topic Re: DOF question regarding f2.8 vs. f4. in EF & RF Lenses

DOF question regarding f2.8 vs. f4.

canonshooter — Fri, 14 Dec 2012 21:33:16 GMT

I am just thinking of blurred background with surperior subject IQ and I now shoot a 5DMkIII. I realize two other factors beyond aperture affect DOF so lets assume:

Focal length of 70mm
Distance to main subject 8-10 feet.

I am asking because I am considering returning my 24-70mm f2.8 MkII for the new f/4 version with IS. I have had the f/2.8 for about 10 days and I can't control camera shake consistently with anything below 1/100 of a second. I rented the Tamron version with VC to compare with the Canon. The VC worked fair, but to consistently get sharp images I needed 1/60 sec plus. Just not equal to the Canon H-IS.

I am spoiled with my 70-200mm f/2.8 MkII with IS and I can handhold this lens at 1/30 sec with great results. Before anyone starts suggesting that I practice or change my technique, consider I am 65 and not that steady of hand.

Thanks for your help, I look forward to your replies.

Re: DOF question regarding f2.8 vs. f4.

cicopo — Fri, 14 Dec 2012 22:33:52 GMT

I'm not sure just what you're trying to do & here's why. The shallow DOF is directly related to the wide aperture & not the slow shutter speed. You can use a very high shutter speed at f2.8 & it won't effect the DOF anymore than a slow shutter speed. You seem to be confusing the background blur that panning at a slow shutter speed induces. I ran into someone a few years ago trying for the background blur by shooting his 70-200 f2.8 L wide open in bright sunlight. He knew it wasn't working out so asked how I do it & I explained that by using f2.8 in really good light it forced the camera to use a very high shutter speed so even if he was panning nicely he couldn't get the desired effect.

So in the simplest of terms the DOF is relative to the aperture, (wide = shallow, small = deep) and whether it's a full frame body (more shallow) or a crop body (deeper DOF for the same aperture).

Here's a good example of panning blur to prove my point, it's at 1/60 sec & f18 (EIGHTEEN) shot by someone who is a smidgeon older than you who also relies on IS whenever possible.

Re: DOF question regarding f2.8 vs... f4.

canonshooter — Sat, 15 Dec 2012 01:31:23 GMT

Dear cicopo:

I only referenced shutter speed to provide a reference to my camera shake problem. I do understand that shutter speed has nothing to do with DOF, only aperture, focal length and distance to subject affect DOF. I also understand panning to achieve a blurred background and represent movement of the main subject while maintaining focus of that main subject.

What I was asking (given the parameters I listed) is what is the difference in the DOF at f/2.8 compared to f/4 and can similar DOF be achieved with both apertures?

Re: DOF question regarding f2.8 vs... f4.

cicopo — Sat, 15 Dec 2012 01:40:30 GMT

OK, in that case you can get the answers here. Enter your settings on the left & the answer is on the right. It looks like they are relatively close at that distance.

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

Re: DOF question regarding f2.8 vs... f4.

canonshooter — Sat, 15 Dec 2012 02:02:20 GMT

Thanks, I could not recall the name of the DOF website. Now, I have it bookmarked.

Re: DOF question regarding f2.8 vs. f4.

ScottyP — Sat, 22 Dec 2012 19:51:37 GMT

Every time I look at one of those DOF calculators, I am amazed I get any in-focus shots at all when using f/2.8 (or wider). So very shallow and unforgiving.

If you have a lot of background distance to work with, and/or if you can get closer to the subject using the highest telephoto possible for the framing, you can get blurry backgrounds at f/4 and at f.5.6 even.

Especially on a FF camera, which gives you 1 1/3 stops shallower DOF compared to the same aperture on a crop body. F/4 on a FF body gives you 1/3 shallower DOF than f/2.8 can on a crop body, which is nice.

Good luck!

Re: DOF question regarding f2.8 vs. f4.

canonshooter — Sat, 22 Dec 2012 21:23:52 GMT

ScottyP, thanks for your reply. I am really struggling with keeping the 24-70 vII without IS or returning it and preordering the f/4 version with IS. I feel like I really need the IS and just a little concerned about giving up the blurred background qualities. I can always boost the ISO on the 5DMkIII and gain the f-stop I would loose.

I agree FF gives much better blurred backgrounds compared to my 7D and that is why I went with the 5DMkIII. And the new 24-70 vII is a wonderful pair, BUT the lack of IS has me paranoid. I shoot mainly events/receptions (low light), on-site portraits usually without a tripod. As you know, most shots look great on the LCD only to get back a see OOF shots that make me want to pull my hair out.

And do you think there is any chance the f/4 IS version will match the f/2.8 MkII version IQ, because in my opinion it is very, very good?

Re: DOF question regarding f2.8 vs. f4.

ScottyP — Sun, 23 Dec 2012 04:50:52 GMT

If you thought your 7D gave you good blurred backgrounds with an f/2.8 lens, then you will be even happier with f.4 on the full frame 5D3, as it will be better than that. If the IS is important, then do it. Take the $1400.00 difference you are saving with the cheaper 24-105 and buy a lt of other stuff you need or want.

As for the new 24-70 f/4 IS, vs. the f/2.8 mk2, who knows. Maybe.

Probably will be sharper than 24-105 because it is newer design, and because it covers a shorter focal range with (presumably) fewer optical compromises. But probably the kind of difference you'd only be able to see in a photo of a test pattern. Plus, that will be a long time to wait. You could buy a used 24-105 on Craigslist or Ebay, and use it for a few years and then sell it for the same thing you paid for it, so it is like a free lens rental!

Re: DOF question regarding f2.8 vs. f4.

Samsen — Sun, 23 Dec 2012 13:08:25 GMT

"I am really struggling with keeping the 24-70 vII without IS or returning it and preordering the f/4 version with IS. I feel like I really need the IS and just a little concerned about giving up the blurred background qualities. I can always boost the ISO on the 5DMkIII and gain the f-stop I would loose."

Let me make it easy for you.
Just Don't.

Why?

1- IS is invented to compensate for a higher (Wider) F number. At best IS when turned on, is hopped to add one to one and a half F stop. If you can supliment the F with REAL and OPTICAL value (Your current lens with F2.8 as opposed to your proposed lens with F4) why should you ever think of that if you know the concept of IS?

IS don't do magic. If you are feeling better because you are having technology assisting you, then be fair to the lens and compare IS vs Non-IS in the same exact F. A good example would be 70-200mm F2.8 without or with IS or its sister lenses, F4 without or with IS.

I would think you will not see any benefit of IS with F4 and what you get right now with non IS F2.8 would be almost repeated with shooting F4 with IS, that is at best.

2- In my experience F2.8 24-70mm is one of the best if not simply The Best, walk around lens Canon makes. Please don't believe me and ask it for yourself from several people.

3- You will badly miss the Bokeh F 2.8 is giving you right now. Wait and see if I am not right.

4- If you like to see "Why there is so much hat for the New 24-70 F4" just read this thread: L I N K

5- The benefit of IS becomes really apparent when using a Tele lens. At 24mm you will hardly see any benefit unless the word IS has some sort of tranquil effect on you. Effect at 70mm is marginal to say the most.

"most shots look great on the LCD only to get back a see OOF shots that make me want to pull my hair out."

Next time make sure to use 10x mag on LCD and you will see all should.

"usually without a tripod. "

Why don't you consider using it or at least a Monopod. You will gain at least 2 F right there.

Re: DOF question regarding f2.8 vs. f4.

ScottyP — Thu, 27 Dec 2012 03:59:32 GMT

@Samsen:

A few points regarding your last post:

1.) Canon claims 4 stops of benefit on its newer IS lenses. The older systems claimed 3 stops but usually provided about 2 stops of benefit. That is more than the 1 to 1.5 stops you cite.

2.) I am not sure what you mean when you say "IS is invented to compensate for a higher (wider) F number". First of all, a wider aperture is a LOWER F-number, not a higher one. Secondly, I am not sure I understand the point.

IS does one thing, which is to compensate for camera shake at slower shutter speeds when hand-holding. One CAN get the shutter speed up by going with a wider aperture, true, but one does not always WANT a super-narrow DOF. If you are trying to shoot a cluster of 3 or 4 people and they are only 10 - 15 feet away, and they are not lined up shoulder-to-shoulder for you, then you may not be able to get all their faces in sharp focus inside that narrow plane of focus at f/2.8.

IS is a useful tool for a walk-around lens as much as for telephoto. True, a telephoto multiplies the camera shake, but your walk around lens will tend to be shot indoors under dim light a lot more than a telephoto is. If you lower shutter speed to compensate for the dim light, that magnifies camera shake too.

Re: DOF question regarding f2.8 vs. f4.

canonshooter — Tue, 25 Dec 2012 01:29:22 GMT

Thanks ScottyP, I didn't understand or agree with Sasen's post either. Your points are more aligned with my understanding. So your response leads me to a follow-up question. Do you think the image quality of the f/4 (with IS) can come close to the 24-70 f/2.8 II? And if the only thing I am giving up is one f/stop in DOF and light, I am thinking I should go for it for the benefit of IS. I can always boost ISO on the 5DMkIII to make up for the one stop loss in light (f/2.8 vs f/4).

Thanks again for your help and Merry Christmas.

Re: DOF question regarding f2.8 vs. f4.

ScottyP — Thu, 27 Dec 2012 04:00:11 GMT

(Kudos to you, B/T/W) All is speculation of course, but I do know that back before the new 70-200 f/2.8 IS MK 2 came out, it was common sentiment that the f/4 version of 70-200 was sharper than all the f/2.8 versions (both IS and non-IS).

So presumably a NEW version of the f/4 24-70 might be better than or at least as good as the new f/2.8 24-70.

Don't know if you can extrapolate anything from that bag of apples and oranges!

If you were to buy used lenses (Craigslist, Photography On The Net, etc.,) you can usually buy a lens, use it indefinitely, then sell it for what you paid (or more?). I have not done this yet (lazy) but if you did, you might literally have nothing to lose and perhaps something to gain.

With my new FF camera (compared to my crop), I find that a lot of the time I have no desire whatsoever to use aperture wider than f/4. Too much of the photo is going to be OOF for many shots, and it is more easy to just miss focus completely. Plus just like you said, the much-improved IQ at high ISO means you can just jump up a stop or 2 or 3 on ISO.

If you go ahead and grab yourself a Canon 85mm f/1.8 with your savings ($385.00), you retain the option for super-shallow DOF, plus the sharpness and lightness of a prime. That way you have that capability for very little $$, and yet your walk-around zoom can have IS.

Just my impression, though. Happy New Year!

Re: DOF question regarding f2.8 vs. f4.

Samsen — Thu, 27 Dec 2012 07:11:58 GMT

Scotty: Sorry not to escalate an unnecessary war of words that has no benefit for any one but I could not pass without answering to your statements.

I am not sure what you mean when you say "IS is invented to compensate for a higher (wider) F number". First of all, a wider aperture is a LOWER F-number, not a higher one. Secondly, I am not sure I understand the point.

The reason that you don't understand is that you don't pay attention or look deep.

Its plain English:

ap·er·true

/ˈapərˌCHər/

Noun

An opening, hole, or gap.
A space through which light passes in an optical or photographic instrument, esp. the variable opening by which light enters a camera.

Synonyms

opening - hole - orifice - gap - vent - mouth - slot

Now take the word "Aperture" and replace it by Hole.

wider HOLE is a LOWER F-number, not a higher one

Really?!! Is that what you try to tell me and others agree with you. May be The Kudos is to be taken back:)

Please pay attention to what you read and do not Assume...

__________________________________________________

Canon claims 4 stops of benefit on its newer IS lenses. The older systems claimed 3 stops but usually provided about 2 stops of benefit. That is more than the 1 to 1.5 stops you cite

Do you only read reviews or actually shoot with the IS lenses too. I only talk of my own hand on experience and firmly believe in what I say as I have learned through experience and not what others say.

__________________________________________________

but one does not always WANT a super-narrow DOF

You seem not get it at all. If you have a lens that has wider F (Lower number F), then only you can get a bokeh by choosing that wide hole/aperture, whenever needed. Say F2.8 of first lens. If the second lens has F4 as largest hole, then you CAN NOT get the bokeh. What bokeh is and how DOF is to be handled is a totally different issue that a knowledgeable photographer knows. The second lens simply CAN NOT provide that bokeh because it doesn't have F2.8

__________________________________________________

IS is a useful tool for a walk-around lens as much as for telephoto.

Absolutely wrong. Again you rely on what you read and I talk of my own experience.

You simply DO NOT NEED IS for an Ultra Wide angle lens.

If any one tells you the opposite, they want something out of your wallet supported by your lack of understanding.

Let go to extreme of the example:

I can take raser sharp night image with my 11 or 10mm focal lenght lens, handheld when shutter speed is 1 second.

Same Me, with same breath holding techinque and muscular capabily can not take any sharp image with a 500mm lens when speed is 1/50 even 1/100 sec.

IS is meant to use with tele lenses. As it became popular, its been added to any focal lenght lens just because some ignorant shopper who donot understand physics and at the same time are featureholic simply buy them.

Peace! and Happy New Year to All.

Re: DOF question regarding f2.8 vs. f4.

canonshooter — Thu, 27 Dec 2012 13:28:30 GMT

Samsen, Both ScottyP and I have a dictionary, an understanding of photography and a nice exchange of ideas. What we don't need is your intrusion, go away please and thank you.

Re: DOF question regarding f2.8 vs. f4.

ScottyP — Fri, 28 Dec 2012 18:17:55 GMT

While he has his dictionary out, he should brush up on his spelling. His shortcomings in that area give an unintended ironic quality to his writing when he is calling people things like "ignorant."