Is there a difference in IQ based on Shutter Speed?

[johndevane]

Hey guys,

I've got a technical question about digital camera processors... Does the camera's digital imager perform better at slower or faster shutter speeds?

In other words, if I don't need to worry about motion blur, or DOF or noise issues, should I try to get a slower shutter speed to help the camera do it's work?

In this picture I was at 1/60, f14, ISO 100. Would it be "easier" for my camera to capture the image at a faster SS and f5? Or maybe a slower SS and f20? Therefore increasing the image quality?

I've heard something about keeping the ISO and the SS the same makes a good image, but I haven't found info on this subject.

Thanks in advance,

John.

[Jim G]

Makes no difference... at least, not purely based on shutter speed. I don't believe there's any reason why keeping the shutter speed and ISO figures the same would possibly result in a superior image. I sure don't use ISO 1600 with 1/1600 shutter speed ;)

Image quality will be highest at ISO 100 and progressively decline as you head up towards 1600 and 3200... if you want the best possible IQ for a given situation use the lowest ISO you can get away with. Lower ISO will make for a longer shutter speed - it won't be the SS that'll change the IQ, it's the ISO.

[Stocky]

iso 100 and an exposure of less than 1-5 seconds should make noise a non-issue, so the only reason I can think that shutter speed would make a difference, if you don't care about aperture, is camera shake. A solid tripod would fix this. I am not sure what shutter speeds are most sensitive to shutter slap though.

[Glenn NK]

If you've noticed a difference in IQ with shutter speed, then you are likely experiencing movement of the camera during exposure. Obviously handheld exposures are most likely to reflect movement, but tripod exposures will record movement also if the vibrations caused by the mirror "slapping up" are not damped out when the shutter opens.

This is why mirror lockup (MLU) is often recommended - allow a couple of seconds after the mirror goes up for vibrations to die down, then release the shutter. It doesn't matter what the shutter speed is when mirror slap is the problem as it goes up at the same speed no matter what the shutter speed. Vibration caused by the shutter opening is also a possibility, but it's generally considered to be very small. The closing of the shutter also imparts vibrations, but since it's closed, it has no effect on the image.

A cheap tripod can also contribute to movement, particularly if there is any wind.

The first article is long, but worthwhile reading:

http://markins.com/charlie/report4e6.pdf

http://www.luminous-landscape.com/tutorials/understanding-series/mirror-lock.shtml

http://www.luminous-landscape.com/essays/tripods_&_heads.shtml

As long as your long images aren't being over-exposed, there should be no discernible differences with various shutter times.

[gjl711]

..the only reason I can think that shutter speed would make a difference, if you don't care about aperture, is camera shake. A solid tripod would fix this. I am not sure what shutter speeds are most sensitive to shutter slap though.
I would venture a guess that whatever shutter vibration you do get from all the mechanical devices flying around would most be noticeable at less than 1/60 but more than 1/2 second.

[johndevane]

Thanks for the quick resonses,

I'm not having a problem or noticing differences in IQ with different shutter speeds, I was asking if I should try to use a slower or faster SS when conditions permit.

For instance, in sports we can't adjust much because we need a fairly fast SS to avoid motion blur. But in scenery we could adjust the SS quite a bit. If it would help make a better image, I'd like to know which way to adjust.

Is the camera straining at 1/4000 and having trouble imaging so fast? Or is the camera straining at 1/40 and having trouble imaging so slow? I just want to be nice to my camera and have it be nice to me in return! :)

[gjl711]

..

Is the camera straining at 1/4000 and having trouble imaging so fast? Or is the camera straining at 1/40 and having trouble imaging so slow? I just want to be nice to my camera and have it be nice to me in return! :)
The speed of the shutter is totally independent on the electronics ability to read the sensor. The read does not happen while the shutter open, but after it closes. Think if the process this way.

Buffers cleared.
Shutter opens exposing sensor
Shutter closes, no more light hitting sensor
Electronics reads the individual pixels and assembles the pic.All the processing happens after so the speed of the shutter is irrelevant to the ability of the camera to capture that data. The shutter itself also moves no faster the higher the shutter speed, it’s just that the gap between the blades becomes closer.

[RTMiller]

The shutter itself also moves no faster the higher the shutter speed, it’s just that the gap between the blades becomes closer.
Really? Interesting. I did not know that. I knew about the slit/gap size but I just assumed that the speed varied also. Very interesting.

[Wilt]

Mirror-slap induced vibrations have been shown in testing to be most problematic at shutter speeds between about 1/8 and 2, as the vibrations occupy a larger fraction of the total exposure time when inside that range. That was done with 35mm film cameras a couple decades ago.

[Glenn NK]

I'm not having a problem or noticing differences in IQ with different shutter speeds, I was asking if I should try to use a slower or faster SS when conditions permit.

I tend to use the fastest shutter speed that will still enable a reasonable ISO and an aperture for adequate DOF.

[Tixeon]

Hey guys,

I've got a technical question about digital camera processors... Does the camera's digital imager perform better at slower or faster shutter speeds?

I've heard something about keeping the ISO and the SS the same makes a good image, but I haven't found info on this subject.


All good answers above, but, I'll touch on the subject of keeping the ISO & the SS the same. This goes back to the Sunny 16 rule. Brief description: When setting exposure manually in bright sun conditions, set the f/stop to 16 & the shutter speed to that of the ISO for a good exposure.

[DocFrankenstein]

It doesn't make a difference for shutter speeds of less than a second.

When you open your shutter for a really long time, like 30 seconds or a couple of minutes, you will get a bit more noise.

[swampler]

I'll touch on the subject of keeping the ISO & the SS the same. This goes back to the Sunny 16 rule. Brief description: When setting exposure manually in bright sun conditions, set the f/stop to 16 & the shutter speed to that of the ISO for a good exposure.
You beat me to it. This is exactly right.

[Glenn NK]

It doesn't make a difference for shutter speeds of less than a second.

When you open your shutter for a really long time, like 30 seconds or a couple of minutes, you will get a bit more noise.

Yessiree. Very good point.

So, in the range of 1/8000 second to around 1/2 second or so, the answer to the OP's question would there is no discernible difference in IQ provided there is no movement of the projected image on the sensor (whatever the cause of the movement).

Far more important is exposing as far as possible to the right of the histogram without blowing out the highlights. And let the blacks fall where they may - you can't do anything about the blacks anyway without using a technique like HDR.

[johndevane]

Ahhh... the sunny 16 !

That's where I heard it. Thanks again to all.

John.

[johndevane]

Glenn,

We must have been typing at the same time... I agree with your last post. It seems to me that there is no real difference in IQ based on SS, and it's way more important to get correct exposure.

Now if I could just manage to get a shot with the correct exposure I might see for myself! :)