Lens and Shutter speed question - two part

jcoutts

jcoutts

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Justin
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Just wanted to get peoples views on this. Firstly I am talkng "TV" setting here If I am to use a zoom lens say 70-300. At full focal length minimum shutter speed should be around 1/300, and that is a minimum to avoid shake. YES/NO.

My question is then, if I know I am using at wide open, or at 70mm can I then get away with 1/70 or 1/100 say, is that how it works..???

Personally as long as the conditions allowed I would probably just use 1/300 or above all the time if I had that particular lens on.

Same as if I had a 18-55, lens on I would proably leave the shutter speed at 1/60 whatever the focal length.



My other part to this question is if I have the setting at "AV" does the camera modify the settings enough on the shutter speed to allow for camera shake - I think not because it will adjust to get exposure and so you could end up with a too slow speed such that it will not avoid shake. So then on "AV" setting again If I up the ISO does the shutter setting get better because I am allowing more light to enter the camera. :bang:

Think I understand it, but just wondered how the camera does it. Want to understand it better. :thinking:
 
You have to take the crop factor into consideration as well as far as I know 1/(Focal Length * Crop Factor)

I'm sure some of the more experienced people will be along to give a good explaination
 
A lot will depend on how good your handheld technique is to be honest. You will soon learn what your minimum shutter speeds are to achieve a shake free result.

The general guide though is indeed that the shutter speed would match the focal length (crop factor taken in to account as well) so it's a good place to start. You can then work down the shutter speeds to see what your minimum requirement would be for reference.

If you are shooting in AV, then the shutter speed will be adjusted to balance the exposure, yes, but you can up the ISO if need be to bring the shutter speed back in to line if it slides to too slow a setting.
 
300mm plus crop of 1.6 = 300x1.6 = 1/480 sec. I think.
 
jcoutts said:
Just wanted to get peoples views on this. Firstly I am talkng "TV" setting here If I am to use a zoom lens say 70-300. At full focal length minimum shutter speed should be around 1/300, and that is a minimum to avoid shake. YES/NO.

My question is then, if I know I am using at wide open, or at 70mm can I then get away with 1/70 or 1/100 say, is that how it works..???

Personally as long as the conditions allowed I would probably just use 1/300 or above all the time if I had that particular lens on.

Same as if I had a 18-55, lens on I would proably leave the shutter speed at 1/60 whatever the focal length.



My other part to this question is if I have the setting at "AV" does the camera modify the settings enough on the shutter speed to allow for camera shake - I think not because it will adjust to get exposure and so you could end up with a too slow speed such that it will not avoid shake. So then on "AV" setting again If I up the ISO does the shutter setting get better because I am allowing more light to enter the camera. :bang:

Think I understand it, but just wondered how the camera does it. Want to understand it better. :thinking:
Click to expand...

To start off with ...YES.

The Rule of thumb...and it is exactly that...states that (handheld) the the shutter speed should be at least that fraction of the focal length so you are quite correct in using 1/300 as a minimum shutter speed for 300mm and so on.

People are different though and I rarely shoot anything below that as I am as stable as any bowl of jelly...but then I have also had some very nice shots at 1/8 or so with a 50mm lens...which should strictly not happen unsupported...

This is totally independantfrom the crop factor as it (the crop factor) is simply a matter of perspective of the image disc related to sensor size.

In plain English...if you could put a full frame sensor inside your 400/450D whilst shooting with, say, the 18-55 kit lens, you would have the exact same image as what you would have if you could take the same shot with the same 18-55 on a FF body with one important difference.

Due to the smaller sensors in the FOV Crop bodies, the 18-55 (EF-S) or any other "Digital/DX" lens was not designed to project an image onto a rectangle of 24 x 36mm.

It was designed to project an image onto a much smaller (22.2 x 14.8mm) or whatever size sensor.

Because of the smaller sensors in the FOV Crop bodies the sensors do not record the complete image a "Film lens" would be able to project and therefore it appears to be a longer focal length.

As for the second part of your question you answered your own question beautifully and correctly.

Your camera should also have a way of telling you when you want it do do something it cannot do.

Example...if you shoot an image at f/1.4 (AV) and 1600 ISO in bright daylight, the maximum shutter speed should surely be blinking 1/4000 or 1/8000...this is your camera's way of telling you that it is not happy with what you are expecting it to do.

In low light it might not give you any immediate visual warning but the audible long shutter (if unsupported) should be a dead giveaway...

HTH
 
^ What he said...

I always use the following guideline for handheld (no IS) shots 1/60th or 1/focal length (no crop factor multiplication) which ever is the fastest.

So with my 200mm lens I would shoot at 1/200th, but on my 17mm lens I would shoot at 1/60th...
 
Do remember that exposure (and photography by implication) is always a matter of give and take.

The "Three Kings" are shutter speed, aperture and (film) speed...or rather, ISO sensitivity in this century;)

Let us revert to the 1970's (even if just for a few moments) and forget that cameras have any automated abilities...

You would typically adjustshutter speed and aperture size (f/stop) after you loaded a roll of film suited to your shooting situation at the time.

This would have a bearing on the type of lens you would have chosen for the shoot. You wouldn't (normally) shoot portraiture with a wide angle prime...you would have chosen a 135mm f/2 or f/2.8 or something similar.

The point I am trying to make in a VERY roundabout way is that, no matter what lens/body combo you shoot, there are limitations on the end result you can achieve.

Some have work-arounds, some don't. You can only compensate so far before you have to consider changes to the hardware.

Yes, IS / OS / VR or whatever you call it made things easier but also changes the rules a bit.

Sensor size could make a difference...ISO can be bumped up or adjusted down without the need to cut and reload or finish the current roll...but all of these add to new rules in the game.

So do tripods, reciprocity failure, white balance and hot pixels...

All seemingly unrelated aspects but all come back to exposure...

Hope I haven't completely confused you now...master the basics first but learn all the peripheral issues too.
 
Thanks Anton.. your comment..

People are different though and I rarely shoot anything below that as I am as stable as any bowl of jelly...but then I have also had some very nice shots at 1/8 or so with a 50mm lens...which should strictly not happen unsupported...
Click to expand...

Thats exactly what I was trying to figure out, I got a shot at 1/25 about mid way through focal 17-70, so I was surprised to see that it came out o.k. I was on "AV" at the time and I just thought thats going quite slow.. As you say you can hear it...... Compared with the shot I actually got when I switched to "TV" and raised to 1/50.

Obvioulsy it was a lot darker and under-exposed, but it was O.K probably could have pulled it up a couple of stops in Lightroom and made it useful.

Just wanted to understand it a bit better.

Thanks again :thumbs:
 
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