Choosing shutter speed for an IS telephoto lens

[Dazz1]

The rule usually followed is to use 1/250 shutter speed for a 250mm tele shot. My question is, if the lens is stabilised, like my Canon IS lens, do you allow slower shutter speeds, and if so how much slower - 1/125, or even 1/60 (as they claim up to 4 stops improvement)?

[ameerat42]

With the Sig 50-500 and with much care, I can sometimes manage 1/100sec. 1/160sec is routinely OK.
Am.

PS: Oh, at 500mm, I mean.

[ROA44]

Ok this is a new one for me. So are they saying that in the case of say a zoom lens that if you set at 250mm then 1/250 for S/S,
300mm 1/300, 400mm 1/400

[ameerat42]

Yes, but in practice and with practice you could vary this.
Am.

[ROA44]

How does that relate to aperture or adjust accordingly to get correct exposure. Woops better get going for work catch all later

[fillum]

Don't forget that although stabalisation compensates for camera shake at lower shutter speeds, it is often your subject (if moving) that will determine your slowest practical s/s.

Manufacturers will give a general claim but actual slowest s/s will vary between individuals (grip/stance, shutter release technique, etc) and situations (something to lean against, how windy, etc).


Cheers.

[Dazz1]

With the Sig 50-500 and with much care, I can sometimes manage 1/100sec. 1/160sec is routinely OK.
Am.

PS: Oh, at 500mm, I mean.

So, that's very roughly the 4x improvement. Looks like I should be well safe at just halving the speed to 1/125 for mine at 250mm. Thanks.

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How does that relate to aperture or adjust accordingly to get correct exposure. Woops better get going for work catch all later


I don't think aperture matters, this is just about movement and shutter speed.

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Don't forget that although stabalisation compensates for camera shake at lower shutter speeds, it is often your subject (if moving) that will determine your slowest practical s/s.

Manufacturers will give a general claim but actual slowest s/s will vary between individuals (grip/stance, shutter release technique, etc) and situations (something to lean against, how windy, etc).





Cheers.


Yep, I'm sure the 4x is just under ideal conditions. ... and yes, stationary subject.

[arthurking83]

How does that relate to aperture or adjust accordingly to get correct exposure. Woops better get going for work catch all later

Some cameras nowadays have the smarts to help with this respect.

If you know your exposure triangle well enough, and know how your camera performs at specific ISO values, then you have a few options with this rule.

you can just shoot manually .. so you know your FL is 250mm, and with a non stabilised lens the recommendation is to use 1/250s as the shutter speed, and you then select the Aperture variable yourself.
This to me is a semi Aperture Priority mode(which I use sometimes) where I still want control of the Aperture, but want to maintain a specific Aperture value as well.
Of course if you don't watch the exposure meter in doing this, of course you risk botching exposure!

I think many folks will agree, that auto ISO is a very handy feature to use in the sorts of situations where you want to maintain control over a minimum shutter speed AND control over aperture too.

In general keeping shutter speed at a predefined setting is best done in Shutter Priority mode.

As said earlier, some cameras have the brains to help you configure pre defined lowest shutter speed limitsm based on the focal length of the lens in use! :th3:

That is, with some cameras, if you choose to use auto ISO, they may ask you to set a predefined shutter speed as the slowest that you want to hit before ISO levels are boosted.
One of those options may not be a specific shutter speed at all, but a percentage ratio of the focal length of the lens mounted on the camera at the time.

That is, if you currently have a 200mm lens, it will allow you to choose 1/focal length(ie. 1/200s) or a ratio of that which is basically an allowance for technique or optical stabilisation enabled.

So if the exposure triangle allows for 1/200, or more, and your Aperture setting without boosting ISO .. ISO will remain low. If exposure value is low and something needs a boost, ISO will rise before allowing the shutter speed to dip into the too slow range for the lens.
Similarly, if you then mount or zoom too 400mm, the camera will try to maintain a shutter speed in the 1/400s range .. before boosting ISO .. and so on and etc.
And again, with the better featured cameras, they also allow a ratio of the shutter speed, to account for varying techniques/abilities, and or optical stabilisation.

So you can set this 1/focal length rule as part of the auto ISO feature, but you can also specify if you prefer it to be slower or faster. On the D800(that I know) there aren't actual values to choose, just this slower/faster scaling.
On the scale options, the centre line is basically setting for 1/focal length, and there are two stops to allow faster than 1/focal length(ie. if one is a bit unsteady) and two settings to go slower(ie. if you have stabilisation or have good technique.

On the D800 this sliding scale amounts to roughly 25%, 50%, 1/focal length, 150%, and 200%.

So on a 200mm lens, this will provide about 1/50s, 1/100s, 1/200s, 1/300s, and 1/400s shutter speeds(where possible).
They're not hard and fast settings, just approximations .. but the beauty is that the camera does it all for you, based on your knowledge of your(and your gear's) abilities.

[mpb]

An interesting topic and I have not clue. I suspect the modern stabilisation will often allow for slower shutter speeds that the rule of thumb suggests.

As far as the rule of thumb goes, my question is does the size of the sensor have an effect?

I would say it does, therefore if the 1/focal length applied to 35 mm cameras then on a smaller sensor it should be incresed by the crop factor, IMHO. I base this on the effect that the same movements will be over a greater portion of aa smaller sensor compared to a larger one, if that makes sense.

At the end of the day it is not a scientific hard and fast rule, just a guide.

I try and practice 1/2 x focal length based on experience, however I will do what ever it takes to get the shot :D.

[arthurking83]

......

As far as the rule of thumb goes, my question is does the size of the sensor have an effect?

I would say it does, therefore if the 1/focal length applied to 35 mm cameras then on a smaller sensor it should be incresed by the crop factor, IMHO. I base this on the effect that the same movements will be over a greater portion of aa smaller sensor compared to a larger one, if that makes sense.

At the end of the day it is not a scientific hard and fast rule, just a guide.

I try and practice 1/2 x focal length based on experience, however I will do what ever it takes to get the shot :D.

I've never seen any evidence, posted by others or in my own experiences that suggest a cropped sensor will require a faster than 1/focal length rule.

In fact it shouldn't be so if you think of the logics behind the workings of a lens.

Other threads abound on how lenses work, but a lens's magnification is fixed, and the fact that the lens is mounted to a cropped body doesn't increase it's magnification in any way.
It may look like it, but it's not the simple point of using a cropped sensor camera.
In fact it's more likely due to the pixel pitch of the sensor in the camera .... so what many perceive as magnification due to the cropped sensor is actually psuedo magnification due to the higher pixel pitch of most cropped sensors.
As sensors get smaller, they generally have an inherently higher pixel density compared to a larger sensor camera. The more compact cameras(even the micro four thirds types usually have much higher pixel densities.

So the answer is really more along the lines of: does the increasing pixel count of a given sensor size affect this 1/focal length rule!!

I believe it does ..... and while it's not a major issue for me, I never had any trouble with 1/focal length using the 12Mp D300
Whereas I've found I produce more misses with 1/focal length on the 36Mp D800(which is effectively a 15Mp APS-C camera).

I haven't tested for any differences between using crop mode or full frame mode on the D800 and I doubt I'll find any differences anyhow.

Where I used to easily achieve consistent results with 75mm on the D300 at say 1/40s or so, on the D800, I found more misses than hits ... and as a result had to attempt to maintain faster shutter speeds.
In the end, after lots of 'umms and ahhs' I finally got a stabilised lens to account for my lax technique.

Now I think I have to do the same with the 70+ mm focal length range too.

[vk2gwk]

I think that sensor size does influence the "minimum shutter speed should be 1 divided by the focal length" rule . That rule is actually based on the opening angle of the lens. The longer the focal length, the narrower the opening angle and the more possible camera shake influences the image quality. As the opening angle of a lens with a certain physical focal length on a crop sensor camera is narrower than on a FF it makes sense to go for a higher shutter speed.

As far as IS is concerned: On my 100 - 400mm lens I can go one and max. two stops down on the above rule. Four stops is too much of a claim IMHO.
Another thing about IS: make sure you check if the IS needs to be switched off when using a tripod... Some lenses' IS system "sense" the tripod but other don't.

[mpb]

I've never seen any evidence, posted by others or in my own experiences that suggest a cropped sensor will require a faster than 1/focal length rule.

In fact it shouldn't be so if you think of the logics behind the workings of a lens.

Other threads abound on how lenses work, but a lens's magnification is fixed, and the fact that the lens is mounted to a cropped body doesn't increase it's magnification in any way.
It may look like it, but it's not the simple point of using a cropped sensor camera.
In fact it's more likely due to the pixel pitch of the sensor in the camera .... so what many perceive as magnification due to the cropped sensor is actually psuedo magnification due to the higher pixel pitch of most cropped sensors.
As sensors get smaller, they generally have an inherently higher pixel density compared to a larger sensor camera. The more compact cameras(even the micro four thirds types usually have much higher pixel densities.

So the answer is really more along the lines of: does the increasing pixel count of a given sensor size affect this 1/focal length rule!!

I believe it does ..... and while it's not a major issue for me, I never had any trouble with 1/focal length using the 12Mp D300

I haven't seen anything posted or written either, I just put it out there based on my own assumptions, and it looks like you agree, and yes it most likely has more to do with pixel density.

However if you think of it this way:-

If the movement/shake causes movement of the image of say 0.1 mm at the sensor horizontally. That represents 0.277% of the image on a full framed sensor and 0.423% of the image on an APS-C sensor.

So even with the same pixel density it is affecting more of the image.

Mark

[michaellxv]

I haven't seen anything posted or written either, I just put it out there based on my own assumptions, and it looks like you agree, and yes it most likely has more to do with pixel density.

However if you think of it this way:-

If the movement/shake causes movement of the image of say 0.1 mm at the sensor horizontally. That represents 0.277% of the image on a full framed sensor and 0.423% of the image on an APS-C sensor.

So even with the same pixel density it is affecting more of the image.

Mark

By that same logic, if you subsequently wanted to crop the image that 0.1mm becomes a greater percentage of the final result. Is this something to watch out for also?

Very interesting topic.

[Dazz1]

By that same logic, if you subsequently wanted to crop the image that 0.1mm becomes a greater percentage of the final result. Is this something to watch out for also?

Very interesting topic.

Good to hear my questions aren't wasting people's time :)

I did read on one web page that you need 1/400 for a 250mm lens on a 1.6 crop factor sensor camera. But that's only one, and many others never mention crop factor at all on this topic, and there is a lot of misinformation out there on the web, so I thought I'd pose the question here.

[fillum]

As far as the rule of thumb goes, my question is does the size of the sensor have an effect?No. And yes.

Theoretically the size of the sensor should be considered, however for practical purposes (particularly when comparing APS to FF) the differences between individuals and shooting situations is probably greater than the 'half-stop difference' between the sensors, so the rule-of-thumb is still reasonably applicable. Like mpb, photographers should determine their own performance relative to the rule - whether they are generally a bit more steady or a bit shakier than the 'rule' suggests.

AK is correct about a lens behaving the same way regardless of the sensor size, however I think in this case we need to consider what is happening to the final output rather than what is happening at the sensor. The image from the smaller sensor needs to be 'blown up' more than the FF sensor for a specific output size (eg 8x10 print), so the same amount of blur at the sensor will appear larger on the print from the APS sensor compared to the FF sensor. (This is also why the circle-of-confusion on APS is 2/3 of that of a FF sensor).

With regard to sensor resolution I'm not so sure but I think the difference might show at the sensor but not at the final output. For example camera shake would probably be more apparent on a D800 image viewed at 100% compared to a D700 viewed at 100% but if you produced an 8x10 print from both they would be similar.




Cheers.