Whenever I take photos in bad lighting I always wonder if I should use a higher ISO camera or instead use brighter lighting. Please no opinions- just comparisons!
You can realistically use either. However both come with their own limitations and drawbacks.
If you use high ISO then your image quality will start to degrade, causing what is commonly referred to as noise in the image. This means people generally try to avoid using high ISOs when shooting photographs.
On the other hand if you use brighter lighting then you eliminate any degradation towards image quality. However you then have the problem of how your going to achieve brighter lighting. This could involve artificial lighting such as strobes and continuous . Which can be troublesome on their own sometimes.
The best thing to do is experiment with different combinations and explore the limitations your camera has with regards to high ISO. Aswell as the use of additional lighting.
Does "brighter lighting" mean you have control over the scene, or (like other answerers assume) you are referring to a hand-held flash?
If you are lighting the scene, or can influence the lights being used for the situation, then by all means use brighter and better-quality light!
If you can place remote slaves ahead of time, "more light" that way is good.
If you are just using a brighter hand-held flash (not quite "on-camera", but on a mast on your camera frame, so I don't call it "on camera"), the tradeoffs are all the flash issues: inky shadows, stark lighting without ambient fill, and background falling off into darkness.
The tradeoff to using higher iso is more noise.
It's not a either/or question though: you are balancing the two issues. The wrong choise can give you the worst of each, flash-look and grainy; the right choice will balance the effects.
I can't give specific numbers. It depends...
- how much noise can you take? What amount would not even be noticed? That depends on print size, whether you are cropping out of a larger shot, the camera's performance, and who knows what else.
- how much work do you do in Photoshop after taking the picture?
- what is the background? If there is a wall then no worry about fall-off. If the shot is a room without a near subject than the falloff can be addressed with a gradent exposure boost.
- what is the ambient level of light? If you are already way past it, adding more flash won't change much. If you can get less stark "flash look" with the higher iso, then it might be worth it.
Does "bigger flash" mean getting a high-end portable strobe with diffusion? Then more power will give room lighting fill and not just ugly "flash look", so there is less of a downside. Except for the 4-digit price tag.
Try it. See what different approaches do, in a non-critical venue where you can just practice and play around with the equipment.
The above should help you look critically at the practice shots, and you can evaluate the differences. If you can rent a new strobe or equipment, do that again to see if it's worth the investment.
It's sort of like the problem of not having a long enough lens to magnify a different object: you can use digital zoom, or crop ("blow up") the image in post processing, but the image degrades. You are using a digital trick to compensate for the lack of good light, or signal, coming into the camera lens in the first place. Better to use a telephoto.
Same with low light. Using a high ISO is a post-light collection technique for changing the range of light sensed (post sensor gain), but it's still too little light. The result is noise, since the technique also sort of magnifies that (really what happens is the noise is sorta the same, but now the signal, the light we wanna record has dropped closer to the level of the noise).
So the best solution is always to get more light in to the sensor. Faster lens, bigger aperture, external light source. That's even true in regularly lit scenes, hence the ETTR "Expose to the Right" technique. But of course, as noted, that involves trade-offs. You could get a better camera body/sensor, or maybe a faster lens. Or add light. Or use other techniques: with stationary objects you can even use longer exposures, and HDR or other stacking techniques.
Your question doesn't really have a right answer in the abstract. A night sky shot is different than a dimly lit interior shot of dancers. It's gonna be a different answer for each photo.
It depends. There are several competing factors to think about, such as:
- Having brighter lighting will kill any ambient light (if there is any). Obviously this is an artistic choice. Sometimes you might want this, other times not.
- Shooting at high power will increase your flash recharge time, possibly up to several seconds. If you are shooting people, for example, either you will keep them waiting awkwardly long if they are posing for you, or you could miss the perfect moment if you are shooting candids.
My overall advice is to not worry too much about creeping in to the higher ISO ranges, and focus on getting the shot you want. Though of course be aware how high is too high with your particular camera.
With regards to shutter speed, it is often said that you can reduce noise in post, but you can't fix a blurry subject. Similarly, you can't fix a hopelessly unexposed background, and you can't bring back an opportunity that you missed because you were waiting for you flash to come back from a full discharge.
Do you like apples or pears better? Photography is an arbitrary choice too, of style.
The photographers using flash or studio lighting are in one camp, adding necessary and sufficient light for the purpose and situation (sometimes based on what will sell better). The available light people are in the other camp, thinking the situation should be retained as a major part of the photo.
Judging their typical results should aid in choosing your own style.