Setting ISO

[Cyrano]

I can manually set the ISO on my Canon 70D camera. What are the changes in picture qauality, if any, from setting the ISO high or low. I know if set low, there is the chance of moving the camera during the exposure with consequent blurring of the image, but I'm interested in the direct effect ISO settings may have on picture quality.

 

[Watchdog]

I can manually set the ISO on my Canon 70D camera. What are the changes in picture qauality, if any, from setting the ISO high or low. I know if set low, there is the chance of moving the camera during the exposure with consequent blurring of the image, but I'm interested in the direct effect ISO settings may have on picture quality.

The higher you go with ISO settings, the more "grain" you'll see in the finished image. I still use the term "grain", even though it primarily applies to film. In digital terms, we refer to it as "noise". Higher ISOs equal more digital noise.

When light and subject matter permit, I shoot at ISO 100. This gives me the smoothness I want. I always shoot at 100 in the studio or when using studio lighting. I'll shoot at 100 in bright outdoor light. If I want to shoot on overcast days, I'll open up the aperture and still try for ISO 100.

When I'm shooting action, I'll bump up to at least ISO 400, and often all the way up to 1600 and fast shutter speeds.

Remember at higher ISOs and faster shutter speeds, you're letting in less light, so you'll need to open up your aperture accordingly.

A lot of this is personal preference. As a photographer, you are the one who decides how you want the finished image to look.

Also, I always shoot in manual mode. I want to be the one who makes image decisions. I don't want some camera-based algorithm deciding how to properly expose for a shot.

As an example, the photo below was exposed at ISO 100, f/5.6, and 1/100. It was outside in very open shade. The lens used was the Canon 70-200mm f/2.8L IS. I might could've stopped down to f/8, but I'm satisfied with it as it is.

Don't know if this helps you any...it's just some of my thoughts.

 

[Tom S.]

What changes is the grain of the picture. In film (remember that stuff?) there was quite a difference between 100 and 400 when 400 color film was first introduced. With digital, it isn't nearly as noticeable until you start getting higher, like 1600, depending on the camera.

 

[DWalt]

ISO is basically film sensitivity to light, and regarding a digital sensor, it means much the same thing. At high sensitivity (high ISO), various artifacts and noise may be introduced into the image (analogous to grain in film), but many current cameras incorporate some sort of electronic filtering to reduce that effect somewhat. Best way to see what your camera does it to try it at different ISO settings.

 

[vt_shooter]

You basically want to use the lowest ISO you can. The way I approach selecting ISO is I figure what aperture I want to use, then I figure the minimum shutter speed I want that likely will give me the desired sharpness (or motion blur), then I select the ISO will provide the proper exposure for that aperture / shutter speed combination. By approaching it like this I am ensuring that I use the lowest ISO that will give me the other technical qualities I want. If I’m exposing with flash, it’s a different ball game - I have a feel for how much flash power I have available, and I simply use the aperture and distances that will work best given the flash power.

 

[Cpo1944]

I really love photography and my Nikon D-800 for serious images I work quite hard to get the best possible stuff, so its aperture or Manual mode.
When I am just doing snap shots, I set the ISO to auto and let the camera decide up to the max. I set it for usually 1600. I set the minimum auto shutter speed -usually twice the focal length of the lens I`m using. That way I can rip off quick shots and only concentrate on composition and not worry about exposure.
With the ISO in auto thats one less thing to worry/think about.

 

[Ben_hutcherson]

ISO is an abstraction in digital cameras from very specific definitions regarding light sensitivity of film.

Basically, it refers to the amount the signal from the sensor is amplified to produce the final image. Greater amounts of amplification produce greater amounts of noise.

In general, I tend toward the lowest ISOs possible to give reasonable shutter speeds under given lighting conditions. With that said, modern CMOS sensors in DSLRs that you don't see a drastic difference in noise until you get to the extremes of ISO. As a rule of thumb, you do likely want to avoid the highest setting on your camera because it's often achieved using the same amplification as the next setting under and then increasing the brightness in-camera. The effect is somewhat similar to push processing films. In general, if I find myself needing to use the highest setting, I will just intentionally underexpose at the next lowest ISO and then do what I can to recover the shadows from the RAW file-I can usually get something more salvageable that way.

By the way, even on my cheap Digital Rebel noise is pretty well controlled out to about ISO 1600, although it does look a lot better at 400 and under(I can't see the difference from 100-400 at anything other than 100% magnification, which would be a huge print). Back when it was still available, I shot a decent amount of Fujicolor ISO 1600 and even played a little bit with Kodak T-MAX FX3200. The latter was nominally an ISO 400 film(again, there is a specific definition for an ISO rating of a film) that was designed to be exposed at EI3200 and push processed there. It looked okay, although the grain was the size of boulders. The Fuji wasn't a lot better at 1600.

 

[PALADIN85020]

Many SLR cameras will let you limit how high the "auto ISO" feature will let the camera go. I find that I get best picture quality in the range of 100 to 800 ISO, and that's how I set that feature. If I'm shooting in very low light, I can set it to 3200 and usually get a decent picture. Shooting in RAW mode helps in lower light, as you can usually manipulate the RAW image with software to get a more properly exposed picture.

Many cameras will let you set a much higher ISO which will let you shoot almost in the dark. You can expect a lot of "noise" in the photo, but there is some software that will let you alleviate that effect. It will give a sort of smooth plastic effect to the picture, but at least you will get a picture!

By the way, having a tripod helps when shooting in low light and a lower ISO in the 100-400 range. Then a longer exposure is feasible with no ill effects from camera movement. I routinely set my ISO at 100 for my firearms pictures, use a tripod, set the f/stop manually, and then take multiple shots at various longer exposures, picking the one that turns out best. Even then, I'll adjust the RAW image to get as near to a perfect JPG as possible. This is a long way from snapshots, but the results are well worth the trouble.

John

 

[Cyrano]

Thanks for the education, guys. I have a much better understanding now of what I'm doing. I do my gun photography on a copy stand, and use ISO 200 which I guess is OK. I got to wondering about this since I just got a 400mm lens and thought about using it hand held. Shutter speed would have to be about 1/800 sec, and the max aperture of that lens is f 4.5, so I'd have to run the ISO up quite a bit, and I was wondering about the effect on picture quality.

 

[5-Shot]

Three ingredients go into making a proper exposure: shutter speed, f-stop and ISO. Each impacts the resultant picture in its own way. Frequently I manually set the shutter and f- stop and leave the ISO for the camera. It works out pretty well with cameras which are tolerant of high ISO's. Otherwise, the lower the ISO the better.

 

[M29since14]

Cyrano, off topic a bit but remember, with your 400 mm lens on a tripod you should be able to go quite a bit lower than 1/800th. With a lens that long, hand-holding is never a great thing at any shutter speed. I was always taught when the lens is 2x or more than standard focal length, default position is the tripod just like the tripod is always default whenever time allows, with any lens.

The old rule of thumb to use the slowest rated film or ISO setting for the job at hand is always a good one, even with the most modern cameras.

 

[Tom S.]

Thanks for the education, guys. I have a much better understanding now of what I'm doing. I do my gun photography on a copy stand, and use ISO 200 which I guess is OK. I got to wondering about this since I just got a 400mm lens and thought about using it hand held. Shutter speed would have to be about 1/800 sec, and the max aperture of that lens is f 4.5, so I'd have to run the ISO up quite a bit, and I was wondering about the effect on picture quality.

Using it hand held is not your best option, even if you increase the ISO to get a faster shutter speed. I'm not saying it can't be done, but using a tripod or monopod will give better results and won't require the higher ISO.

 

[Ben_hutcherson]

Cyrano, off topic a bit but remember, with your 400 mm lens on a tripod you should be able to go quite a bit lower than 1/800th. With a lens that long, hand-holding is never a great thing at any shutter speed. I was always taught when the lens is 2x or more than standard focal length, default position is the tripod just like the tripod is always default whenever time allows, with any lens.

The old rule of thumb to use the slowest rated film or ISO setting for the job at hand is always a good one, even with the most modern cameras.

One of the "best" lenses in my collection is a 400mm 4.5. Back when I dabbled some in action photography-i.e. sporting events and the like-my go to was a high speed film(either Fujicolor 1600 or TMAX FX3200 as mentioned earlier) and always with some form of support. Since a tripod was impractical in many situations, I spent a lot of time with that lens on a monopod and managed to at least get some halfway decent photos at least until it got too dark.

That 400mm lens-like a lot of long focal length, large aperture lenses, has a tripod mount on the lens itself with the intention being that you mount the lens on the tripod and then hang the camera off the back of it. When you have a lens that's 2' long or longer, that's a good way to do it!

 

[Dennis The B]

The rule of thumb @ ISO 100 is to never hand hold a lens using a shutter speed slower than one over the focal length. So, @ f8 a 50mm lens @ 1/50th second, etc. With longer focal lengths, the vibration is magnified more geometrically than linearly.

Even with VR (Vibration Reduction) on lenses, it's always a good idea to use a sturdy tripod and head.

I own a Nikon 200-500mm f5.6 zoom, and I've tried a few hand held shots using ISO 1600 @ f5.6, and the results were barely acceptable. Using photo software like Photoshop, the vibration issues are plainly apparent at magnifications as small as 2X.

I just upgraded my DSLR from a Nikon D200 to a pair of Nikons (D500, D750), and the change in resolution at ISO's 800 and 1600 is a quantum leap, using the same lenses on all three cameras.

 

[Ben_hutcherson]

The rule of thumb @ ISO 100 is to never hand hold a lens using a shutter speed slower than one over the focal length. So, @ f8 a 50mm lens @ 1/50th second, etc. With longer focal lengths, the vibration is magnified more geometrically than linearly.

This is a good rule of thumb for any ISO(it's not specific for ISO 100) but it's important to remember that the rule was developed for 35mm. With other formats, you can generally get away with the 35mm equivalent focal length.

For a crop sensor DSLR, that means that if you a "normal" lens in the range of 30-35mm, you should still shoot for 1/50(or 1/60 on most cameras). Similarly, with an 80mm lens on a 6x6 medium format camera, 1/60 is a workable number.

With steady hands and/or supporting yourself, you can sometimes buy an extra half stop or stop, so 1/45 or 1/30th. Again, depending on how steady your hands are, any sort of anti-shake system can get you 1-2 stops-I can get reasonably sharp photos at 50mm equivalent down to 1/15 or so provided I've not had too much coffee .

Realistically, though, if you're hand-holding and have light to spare, go for the fastest you can get-I suggest 1/125 as a working minimum when possible on a 50mm equivalent lens.

 

[PALADIN85020]

A couple of things I neglected to mention in my previous post - these are hints to get the sharpest picture possible.

1. When using a tripod, turn the shake reduction feature OFF. The SR mechanism will "hunt" for compensation that isn't there, resulting in some movement within the lens or the sensor. Some cameras, like my own, will automatically turn SR off if you are using the manual mode.

2. Do not trip the shutter in the usual manner. Either use a remote or cable, or (preferably) go to the timed delay shutter mode, which allows the mirror on an SLR to flip up first, then the picture is taken a few seconds later. These things minimize movement of the camera related to shutter release.

John

 

[Ben_hutcherson]

2. Do not trip the shutter in the usual manner. Either use a remote or cable, or (preferably) go to the timed delay shutter mode, which allows the mirror on an SLR to flip up first, then the picture is taken a few seconds later. These things minimize movement of the camera related to shutter release.

John

When I'm using my DSLR for a stationary set up(such as for photographing guns or watches) I typically tether it to my laptop and use it in "live view mode." On Canons, at least, this pops the mirror up and gives you a live feed from the sensor on the screen. In addition, the camera will not auto-focus-rather you set the focus yourself although it's done by buttons on the computer screen using the AF motor in the lens. Since at the ranges where I'm usually shooting the depth of field is paper thin even at small apertures, this lets me focus exactly where I want.

In addition, this mode is absolutely vibration free. The mirror is already up and the shutter already open-all that is happening is the camera takes a "snapshot" of the sensor image for the length of time you've specified for the shutter speed.

Fortunately, most 35mm and 35mm-sized cameras these days control mirror slap fairly well although I always use mirror lock-up(or at least pre-fire) on a tripod if it's available. I have to also remind myself to lock up the mirror on the Bronica when I'm on the tripod since that 6x6 mirror does shake things around a lot. Fortunately, the in-lens leaf shutter induces virtually no vibration.

 

[THE PILGRIM]

I just go live view with my Nikon 5500.
It auto focuses in live view.
Sometimes I will go manual focus and select my main focus point.