bright fluorescent light?

[fivaxis]

I use my A60 for photographing jewelry, it works pretty well for what it is but is getting a little old. I use a white light box that I built, it has 4 two foot long fluorescent bulbs in it. One problem I have is that the brightness fluctuates a lot, from picture to picture one will be bright and washed out, the next will be too dark. This is on manual mode, so it's not because the apeture, shutter speed, or ISO are changing it's something else.

One interesting thing is that once I've held the shutter half way down and it's focused on the jewelry, it will fluctuate from dark to bright. Other times it will focus and then it won't fluctuate.

Now this is something I can live with for now, but my concern comes when I contemplate which camera to buy next. I recently purchased an A510 for my brother which is supposed to be the latest version. However I tried taking a picture with it in the light box, and it absolutely could not focus. Here is a brightly lit object and it couldn't focus on it. It does ok otherwise.

I figure it must have something to do with the vibration frequency of the lights, I'm wondering if this is a problem with just Canons or digital cameras in general? It makes me think twice about getting a new Camera, I would hate to spend a lot of money on one and find out that it can't even take a decent picture.


Here is an example, these two were taken back to back with the same settings.

http://www.fivaxis.com/darklight.jpg


Here is an approximation (using Photoshop) of what kind of picture the A510 took (camera is not around so I had to recreate it)


http://www.fivaxis.com/blurredring.jpg

[S45_fornow...]

Are you using Auto White Balance, or setting the white balance manually to the Flourescent setting? What is the metering on the camera set to? Are you using macro mode or full zoom without macro?

[Curtis N]

Fluorescent bulbs are actually pulsing at 60 cycles/second. I don't have much experience using that kind of lighting but I would guess that if your shutter speed is too short it could lead to exposure fluctuations.

Auto focus relies on contrast - it needs a sharp line of bright/dark at the focus point. This may be the problem with this image and you may need to focus manually.

[Mernya]

Sure could Curtis. It is the same reason you should be bumping your CRT monitors to at least 75 Hz if you have fluorescent lights. It is responsible for the flicker-effect.

[CyberDyneSystems]

I'm missing the point.. you show two fine photos taken with god knows what camera.. then a third intentionally "messed up" in photoshot and say this is what a Canon would look like ... but ti too wasn't taken with a Canon. ???

I'm unconvinced .. I've never had this problem or seen it. And by showing as a Photoshopped image taken by an unknown camera .. how are we supposed to comment?

The only possible advice.. "Don't photoshop your images to look bad" :confused:

[S45_fornow...]

I'm missing the point.. you show two fine photos taken with god knows what camera.. then a third intentionally "messed up" in photoshot and say this is what a Canon would look like ... but ti too wasn't taken with a Canon. ???

I'm unconvinced .. I've never had this problem or seen it. And by showing as a Photoshopped image taken by an unknown camera .. how are we supposed to comment?

The only possible advice.. "Don't photoshop your images to look bad" :confused:

Tell us how you really feel, CDS. :lol:

[Bodryn]

Fixavis: If you take your photos with the aperture stopped way down to f/8 or higher if you can, and with a slow shutter speed, say 1/10 sec or slower, you should have no problem with the far faster flourescent flicker. Also, to be sure that exposure conditions are constant, if you haven't done so, use a tripod and the 2 second self-timer to avoid camera movement. Also if your A60 is like my A70, and you use the manual settings, you can set the focus manually as well as the aperture and shuuter speed, and it should stay there and not change. Hope this helps.

[fivaxis]

If you actually read the post you would know what camera it is.

I'm missing the point.. you show two fine photos taken with god knows what camera.. then a third intentionally "messed up" in photoshot and say this is what a Canon would look like ... but ti too wasn't taken with a Canon. ???

I'm unconvinced .. I've never had this problem or seen it. And by showing as a Photoshopped image taken by an unknown camera .. how are we supposed to comment?

The only possible advice.. "Don't photoshop your images to look bad" :confused:

[fivaxis]

Thanks. I have the apeture set at 8, shutter speed 1/100. I was using macro, but I found that going to manual focus seemed to help. I'm using a tripod also.

Fixavis: If you take your photos with the aperture stopped way down to f/8 or higher if you can, and with a slow shutter speed, say 1/10 sec or slower, you should have no problem with the far faster flourescent flicker. Also, to be sure that exposure conditions are constant, if you haven't done so, use a tripod and the 2 second self-timer to avoid camera movement. Also if your A60 is like my A70, and you use the manual settings, you can set the focus manually as well as the aperture and shuuter speed, and it should stay there and not change. Hope this helps.

[Bodryn]

If you are using a shutter speed of 1/100, you probably will have that flicker problem; i.e., the fluorescent is probably not giving off a steady light even though it may seem so, and depending on how your shutter happened to synchronize, the fluorescent may or may not be bright at that particular moment. This is why I would suggest a much slower shutter speed: several flickers would occur within a slower shutter speed and the flicker would be irrelevant.

Or if you must use a fast shutter, you might consider using another type of light source such as a color-corrected incandescent light bulb.