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Enthusiast
Posts: 3
Registered: ‎04-08-2017
Message 1 of 6 (432 Views)
Accepted Solution

Exposure changes during burst Sony a6300

I shoot a lot of sports movement in continous mode with the a6300 and am having problems in maintaining constant exposure within the burst. I use the manual shooting mode with short shutter speeds, constant aperture, ISO and white balance. My focusing is on DMF. Also turned the D-R OFF, and have tried with all of the different AEL w/ shutter settings, but the camera still makes exposure changes to the individual images. Also tried the AEL lock in AF/MF - AEL handle without success.

 

Attached links to two JPEGs from the same burst to show what I mean:

Image 1

Image 2

 

Would really appreciate if someone could help me out with this issue.

 Mikko

Professional
Posts: 1,661
Registered: ‎01-08-2015
Message 2 of 6 (414 Views)

Re: Exposure changes during burst Sony a6300

[ Edited ]

Since the photos you linked to don't contain the associated Exif data, it's impossible to say for certain what settings might cause the 2 images to be different.

 

If you're using M (Manual Exposure) mode, the only possible explanation is that the lighting conditions changed.

 

If the lighting is fluorescent, you need to remember that fluorescent bulbs do not emit a constant stream of light. They actually blink 120 times per second, which is too fast for you eyes to detect, but not for your camera. If you're using a very fast shutter speed, it's possible that, in one shot you're not picking up the same amount of light as you might in the next. In that case, you should use a slower shutter speed, possibly 1/125 or even slower. After all, for that kind of activity, the subject movement isn't very fast, so you don't need to use very fast shutter speeds. Basketball, on the other hand, would require a faster shutter speed, but that wouldn't be played under fluorescent lights.

¹ The Lens is the Thing
² 'Full Frame' is the new 'Medium Format'
³ "One good test is worth a thousand expert opinions." - Tex Johnston, Boeing 707 test pilot.
Enthusiast
Posts: 3
Registered: ‎04-08-2017
Message 3 of 6 (402 Views)

Re: Exposure changes during burst Sony a6300

Thanks for the reply!

 

I actually don't know how to get the Exif through Dropbox so here are the details side by side: Details. And the images:

 

Image 1

Image 2

 

I was thinking about the lighting, but wasn't convinced it would have such a big difference on the photos. And there's seems to be two different types of "effects": in some photos you can see this moving wave of shadow which I can believe is from the lighting, but in some it seems to directly affect the white balance like in the two linked examples. Any thoughts on these differences?  

Professional
Posts: 1,661
Registered: ‎01-08-2015
Message 4 of 6 (358 Views)

Re: Exposure changes during burst Sony a6300

[ Edited ]

FYI, for the 35mm f/1.8 OSS lens, I'd try to use an aperture of f/4.0 to get the sharpest possible image. Using either larger od smaller apertures results in less sharp images especially in the edges and corners.

 

You used the M (Manual Exposure) mode, so the variations in the brightness of your images can only be attributed to the lighting.

 

Electricity is delivered as Alternating Current (AC) which means that the electrons are shifted back and forth through the circuit at a rate of 60 Hz, or 60 cycles per second, a cycle being a complete shift from rest to flowing in one direction to rest to flowing in the other direction and back to rest. While incandescent lights use a glowing filament whose brightness doesn't change with the portion of that cycle, fluorescent lights use a gas which glows as the electrons move. The result is that while incandescent lights glow constantly, fluorescent lights blink very quickly at 120 times per second, faster than the human eye can detect.

 

... but not faster than the camera can detect.

 

You're using an exposure time of 1/250, which is about the duration of a dim-bright-dim portion of the cycle of a fluorescent light, but its also about the duration of a bright-dim-brigh portion. If you happen to press your shutter button to coincide with a mostly bright portion, you'll capture a brighter image than if you caught a less bright portion. That could account for the differences that you're seeing.

 

Further, your mention of the "moving wave of shadow" and the shifting white balance provides me with more evidence that this is what's actually happening.

 

If the venue uses two different kinds of lighting, for instance, both incandescent and fluorescent, then if the exposure occurred during a mostly bright portion of the cycle, then the shadows cast by the fluorescent bulbs would be more prominent than the shadows from the incandescent bulbs. But if the exposure occurred during a mostly dim portion, then the shadows cast by the incandescent bulbs would be more distinct. In addition, since the light from incandescent bulbs has a different color temperature than the light from fluorescent bulbs, you could expect to see a change in the white balance from one exposure to the next, depending on the proportion of light from the different light sources.

This makes sense because venues like yours select lighting based on safety and energy consumption, not photography. Shooting indoor sports/action is tough at the best of times. The only places where it can be done without concern is in basketball arenas for teams that have television contracts. Those contracts pay for the better lighting that television needs, and which photographers can benefit from. Otherwise, there's no telling what you'll get.

 

The only solution I can suggest is that you use a shutter speed of 1/60, so that the exposure time encompasses an entire cycle from the fluorescent lights, whenever you happen to press the shutter button during the cycle.

That should allow you to decrease the ISO from 3200 to 800. Unless she sprinkled pepper on her bare skin before her climb, I think you're getting a lot of image noise using ISO 3200. Using ISO 800 should clear that up a bit.

¹ The Lens is the Thing
² 'Full Frame' is the new 'Medium Format'
³ "One good test is worth a thousand expert opinions." - Tex Johnston, Boeing 707 test pilot.
Enthusiast
Posts: 3
Registered: ‎04-08-2017
Message 5 of 6 (333 Views)

Re: Exposure changes during burst Sony a6300

Believe it or not, but this makes perfect sense. Before I saw this reply, I went back to the gym and tested with shutterspeeds 1/80 and 1/160 holding all other settings constant. The slower shutterspeed resulted in way less effects in the burst. There was still some sligth "shadowing", but no white balance like differences as I described before with 1/250.

 

Thanks for the comprehensive input, and I'll definitely try with the aperture and lower ISO sensitivity you suggested.  

Highlighted
Professional
Posts: 1,661
Registered: ‎01-08-2015
Message 6 of 6 (324 Views)

Re: Exposure changes during burst Sony a6300

[ Edited ]

I still think you should try 1/60 to keep the exposure time in sync with the fluorescent lights, but I'm glad to hear that you're problem is resolved (sort of). And considering your subject, you shouldn't have to worry about motion blur.

 

... unless someone falls.

¹ The Lens is the Thing
² 'Full Frame' is the new 'Medium Format'
³ "One good test is worth a thousand expert opinions." - Tex Johnston, Boeing 707 test pilot.

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