Are lenses at F2.8 really necessary?

ChrisHeathcote

ChrisHeathcote

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Was just looking at upgrading my glass, now Christmas is over, and was looking at canons L series lenses. What with F2.8 lenses being so much heavier and more expensive than their F4 counterparts and with IS and cameras having much higher ISO capabilities. What are the benefits of F2.8. The only one I have found for myself is the ability to retain AF with a 2x converter. Can anyone else think of any others
 
Same reason that you'd choose an F4 lens over an F5.6 lens or something I guess? More flexibility. If the situation is suitable then you can make use of the extra aperture to use shorter exposures or you can use the extra aperture to isolate your subject better with bokeh?

Being able to use an extended without losing too much is also a bonus :)
 
Also, with lenses of F2.8 or greater some of the AF points in your camera work with increased sensitivity/accuracy. Plus getting more light onto the AF sensors is always a good thing anyway.
 
My 70-200mm f/2.8 sigma was invaluable at my daughters' nativity plays.

It was also great taking photos in the lowish light at the park
 
At the park ISO 800 and the nativity 1600. The nativity was in a low lit church and without flash I was still managing around 1/50 shutter speed.


The d3100 isn't the best at high ISO, so I try to keep it as low as possible.
 
I had a 70-200 f4 and upgraded to the 70-200 f2.8. The 2.8 is bigger and heavier but feels much more comfortable in the hand for me at least.

It is also very very sharp and is my best lens (all my lenses are Ls)

If you are in a dark venue you have a greater chance of accurate AF than with an f4 lens too as there is a stop more light coming in.

Neil
 
ChrisHeathcote said:
Was just looking at upgrading my glass, now Christmas is over, and was looking at canons L series lenses. What with F2.8 lenses being so much heavier and more expensive than their F4 counterparts and with IS and cameras having much higher ISO capabilities. What are the benefits of F2.8. The only one I have found for myself is the ability to retain AF with a 2x converter. Can anyone else think of any others
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Try shooting in a church!! I have plenty of images from weddings where I have had to use either the 24-70 or 70-200, at ISO 3200, at 2.8 and still only just got a useable shutter speed. Plenty too where I have used my 85mm 1.8 wide open for same reason, and even a 50mm 1.4, also wide open.

Basically it comes down to what you use the lens for most - if it spends most of its time sitting on a tripod shooting inanimate subjects, then 2.8 probably will be an unnecessary luxury for anyone but those needing the best quality money can buy, especially if you are normally using the 'sweetspot' area that most lenses seem to share [f8 to f11-ish] and you can get the same or near as damn it the same IQ from something less weighty. However, having the extra stop offers more creative and practical options, simple as that.
 
when will people learn that a camera can have as many focus points/modes and tomfoolery as you like, the fundamentals are still the same

- what is the apeture
- what is the shutterspeed
- what ISO is the film or sensor
- what is the lens focused on
- what focal length is the lens

upon firing the shutter, once all those things are set, no amount of camera magic will make anything else more or less or better or worse in terms of exposure
 
also a 2.8 lens wide open will be more use on a moving target than VR. :thumbs:
 
a 2.8 will have better resolution at smaller apertures...there is an optimum aperture for all lenses after which resolution deteriorates and other effects start to creep in
except in the case of flat field macro lenses which are computed to give flat field images right to the very edge at any aperture without any distortions....and cost a lot more

i would personally accept a 2.8 but wouldnt really go for one and pay a lot
i usually take shots in the f4-f8 region on medium wide angle and if i really needed a lot of out of focus stuff in the background would use the long zoom setting and up the iso

cheers
geof
 
Of course they are necessary! As are f/2.5, f/2, f/1.8, f/1.4 and f/1.2 lenses.

They all let more light in, even with a better sensor, they will always retain light advantage and enable faster shutter speeds.

Rubbish thread.
 
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JayD said:
Might be rubbish to you with your vast experience and superior knowledge, but to beginner/intermediate photographers like me, threads like this are invaluable!
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Ok, maybe rubbish was a bit blunt!
 
Short answer: Yes.

If you ever shoot gigs, plays in low light, weddings in dimly lit churches, ambient lit portraits, wildlife on dim evenings ... 2.8 just owns f/4+ in all cases.
 
travellingcello said:
Also most if not all 2.8 lenses will be sharper at F4 than a lens with a max aperture of F4.
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The f/4 IS was sharper than the f/2.8 IS at similar aperture supposedly, which would make sense as it is easier to correct an f/4 lens than an f/2.8.
 
Laudrup said:
The f/4 IS was sharper than the f/2.8 IS at similar aperture supposedly, which would make sense as it is easier to correct an f/4 lens than an f/2.8.
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The f/4 IS is probably THE exception to the rule, an absolute cracker from what I've read.
 
JayD said:
Might be rubbish to you with your vast experience and superior knowledge, but to beginner/intermediate photographers like me, threads like this are invaluable!
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Thank you for that Jay, unfortunately I do not have the expertise or possibly budget of Jim, my comment would be if you feel this strongly, you don't have to contribute.

For me though as Jay said these forums are invaluable in our learning experience. My thought was simple, my main photography is landscape, portrait where I can use speedlights (I am looking to expand into strobes). My lowlight stuff is mainly landscape on a tripod and with IS I could handhold at lower speeds, my 60D is also acceptable to my eye at ISO 800. For the rare occasion I would be in a church at a wedding, I would consider hiring a F2.8, also as a guest I may stick out a little with a 70-200 F2.8. I wouldn't want to upset the pro. With regards to wildlife and studio, isn't it better to shoot at around F8/11, so as to have slightly larger DOF. Even my current sigma 70-300 gives a nice Bokeh at 200mm. The lenses I am considering are the 70-200 f4L IS and the 24-105 F4 L IS. Both these would come to about the same as a 70-200 F2.8 L IS USM ii. I would buy 2 nd hand, so if I decide to upgrade later, I shouldn't lose much money.
 
If you need f2.8 then it's got to be the sigma.
However as your areas of photography are primarily landscape and studio work then I can't really see why you'd need a 2.8 lens at all and the Canon f4 would be the best bet.
 
ChrisHeathcote said:
Thank you for that Jay, unfortunately I do not have the expertise or possibly budget of Jim, my comment would be if you feel this strongly, you don't have to contribute.

For me though as Jay said these forums are invaluable in our learning experience. My thought was simple, my main photography is landscape, portrait where I can use speedlights (I am looking to expand into strobes). My lowlight stuff is mainly landscape on a tripod and with IS I could handhold at lower speeds, my 60D is also acceptable to my eye at ISO 800. For the rare occasion I would be in a church at a wedding, I would consider hiring a F2.8, also as a guest I may stick out a little with a 70-200 F2.8. I wouldn't want to upset the pro. With regards to wildlife and studio, isn't it better to shoot at around F8/11, so as to have slightly larger DOF. Even my current sigma 70-300 gives a nice Bokeh at 200mm. The lenses I am considering are the 70-200 f4L IS and the 24-105 F4 L IS. Both these would come to about the same as a 70-200 F2.8 L IS USM ii. I would buy 2 nd hand, so if I decide to upgrade later, I shouldn't lose much money.
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You don't need a massive budget, or L series lenses.

Look at prime lenses, the Canon 50mm f/1.8 can be had for £70 new, and gives you the depth of field and light gathering advantages.

The Canon 35mm f/2 can be had for £200 new (certainly not L money but easily L quality)...

...and the absolutely stunning and possibly my favourite prime, the Canon 85mm f/1.8 can be had for £300.

All three are great for weddings and low light interiors.

Personally, I find f/2.8 looks nice on wildlife as it separates the background from the subject, and also it's essential when shooting in dark wooded areas etc.

Ps - apologies for calling the thread rubbish, it isn't and as I said earlier I was a little blunt. But, the reason I was critical was because if the way I interpreted your OP which I read as basically saying "are fast lenses needed these days with better sensor tech"? Your last post explains your point better!
 
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No problems Jim, maybe I could have worded slightly better, but unfortunately I have a habit of writing as I think. As always the advice is very helpful. I already have the 50mm f1.8. I shall have a look at the 35mm F2 as well, this would effectively give me approx 50mm and 85mm equivalent FL. Jim the length you mentioned, were you referring to them being on a FF? My shopping list has now grown to:

Canon 24-105 F4L
Canon 70-200 F4 L IS
Canon 35 F2
Just need to speak to bank manager (wife) :-)
 
ChrisHeathcote said:
No problems Jim, maybe I could have worded slightly better, but unfortunately I have a habit of writing as I think. As always the advice is very helpful. I already have the 50mm f1.8. I shall have a look at the 35mm F2 as well, this would effectively give me approx 50mm and 85mm equivalent FL. Jim the length you mentioned, were you referring to them being on a FF? My shopping list has now grown to:

Canon 24-105 F4L
Canon 70-200 F4 L IS
Canon 35 F2
Just need to speak to bank manager (wife) :-)
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I use them on both, but mostly on my cropped 50d. The set of primes I mentioned, for me, cover a very useable range on a crop. The 35mm f/2 is also useable as a "do it all" lens, I love it.

The 85mm is of course tighter, but is great for dimly lit interiors as even at f/1.8 it's pin sharp, and I mean sharp! As is the 35mm at f/2. Two excellent primes sharp wide open, and that's what you want. The 50mm needs stopping down to about f/2.2 - 2.5 but at the price it is we can't complain!
 
I'd need considerably better high iso performance before I'd consider not needing F2.8 lenses, when I'm shooting indoors for pretty much anything (at home, live music, pubs etc.) F2.8 is the bare minimum even at iso 6400 to try and get usable shutter speeds. Faster primes are of course handy as they give a bit more leeway in low light but you lose the flexibility of being able to zoom.

For the 70-200mm I'm usually shooting moving subjects and need a high shutter speed which is where the F2.8 comes in handy as even in what seems like ok natural light it still doesn't necessarily give that good a shutter speed without opening up the aperture.

John
 
JohnMcL7 said:
I'd need considerably better high iso performance before I'd consider not needing F2.8 lenses, when I'm shooting indoors for pretty much anything (at home, live music, pubs etc.) F2.8 is the bare minimum even at iso 6400 to try and get usable shutter speeds. Faster primes are of course handy as they give a bit more leeway in low light but you lose the flexibility of being able to zoom.

For the 70-200mm I'm usually shooting moving subjects and need a high shutter speed which is where the F2.8 comes in handy as even in what seems like ok natural light it still doesn't necessarily give that good a shutter speed without opening up the aperture.

John
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Isn't the DOF really shallow at F2.8
 
Another spin is getting a 300mm f2.8 & putting a x2 t.c. On which would give you a fast hand holdable 600mm lens.
I own a 600mm f4 & I'm considering this option.
 
ChrisHeathcote said:
Isn't the DOF really shallow at F2.8
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The only equivocal statement you can make is that the DOF will be smaller at 2.8 than at 3.5 or 5 or 22 with all other settings being equal. f/2.8 on a 30mm focal length and a 10m focal distance is quite a large DOF when compared to a 200mm focal length using the same f/2.8 aperture, the same camera and the same 10mfocal distance.

The measurable DOF is dependant on the camera used, the focal length, the focal distance and the aperture.

Have a play with the DOF calculator to see how each attribute affects the DOF.
http://www.dofmaster.com/dofjs.html
 
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