Need help on understanding dslr camera and lenses system

[saabuldin]

I want to buy a dslr camera and a first lens with it. Im confused on how the system works. heres a few questions.

1. does the camera have the aperture settings or is it the actual lens which has the settings?

2. ive seen some lenses which state only 1 aperture for example "eos 50mm f/1.8" does this mean i can only use the lens at this aperture?

3. Is there a lens which can cover everyday shooting for example. decent focal range, decent macro, a bit of zoom, full manual aperture, shutter, iso settings. Something like the bridge cameras but having it in a lens version instead. (doesnt have to have the superzoom feature)

Thanks in advance. I might be asking more questions so please bear with me. Im new to photography and would like to get into it.

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[AverageJoe]

1. The lenses determine aperture restrictions (i.e. 1.4 or 4-5.6). However the camera body is used to SET the aperture.

2. Lenses with one aperture are stating their largest aperture. This means a lens that has a zoom range of 18-55mm with f3.5-5.6 can shoot at 18mm at f3.5 but only down to 5.6 when zoomed all the way in at 55mm. Higher quality glass like the 24-70mm 2.8 can stop down to 2.8 throughout the entire zoom range.

3. Yes, there are 24-105, or 28-135mm or even a 18-200mm. However, don't expect one of these lenses to do everything perfectly.

I'm probably not explaining this very well, but someone else will come along and fill in the gaps. Welcome to the forum.

[Village Idiot]

I want to buy a dslr camera and a first lens with it. Im confused on how the system works. heres a few questions.

1. does the camera have the aperture settings or is it the actual lens which has the settings?

This is dependent on the lens.

2. ive seen some lenses which state only 1 aperture for example "eos 50mm f/1.8" does this mean i can only use the lens at this aperture?

The aperture shown is the widest aperture at which the lens can open up to. A lens with just f/1.8 will have a widest aperture or f/1.8. A lens that is labeled f/3.5-5.6 has an aperture that changes as it zooms. As the lens zooms in, the widest possible aperture gets narrower and narrower, going from 3.5 to 5.6.

3. Is there a lens which can cover everyday shooting for example. decent macro, a bit of zoom, full manual aperture, shutter, iso settings. Something like the bridge cameras but having it in a lens version instead. (doesnt have to have the superzoom feature)

There are lenses that are that serve a general purpose, but they usually will not be good at different kinds of specialty work. General purpose lenses, like a lens that will zoom from 18mm to 200mm will usually not be as good quality as say a prime or a shorter ranges zoom. Prices will usually reflect this.

You can buy 70-300 zoom lenses with a variable aperture that's widest aperture changes with the zoom, as explained for your second question, for about $300. Canon and Nikon both make 70-200 f/2.8 Lenses with some sort of image stabilization that are better than the 70-300 variable aperture lenses. They cost about $2,000-$2,500.

[saabuldin]

2. Lenses with one aperture are stating their largest aperture. This means a lens that has a zoom range of 18-55mm with f3.5-5.6 can shoot at 18mm at f3.5 but only down to 5.6 when zoomed all the way in at 55mm. Higher quality glass like the 24-70mm 2.8 can stop down to 2.8 throughout the entire zoom range.

yes i understand now but does that mean at 18mm focus, i can open up aperture to like f/22 if the camera lets me.

[Vinny]

You have the idea backwards. Smaller numbers = larger apertures and larger numbers = smaller apertures ... opposite of what seems logical to non photographers. The answer to your question is if a zoom lens has a fixed largest aperture (say 2.8) you can use the zoom at that f stop throughout the zoom range. All lenses will be able to close (bring the f stop to a larger number) their aperture to the lowest they can go without any problems. But as you close down the aperture you need to compensate for the lack of light and lenses can have image quality issues.

And 18mm is a focal length vs focus.

[O|||||||O]

2. Lenses with one aperture are stating their largest aperture. This means a lens that has a zoom range of 18-55mm with f3.5-5.6 can shoot at 18mm at f3.5 but only down to 5.6 when zoomed all the way in at 55mm. Higher quality glass like the 24-70mm 2.8 can stop down to 2.8 throughout the entire zoom range.

yes i understand now but does that mean at 18mm focus, i can open up aperture to like f/22 if the camera lets me.

Yes - but you would be stopping down, not opening up.

3.5 (or whatever it might be) is just the maximum aperture possible on the lens. You can still use smaller ones (which would be a larger number).

[KmH]

Yep! Aperture values are fractions of the lens focal length. So f/2 means the lens aperture diameter is 1/2 the lens focal length, and f/4 means the lens aperture diameter is is 1/4 the lens focal length.

Obviously, lens focal length is a variable. A zoom lens zoomed to 100 mm that has the aperture set to f/2 has a lens opening that is 50 mm wide, and 25 mm wide when set to an aperure of f/4. A 200 mm lens set to f/2 has a lens aperture diameter of 100 mm, etc, etc, etc.

In other words the letter f = 1, and with fractions, the bigger the bottom number the smaller the value.

Lenses that have a range listed , like an 18-55 f/3.5-5.6 lens are called variable aperture lenses, because the maximum aperture changes automatically when the lens is zoomed from 18 mm to 55 mm. Lenses that have a single number like a 17-55 f/2.8 lens are called constant aperture lenses because if set to f/2.8 at 17 mm and then zoomed towards 55 mm the lens stays at f/2.8.

Variable aperture lenses are less expensive than constant aperture lenses.

[JustAnEngineer]

KmH explained it well. The EF 50mm f/1.8 lens can open up to as large an aperture as f/1.8 (50mm ÷ 1.8 = 28mm opening). It can stop down as small an aperture as f/22 = 2.2mm opening. It can do this in steps of 1/3 of an f-stop.

f-stops are useful because they tell us something about exposure. Each number of f-stop goes up by the square root of 2, and each f/stop cuts the amount of light reaching the sensor in half compared to the previous one: f/1.4, f/2.0, f/2.8, f/4.0, f/5.6, f/8.0, f/11, f/16, f/22, f/32.

Comparing the EF 50mm f/1.8 lens to the EF-S 18-55mm f/3.5-5.6 lens, we see that when the 18-55mm zoom lens is zoomed in to the 50mm focal length, it has a maximum aperture of f/5.6. That gathers just one tenth as much light as f/1.8.


Back to your question about a general purpose lens. If you get a recent Canon EOS DSLR, it's probably going to come with the EF-S 18-55mm f/3.5-5.6 IS wide-normal zoom lens in the kit. This focal length covers a great deal of useful photography. You can take a lot of good photographs with the kit lens. If you want to shoot with shallow depth of field or in low light, the EF 50mm f/1.8 lens is a very inexpensive addition to your kit (about $100). If you want to bring far away objects closer, the EF-S 55-250mm f/4-5.6 IS telephoto zoom lens can do that (less than $300). You can of course get larger, longer or more professional lenses that cost thousands of dollars, but these three lenses can cover a very large range of photography.

[saabuldin]

thanks to everyone.

[heyjoe]

Lenses that have a range listed , like an 18-55 f/3.5-5.6 lens are called variable aperture lenses, because the maximum aperture changes automatically when the lens is zoomed from 18 mm to 55 mm. Lenses that have a single number like a 17-55 f/2.8 lens are called constant aperture lenses because if set to f/2.8 at 17 mm and then zoomed towards 55 mm the lens stays at f/2.8.

Variable aperture lenses are less expensive than constant aperture lenses.

Question: On the standard consumer zoom lenses, is the aperture "fixed" to the focal length?

For example, say we have a 70-300 f/3.5-5.6. Wide open the aperture is 3.5. As I "zoom in" on a subject the aperture changes (larger numbers, smaller opening, obviously). Is the aperture on these type of lenses always fixed to the focal length?

[AverageJoe]

Question: On the standard consumer zoom lenses, is the aperture "fixed" to the focal length?

For example, say we have a 70-300 f/3.5-5.6. Wide open the aperture is 3.5. As I "zoom in" on a subject the aperture changes (larger numbers, smaller opening, obviously). Is the aperture on these type of lenses always fixed to the focal length?[/QUOTE]

Yes, if you set your lens to f3.5 at 70mm and start zooming in, you'll notice the aperture values change as you zoom in and once it zooms all the way into 300mm you'll notice you are at f5.6 and you won't be able to open back up to f3.5 unless you zoom all the way out.

This is why the expensive lenses, say the 70-200mm f2.8 has only one aperture value associated with it, it can be opened all the way up to f2.8 throughout the entire zoom range.