Telephoto IS on 1.6X FOV crop

[saurabh1]

Does anybody know if 3-4 f-stops of IS quality change when the lens is being

using with a 1.6X FOV camera. Comparing a full frame camera and a 1.6X FOV

camera, I need to hold my hand more steady on 1.6X camera to get equally sharp

pictures without IS. This is just because there is more "zoom". This means when

IS is activated, it needs to do more work on a 1.6X FOV camera to deliver

equivalent sharpness. So do I see less effect of IS on a 1.6X camera?

[mendel_leisk]

I think your speculation is right: the 1.6 cropped image will reveal any remaining blur to a greater extent.

[shambrick007]

I think you speculate too much...just get it.

[michael_ziegler2]

The rule of thumb for hand holding is to take the focal length and use the reciprocal as the minimum shutter speed. Anything below that should not be hand held unless you are using a IS lens. I believe the claim is 2-3 stops compensation is acceptable. Eg: at 100mm time should be 1/100 sec. With IS you could go as low as 1/25 sec. When using a crop camera, you should use the multiplication factor in determining the focal length. Eg: 100mm x 1.6 = 160mm. Then the hand holding time must be 1/160 sec. Without IS. If you are using IS you might hand hold a TV as low as 1/40 sec.

[gdanmitchell]

I guess it is all theoretical, but here is my thinking on this.

 

I would expect to still get the same number of stops of improvement, but the starting

point on a given focal length is a faster shutter speed on a crop sensor camera since it

effectively provides a "longer" lens.

 

Example: Using totally made up number, imagine that you could hand hold a particular

lens at 1/200 second on a full frame camera. I believe that you would want to set the

minimum shutter speed to 1/320 if you used this lens on a 1.6 crop sensor camera.

 

Now, whatever effect IS will have should work from that starting point. So, if you get the

theoretical 3 stops improvement you could shoot this lens/camera combination at 1/25 of

full frame and 1/40 on a crop sensor body.

 

I guess a short answer might be: Yes, it seems like there might be a difference, but it

would not be a big one.

[jwhite3.0]

Technically I don't know but anecdotally I can say you will have no problems. If the camera has to work more then sobeit. On a 20D I've used a full line of Canon IS lens from the 28-135 IS to 600mm f/4 IS and had no problems with sharpness.

[lester_wareham]

The stops advantage depends on the generation of IS, earlier ones give about 2 stops.

 

Another way to look at the FOV issue is to multiple the handhold guide shutter speed by the crop factor and figure the IS advantage from there, at least thats what I do. So a non-IS 100mm lens on a crop camera use 1/160 as the minimum handhold speed.

 

Note that in some case the idea of stops advantage is a bit simplified, the amount of advantage reducing as increased sharpness is desired.

 

So for example measurements I did on my 24-105 f4L IS @ 24mm showed an advantage of between 0.5 to 3 stops handheld depending on the sharpness criteria of a MTF 50% point of between 30 and 50 lp/mm. Needless to say the most advantage was available at the softess end of the sharpness range.

 

http://www.zen20934.zen.co.uk/photography/LensTests/IS_Tests/EF_24_105mm_f4L_IS/index.htm

[bobatkins]

IS doesn't depend on format size.

<p>

If you get 3 stops imporvement on full frame, you'd get 3 stops improvement on APS-C, 4/3 or on a tiny sensor digicam.

<p>

The difference is 3 stops improvement over what? The "What" is different for the same focal length lens on each format.

<p>

If you think you can hand hold a lens at 1/100s on full frame, on an APS-C format camera with the same lens you would need a shutter speed of 1/160s to produce a print of the same size and degree of sharpness.

<p>

See, for example, <a href="http://www.bobatkins.com/photography/tutorials/is2.html">How well does IS work</a>

[saurabh1]

Great! Thanks everybody for your responses. I won't have to justify getting IS anymore ;)

[andrew robertson]

Oh, man, IS is great for what it does. I wouldn't ever buy another long lens without it.

[vivek]

Think of the 1.6X as the cropped version of FF being shown to you. Now why would it matter if the sensor is 1.6X or 1.0X? Bob is right, IS does NOT depend on the sensor format.

 

That being said, if you use telephoto, even MEDIUM telephoto, then IS is really invaluable.

 

-- V

[lauren_macintosh]

If your so worried about sharpness ,Get a good tripod!

[lester_wareham]

"If your so worried about sharpness ,Get a good tripod!"

 

Indeed, but IS can still help in some case as noted above.

 

If you can't use a tripod, use a monopod. Agains IS will help with a monopod.

 

If you can't use a monopod be very glad you have IS!.