f/2.8 with IS --- vs --- f/4 with IS

[coachboz68]

I'm going to ask an imperfect question, so bear with me, but I think it will lead to the answers I am looking for.  Iv'e started a new thread but this topic arises in many other threads in different bits and pieces. 

Let's take a lense like the EF 16-35 where we have the choice of f/4 with IS that (I believe) is rated at something like 4 Stops, and the f/2.8 with no IS. 

Let's further assume that I'm going to do walk-around city/street shooting where I will most frequently shooting WITHOUT a tripod. 

While the 2.8 affords me faster shutter speeds, I am afraid that the shallow DOF will be undesirable in many shots.  Therefore, for mostly handheld shooting where shallow DOF is not desireable, would one be better off with the IS with a min of f/4 given shutter speed (for these kinds of pics) is not the major concern?  

I know there are a lot of variables still left unexplored, so the answer will likely still be "it depends" but hopefully this the above scenario is enough to help me start understanding the real-life tradeoffs between a smaller aperture with IS vs a larger aperture without.  

Thanks

[diverhank]

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@coachboz68 wrote:

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@Waddizzle wrote:

It is a wide angle lens.  With a fast shutter, the lack of IS won’t matter.  Besides, the only times I use f/2.8 with my 16-35 is in close quarters when I am indoors.  Otherwise, I am shooting at f/5.6 to f/8 outdoors on bright sunny days.

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Thanks.  Only part of my question is practical; the bigger reason is trying to learn about the tradeoffs.  Toward that end... in poor light scenarios, the only way to get the faster shutter speed is with f/2.8, which concerns me as too shallow DOF for a lot of shots.  More specifically, I was shooting a prom event using my 70-200 at f/2.8 and had several shots where the DOF was so shallow that in a side-by-side shot, with one person slightly back, the back person was out of focus while the front person's face was tack sharp.  I also know this is my fault for not understanding (quickly and in the moment) how DOF is affected by zoom and distance to target.  As I said, just trying to learn.  

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Focal length plays a major part in depth of field.  For 16-35 range, unlike the 70-200, the depth of field at f/2.8 is not that shallow.  You really need to look into hyperfocal distance to have more understanding and control of your DOF.

@Granted that you don't usually use f/2.8 too often on a "landscape" lens but there are many cases f/2.8 comes in really handy.  For example, take a look at this picture I took recently in Copenhagen - I was on a moving boat so I needed decent shutter speed.  I also wanted ISO 100 - So I took this picture @ FL 26mm; 1/400; ISO 100 at f/2.8 - focussed at 30 feet which was the hyperfocal distance so I know that everything 15 ft from me to infinity will be in reasonable focus.  Canon 5DSR, Canon 24-70mm f/2.8L II USM lens.

Similarly, below is a picture I took a couple of years ago in Kyoto, Japan -  it was getting dark and I was without a tripod...I left my tripod back at the hotel because I had been walking so much during the day in 90 degrees , 90% humidity condition and I was exhausted.  By late afternoon, I had nothing with me except the camera and lens.  Same thing - focused at hyperfocal distance (40 feet)...decent DOF at f/2.8 -  Canon 5D Mark III, Canon 24-70mm f/2.8L II USM; FL 31mm; 1/60; ISO 4000

[Waddizzle]

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@coachboz68 wrote:

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@Waddizzle wrote:

It is a wide angle lens.  With a fast shutter, the lack of IS won’t matter.  Besides, the only times I use f/2.8 with my 16-35 is in close quarters when I am indoors.  Otherwise, I am shooting at f/5.6 to f/8 outdoors on bright sunny days.

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Thanks.  Only part of my question is practical; the bigger reason is trying to learn about the tradeoffs.  Toward that end... in poor light scenarios, the only way to get the faster shutter speed is with f/2.8, which concerns me as too shallow DOF for a lot of shots.  More specifically, I was shooting a prom event using my 70-200 at f/2.8 and had several shots where the DOF was so shallow that in a side-by-side shot, with one person slightly back, the back person was out of focus while the front person's face was tack sharp.  I also know this is my fault for not understanding (quickly and in the moment) how DOF is affected by zoom and distance to target.  As I said, just trying to learn.  

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I have often [used] this link to select lenses and focal lengths before leaving the house.

http://www.dofmaster.com/doftable.html

It describes the hyperfocal distance, too.

[coachboz68]

Super helpful. Thanks.