Canon 24-105 F4L owners/users. Few questions.

[clanthar]

oh? is that all it makes as far as DOF goes and how much difference it is between f stops?

Yep, given that you can back up the extra distance with the 105mm versus 70mm long end, the difference between f/2.8 and f/4 ends up being about the same as a digit on your finger -- it's a wash.

Joe

P.S. Before you believe anything you read on this forum, do the math.

 

[bikeboynate]

Wait so the 24-105 has better DOF than the 24-70?

 

[clanthar]

Wait so the 24-105 has better DOF than the 24-70?

Wait! No one said that.

I said that if you're trying to take advantage of the shallow DOF that you get from large f/stops then, given the extra magnification you get from the 105mm versus 70mm long end of the 24-105, you wind up in pretty much the same place with f/4 and 105 as you do with 70 and f/2.8 -- it's a wash. Hold up your forefinger and look at the last digit on the end -- I'm saying that doesn't amount to much when comparing DOF between lenses.

Again look at the last digit of your forefinger and consider the going price on Amazon.com. Is that much less DOF worth $300.00 and 1X less zoom capability? Do the math.

Joe

 

[bikeboynate]

Wait so the 24-105 has better DOF than the 24-70?

Wait! No one said that.

I said that if you're trying to take advantage of the shallow DOF that you get from large f/stops then, given the extra magnification you get from the 105mm versus 70mm long end of the 24-105, you wind up in pretty much the same place with f/4 and 105 as you do with 70 and f/2.8 -- it's a wash. Hold up your forefinger and look at the last digit on the end -- I'm saying that doesn't amount to much when comparing DOF between lenses.

Again look at the last digit of your forefinger and consider the going price on Amazon.com. Is that much less DOF worth $300.00 and 1X less zoom capability? Do the math.

Joe

So theoretically the 105 has comparable DOF and Bokeh to the 70 when at their longest focal length?

 

[Hardrock]

Camera to subject and subject to back ground also has a lot to do with washing out the back ground. A 150 mm lens at f8 will completely blur out the back ground if the subject is close to the camera and the background is far from the subject. Take your 70-300 and do a headshot at 300 at f5.6 and then take your 24-105 and do a headhsot at 100 and 5.6 and see the difference. But the subject, camera, and back ground need to be the same. That is one of the reasons longer focal length lens are preferred. Hope this helps.

 

[clanthar]

Nothing theoretical about it. With subject framing held constant, 105mm at f/4 produces comparable DOF to 70mm at f/2.8. You're shooting a head and shoulders portrait. You focus on the subject's eyes. You take the photo with the 24-105 zoomed out to 105mm at f/4. Punch the numbers into the calculator and out comes about 6 inches of DOF behind the point of focus. In other words the back of the subject's head is already getting pretty soft.

Now switch to the 24-70. Zoom to the 70mm end and to frame the same shot you'll have to move in a few feet. Shoot at f/2.8 and punch the numbers into the calculator and out comes about 5 inches of DOF behind the point of focus. The difference is less than the length of your finger.

I ran the math assuming a COC for a 35mm camera since both those lenses were designed to that format. If you redo the math with a COC for a cropped sensor you'll get slightly different results with more DOF in both cases, but still a very minor difference.

As for bokeh, you'd have to shoot them to see since that phenomena depends on things like the shape of the aperture blades.

Joe

 

[Big Mike]

:thumbsup: to clanthar for doing the math.

It should also be pointed out that the difference between F2.8 and F4 is only one stop. That's the difference between shooting at ISO 200 and ISO 400. Yes, of course, F2.8 will always let in more light than F4 and there will be times when that one stop will make the difference, but if you consider that many modern DSLR cameras can easily shoot at ISO 3200 (or maybe 6400 if you have a 5D mkII), then are you really limited by F4 as a maximum aperture?

Another thing to note is the size & weight. The 24-105mm isn't small, but the 24-70mm is nicknamed 'The Brick' and for good reason. It's as big and as heavy as a brick....not ideal for a 'walk-around' lens.

 

[dakkon76]

Not that I have the money for either lens at the moment, but the big thing for me vs the two is that, while the 24-70 will let more light in ... it does so by narrowing your DOF. Great if you want some good bokeh, but not so great for the times you don't. That's where having IS over bigger glass would come in handy. There are lots that say you don't need IS on the 24-70 f/2.8 because of it's speed, however if you are shooting in the evening or in very low light... that much more light still may not help you out a whole lot, whereas the IS may have given you a much better shot.

 

[kwik]

I bought something. Pics coming later tonight....maybe....hopefully my baby will go to sleep soon so I can have a few extra min to upload some on my pc :lmao: