving off pulses that might interfere with the sensor.

We have energy efficient, soft white fluorescent bulbs. White
balance has been a little tricky since we began using these lights.

I didn't associate the occurrence with lighting - but maybe.

--
Kind regards
Imqqmi



http://www.pbase.com/imqqmi

 

[RedFox88]

Shooting iso1600 and under exposing it by a good 1 stop, which your photo is, will lead to noise and banding in the dakest of shadows.

Just properly expose your high iso shots to avoid this, which means monitoring your histogram after your shots and use exposure compensation if necessary.

 

[Oak and Acorn]

We have energy efficient, soft white fluorescent bulbs. White
balance has been a little tricky since we began using these lights.

I didn't associate the occurrence with lighting - but maybe.

I'm going to guess this as the culprit. Try replicating the issue under different lighting types and see what happens. Then, try replicating it under the same lighting conditions as the image you've posted in this thread. You should get your answer one way or another using this techinique.

--
bryan
--------
http://bryanw.zenfolio.com/
http://www.flickr.com/photos/oakandacorns/sets/



Canon 50D Images: http://bryanw.zenfolio.com/p949109255

 

[steinr98]

Try shooting outside under low light conditions or about the same darkness as you had inside. This should tell you if the lights are the problems. I think you are way off base looking at phones and power problems. Shooting @1600 ISO can cause all kinds of problems and noise under low light. Try shooting in normal light and check the lens and camera- if the setup is bad it won't matter what the light conditions are.
--
Steinr98

 

[Fadia]

Ok, here is an update. We went to the circus last night. Again it was a very difficult shooting environment. Heavy contrast with spotlights in a dark arena. Lighting was frequently changing so I shot in AV and allowed the shutter to adjust appropriately. I was shooting wide open, again using the 85 f1.8. About half the time I did stopped down to 2.0 (I am glad I did because I got some really bad CA at 1.8)

I had a few pics present this banding pattern, but not nearly as many. I took about 100 pics and about 5 presented the banding problem. I tried to examine the exif of the pics that had the problem to see if there was pattern. Here is what I noticed. The pics that presented the banding problem tended to over-expose and blow the highlights with a shutter speed below 1/200. Typically, I had overexposed performers in the spotlight in these pics.

The pics where I nailed the exposure on the performers never presented the banding problem. These exposures were typically over 1/500. The background of these pics were dark shadows, but were clean other than the noise.

So what I am saying in all this is that I was able to recreate the banding in the shadows of high dynamic range pics that I had overexposed highlights.

As an example - in a sequence of 4 pics I caught a tiger jumping. The 2nd pic of this sequence I got a good portion of the tigers underside which was mostly white. The highlights on the bottom side were blown and the banding presented itself. The other 3 pics that did not have blown highlights were fine - these pics did not capture the white underside, but the orange back.

I would post some pics, but the circus made an announcement that the pics you might take were for your own viewing pleasure only. Not sure if I could legally do so.

 

[guinness2]

I recognized similar effect recently, when I set up for ISO1600 and later +2EV in DPP.

I concluded it was due to pushing things to its limit and was able to remove in noise reduction.Unfortunately I was also using the AI servo and IS on 400D/17-85, so I can't exclude this , but your effect seems to me more regular and similar to interference (electrical or fluorescent light) than my one.

I send you an example as a negative comparison. (It was taken in portrait position.)