So I do a lot of inside photos. The problem that I'm having is a need a fast shutter speed without a flash. Like horses inside an arena. I can't have a flash but I need to take still photos. But the higher the shutter speed I have, the darker the photo. Advice, please?
When you're using the lens at the widest aperture and the photo is still too dark at the longest acceptable shutter time, then the only exposure parameter you have left with that lens is to raise the ISO. Then shoot raw and deal with the noise in post processing.¹
Ultimately, to get better image quality in dim light when you can not increase the exposure time (that is, you can't use a slower shutter speed) due to subject movement, there are two options to improve your results:
- Use a lens with a wider maximum aperture. We call lenses with wide maximum apertures "fast" lenses because they allow faster (shorter) shutter times at the same ISO than lenses with narrower "slower" apertures. Conversely, they allow lower ISO with the same shutter speeds. In your case, they would provide a brighter image using the same exposure time and ISO.
- Use a camera with better low light performance. This usually means a camera with a larger sensor for any significant improvement over another recent camera model, though a newer model may give incremental improvement over a slightly older model with the same sized sensor.
Since you haven't told us what kind of camera or lens you are using, we're going to make some assumptions so we can illustrate the concepts outlined above.
In the first case, let's say you're using a several generations older Canon APS-C body and a lens like the EF 15-85mm f/3.5-5.6 IS. You've got some room for improvement that won't cost you an arm and a leg. Maybe an EF 135mm f/2 or 200mm f/2.8 prime lens, or a 70-200mm f/2.8 or f/4. Maybe an 80D or 7D Mark II that are both better low light performers than something like the Rebel T3/1100D from back in 2011.
In the second case, let's say you're shooting with a Canon EOS 70D and an EF 70-300mm f/4-5.6 IS lens. The upgrade path here is going to be considerably more expensive.
The 70D, which came out in 2013, is a pretty good camera but the 80D that replaced it in Canon's lineup in 2016 is noticeably better, especially in low light.
As much as the 80D is improved over the 70D, even the older full frame 5D Mark III introduced in 2012, which uses the same basic sensor technology as the 70D does, will still give better low light performance than the 80D, which uses a newer sensor technology, when all other things are more or less equal.
This is because a full frame sensor has over twice as much surface area to collect light as the APS-C sensor does.
The biggest problem for most of us is that an "equal" lens for a full frame camera must have a 1.6X longer focal length to give the same view from the same shooting position than an APS-C camera. As you may have noticed, longer lenses, particularly those with wide apertures, get very expensive very quickly.
So let's say you are using your 70D with the EF 70-300mm f/4-5.6 IS. At 300mm, which is what you mostly use to frame the horses as large as you can, the maximum aperture is f/5.6. That's considered fairly "slow" by sports/action standards. A 300mm f/4 lens would be twice as bright at 300mm as your 70-300/4-5.6. A 300mm f/2.8 lens would be four times as bright at 300mm as your 70-300mm/4-5.6.
Why not just go out and buy a 300mm f/2.8 or 300m f/4?
- 300mm f/2.8 lenses are very expensive. The newest version, the EF 300mm f/2.8 L IS II runs around $6,100 from authorized dealers in the U.S. If one can afford it, they're some of the best lenses made. Most of us can't justify spending that much on a lens unless it gives us an opportunity to sell enough images to pay for it that we wouldn't be able to get with a cheaper lens. Even many full-time pros will rent such lenses on an "as needed" basis rather than buying them.
- 300mm f/4 lenses are older designs, if they're even still available. Canon's 300mm f/4 lens, which is still in the catalog in 2018 and considerably cheaper at around $1,350 than a 300/2.8, hasn't been updated since 1997 when it was introduced. A lot of progress has been made in lenses over the last two decades. Some of it is in the optics, but it is even more so with regard to Image Stabilization or IS. The EF 300mm f/4 was only the second IS lens Canon produced. Although the EF 300mm f/4 L IS does have IS, it is an early first generation IS that takes roughly one second to start up, and only provides for two stops or so of shake reduction. The latest IS systems from Canon can provide up to five stops of shake reduction, start up near instantly, can sense several different shooting conditions and adjust appropriately, and correct for more than just the angular motion of the earliest IS systems. Other lens makers have similarly "abandoned" 300mm prime lenses slower than f/2.8, and their 300mm f/2.8 primes are in the same price range as Canons.
- You could consider a third party lens. Sigma has made several generations of 120-300mm f/2.8 lenses. The latest is in the Sigma 'Global Vision' series that allows the user to update firmware and micro-adjust Autofocus calibration in more detail than provided by camera manufacturers using a computer connected to the lens via a USB dock. The Sigma 120-300mm f/2.8 DG OS HSM Sport sells for about $3,400. It's not quite as good optically as the recent Canon 300/2.8, but it is close enough for many at half the cost. Tamron has introduced an SP 70-200mm f/2.8 Di VC USD G2 that can go head to head with Canon's EF 70-200mm f/2.8 L IS II or III. Like the Sigma Global Vision series, the latest Tamron is compatible with what Tamron calls their 'Tap-in' dock to update firmware and calibrate AF.
If you upgrade to a full frame sensor, you gain about one stop of brightness in terms of the same signal-to-noise ratio. So an image at ISO 3200 on a FF camera should look about the same in terms of noise as an image at ISO 1600 on an APS-C camera with the same generation of sensor technology. Or to put it in the terms that would affect your situation: With the same aperture, an image from the FF camera shot at 1/800 second and ISO 3200 would be about as noisy as an image from the APS-C camera shot at 1/400 second and ISO 1600.
There are some FF models starting around $1,500 or so, but they might be a bit limited in terms of autofocus for what you're shooting. The better sports/action FF bodies start at about $2,500. And when you make the jump to FF, you also lose "reach" with the same lens. Your 300mm lens' field of view on a FF camera looks like a 200mm lens field of view on the APS-C. If you think 300/2.8 lenses are expensive, you don't want to know what a 500/4 or 400/2.8 costs!
So what are us mere mortals that have little hope of selling enough images to pay for a $10,000-15,000 camera/lens combination to do?
- Use the best APS-C "sports" body we can afford if we need the "reach." If we don't need the reach, use the most affordable FF body that gives us the AF performance we need.
- Use a 70-200mm f/2.8 (or maybe that 120-300mm f/2.8)
- If most of your horse arena shots are during a concentrated period of time, consider renting a longer and faster lens, such as a 300/2.8 or 400/2.8. Keep in mind that such lenses require better camera handling and shooting technique. You should probably allow a couple of days to practice with such a lens. We have a few questions here that talk about how to do it.
- Crop if needed to get the "reach" we want.
- Shoot raw and deal with the noise in post processing.¹
¹ The linked question is about ice hockey, but shooting horses in indoor arenas is not really that much different than shooting hockey players in indoor arenas, other than the background is brown dirt instead of ice.
TL/DR. Increase your ISO to 3200+ and/or get a faster lens.
The exposure (lightness/darkness) of the image depends on three factors: ISO, aperture, and shutter speed (also known as the exposure triangle). The lower the ISO, the smaller the aperture (bigger the f-number), and the faster the shutter speed, the darker the image will be.
So, to get a faster shutter speed, you probably have to increase the ISO, or increase the aperture or both. Assuming you're already increasing the ISO, shooting RAW, and post-processing for noise at ISO 3200 or 6400, then your lens is your most likely big limit.
Most lower-cost telephoto zoom lenses will have a maximum aperture of f/5.6 at the long end. That is, if you're zoomed in all the way, then f/5.6 is the widest you can open the lens. And you really need something f/2.8 or wider for available light shooting with higher shutter speeds, if you don't want to go up to ISO 3200.
I once shot showjumping in a well-lit arena at night from the stands with a Canon APS-C body and the EF 135mm f/2L USM (a $1000 lens, new). And I used ISO 400 with f/2 to get decent exposure. With an f/5.6 lens, I would have been three stops slower (-3EV), and would have had to use ISO 3200 to get equivalent exposure. If the light levels were lower, I'd have had to increase even more.
For indoor photography without flash the best you can do (in your case) is to take photos in shutter priority mode. And set ISO to auto. The same will be in manual mode, required shutter speed, wide open aperture and ISO to auto. In such circumstances you can benefit from fast lenses like 70-200mm/f2.8, 300mm/f2.8 depend of the distance to the object.
Set the lens to wide open and then let the automatic exposure select the shutter speed.
In fact one reason why some photographers use a prime lens is that a fast lens is affordable and compact as a prime lens. For instance, a 1.4 DSLR lens is usually available at 35mm, 50mm, and 85mm focal lengths. The 1.4 50mm lens could be a basketball lens on a DX DSLR or the 1.4 85mm lens could be a basketball lens on an FX DSLR.
But furthermore, if the subject is not moving then a tripod can be used with slow shutter speeds. Or the tripod can be panned with the subject if the subject is moving.
As a last resort, set the digital camera ISO to higher levels.