Why does my photo become darker around edges?

[janiece_struble]

Hey guys!

 

I have looked around for this for a couple days and can't find anything

relating to this anywhere. Can anyone tell me why my photos become darker

around the edges and how to fix the problem?

 

Here is the setup:

 

I'm using whiteboard- which I've heard gives that nice reflective look- which

it does, but also reflects my lights which then I must fix in photoshop. I

don't have a lot of room to work with, as this only comes in 4X8 sheets. I

have 1 for the background, and 1 for the floor. Then I have to fix the joint

in photoshop to make it look seemless. Anyone else use this stuff- if so how

do you work with it (add sheets to make it bigger and look seemless). I have 2

umbrella lights and the flash on my camera (NOT the built in one) to help make

the background white, overall it looks ok, but gets darker around the edges

(I'm not sure if I'm posting this right, but hopefully it works). Any

suggestions on fixing this so I don't have this problem next time?

 

Thanks

[Matt Laur]

There's something not right with that attachment. Please size it down to 500 pixels or so (it will still let folks see what's going on, and won't be so huge).

[janiece_struble]

Hope Im doing this right, try this image...

[Matt Laur]

Can you be more specific about your lights? Are they all strobes, or are some of them hot lights?

 

Usually the white foam core is used to help as a reflective surface... and muslin or white seamless paper can serve as your (no-joint-having) backdrop.

 

Overall, I'd say that you image looks underexposed. You need to open up the aperture on the lens and/or slow down the shutter. Ideally, you'd get that camera strobe OFF of the camera.

[elf]

get a roll of seamless.

 

Do you want the bg to be white?

 

If not, why not just crop the image down?

 

If you want a uniform tonality all the way across and up and down you'll have to use more

light. The dark corner is light drop-off.

[janiece_struble]

My lights are not strobes, but rather continuous. So, both of them are hotlights, then my flash. So would you guys put the paper down, then put the white down on top so it would reflect? I have never bought any of the paper before, do you guys know a good (cheap) place to buy it?

Yes, I want the bg to be white. I like the idea of it zoomed out, because when I cropped it in photoshop - I dont' know, I just didn't like it as well for some reason. So, next time I do this, just get more lights onto the background?

[Matt Laur]

I would put the paper down, and just use the paper. You don't need reflection below and behind your subject, you need more ligth coming from in front. If your lights are in umbrellas, they're probably already nicely diffused. But if a lot of your light from those is spilling uselessly elsewhere in the room, use those sheets of foamcore to bounce that light back into the scene from the sides, and from next to or behind the camera.

 

Consider NOT using your strobe, and just use a longer shutter speed on your camera to get a proper exposure. Set your white balance to tungsten to get the color right.

[elf]

Well, if your continuous light are tungsten, i.e. hotlights, they're going to have a different

and warmer spectrum than the flash, which is daylight balanced. So right there you're

going to get the pink/yellow tone in the background. So either you use tungsten film and

shoot with just the hotlights, or you color correct the backdrop in photoshop after the fact

(quite difficult and time consuming), or you use strobes.

 

As for using the fomecore for bounce, I'm not certain why you want it behind the kid. You

really don't need to light the kid's back!

 

But, whichever kind of lights you're using, you need more on the backdrop to make it

white, and you need to not mix the type of lights you're using.

 

I'm no expert on this, but I think most people light the backdrop separately from the kid -

2 sets of lights the same temperature, or better yet, more lights for the backdrop, just to

be certain of having enough.

[g._armour_van_horn]

To answer the question in the title of your post, you are seeing a little lens vignetting at the corners. The drop-off is too abrupt to be from the lights, and far two symmetrical. If you're using a filter of any kind, take it off. If you're using a zoom, zoom in a little and step back, zooms are much more likely to vignette at the wide end.

 

Note that you also have a light falloff in the upper left corner, but that just makes the lens vignette more pronounced there. I'm not sure why there isn't any in the lower right, maybe a little more light on that corner?

 

Van

 

Van

[manitas]

Aside from the background not being perfectly white, this looks to me like vignetting or light

falloff due to the design of the lens. were you using a hood of any kind?

 

I suggest you look at Mr. Rockwell's review of the 18-135 lens you used.

 

Beautiful photo, by the way.

[peter_j2]

I used Photoshop CS 2's Lens Distortion corrective tool to remove most of the vignetting. But, you can see a bit at the top left corner.<div></div>

[peter_j2]

I also played with Canon's DPP. Since your image is not in .CR2 format, I couldn't use DPP's periphery tool to reduce the vignetting or light fall off. I just quickly adjusted the image with some of the levers to remove the yellowishness.<div></div>

[musubi1000]

Shooting on a white background with hot lights = underexposed and color cast.

 

If your savy enough set a custom white balance to clear the color cast in camera not in photoshop. To get proper exposure meter off a grey card or review the histogram if you know what your doing. Since you're shooting with hot lights your shutter shouldn't be any faster than 1/60-1/125 even @ f2.8. If you are shooting with the aperture wide open you will see light fall off in every lens. To reduce the fall off stop the lens down but only if you can hold a decent shutter speed.