What's going on here?

[www.philwinterphotography.]

Hello, I hope I have this in the correct forum, as I suspect this is an

equipment issue. Notice the "seam" where the images overlap. The entire left

side of the right image is about 1/4 stop darker than same place in the left

image. Both images were shot with a 10D and 28-135 IS (IS off, btw), on

manual at 6 sec, f11, ISO 100, RAW mode, converted in Breezebrowser to tiffs

with no exposure compensation in the RAW conversion. Assembly was in PSE2.

 

Anythoughts on this problem and a potential solution?

 

Thanks,

 

Phil

[beauh44]

Hi Phil, Very strange! Couple of thoughts: Is this the only shot that this has happened or is it repeatable? It could've been some weird anomaly (sunspots? at night? I dunno!) if it's just this one shot. On the other hand if it keeps happening no matter the lens, I'd say it's time to contact Canon and have them take a look at your camera. Good luck!

[bdp]

Looks to be shot right around sunset, shortly there-after. My guess, is that in the few seconds it took to realign the shot... the sky got that much darker.

[leopoldstotch]

Its because the sun was on the right side of the lens, which makes the left side appear darker. When you moved the camera to take the left half of the picture, the right side of the left image would be brighter than the left side of the right image because the sun is on the right side of the lens in both cases. I know that sounded confusing, so If I need to word this better just post a confused statement.

[leopoldstotch]

Wait..I've figured a simple way to put it: The light source is on the right, so the right side of the two images will be brighter than the left. A few minutes in photoshop can fix this.

[delwyn_ching]

It's definitely not because the sun was on the right side of the frame. The delineation between the lighter and darker side is a straight line so it's either the equipment or the software (something man-made). Try different lenses first with similar lighting situation. If still there, it's most likely your camera needs to go to the shop for examination.

 

Good luck

[leopoldstotch]

<p><i>"Notice the "seam" where the images overlap."</i></p>

<p>This is two images stitched together right?</p>

[J.W. Wall]

I'd go with Bob's guess.

[keith_van_hulle1]

I'm with Bob and Leopold. Camera was set on Av, Tv, or Prg and, with the change to get the second shot, the meter changed the exposure. When stitching photos, you have to shoot in Manual and fool the meter.

[fourfa]

same white balance?

[mark u]

Don't use PSE2 to stitch panoramas. Try using Panorama Tools via PT Assembler or PTGui instead. I think the time difference between the exposures might well account for the darkening sky at a time when light levels are falling very rapidly. You may do better by fine tuning the exposure compensation in the conversions (although PT can help with that too).

[les]

There is a gradient in lightness :lighter on the right of each pic, darker on the left.

[ilia]

I would agree with Bob - light changes really fast right after the sunset, 1/4 of the stop may happen in less than a minute. When I took this <a href="http://d6d2h4gfvy8t8.cloudfront.net/154321-lg.jpg">shot:<br><br><center> <img src="http://d6d2h4gfvy8t8.cloudfront.net/154321-sm.jpg"></center> </a><br><br> I had a series of shots made back-to-back in Av mode, and shutter speed was constantly going up from 10s to 15s and then to 30s

[drew_para]

Going by the information that he provided, it sounds like he took the pics in Manual... I certainly think the change in light sounds like a likely culprit. I would recommend shooting a uniformly lit wall or a clear blue and see if the image is dark on the left side. Perhaps there is some other issue. I have not done much pano work since switching to an DSLR, but I have had issues with night panos in the past (with a Canon S2 IS) but I chalked that up to the variations in light causing subtle amounts of flare... Sounded good when I told myself, so it must be the case.

 

Good luck!

[images_in_light_north_west]

I have seen this before you have to be very careful how you meter

[neild]

I'd go with Bob (changing light: I've seen it myself in my stitched shots). Another possibility is a slight vignette or corner-darkening, so subtle that you don't see it normally, but realigning blue sky really shows up even tiny changes in brightness. Both effects may be working, one doesn't prevent the other.

[musubi1000]

Has anyone even tested their camera lens combo set on M , shot w/the same exposure and judged the results. I've seen +- almost a full stop with the same exact exposure with a particular lens I was testing. Although I do believe the time lapse between exposures mentioned above was the culprit.

[JeffOwen]

As was suggested a few moments in PhotoShop and all can be corrected. I used levels and a the clone tool to hide the seem. Normally I would use the erase tool to blend the two images.<div></div>

[awindsor]

There are various stitching programs that will fix this reasonably seamlessly. I recommend Enblend.

 

http://enblend.sourceforge.net/

 

Exposure problems are common when you use a wide angle lens. Vignetting shows up when the edges are matched against the brighter middle of the image.

[m_barbu1]

I agree with Leszek that the reason is likely just because of the gradient.

[www.philwinterphotography.]

I really appreciate all the thoughtful responses to my question. I'm going to test the camera/lens on a blank wall, if that turns out OK, then it must the be time delay in repositioning the camera. Although that only took a few seconds.

 

A few weeks ago, I did a five image pano during the day, and I left the polarizing filter on to darken the sky. It did that alright, but the brightness differences from image to image were awful. I knew the polarizer would do that, so I got what I deserved!

 

Jeff, that's a great job on the image. I've tried over exposing the second (right) image in the RAW converter by 1/4 to 1/3 of a stop, but can't hit it right on. My next step will be to use the eraser tool at a low opacity to blend the two. That's worked well in the past.

 

Finally, after many years of shooting, I've become a fan of night photography. I'll post some images shortly.

 

Thanks!

 

Phil

[m_barbu1]

<p><i>I really appreciate all the thoughtful responses to my question. I'm going to test the camera/lens on a blank wall, if that turns out OK, then it must the be time delay in repositioning the camera. Although that only took a few seconds.</i></p>The time delay may contribute a little, but it's likely the gradient (dark to light) that is causing you the most angst.