Why is it important to have a 2.8 lens

This is a newbie question. I have a d50 and a kit lens (f3.5-5.6 (18-55 mm). My main question is why is it important

to buy a 2.8 lens, when those that have f3.5 are way cheaper. what does it actually do to your pictures?

There are two reasons for owning a faster lens. The first is that a larger aperture allows you to use a faster shutter speed for a given film/sensor sensitivity- not as important with high-speed/low noise sensors but still useful (especially for sports and nature photogs).

 

The second (and for most photographers primary) reason is that a larger aperture allows a shallower depth of field. This means you can more easily throw the foreground and background out of focus to isolate your subject.

It really isn't important for a newbie! Advantages to the user of wider aperture lenses include greater ability to shoot in situations which have less light, a greater "blur" on objects not in focus when shot wide open, and generally these lenses are higher in quality and performance than kit lenses. Having said that, they are generally more expensive, heavier to carry around, and accessories are also more expensive.

1) Faster shutter speeds for a given sensor speed. Think sports or wildlife.

2) Shallower depth-of field. Useful for isolating subjects from foreground and/or background.

It is important if

 

1) You are working in lighting conditions that would prevent you from achieving the appropriate shutter speed to either freeze motion or prevent blur from camera shake with a f/3.5-5.6 lens.

 

2) You want to further isolate your subjects from their background using the shallow depth of field a larger aperture provides.

F2.8 lenses are usually top of the line, sharper, better contrast, more rugged, less prone to flare, and the 2.8 aperture allows for faster autofocusing.

A f2.8 lens may not be 'important' for you. You may be able to get all the great shots you want with the kit lens. However the smaller the 'f' number on a lens of a certain focal length, the more available light it lets into the camera. The result being the ability to use higher shutter speeds and/or the ability to get proper exposure without the need for flash. Smaller 'f' number = bigger lens diameter = higher price

It will allow you to shoot at lower light levels while keeping your shutter speed at a useable handheld level -- useful if you want to shoot indoors without flash or for sports/action shots. The other advantage is that depth of field can be limited for creative effect. It can be a useful feature - at a cost, it depends on your photographic interests. It has to be remembered that even the best lens will not perform at its best when used wide open, closed down two stops is usually when a lens is at its sweetest. In the case of your kit lens I would suggest that you aim to shoot at f8 where possible for general shots to give optimum quality. Experiment a bit - take a series of shots at different aperatures of the same subject while focusing on the same point each time --pick a subject with foreground & background features and focus on a foreground feature.

Hope this helps a bit-- feel free to come back with more questions for clarification.

Regards Pete.

they simply let more light in... it allows for lower ISOs, faster shutter speeds, less depth of field when desired and they are generally made better than kit lenses, optically and physically.

 

If you really want to know the answer to this quesiton, buy a nikon 50 1.8 lens. They are $109, and one person in a similar stage as you told me that it made photography fun again. That lens should be a must have for everyone with a D50.

If having an f/2.8 lens is important to you or not mainly depends on the kind of images you take.

 

If you mainly take landscape images, and your desire is to get the largest depth of field that is possible, an f/2.8 lens doesn't help you much.

 

If you're more into portrait photography, you'll want an f/2.8 lens (or very likely even a faster one). Large apertures (small numbers) help to isolate the subject from the fore- and background with the shallow depth of field they produce.

 

There are other side effects of large aperture lenses ... the brighter viewfinder, better AF (at least some cameras can use high precision AF points only with lenses that are at least f/2.8).

 

Also, most f/2.8 zooms maintain the f/2.8 throughout the whole zoomrange, whereas the lens you mentioned has a variable aperture (f/3.5 at the wide end, f/5.6 at the tele end). This can be a bit cumbersome at times. (When using flash for instance).

study aperture...

 

the wider maximum aperture lets in more light that gets you

a) faster shutter speeds for stopping action

b) more light means you can shoot in lower ambient light

c) better ability to blur distracting backgrounds

d) usually the faster glass is built better but not always

A 2.8 lens lets more of the light which goes into the front, go out the back. This ratio is what the number stands for. Lenses with a lower number allow for faster shutter speeds, which allows for hand-held photos in lower light.

 

If used wide open at F2.8, the lens would blurr the background more and better, than a "slower" lens like a 3.5 or 5.6. Blurring the background is often preferred by portrait photographer.

 

See these sample photos made with an expensive F1.2 lens:

 

http://www.pbase.com/cameras/canon/ef_85mm_f12_l_usm_ii

 

I hope this has helped. J.

It will allow you to shoot in lower light situations whilst keeping a usable shutter speed for handholding the camera. Can be useful if shooting indoors without flash. It will also allow you to keep your shutter speed high for action/sports photography. Another feature is that depth of field can be restricted for creative effect. An f2.8 lens is more complex to make thus the higher price. It has to be remembered that even the best lens will not be at its best when used wide open - the general consensus is that about 2 stops down from maximum aperture will give optimum quality. I would suggest in the case of your kit lens to shoot at f8 where possible to give the best results. Much depends on your photographic interests, if you are into action photos then spend the money on a fast lens. If your interests are more general then your kit lens will be fine. Experiment a bit with the depth of field aspect, take a series of shots of the same subject at the full range of apertures. Pick a subject with foreground & background interest & focus on the foreground for each shot.

Hope this helps. Come back for clarification if needed.

Regards Pete.

f2.8 is relative, it's fast with normal zooms but so-so with normal primes. With something like Canon's 50mm primes, that's *really* slow. Canon's slowest 50 is f1.8, and there is a f1.4 that is a step up in build, but still a bit clunky and in need of an upgrade.

 

Every stop you gain (sounds like a song?) affords you a doubling of shutter speed for stopping motion, which can make or break low light interior shots, particularly when hand holding.

I scan read all of the answers and most reasons explain the value of F2.8 to create images, using that F2.8 aperture.

 

***

 

Having an F2.8 lens, (or any ``fast`` lens), allows the photographer much less eyestrain and more clarity through the viewfinder (which Rainer T mentioned).

 

I think this point is often missed, and its importance glossed over, especially if you want to shoot indoors or in dimmer light, and especially with an APS-C format (a crop camera): because most have quite dark, small viewfinders, anyway.

 

A brighter viewfinder makes it much easier to compose and frame the scene in camera, and to manually Focus, or to check Focus, and to some limited extent, check the Depth of Field.

 

Even if the fastest aperture of F2.8 is seldom used to take the picture, a faster lens is much easier to work with day to day, than a slower, F5.6 lens, for example.

 

WW

In addition to what others already said, a fast lens makes the viewfinder brighter. Furthermore, it makes for a shallow depth of field through the viewfinder, which can help you focus precisely.

Why stop at 2.8? There are inexpensive prime lenses with f1.4 up to 2.8. I have 4 non-"L" primes, all 2.8 or faster. The whole

bunch cost about the same or less than one heavy 2.8 zoom and the image quality is equal to the expensive zoom. While I can't

zoom, I can shoot a 35mm lens at f2.0 or a 50mm lens at f1.4. It's a big advantage which, for me, out weighs the advantage of

zooming with the lens.

 

Of course for some photography, a zoom lens is a big advantage, but Tuesday, the original poster, is a "newbie" and perhaps

might like to try a 50 f1.8 lens for <$100 rather than invest in a $1500 zoom.

Since this is a beginner forum, maybe more beginner language would help. I'm just out of beginner-hood, and fancy photo lingo is hard to understand if you're new to it! Just kidding about the "fancy photo lingo" - it's important to learn the terms of the trade because it will help you express yourself and ask appropriate questions! But, here's a more pedestrian-type of answer: A 2.8 lens opens wider letting in more light when you take a picture, so you can use it in darker settings. You can take pictures longer in the evening as it gets dark outside, and you can take pictures indoors without using a flash as often. When you use just the available light indoors, the pictures are usually a lot more attractive when you don't use a flash. So with the kit lens, you'd probably have to use a flash inside unless there's some really good lighting. Also, if you use a lens at f/22, the "depth of field" or what all is in focus in the picture is much greater. For example, the people, the cars behind them, and the trees behind the cars would all be in focus and that's sort of characteristic of "snapshots". Snapshot cameras are successful because everything in the picture is in focus and people using snapshot cameras like it when their whole picture is in focus, but they don't know how to get that "professional portrait" look. If you use a lens at f/11, maybe only the people and the cars would be in focus and the trees would give a nice blur in the background. If you use a lens at f/2.8, only the person's face would be in focus and everything else farther back and in front of the person would be blurry (you'd have shallow depth of field). This gives the picture more of a "portrait" look rather than the "snapshot" look. But like several of the folks who've given answers to this question have mentioned, you rarely get the best picture from any lens at it's extreme ends, so you probably wouldn't want to shoot much right at f/2.8, but a couple of "stops" down from that meaning closing the aperture a little (which means bigger numbers like f/8) to get the lens to give you its best picture (where the lens is "sweetest"). So, with an f/2.8 lens, you can get some really beautiful pictures using lower light both indoors and outdoors where you'd have to use a flash to get enough light with your kit lens, and you can get more of a "professional" look to your pics when you use a more shallow depth of field where not everything in the picture is in focus. Do you need a 2.8 as a newbie? No. Play with your lens at it's larger apertures (smaller numbers) in low light and outdoors where you want one thing in focus to really bring attention to it instead of the entire picture in focus, and see if you like it. If so, then save for a 2.8. But if you're a newbie, there're are a zillion other things you can learn and do with your lens before you have to have a 2.8!

Thanks everyone! I mainly use my camera for landscape photos but get very very frustrated when I have to use it indoor with low light situations (like weddings etc.) therefore, a 2.8 is helpful! =)

I would point out that f/2.8 is less than one stop from f/3.5. Most responses, and the results you would see, would be more applicable if you were talking about a much faster lens like an f/1.8

I think you came close to answering your own question. ;-)

 

Perhaps you can take one for a test drive, buying lenses to test can be frustrating. With a lot of experience and

research you may be more able to narrow your needs and wants, with the latter more important of course. ;-), I am of

course paraphrasing Bob Dylan.

 

I think we all have a few "supplimental" lenses.

> I would point out that f/2.8 is less than one stop from f/3.5. Most responses, and the results you would see, would be more applicable if you were talking about a much faster lens like an f/1.8 <

 

Agreed that there will be more difference noticeable if we were comparing the kit zoom to a fast prime, like the 50mm F1.8.

 

But it is important to note that there still will be significant differences, if we compare the kit lens to an F2.8 lens (or an F2.8 NON varying maximum aperture zoom lens).

 

***

 

Tuesday has a lens which has a varying maximum aperture, across the zoom range.

 

At FL = 18mm the largest aperture is F3.5, and likely there will be little difference noted at that Focal Length, than if she had F2.8 available.

 

BUT at FL = 55mm the kit lens is only capable of F5.6, as a maximum aperture.

 

There are a substantial differences with an F5.6 lens (especially in low light) to that of an F2.8 lens.

 

Moreover, the 18 to 55 F3.5 to F5.6 moves to these Maximum Apertures (approximately):

 

F4.0 around FL = 22mm

 

F4.5 around FL =28mm

 

F5.0 around FL = 38mm

 

F5.6 around FL = 45mm

 

Differences in maximum aperture available will, IMO, be noticeable by most photographers comparing the kit lens from around 28mm and beyond to 55mm, to another lenses, of the same FL, with F2.8 available.

 

WW

The real irony here is that we're all talking about 2.8 as if that were a fast lens. Back in the days before zooms took

over, f/2 was more or less the standard speed for a "normal" 50mm lens, and anybody who could afford it -- including

beginners -- went for a

1.4 or 1.2. Wide angle lens and portrait length lenses were available to 1.4, and you didn't have to go as slow as a

2.8 until maybe something like the Nikkor 105/2.5. Even that was a hair faster. Even a 180 was 2.8. If a manufacturer

had put out a 5.6 55mm in the 1980s they would have been laughed out of the room and if it had come out in April

everyone would have thought it was an April Fool's joke. Faster film or more sensitive chips are not the answer --

you're throwing away image quality by cranking up the ISO to compensate for a slow lens. Maybe the image is

still "good enough," but all else being equal it's not as good as the same camera and chip at a lower ISO. I know

most people can't afford a 300 2.8, myself included. And I know fast zooms are more epensive to build. But how did

it ever come to this?

I think it's more important to gain experience with the gear you have, and let that experience guide you toward your

next lens, filter, gizmo, etc. I've seen so many shooters throw money at a problem only to come up empty handed

and thousands of dollars lighter. Try it my way, and you'll know when it's time for that faster lens.

Bill P.

I have been using Canon's 70-200mm f/2.8 L IS and I couldn't do what I do without it. I am a wedding and family

photographer and I find myself in some dark places, and I like to shoot available light if I can, although even with a 2.8 I

cant always. Another option of course is to get a prime lens that is even faster and for that I like Canon's 85mm f/1.2 L I

can get a lot of light in with that for sure, 4x as much as a 2.8. Of course the bokeh don't hurt either.

 

Lorin

 

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