Digital artifact?

[teamster633]

I'm only in my eighth month of digital photography so I know there are some things I haven't learned yet. As a whole, the transition from film has been smooth and intuitive. As the summer has progressed, and I've regressed into all too familiar subjects, however, the problem illustrated above has me puzzled. I never saw anything like this in film. Many times I got the exposure horribly wrong but, anytime I managed to hit the exposure correctly, the image was good. So far, anytime anything approaching the full orb of the sun (or even the moon for that matter) is in the frame, I get that weird, burnt-in halo. I've tried altering the aperture. I usually spot-meter the sky and underexpose by around 2 stops...sometimes even more. Lately I've seen some wonderful sunrise/sunset pictures here so I know it's possible. Could someone fill me in on what I'm doing wrong or should be doing differently?

[ManiacJoe]

1. Sensor bloom?

I may not have the name correct. Basically, when a large section of the sensor gets greatly overexposed, some of the near pixels get affected, too.

[Schema Thing]

2. What camera/lens combo is that pic, and ...

... what film camera/lens combo would you be comparing too?

[teamster633]

3. EOS 50D w/ EF 70-200mm f 2.8L

I had a number of film cameras over the years but, they were all Canons. The most recent was an EOS 3. Most of the time, when I was shooting a sunrise, I would have used an old Sigma 500mm f7.2.

Certainly, the current lens is far superior to the Sigma (which I still would have used yesterday but, that's another story). The EOS 50D does lack some of the features I had available to me with the EOS 3 but, in this case, the ability to proof the exposure in real time would seem to outweigh anything that the 50D is otherwise lacking.

[Schema Thing]

4. hmmm, velly interestink!

This may or may not be related, but my intuition would tell me that the horizon line (the trees or brush) I'm seeing in that picture should be in better, if not perfect, focus. I may be totally fooled by the relative distances of course.

You may want to check that your infinity focus is truly focusing at infinity.

[teamster633]

5. On closer inspection, I'd have to agree that the horizon line is a little soft.

My original thought was to use the bridge I was on to frame the sunrise. When it became apparent that was impossible, I don't remember where I chose to focus. Certainly the trees would have been the obvious choice but, having gotten up way too early to do this, I don't know for sure. I know I chose to use manual focus since I was setting my exposure from the sky and recomposing the frame kept resetting the exposure reading. The exposure was set manually as well; at least 1 stop under but, maybe 2 stops under. The camera was on a tripod and the shutter was on a remote release. Here are a few other examples and an old film shot for comparison.

Film:


CMOS:


CMOS with RAW adjustment:


As you can see, the film shot shows no trace of this phenomenon. The second shot is the first time I tried to shoot a sunrise with a digital camera and the first time I saw anything like this. The third shot demonstrates that I can diminish the problem using the Recovery slider in Adobe Camera Raw but I can't eliminate it.

[Schema Thing]

7. the .raw adjustment

....is much closer to your film exposure (is the film neg or transparency? what film?)



again though, it looks to me like the beach in your cmos photo is pretty sharp, which probably means that your sun is not sharp. And your cmos exposure is considerably hotter than your film exposure. The focus and the exposure together could possibly account for this.

You'll also want to consider what f stop/film speed combination you've been using.


You can't really make any determination until you actually have apples to apples comparisons. Or, in this case, you don't need to worry about film, but rather just see what the digital camera/lens combo can do. The nice thing is that a frame of digital doesn't cost anything, so test away!

I know Canon has had some odd focusing problems in the past few years, so it's a good idea to make sure the lens is focusing where is is supposed to be anyway.

[teamster633]

6. A possible answer?

"Highlight Rendition: Digital still has a huge problem with highlight reproduction, presuming you, like me, shoot into the sun or other sources of light. Film for hundreds of years has naturally had "shoulders" in its characteristic curve. This means that even with severe overexposure in places that the highlights are rendered naturally on film, even contrasty slide film like the Velvia I love.

On the other hand, at the dawn of the 21st century digital capture is more linear than logarithmic as film is. This means that digital cameras often have better shadow detail than my Velvia, but can have horrid, unnatural highlights if overexposed even a third of a stop.

Specifically, digital clips hard as soon as you are a few stops over zone V. This could be OK, however unfortunately in color one of the three color channels (red, green or blue) usually clips first, throwing the hue (color) into all sorts of weird shifts in the areas the image transitions from bright to pure white. This is why digital camera images may show all sorts of nasty, unnatural hue (color) shifts in the brightest areas."

This is from 2006 by Ken Rockwell (but still sounds plausible today). If this is the problem, what can I do to get around it? I see some stunning sunrise/sunset pictures here so there must be some technique that I'm not aware of. Or does this have to be resolved in post?

[Schema Thing]

8. maybe but not likely

First you have to determine if you really have a serious problem.

That means testing to make sure it does or doesn't happen if

A) you get your exposure low enough - you need to test this both with aperture and shutter speed, because staring down the barrel of the sun is definitely something that is going to look different at different apertures. (and f 7.1 on one lens will not be the same effect as f8 on another lens; though your canon lens should be very good at most all apertures.)

and

B) you get your focus sharp on the sun (infinity focus), or at least sharp enough.


Once you've done those things, and if you don't have a "ring-around-the-sun" problem, then you may want to try shooting multiple exposures for the sun and the rest of the image to combine (HDR).

Hope I've been some help!

[teamster633]

9. Definitely some food for thought.

Thanks for your input. It isn't often that I bother to get up early on a day off to take those kind of shots anymore so it bothered me that something which I rarely gave a second thought to was suddenly giving me technical difficulties.

[Schema Thing]

10. I know what you mean.

btw, I meant to tell you that your image with the ship is great!

[NashVegas]

11. I Would Think MP/DPI Would Be The Issue

I used to take a lot of concert photography, stage lights were always an issue, especially at lower MP/sensors when digital cameras first came out.

15MP still isn't all that great, compared to film, at capturing the most subtle, gradual changes in the color scale.