Choosing a lens

[JonZenor]

Hey guys, I'm brand new to the SLR world (got my first camera last week!) and I have a couple of questions on choosing a lens.

Question 1 I know that I an buy any Canon EF or EF-S lens (I have a Canon Rebel T1i), but what do I look for if I am looking for non-Canon lenses?

Question 2 What is the difference between my kit 18mm-55mm lens and a "wide angle" 18mm-55mm lens? (i.e. Sigma 18-50mm wide angle) Will both lenses not show the same thing?

Question 3 Is there a difference in choosing a lens that accepts 58mm filters vs 52mm filters? Obviously having the same size is better so I don't have to buy multiple sizes of filters or get a size adapter, but beyond that, is there a difference in what the lens sees?

For now those are the only questions I have.

[alarmc]

Jon-- I have the same questions for the same camera. I've had my T1i for about 5 weeks. I would also like to know what filters do I need right now, and what kind of tripod for between $35-80 would get me started?

[OsmosisStudios]

1: Depends on the brand. Sigma, Tamron, and Tokina each have their own wording for their terminology.

2: Your kit 18-55 and the Sigma 18-50 you list are essentially the same. Strictly speaking, 18mm is wide, so they can call it that. I would sincerely avoid buying from that company though (47th street photo): they're terrible.

3: There is no real difference between a 52 or 58mm filter diameter. The diameter of the lens is usually a factor of the aperture: since aperture is a factor of the focal length, the diameter has to be at least big enough for the aperture.

If you have a 100mm f/2 lens, it means that the maximum opening of the aperture is 50mm across. So you'd need at least a 50mm diameter. If you have a 200mm f/2, then the max aperture measures 100mm across, so the lens has to be considerably larger.

[JonZenor]

Thank you very much for taking time to answer Osmosis.

Originally Posted by OsmosisStudios

1: Depends on the brand. Sigma, Tamron, and Tokina each have their own wording for their terminology.

Okay, so I just need to research each company's lens before buying to ensure compatibility.

Originally Posted by OsmosisStudios

2: Your kit 18-55 and the Sigma 18-50 you list are essentially the same. Strictly speaking, 18mm is wide, so they can call it that. I would sincerely avoid buying from that company though (47th street photo): they're terrible.

Dang, that sucks. I was hoping that because it was wide angle that the lens would end up seeing more, but as I was researching my dSLR (and reading dSLR & Photography for Dummies) I realized that my thinking was wrong. What really sucks about it, I have this lens on my wish list and I think someone got it for me for Christmas... Now to go find an affordable wider angle lens :P

Originally Posted by OsmosisStudios

3: There is no real difference between a 52 or 58mm filter diameter. The diameter of the lens is usually a factor of the aperture: since aperture is a factor of the focal length, the diameter has to be at least big enough for the aperture.

If you have a 100mm f/2 lens, it means that the maximum opening of the aperture is 50mm across. So you'd need at least a 50mm diameter. If you have a 200mm f/2, then the max aperture measures 100mm across, so the lens has to be considerably larger.

I didn't think filter size made a difference, but thanks for the technical explanation, I actually understand all of that a little better now.

Originally Posted by AlarmMC

Jon-- I have the same questions for the same camera. I've had my T1i for about 5 weeks. I would also like to know what filters do I need right now, and what kind of tripod for between $35-80 would get me started?

I bought some basic filters at Best Buy for $20 to work for now. I found some good filters and tripods on Amazon.com that I added to my wish list. Search there and make sure to read customer reviews, they tend to point out good and bad products.

[OsmosisStudios]

Adding "wide-angle" to the description does nothing. The important part is the numbers

AF-S 18-55 f/3.5-5.6 VR (your kit lens)
AF 18-50 f/3.5-5.6 DC (the Sigma)

The focal length and apertures are the same, therefore the lens will give you the same field of view.

If you want wider, look for the SIgma 10-20 or the Nikon 10-24

[JonZenor]

Originally Posted by OsmosisStudios

Adding "wide-angle" to the description does nothing. The important part is the numbers

AF-S 18-55 f/3.5-5.6 VR (your kit lens)
AF 18-50 f/3.5-5.6 DC (the Sigma)

The focal length and apertures are the same, therefore the lens will give you the same field of view.

If you want wider, look for the SIgma 10-20 or the Nikon 10-24

Will a Nikon lens work on my Canon?

[OsmosisStudios]

Out of the box? no. With an adaptor or modifications? yeah. But it'll be limited.

If you've got Canon, buy Canon (or Canon Mount). Because the EOS mount has the shortest flange/sensor ratio, you can get adapters for many other mounts (including Nikon). There are some people using Nikon 14-24 f/2.8 lenses on their 1Ds MkIII, but they lose AF, EXIF, etc.

[inkista]

Os has answered most everything, but just a few notes.

Originally Posted by JonZenor

Question 1 I know that I an buy any Canon EF or EF-S lens (I have a Canon Rebel T1i), but what do I look for if I am looking for non-Canon lenses?

The risk you take with a third party lens is often about future compatibility. Canon will make sure that all of its lenses will work when they change the electronic communication signals in the camera mount to account for a new feature, but they're under no obligation to make sure that 3rd party lenses work as well. All the 3rd party manufacturers are reverse-engineering. If you're buying an older used Sigma/Tamron/Tokina/Vivitar, etc., you want to make sure that it works on the current mount. Some of the older Sigmas need to be rechipped to autofocus correctly.

Question 2 What is the difference between my kit 18mm-55mm lens and a "wide angle" 18mm-55mm lens?

I highly recommend reading this lens primer before you go lens shopping. It'll tell you about the major features of lenses, such as focal length, maximum aperture, and stabilization, and what they mean in terms of practical application. DO NOT ignore the importance of the max. aperture f-numbers. Most beginners look only at the focal length, without realizing the huge usability difference between an f/4 and an f/2.8 lens. While in this case, there isn't much difference between your kit and the Sigma, the same cannot be said of the difference between the kit and the EF-S 17-55.

Other things you may want to look for are silent focus motors, build quality, handling, and whether the lens focuses/zooms internally. But these are more minor considerations. The other thing you'll want to do is read a variety of reviews on a lens, simply because of copy variance, and because different photographers look at different things. The fredmiranda.com site has a place where people can submit lens reviews, and it can be very valuable to read 20 conflicting reviews on the same lens, if possibly a bit confusing.

Question 3 Is there a difference in choosing a lens that accepts 58mm filters vs 52mm filters? Obviously having the same size is better so I don't have to buy multiple sizes of filters or get a size adapter, but beyond that, is there a difference in what the lens sees?

Not really. The filter size doesn't necessarily directly relate to optical qualities of the lens, although there can be a rough equivalency to max. aperture. But I have a 50mm f/1.8 lens that takes a 52mm filter, and a 50mm f/1.2 lens (bigger max. aperture) that takes a 49mm filter. So, filter size isn't a good guide to anything but filter size.

Originally Posted by alarmc

I would also like to know what filters do I need right now, and what kind of tripod for between $35-80 would get me started?

A tripod between $35-80 probably won't be good for much, tripod-wise. With tripods, you can have two of any of the following three things: low cost, low weight, stability. The thing is that the main feature you want in a tripod is stability. Motion blur is why you got a tripod in the first place. In the price range you're looking at, almost anything you look at isn't going to be that stable, especially for a heavy lens/body combination, so it won't be great for long-exposure photography. However, there are some great options if you just want something to hold the camera in place for faster exposures. A gorillapod is one commonly suggested travel tripod. And lighter-weight tippier tripods can be useful. However, the majority of tripods you're going to be seeing are going to have an integrated head, which means you can't swap out or use alternative heads, and if the head breaks, you'll have to replace the entire tripod.

Filters, I'd say get as you need them, rather than looking for a need. You'll accumulate a fair number of them over time. The two most commonly used filters are UV for physical protection of the front element more than for photographic reasons (some folks use 'em, some folks don't), and a circular polarizer for reducing reflected light/darkening skies. In this age of digital, most color filters are unnecessary because of post-processing.

[JonZenor]

Thank you for the detailed answers.

Yeah I know now to lok for lenses with better aperature settings, and I know the book answer as to why but I haven't seen a difference in my camera yet. I'm going to go out next chance I get (which will not be for a while it looks like ) just to play with ISO, aperature, and shutter speed and see how they effect the outcome of the picture. That should be a fun task.

About tripods, I bought a $99 Manfrotto tripod from Best Buy, but am about to go return it and upgrade to the $200 tripod. I like the lighter weight better and the ball head mount. I didn't think I would mind the 3 different screws, one for adjusting each angle, but once I took it out in the field and tried to use it... yeah, that was a pain to quickly adjust. If I'm going to spend that much on a tripod I had better get one I will be happy with.

[inkista]

Originally Posted by JonZenor

Yeah I know now to lok for lenses with better aperature settings, and I know the book answer as to why but I haven't seen a difference in my camera yet. I'm going to go out next chance I get (which will not be for a while it looks like ) just to play with ISO, aperature, and shutter speed and see how they effect the outcome of the picture. That should be a fun task.

It is fun. The only thing here is that if you're using the 18-55 kit lens, you really don't have a heckuva lot of aperture to play with. One of the most-recommended "training wheel" lenses for a new Canon dSLR shooter is the EF 50mm f/1.8 II. It's about $100, which makes it dirt cheap as lenses go.

Compared to the 18-55 kit lens used @55mm, the max aperture of the 50 is f/1.8 vs. f/5.6. f/2 is three stops faster than f/5.6. Which means 2³, or eight times the amount of light. That's the difference, exposure-wise, between iso 100 or iso 800, or 1/30s vs. 1/250s. And if you use both lenses at f/5.6, the 50 will be sharper and exhibit less CA.

The drawbacks to the thrifty fifty are that it's got a plastic mount, the manual focus ring is a PITA to use, there's no focus scale, it's only got five aperture blades (so out-of-focus highlights can display as pentagons), and it's not USM, but its virtues of wide max. aperture, low cost, and good optic quality usually outweigh those issues for most people.