Depth of field, 200mm @ f2.8 vs f4

Yet another 70-200 thread...

I know all the differences in aperture, IS, weight etc etc etc. The price difference is negligible - £945 vs £985.

What I'm interested in is how much does the DoF change from f2.8 to f4 in the 150mm - 200mm range. I can test this at 100mm since I have a 100mm f2.8 lens. In this case, the answer is "not much". But at 200mm?

Basically, I've come to the conclusion that many people have - I would like a 70-200 for events, so called environmental portraits. Therefore DoF is important to me.

Thanks!

The easiest solution for you is to use a depth of field calculator. This one is probably the most popular on line.

I only have the 70-200 f4 and have never used the f2.8 so can't compare, but I'm very happy with the dof on the f4, although I use it mostly at 200mm for full effect

f4 @200mm

IMAGE LINK: http://s1230.photobuck​et.com …6908_zpsdd88154​2.jpg.html

^ f4 still looks pretty good, as far as bokeh

I don't think the difference is that huge for a lot of subjects, but I'm also sure it could be very handy at times, like this...

This is with my Vivitar Series 1 70-210/2.8-4 at near 200mm and presumably f3.8-4 (it's variable aperture, but at the long end it's basically an f4 lens)

IMAGE LINK: https://flic.kr/p/gXfJ​Gu

^ I think the photo is great as is.

pkim1230 wrote in post #17047563
^ I think the photo is great as is.

Thank you, I appreciate that I didn't say I dislike it, but it does make me sort of want an f2.8 70-200

EverydayGetaway wrote in post #17047640
Thank you, I appreciate that I didn't say I dislike it, but it does make me sort of want an f2.8 70-200

Believe me, the picture wouldnt look that good at f/2.8. The boy in the foreground would be totally blurred out, and sometimes a little less bokeh makes the pictures look like from the old days

Great pictures you both!

Bokeh is the quality of the blur not the amount of the blur. You can't have more or less bokeh.

FEChariot wrote in post #17047650
Bokeh is the quality of the blur not the amount of the blur. You can't have more or less bokeh.

Okay then more DOF, but i guess everybody knows what i mean

davidfarina wrote in post #17047645
Believe me, the picture wouldnt look that good at f/2.8. The boy in the foreground would be totally blurred out, and sometimes a little less bokeh makes the pictures look like from the old days

Great pictures you both!

FEChariot wrote in post #17047650
Bokeh is the quality of the blur not the amount of the blur. You can't have more or less bokeh.

I understood what davidfarina said perfectly fine because he phrased it as "less" bokeh, instead of something like "worse" bokeh. Bokeh also means "blur" in Japanese, so in Japan, it wouldn't be wrong to say 'less' bokeh or 'more' bokeh.

EverydayGetaway wrote in post #17047640
Thank you, I appreciate that I didn't say I dislike it, but it does make me sort of want an f2.8 70-200

I have to agree. Any more out-of-focus blur wouldn't have made the shot better. It's actually perfectly shot. f/2.8 might start to run the risk of too little depth of field when sometimes you want to see some details in the out-of-focus areas.

I find I set my f/2.8 to f/4 because depth of field becomes too thin at close tight distances.

FEChariot wrote in post #17047650
Bokeh is the quality of the blur not the amount of the blur. You can't have more or less bokeh.

There's no sense in being pedantic about it, everyone knew what the TS meant...

davidfarina wrote in post #17047667
Okay then more DOF, but i guess everybody knows what i mean

You mean "less" DOF Depth of field is how much of the image is in focus, so more DOF would mean less blur.

VWDOF is a powerful downloadable calculator that calculates DOF as well as the amount of blur at set distances:

http://toothwalker.org​/optics/vwdof.html

crunchie wrote in post #17046872
Yet another 70-200 thread...

I know all the differences in aperture, IS, weight etc etc etc. The price difference is negligible - £945 vs £985.

What I'm interested in is how much does the DoF change from f2.8 to f4 in the 150mm - 200mm range. I can test this at 100mm since I have a 100mm f2.8 lens. In this case, the answer is "not much". But at 200mm?

Basically, I've come to the conclusion that many people have - I would like a 70-200 for events, so called environmental portraits. Therefore DoF is important to me.

Thanks!

That is difficult to answer because it is mostly based on camera to subject distance. I tend to hang around 3.5 to 4 on my lens a lot when I am in good light mainly because I can get just enough of the environment in "soft" focus to help frame the sharp in focus areas. But when I am in an environment where things are too busy, there are people that I cannot avoid because of the general nature of candids I take I will drop down to 2.8 just to better isolate the subject (or if in low light and I need to jack up speed more than ISO allows) 2.8 is handy. I take many shots at 2.8. But as far as DOF it mostly matters only if you work low light a lot or if you are attempting stronger isolation of subject.

In a more controlled environment f4 is perfect.