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Who invented the camera lens?

Help a guy pick a camera lens?

  • I'm in the market for a new camera lens. I'm attempting to do my "due diligence" - if I'm going to pony up and drop $500 - $600 on a lens, I want to make sure it's right - but a lot of this information doesn't make sense to me. Step inside, would you? I have a Canon EOS Rebel XTi that I bought a couple of years ago as a gift to myself before I went on a trip abroad. I love it. It's a great camera, and I feel guilty because I'm sure I use a very small percentage of the camera's great features.. but.. um, be that as it may, I'd like to use it a bit more and I think this involves buying a new lens. I only have a single lens right now. My goal, when I purchased it, was to get a decent "jack of all trades" lens... something engineering for no particular use that would take good "point and shoot" photos. To that end, I bought a Canon EF 28 - 105mm 1:3.5 - 4.5 lens. I've been very happy with it. However, recently I've been getting into model making, and part of what I want to do is exhaustively photograph said models. My camera and my "stock" lens do great for some of this stuff, but what I really want is the ability to take some really nice macro shots of some of the really fine detail. So, I've done some research, and the "INTERNET" seems to think that http://www.usa.canon.com/consumer/controller?act=ModelInfoAct&fcategoryid=155&modelid=7400 is a great macro lens for the Canon XTi. For those opposed to link clicking, it's a EF 100mm f/2.8 Macro lens. Now, I would just blindly click "BUY" but I don't want to be that guy. I want to try to understand what I'm getting at here, because some things don't add up. My basic, brutish knowledge seems to break down like this - it seems like lenses have two basic features.. maximum aperture and focal length. Ok, so, the textbook definition of focal length (which you already know) is "focal length is measured in millimeters (mm) and it represents the distance from the optical center of a lens to the digital camera sensor when the subject of the photo is in focus." So, if I want to be taking close up macro shots of my models, it would seem that I would want a low focal length. That's one of the main problems with the lens I have now - whenever I get close enough to pick up the detail I want to capture in one of my shots, I can't focus it. Yet, from everything I've read, 28mm is a pretty low focal length, right on the edge of a wide-angle lens, so I'm wondering why that gives me so much trouble. This is even more confusing because the macro lens I link above is a fixed 100mm focal length, which seems *worse* than the lens I have now. The other issue is also aperture... aperture is how wide the lens can open up to let light in. So, the lens I have now is a f/3.5 - 4.5. I would assume that for macro shots maybe I would want a little bit of a lower aperture? I notice the macro lens I link up there is a f/2.8, for example. But, of course, what I find most confusing is that none of this seems to define what a macro lens is - it seems that a macro lens is a "a lens that can achieve a magnification of 1:1. That is, an object is the same size on the sense as it actually is. That is, an 18mm long bug will take up 18mm of the sensor or film frame. It generally does this by being able to focus quite closely." Ok, great, but where is this defined by the technical specifications of the lens? Do you just look for a lens that had the word "macro" in it or can its magnification be derived from the other technical stats? And now I have a headache. So, to summarize... I have a Canon XTi. I want to be able to take beautiful macro photographs of fine detail on my model, and I want to purchase a macro lens that will help me achieve this. Except I'm stupid and I don't understand.

  • Answer:

    I think you're confusing focal length with minimum focus distance. Minimum focus distance is, of course, how close you can get to the subject and still focus on it. This is where you're running into a problem with your current lens, because when you get close enough to get the framing you want, you can't focus there. The 100mm macro lens you're looking at has a minimum focus distance of about 1 foot, which you can find out by looking at the detailed specs on various web sites. And that is, I think, measured from where the sensor in the camera is, not the front of the lens. I have this lens and would say you can get pretty damn close to things and still focus on them. The 100mm focal length describes, basically, the "amount of zoom". With your current lens, when it's at its widest zoom, the focal length is 28mm, and zoomed in as tight as it will go, the focal length is 105mm. So a 100mm macro will give you about the same framing as your current lens does when zoomed all the way in. You'll just be able to focus a lot closer because of the shorter minimum focus distance. You are likely going to want a lot smaller aperture than f/2.8 (higher numerically) because when you focus this close, the depth of field is very shallow. In other words, only things in a very narrow range of distances will be in focus, and everything else will be blurred. You have to bring the aperture way down to get acceptable depth of field for a lot of macro photography. Like F/11 or F/16 is not at all unusual. A lot of lenses say "macro" on them when they have some kind of ability to focus at a short distance. These are often not true macro lenses. The definition you read is the right one -- it's a real macro lens when it can produce an image on the sensor that's at least as big as the subject. That's described in the specs as a 1:1 magnification. That's as big as many macro lenses go, but there's at least one out there that goes up to 5:1 (fills the picture with a grain of rice!) In a nutshell, a 100mm macro will let you take a picture of something about the size of a coin and fill the whole picture with it. It'll be able to focus close enough to actually do that. It will be difficult to get much of the picture in focus unless you use a very small aperture, but you can do that with the lens you're considering. Holding the camera very steady and lighting the scene are additional challenges when photographing very small things.

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Ok. I am convinced. I will buy said lens. Thank you guys. Now, two other issues.. 1. A ring flash, eh? Any suggestions? 2. I also get the sense that for this kind of photography a tripod and remote trigger of some kind are almost a necessity - there's not going to be any "holding the camera very carefully and pushing the trigger". Any suggestions? Things to look out for?

kbanas

I have used the 100mm 2.8 macro lens extensively, both in the field and the studio, and it's an extremely fine piece of glass. Regarding the ring flash - it's great for filling in shadows in your model, but it will give you a very particular kind of light. You could also use regular speedlites, like the 430EX to give you a bit more shape in your light. Also, check out http://strobist.blogspot.com/2006/07/how-to-diy-10-macro-photo-studio.html from Strobist. If you want to get a bit more flexibility with your light, the Canon MT-24EX twin light system is extremely good, but a bit more expensive.

Magnakai

You could get away with a desktop tripod like the http://joby.com/gorillapod/slr or a http://www.thepod.ca/ if you're taking pictures of models. Do you have a http://www.thinkgeek.com/electronics/a205/? If you aren't ready to invest in a ring flash quite yet, you can get good results out of that kind of setup. You could even build one with a boxcutter, a roll of rice paper, and a 16 inch cardboard cube.

Sallyfur

I own the EF 100 2.8 and I freaking love it. I love it so much that I am seriously considering ponying up the full price for the tripod mount ring. You will also love it, and if you don't, the resale on Craigslist and ebay is currently only about $75-100 below the best prices for new ones online.

MrZero

A ring flash, eh? Any suggestions? I've been pretty happy with the Canon one, the MR-14ex. It attaches directly to the end of any of the Canon macro lenses, which is nice. It's a bit pricey though. You can light scenes in many other ways for macro photography, just remember that at small sizes and up close, the camera itself casts an enormous shadow. So forget about any on-camera flash or any light from behind you. A ring flash surrounds the lens, so you get no shadows at all. It's designed for use at close range, where a regular flash may have trouble lowering the power enough to avoid over-exposure. And the Canon one, at least, gives you independent control over the two halves of the ring, so you can get some shadows with it if you want. there's not going to be any "holding the camera very carefully and pushing the trigger" Sometimes you can get away with hand-holding the camera, especially with digital where you can take a ton of shots and keep the best ones. The issue with macro photography isn't just motion blur from a long exposure, which a flash will indeed help with. The problem is mainly that depth of field is so thin that your carefully-focused shot will be thrown out of focus by moving the camera a few millimeters, and a flash won't help with that. Only a tripod will hold it steady enough to keep things in focus reliably. In fact the easiest way to focus at high magnification is to focus the lens for the magnification you want and then move the camera back and forth to focus. You can get macro focusing rails that allow you to do this easily with the camera on a tripod. For getting started, you'll be OK with a regular tripod as long as it lets you get close enough to your subject. You'll probably be OK without a ring flash as well if you get creative with your lighting, but that's harder, so if you really get into it, a ring flash should be your next purchase after the lens itself.

FishBike

Self-timer works well and many cameras are controllable via a cable connected computer which can make the process go that much faster.

mmascolino

Imagine you've got the camera mounted landscape on a tripod, the image is framed just how you want, lighting just so, and now you want to get a couple shots portait. You rotate the camera on the tripod, and now the lens is four inches away from where it was; your framing changes, lighting changes, etc. The "Tripod mount ring" lets you connect the tripod not to the bottom of the camera, where changing orientation changes the entire setup of the shot, but basically to the lens, so you could just rotate the camera to portrait without changing where it's pointing or your lighting setup, etc. You're basically rotating the camera about the centerline of the lens. Remote trigger is nice, but not essential. Self timer works fine. If you're using a flash even that isn't required. What you want to do is avoid the potential motion of the camera when you press the button. Flash freezes motion anyway so it's not a concern in that case, generally.

chazlarson

Yeah, the timer function works great in lieu of a remote switch. I can't speak to the Rebel specifically, but my 30D has a function in the settings where I can change the timer from 10 seconds to 2 seconds. It makes this kind of shooting much easier. All you need to do is get your hand off the body for long enough to keep the shake to a minimum.

quin

First, the 100f/2.8 is really awesome for macro. If you get it, and don't like it, get your head examined. If you want to focus *closer*, you can get an extension tube and focus just about inside the lens. Second, the tripod ring mount is so the tripod is mounted to the lens, not the camera. Better balance that way; also, you can loosen the ring and change from portrait to landscape really easy.

notsnot

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