I am trying to test for a photoshoot of a model on white background and most of my images are coming out very dark unless I increase my aperture to the maximum.

I am using a fixed 50mm lens, shutter of 1/125 and wanted an aperture of F6 or F8 but I can't get the subject bright at all!

I am using this budget kit for lights on background and subject: https://www.amazon.com/LimoStudio-Photo-Video-Studio-Light/dp/B00LV46738/ref=sr_1_5?s=photo&ie=UTF8&qid=1482957339&sr=1-5&keywords=limostudio

  • \$\begingroup\$ You might want to read up on the exposure triangle:photo.stackexchange.com/a/12441/32110 \$\endgroup\$
    – ths
    Commented Dec 28, 2016 at 20:40
  • \$\begingroup\$ Set your ISO to auto, it will adjust accordingly to compensate for your shutter and aperture. You simply don't have enough light, so you will potentially have to deal with a noisy image. \$\endgroup\$
    – Robin
    Commented Jan 9, 2017 at 20:08

3 Answers 3


You have several options: Reduce the shutter speed from 1/125 to 1/60, this will give you one f-stop more. Set the shutter to 1/30 and you gain another f-stop. Likely these slower shutter speeds will be OK. A tripod will insure that the camera motion will not contribute a blur.

The main light, usually high and off to the side is the major contributor to the exposure. To gain more light, move the main closer to the subject.

To gain approximately one f-stop, measure distance subject to main in feet or meters. Multiply this measure by 0.7. This computes a revised closer position for the main. Place the fill at lens height adjacent to the camera. Multiply subject to main distance by 1.4. This math gives you a fill distance that establishes a 3:1 lighting ratio. The 3:1 ratio is the starting position. If more contrast is desired, multiply fill to subject distance again by 1.4. This revised distance delivers approximately a 5:1 lighting ratio that is considered more mescaline.

You can up the ISO by multiplying current ISO by 2. This will give you 1 f-stop more.

  • \$\begingroup\$ Hi. I am using a Bulb Top Lighting 120V 85W (5500K, 4250 Lumens) with an umbrella super close to the subject and at shutter 120 and F4 I am super dark still (200 ISO). Is that normal? \$\endgroup\$
    – samyb8
    Commented Dec 29, 2016 at 15:58
  • \$\begingroup\$ No one can say what is normal as a lighting setup is unique. Why not start by shooing an exposure sequence. Set the shutter at 1/125 and shoot a series at every f-number. Repeat using slower shutter 1/60 and then 1/30 and then 1/15. Repeat the series upping the ISO. Work in full f-stop increment a 2X change. Replace the lamps with higher wattage bubs. Don’t be afraid to purchases bulbs at the local hardware store. Report back your findings. \$\endgroup\$ Commented Dec 29, 2016 at 16:31

Your lighting kit is pretty weak in terms of the amount of light it gives off, so if it's your only source of light, that's why you're underexposed. You're essentially using 4x45W lightbulbs for continuous light that they say is the equivalent of a 200W incandescent bulb. While this is generally higher than most ambient lighting situations it's not higher by much. This would, in my opinion, still qualify as a low light situation, so at 1/125s and f/8, you probably need to be cranked up to an iso over 3200 to get a decent exposure. And you certainly won't be doing a lot with lighting ratios at all. This lower level of light can be good for video, since you're trading off for continuous light.

But flash is generally favored for stills portraits because in that short flash burst, you can get a lot more light--enough to create lighting ratios between the subject and the background that make for more drama. With a speedlight flash at nearer distances, you could easily use iso 200 or 400 with f/8 and your camera's sync speed and get good exposure.

The camera needs a lot more light to see by than your eyes do.

  • \$\begingroup\$ Totally agree. Good source lighting is key. Increasing ISO will introduce graininess/noise - whether this is a problem or not (or in fact ideal) depends on how you want your portrait to look. Increasing ISO is one way of doing it, but personally I think the graininess is limiting. You certainly won't get as sharp detail as you will by improving your lighting. \$\endgroup\$ Commented Dec 30, 2016 at 0:08

You have given us very little relevant information, especially how you are setting the exposure. If you're eyeballing it, for example, then the obvious answer is you're eyeballing it wrong.

You mentioned the background is white. One possibility is that you have the metering system set up so that it is exposing the white background properly, which means the actual subject in front of that background will be underexposed. If spot metering on the subject fixes it, then that was the problem.


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