Approve the Cookies
This website uses cookies to improve your user experience. By using this site, you agree to our use of cookies and our Privacy Policy.
OK
Index  •   • New posts  •   • RTAT  •   • 'Best of'  •   • Gallery  •   • Gear  •   • Reviews
Guest
New posts  •   • RTAT  •   • 'Best of'  •   • Gallery  •   • Gear  •   • Reviews
Register to forums    Log in

 
FORUMS Canon Cameras, Lenses & Accessories Canon EF and EF-S Lenses 
Thread started 24 Dec 2011 (Saturday) 18:42
Search threadPrev/next
sponsored links
(this ad will go away when you log in as a registered member)

How does 4 Stops of IS affect the 1/Focal Lenght rule?

 
Roxie2401
Senior Member
Avatar
355 posts
Likes: 2
Joined Jan 2009
Location: Western PA
     
Dec 24, 2011 18:42 |  #1

Just got the 70-200 f/2.8 MK II and its advertised as having up to 4 stops of Image Stabilization. So, how does this apply to the general rule of having a shutter speed = at least 1/focal length?

For this lens, I'm assuming that means my minimum shutter speed should be 1/200 second without the IS.

So, how does this relate to the f-stop and with the IS on?

Basic question - but its got me scratching my head.

Thanks




  
  LOG IN TO REPLY
sponsored links
(this ad will go away when you log in as a registered member)
windpig
Chopped liver
Avatar
14,996 posts
Gallery: 7 photos
Likes: 1321
Joined Dec 2008
Location: Just South of Ballard
     
Dec 24, 2011 18:48 |  #2

If you can consistently get sharp images hand holding, say, at 1/400, the IS should allow you to hand hold at 1/25. I wouldn't bank on getting 4 stops, but would 3 stops.

As far as FStop, it has nothing to do with IS. All "4 stops" means is that at a given exposure, you should be able to adjust any and all of the exposure parameters in total by 4 stops and still get a sharp image. Lower shutter speed, lower ISO, stop down the aperture, or any combo.

Say you're shooting at ISO400, shutter speed 1/200 and F2.8. To take advantage of say a 3 stop IS, you could lower your ISO to 100 and stop your lens down to F4 using the same shutter speed.


Would you like to buy a vowel?
Go ahead, spin the wheel.
flickr (external link)
I'm accross the canal just south of Ballard, the town Seattle usurped in 1907.

  
  LOG IN TO REPLY
sandpiper
Cream of the Crop
Avatar
7,171 posts
Gallery: 1 photo
Likes: 50
Joined Aug 2006
Location: Merseyside, England
     
Dec 24, 2011 18:54 |  #3

windpig wrote in post #13595272 (external link)
If you can consistantly get sharp images handholding, say, at 1/100, the IS should allow you to hand hold at 1/25.

The FStop doesn't mean any thing. It's all relative to shutter speed, give the same exposure.

So, say you can hand hold at 1/200 at f4, ISO 200. With the IS, you can shoot at 1/50, F5.6 at ISO100.

Those examples are only two stops apart. The 1/FL rule gives 1/200th for 200mm on a FF body as a guide to the minimum handheld shutter speed. 4 stop IS would drop that to 1/25th second.

However, IS does absolutely nothing to help with motion blur from the subjects movement and with most moving things (people moving around for example) you would find that they blurred significantly at 1/25th, so it is only advisable to handhold at that speed with a non moving subject, unless panning with it and wishing to blur the background.




  
  LOG IN TO REPLY
windpig
Chopped liver
Avatar
14,996 posts
Gallery: 7 photos
Likes: 1321
Joined Dec 2008
Location: Just South of Ballard
     
Dec 24, 2011 19:06 |  #4

sandpiper wrote in post #13595286 (external link)
Those examples are only two stops apart. The 1/FL rule gives 1/200th for 200mm on a FF body as a guide to the minimum handheld shutter speed. 4 stop IS would drop that to 1/25th second.

However, IS does absolutely nothing to help with motion blur from the subjects movement and with most moving things (people moving around for example) you would find that they blurred significantly at 1/25th, so it is only advisable to handhold at that speed with a non moving subject, unless panning with it and wishing to blur the background.



Picky picky picky:lol:

I reread and recalculated whilst you were writing.

I was going bring up motion blur, but it doesn't really pertain to the question, at least I didn't think.


Would you like to buy a vowel?
Go ahead, spin the wheel.
flickr (external link)
I'm accross the canal just south of Ballard, the town Seattle usurped in 1907.

  
  LOG IN TO REPLY
sandpiper
Cream of the Crop
Avatar
7,171 posts
Gallery: 1 photo
Likes: 50
Joined Aug 2006
Location: Merseyside, England
     
Dec 24, 2011 19:28 |  #5

windpig wrote in post #13595272 (external link)
As far as FStop, it has nothing to do with IS. All "4 stops" means is that at a given exposure, you should be able to adjust any and all of the exposure parameters in total by 4 stops and still get a sharp image. Lower shutter speed, lower ISO, stop down the aperture, or any combo.

Say you're shooting at ISO400, shutter speed 1/200 and F2.8. To take advantage of say a 3 stop IS, you could lower your ISO to 100 and stop your lens down to F4 using the same shutter speed.

No, you can't just alter any combo of your exposure parameters at will. IS only stabilises the lens to allow a slower shutter speed without camera shake. You then adjust the other parameters accordingly. So, if you use 3 stops slower shutter speed you need to stop down and/or reduce ISO by 3 stops to keep the exposure correct.

In your last example, dropping ISO 2 stops and stopping the aperture down a stop without changing the shutter speed, you would be 3 stops underexposed. You can make those two changes but need to slow the shutter speed to 1/25th to keep the exposure correct.

(oh, and we both need to buy a calculator, I got it wrong as well. 4 stops slower than 1/200th is 1/12th :lol: )




  
  LOG IN TO REPLY
DreDaze
happy with myself for not saying anything stupid
Avatar
18,333 posts
Gallery: 45 photos
Likes: 2945
Joined Mar 2006
Location: S.F. Bay Area
     
Dec 24, 2011 19:31 |  #6

1/200-1/100-1/50-1/25-1/12...so you'd be able to shoot at 1/12...all that assumes that you are stable enough to shoot at 1/200 to begin with...if you can shoot better than 1/200 to begin with then you can go even slower...

bottom line...you can handhold shots that you couldn't without it...experiment a bit if you want to see what the lowest you can go is


Andre or Dre
gear list
Instagram (external link)
flickr (external link)

  
  LOG IN TO REPLY
windpig
Chopped liver
Avatar
14,996 posts
Gallery: 7 photos
Likes: 1321
Joined Dec 2008
Location: Just South of Ballard
     
Dec 24, 2011 20:57 |  #7

sandpiper wrote in post #13595361 (external link)
No, you can't just alter any combo of your exposure parameters at will. IS only stabilises the lens to allow a slower shutter speed without camera shake. You then adjust the other parameters accordingly. So, if you use 3 stops slower shutter speed you need to stop down and/or reduce ISO by 3 stops to keep the exposure correct.

In your last example, dropping ISO 2 stops and stopping the aperture down a stop without changing the shutter speed, you would be 3 stops underexposed. You can make those two changes but need to slow the shutter speed to 1/25th to keep the exposure correct.

(oh, and we both need to buy a calculator, I got it wrong as well. 4 stops slower than 1/200th is 1/12th :lol: )


Geez, and I don't even drink anymore:rolleyes:

You know what I was trying to say, and you elucidated very well:lol:

I hope you and yours are having a merry one.


Would you like to buy a vowel?
Go ahead, spin the wheel.
flickr (external link)
I'm accross the canal just south of Ballard, the town Seattle usurped in 1907.

  
  LOG IN TO REPLY
sandpiper
Cream of the Crop
Avatar
7,171 posts
Gallery: 1 photo
Likes: 50
Joined Aug 2006
Location: Merseyside, England
     
Dec 24, 2011 21:12 |  #8

windpig wrote in post #13595569 (external link)
I hope you and yours are having a merry one.

And the same to you and yours. I hope Santa brings you a nice new lens ;)




  
  LOG IN TO REPLY
Bananapie
Senior Member
Avatar
522 posts
Joined Jun 2011
Location: Seattle, Biloxi, Waco
     
Dec 24, 2011 23:25 |  #9

windpig wrote in post #13595272 (external link)
If you can consistently get sharp images hand holding, say, at 1/400, the IS should allow you to hand hold at 1/25. I wouldn't bank on getting 4 stops, but would 3 stops.

As far as FStop, it has nothing to do with IS. All "4 stops" means is that at a given exposure, you should be able to adjust any and all of the exposure parameters in total by 4 stops and still get a sharp image. Lower shutter speed, lower ISO, stop down the aperture, or any combo.

Say you're shooting at ISO400, shutter speed 1/200 and F2.8. To take advantage of say a 3 stop IS, you could lower your ISO to 100 and stop your lens down to F4 using the same shutter speed.

???????????????

?




  
  LOG IN TO REPLY
nikmar08
Goldmember
Avatar
1,852 posts
Gallery: 4 photos
Likes: 18
Joined Aug 2010
Location: Bangalore, India
     
Dec 25, 2011 00:35 |  #10

Roxie2401 wrote in post #13595260 (external link)
Just got the 70-200 f/2.8 MK II and its advertised as having up to 4 stops of Image Stabilization. So, how does this apply to the general rule of having a shutter speed = at least 1/focal length?

The rule of thumb is 1/(focal length * crop factor). But, in general, you could follow 1/FL. This is without IS.

Roxie2401 wrote in post #13595260 (external link)
For this lens, I'm assuming that means my minimum shutter speed should be 1/200 second without the IS.

Each stop of IS will enable you to shoot at a shutter speed slower by half the previous value without blurriness being introduced due to minor camera shake. So in theory, shooting at 200mm with a lens with 4 stops of IS, you could be shooting as slow as 1/(~12 * crop factor) (4 stops) and prevent blurriness due to minor camera shake from affecting the shots. The reality can be a bit different though as you will realize when you use it for a while in different shooting conditions. As others have stated, depending on how steady your hands, what you are shooting, whether you are using flash and so on, you may/will end up shooting at faster shutter speeds at times.

Roxie2401 wrote in post #13595260 (external link)
So, how does this relate to the f-stop and with the IS on?

The relationship between how the shutter speed, aperture (f-stop) and ISO - the three parameters affecting exposures does not change, with or without IS.


____O
__( \ \_
((_)/ ((_)
Nikhil | Gear List & Market Feedback | Flickr (external link)
Support POTN by donating here: https://photography-on-the.net/forum/donate.p​hp

  
  LOG IN TO REPLY
Roxie2401
THREAD ­ STARTER
Senior Member
Avatar
355 posts
Likes: 2
Joined Jan 2009
Location: Western PA
     
Dec 25, 2011 08:01 as a reply to  @ nikmar08's post |  #11

Thanks for all the information.

Follow-up question: Why the "*crop factor" in the formula? (1/focal length * crop factor)

Is it because a smaller sensor would be more subject to camera shake (Me) than a full frame sensor?

I do have a 7D crop body. So from what I have learned so far, that means for my 70-200 f2.8 this would be 1/200 * 1.6 = 1/320s without figuring in the benefit of the IS or IS = off. Right?

And since I mainly shoot stationary objects and not moving people.........how slow can I go?




  
  LOG IN TO REPLY
sandpiper
Cream of the Crop
Avatar
7,171 posts
Gallery: 1 photo
Likes: 50
Joined Aug 2006
Location: Merseyside, England
     
Dec 25, 2011 08:32 |  #12

Roxie2401 wrote in post #13596654 (external link)
Follow-up question: Why the "*crop factor" in the formula? (1/focal length * crop factor)

Is it because a smaller sensor would be more subject to camera shake (Me) than a full frame sensor?

I do have a 7D crop body. So from what I have learned so far, that means for my 70-200 f2.8 this would be 1/200 * 1.6 = 1/320s without figuring in the benefit of the IS or IS = off. Right?

You take the crop factor into account because the whole thing is based on the angle of view, and the cropped image has a narrower FoV. Imagine that your camera shake is allowing up to 1 degree of lateral movement (it wouldn't be that much but it makes the math simple) over a period of time, and you are using a wide angle lens with, say, 70 degree FoV. Your 1 degree of motion is fairly insignificant as any point in the scene will only move by around 1/70th of the frame width over the whole time. Therefore a slowish shutter speed can be used to cut down how much of that 1 degree is traversed whilst the shutter is open. Now, put a telephoto on, with a 5 degree FoV and the potential 1 degree of motion is 1/5 of the frame width. So, you now need a much faster shutter speed to cut the amount you move down to virtually zero, whilst the shutter is open, as even a tiny degree of movement is now much more significant.

So, yes, on a crop camera, you would be looking at 1/320th at 200mm as your baseline without IS.

Roxie2401 wrote in post #13596654 (external link)
And since I mainly shoot stationary objects and not moving people.........how slow can I go?

Hard to say exactly, a lot depends on how good your bracing techniques are. To take 1/320 and lop off 4 stops would give 1/20th as your baseline with IS on. However, if you aren't particularly steady, you may need faster. Most people, with a little practice following good technique, can go below the guide and still get sharp shots, but it is best not to. It also depends on how repeatable is the shot.

My 100-400L is an old IS design and only good for 2 stops, so on my 5D (FF) that should require a minimum of 1/100th at 400mm. However, I have shot it at 1/50th quite a bit with a very good success ratio and even 1/25th with a sporting chance of getting a nice clean shot out of a burst taking 4 or 5 frames. I prefer a quick burst to individual shots, as it takes the initial squeezing of the button out of the equation for the consecutive shots.

So, you need to try and see what you can manage yourself, but it is always best to stay above the minimum guide as often as possible, maybe taking 1/50th as your ideal minimum, rather than 1/20th. But it's nice to know that, in really bad light, you can get away with going quite a bit slower. Potentially, you should have a sporting chance of getting some sharp shots at 1/5th or even slower, if you have to go that slow.




  
  LOG IN TO REPLY
Sirrith
Cream of the Crop
10,545 posts
Gallery: 50 photos
Best ofs: 1
Likes: 36
Joined Nov 2010
Location: Hong Kong
     
Dec 25, 2011 08:55 |  #13

Roxie2401 wrote in post #13596654 (external link)
And since I mainly shoot stationary objects and not moving people.........how slow can I go?

That is entirely dependent on you. Some people can go slower, some people need to stay at relatively high SS. It may even depend on the day. For example, I was able to take a shot at 250mm at 1/15s with IS one day, and was not able to reproduce it on subsequent attempts the next day. With an IS lens, I still try to keep the SS at 1/focal length, and simply use the IS as a "safety net" when I really find myself unable to keep the SS as high as I'd like, so I don't think in terms of what IS will let me shoot at, but rather, I just try and expose properly while maintaining a fast enough SS to stop camera shake, and I know roughly what I can hold a given lens at on any given day, though it may vary by a stop or more depending on a number of things.


-Tom
Flickr (external link)
F-Stop Guru review | RRS BH-40 review

  
  LOG IN TO REPLY
Roxie2401
THREAD ­ STARTER
Senior Member
Avatar
355 posts
Likes: 2
Joined Jan 2009
Location: Western PA
     
Dec 25, 2011 09:00 |  #14

sandpiper wrote in post #13596689 (external link)
You take the crop factor into account because the whole thing is based on the angle of view, and the cropped image has a narrower FoV. Imagine that your camera shake is allowing up to 1 degree of lateral movement (it wouldn't be that much but it makes the math simple) over a period of time, and you are using a wide angle lens with, say, 70 degree FoV. Your 1 degree of motion is fairly insignificant as any point in the scene will only move by around 1/70th of the frame width over the whole time. Therefore a slowish shutter speed can be used to cut down how much of that 1 degree is traversed whilst the shutter is open. Now, put a telephoto on, with a 5 degree FoV and the potential 1 degree of motion is 1/5 of the frame width. So, you now need a much faster shutter speed to cut the amount you move down to virtually zero, whilst the shutter is open, as even a tiny degree of movement is now much more significant.

So, yes, on a crop camera, you would be looking at 1/320th at 200mm as your baseline without IS.

Hard to say exactly, a lot depends on how good your bracing techniques are. To take 1/320 and lop off 4 stops would give 1/20th as your baseline with IS on. However, if you aren't particularly steady, you may need faster. Most people, with a little practice following good technique, can go below the guide and still get sharp shots, but it is best not to. It also depends on how repeatable is the shot.

My 100-400L is an old IS design and only good for 2 stops, so on my 5D (FF) that should require a minimum of 1/100th at 400mm. However, I have shot it at 1/50th quite a bit with a very good success ratio and even 1/25th with a sporting chance of getting a nice clean shot out of a burst taking 4 or 5 frames. I prefer a quick burst to individual shots, as it takes the initial squeezing of the button out of the equation for the consecutive shots.

So, you need to try and see what you can manage yourself, but it is always best to stay above the minimum guide as often as possible, maybe taking 1/50th as your ideal minimum, rather than 1/20th. But it's nice to know that, in really bad light, you can get away with going quite a bit slower. Potentially, you should have a sporting chance of getting some sharp shots at 1/5th or even slower, if you have to go that slow.

Thanks so much. I hadn't considered the initial squeeze of the button. Makes a lot of sense.

Just to be sure, with your earlier math, can I simply say that for four stops of IS, "divided my base number" from the formula (1/320 in this case) by 16? That would be 1/20s. Or for a 24-105 IS 1/168 divided by 16 = 1/10s? Etc. Would that make a lens with "3 stops of IS" a divide by 8?




  
  LOG IN TO REPLY
sandpiper
Cream of the Crop
Avatar
7,171 posts
Gallery: 1 photo
Likes: 50
Joined Aug 2006
Location: Merseyside, England
     
Dec 25, 2011 09:21 |  #15

Roxie2401 wrote in post #13596733 (external link)
Thanks so much. I hadn't considered the initial squeeze of the button. Makes a lot of sense.

Yes, at longer shutter speeds smoothness is everything. Even pushing the shutter button can cause a small motion in the camera. For good technique you want a good solid stance - Legs apart with the front foot facing forwards and the back foot at about 90 degrees to it. Then use your left hand to cradle the lens and support that, to prevent the rig being front heavy and causing vertical motion, tuck both elbows into your body for maximum support and steadiness. Press the shutter half way to kick in the IS (it can take half a second or so to spin up to speed, so you need to give it chance to settle before taking the shot) and breathe in. Some people say to hold your breath while taking the shot, it is generally better to be exhaling slowly whilst very gently squeezing the shutter release the rest of the way. Some people prefer a rolling motion across the release, that can be a matter of preference, the key thing is not to make a distinct push on the button.


Roxie2401 wrote in post #13596733 (external link)
Just to be sure, with your earlier math, can I simply say that for four stops of IS, "divided my base number" from the formula (1/320 in this case) by 16? That would be 1/20s. Or for a 24-105 IS 1/168 divided by 16 = 1/10s? Etc. Would that make a lens with "3 stops of IS" a divide by 8?

Yes, that's correct. Every complete "stop" (whether talking aperture, shutter or ISO) is always either a halving or a doubling of the light, depending on which way you are going. So, in this case, 1 stop = 1/2, 2=1/4, 3=1/8, 4=1/16




  
  LOG IN TO REPLY
sponsored links
(this ad will go away when you log in as a registered member)

3,515 views & 0 likes for this thread
How does 4 Stops of IS affect the 1/Focal Lenght rule?
FORUMS Canon Cameras, Lenses & Accessories Canon EF and EF-S Lenses 
AAA
x 1600
y 1600

Jump to forum...   •  Rules   •  Index   •  New posts   •  RTAT   •  'Best of'   •  Gallery   •  Gear   •  Reviews   •  Member list   •  Polls   •  Image rules   •  Search   •  Password reset

Not a member yet?
Register to forums
Registered members may log in to forums and access all the features: full search, image upload, follow forums, own gear list and ratings, likes, more forums, private messaging, thread follow, notifications, own gallery, all settings, view hosted photos, own reviews, see more and do more... and all is free. Don't be a stranger - register now and start posting!


COOKIES DISCLAIMER: This website uses cookies to improve your user experience. By using this site, you agree to our use of cookies and to our privacy policy.
Privacy policy and cookie usage info.


POWERED BY AMASS forum software 2.1forum software
version 2.1 /
code and design
by Pekka Saarinen ©
for photography-on-the.net

Latest registered member was a spammer, and banned as such!
1171 guests, 214 members online
Simultaneous users record so far is 15144, that happened on Nov 22, 2018

Photography-on-the.net Digital Photography Forums is the website for photographers and all who love great photos, camera and post processing techniques, gear talk, discussion and sharing. Professionals, hobbyists, newbies and those who don't even own a camera -- all are welcome regardless of skill, favourite brand, gear, gender or age. Registering and usage is free.