Henry Peach

Note:  I reposted this because the previous post had become a spam magnet.  I’m hoping this might throw them off the scent.

In the quick comparisons I’ve been able to do in the past it seemed to me that there was very little difference in image quality between Canon L lenses and Tamron and Sigma lenses with similar specifications, so I’ve usually gone with the Tamron or Sigma lenses at less than 1/2 the price. Recently my Tamron 28-75 f/2.8 wore out, meaning it broke during the course of normal use, not from being dropped or banged around. Having experienced something similar with an f/2.8 zoom from Sigma a few years earlier I decided as a professional wedding and portrait photographer maybe I should invest in some legendary and pricey Canon L glass. So to replace my Tamron 28-75mm f/2.8 I purchased a Canon L 24-70mm f/2.8. Having used it for the last month, while my Tamron was being repaired (under warranty), here are my impressions from owning and using both lenses on a 5D.

First of all the cost difference is huge. The Tamron costs $350 (and currently has a $10 rebate), and the Canon L costs $1190.

The next thing I really notice is that the Canon is almost twice the size and weight of the Tamron, and I thought the Tamron was big when I got it. In my opinion, and I’m a big, strong guy who used to shoot hand held with Hasselblad and Pentax 67II medium format film SLRs, the Canon lens is too big. It’s silly big.

In most shooting conditions I encounter, bright sunlight, outdoor fill flash, indoor flash, studio set-ups, and low light no flash I’ve noticed absolutely no difference in sharpness, color rendition, contrast, etc… Optically they appear the same to me. Both do an excellent job.

One area where the Canon does suffer optically compared to the Tamron is lens flare. This is surprising considering the Canon lens hood is the size of a 10 gallon hat, and the Tamron uses a fairly small petal hood. The Canon flares sooner, and much more significantly.

I also prefer the focal length range of 28-75 over 24-70 (on 35mm format bodies) for weddings, but that’s not really a big deal.

The Canon does seem to be slightly better built lens. It’s got a lot of exposed metal, and seems more durable from outward appearances. It’s also supposedly weather sealed, although this is pretty much meaningless for me as I can’t afford weather sealed, Canon DSLR bodies anyway. I guess I’ll see if I can wear it out as I have the Sigma and Tamron lenses (both were repaired). Hopefully if there are problems they occur within a year, as the Canon warranty is only good for 1 year compared to 3 years for Sigma, and 6 years for Tamron.

My opinion is that overall the Tamron is the better lens especially considering the cost. If the Canon 24-75 f/2.8 had IS (image stabilization) that might be a feature worth an extra $840, but it doesn’t. The Tamron will be my primary normal zoom lens with the Canon as a back-up. Even if the Canon is more durable, I could buy 2 Tamrons and have a chunk of change left over for the price of 1 Canon L. I know the smaller size/weight helps me take better photographs, particularly during 8 hours of wedding day coverage. I also think that the problems I’ve had with both my Sigma and Tamron lenses are somewhat of a fluke as I’ve got other lenses by these manufacturers that have been used hard, and never had a problem. I think it’s much more likely that I’ll break lenses by dropping or bashing them than wearing them out, and I think the Canon lens would be just as susceptible to impact damage.

So to anyone considering Tamron vs Canon don’t believe the L hype, and don’t be afraid to go with the better deal: Tamron.

More pics.

8/1/2008 at The Bottleneck, Lawrence, KS

More pics.

Tiny Tuxedo

8/14/2008 The Jackpot Saloon

Lawrence, KS

More photos from the show here.

Acrobats outside the Lawrence Arts Center

More Busker Fest photos here

Bluegrass jam at Papa Kenos 8/10/2008

More pics from the jam here.

There are basically two kinds of light meters photographers commonly use: incident meters and reflective meters. Incident light meters are hand held devices, and measure the amount of light that falls on the meter sensor. Typically they are used near the subject with the meter sensor pointed at the source of light. Incident meters are very easy to use because they only measure the amount of light, and aren’t affected by subject tonality (lightness or darkness).

The light meters in cameras are reflective meters (which is what the rest of this article will concentrate on). Reflective light meters measure the amount of light reflecting off a subject, and are used by pointing the meter sensor towards the subject. The tonality of the subject influences how much light is reflected (light objects reflect more light than dark objects), so reflective meters are a bit more complicated to use than incident meters, and require the photographer to interpret what the meter is telling them.

Most light meter displays are shown in the viewfinder of the camera, and also possibly on one of the LCD screens on the camera body. These days it usually shows a scale with a center point, and marks running off to either side. One direction is more exposure, and the other is less exposure. The larger of these marks represent one stop each (a stop is a halving or doubling of the amount of light/exposure). The smaller marks in between represent fractions of a stop, and depending on the camera they may be in 1/2 stop or 1/3 stop increments.

With the camera settings adjusted so the light meter is centered on the display scale the exposure will achieve a middle gray tone. If the light meter is pointed at gray wall centering the meter will result in a middle gray tone wall in the photo. If the light meter is pointed at black wall centering the meter will result in a middle gray tone wall in the photo. If the light meter is pointed at white wall centering the meter will result in a middle gray tone wall in the photo. That’s why light meters need to be interpreted; the light meter wants to make the world middle gray, and that may not be what the photographer wants.

When pointed at dark subjects the light meter wants to over-expose, and turn black into gray. The photographer needs to intentionally under-expose from what the light meter says if they want the subject to remain dark. When pointed at light subjects the light meter wants to under-expose, and turn white into gray. The photographer needs to intentionally over-expose from what the light meter says if they want the subject to remain light. Even though the amount of light remains the same, tonal differences in what’s in front of the camera can cause the meter to give different readings. If the photographer wants to accurately record the various tones (and that may not always be the case, but for now we’ll assume it is) the only time the amount of actual exposure needs to change is if the amount of light changes.

Metering Modes: The light meter works as described above in all the different metering modes. The metering mode controls what areas of the scene the meter is checking. Manufacturers like to come up with fancy names for their metering modes, but there are really only a few different options.

Segmented metering: this is the default metering mode for most modern cameras. Canon calls theirs “evaluative mode”; Nikon used to call theirs “matrix metering” (and may still). I’ve also heard it called multi-zone metering, or honeycomb metering. What it means is that the scene is divided up into various sections, and the sections are given different priority in determining correct exposure. For instance a simple segmented metering pattern might be broken up into 5 sections: one in the middle, one at the bottom, one on top, and one to each side. The center is most likely given the most influence in determining the exposure, and the top segment the least influence. This is because people tend to center their subject, and the bright sky is often at the top. If the top was given the same level of influence a bright sky could cause underexposure (the meter would try to make the bright sky gray by reducing exposure).

Partial and spot metering: This means only the center area of the scene is metered. Spot metering means the area is very small for precisely metering small areas of the scene.

Center weighted metering: The whole scene is metered, but the center is given more influence in determining correct exposure. It’s basically segmented metering with only 2 segments: the center, and everything else.

Exposure modes are camera set-ups the manufacturer thinks the photographer will find useful in common shooting situations. Most of the modes offer some sort of automatic or semi-automatic operation. Some are pretty simple and standardized across all the brands such as M, Av, Tv, and P. Newer modes often control more than just exposure, and settings may vary from brand to brand.

Before 1960 there were few cameras with exposure modes. The photographer loaded the camera with film (setting the ISO), and then set the aperture and shutter for the exposure they wanted. By the 1980s auto and semi-auto exposure modes were common.

M or Manual: The photographer sets the aperture and shutter.

Av or Aperture Priority: The photographer sets the aperture, and the camera sets the shutter.

Tv or Shutter Priority: The photographer sets the shutter, and the camera set the aperture.

P or Program: The camera set both the aperture and the shutter.

In the 1990s icon modes were introduced. Icon modes are like Program, the camera sets both the aperture and the shutter, but they allow the photographer some influence in how the camera chooses those settings. Icon modes are symbolized on the camera by small images representing the type of photography they might commonly be used for.

Icon modes have evolved over the years, and now many of them may influence other settings on the camera besides aperture and shutter such as white balance, sharpness, contrast, flash, color, and auto ISO. Read the camera manual or visit the manufacturer’s website so you understand what the camera is doing. Some options, such as raw files, may not be available in the icon modes. Here are some general descriptions.

Portrait: The camera tries to choose a large aperture (small f/#) to get a shallow DOF. Color may be set for nice skin tones. Lower contrast and sharpness.

Landscape: The camera tries to use a small aperture to get a lot of DOF. Greens may be more saturated. Sharpness is increased.

Sports or Action: The camera tries to use a fast shutter speed to freeze action. ISO might be increased. Image stabilization and auto focus settings may be changed.

Night Scene or Slow Sync: The camera combines a slow shutter speed to exposure ambient light in the background and a flash to light foreground subjects.

Shutter, aperture, and ISO control exposure. A slower shutter speed allows light to strike the sensor for longer than a fast shutter speed. A large aperture (small f/#) lets more light in than a small aperture (large f/#). Higher ISOs are more light sensitive and require less light to reach the correct exposure than lower ISOs. Each of the controls can be adjusted to allow more or less exposure.

Correct exposure: Correct exposure is an opinion. Different photographers may envision the same scene differently, and lightness and darkness and tones will all influence the aesthetics of the photograph. It’s up to each photographer to decide what the correct amount of exposure is for the photograph they are creating.

The Bucket Analogy: These days the common mumbo jumbo is that operating a camera in M or manual exposure mode is difficult. Manual exposure requires the adjustment of 3 controls. Most folks complete many much more complicated tasks everyday. If you can fill a bucket of water without making a mess, you can run your camera in manual exposure mode.

Your task is to fill a bucket with water from a faucet. The water represents light. The size of the bucket is like ISO. A slow ISO means a larger bucket and a fast ISO would be a smaller bucket. A large bucket (low ISO) needs more water (light) to fill it. Turning the faucet is like adjusting aperture; it controls the amount of flow. How long the faucet is left on is like the shutter; it controls how long the flow lasts. In this example I’ll say correct exposure is filling the bucket to the rim, although there might be instances in which I’d purposely under fill (under expose) or over fill the bucket (over expose, although the analogy breaks down here as overfilling a bucket isn’t very useful for anything).

The bucket could be filled to the rim by allowing a very fast flow for a short amount of time, or filled by a trickle for a longer amount of time, or something in between. As long as the water is filled to the rim without under or over filling the amount of exposure is the same no matter what the settings.

Stop: Photographers measure light in stops. A stop is a doubling or halving of the amount of light or exposure. Aperture, shutter, and ISO are measured in stops. Here are the 3 controls in 1 stop increments.

aperture: … f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22 …

shutter speed: … 1 sec, 1/2 sec, 1/4, 1/8, 1/15, 1/30, 1/60, 1/125, 1/250, 1/500 …

ISO: … 100, 200, 400, 800, 1600 …

F/2.8 lets in twice as much light as f/4, and half as much light as f/2

1/60th sec is twice the exposure as 1/125th, and half as much as 1/30th.

ISO 400 is twice as sensitive to light as ISO 200, and half as sensitive as ISO 800.

Notice that shutter speed and ISO are easy to figure because doubling or halving the number is 1 stop. Aperture is a little trickier because doubling or halving the number is 2 stops.

Modern cameras often offer adjustment of these controls in 1/2 or 1/3rd stop increments. If it’s 1/2 stop increments there will be one setting between the settings listed above. If the camera uses 1/3rd stop increments there will be two settings between the setting listed above. You don’t have to memorize the entire scale of each setting, just remember that if the camera measure in 1/2 stops then every 2 clicks is a stop, and if it measure in 1/3rd stops then every 3 clicks is a stop. Sometimes even if aperture and shutter controls have 1/2 or 1/3 stop controls, the ISO may only be adjustable in 1 stop increments. Check your camera manual, or do the math (x2 or /2 = 1 stop for ISO and shutter).

I’ll get into how to use a light meter to measure the amount of light later, but for right now assume that you have decided on a correct amount of exposure for the scene to create the photograph you envision. For the sake of example we’re going to say it’s ISO 400 at f/8 at 1/125th. If you decide you want less DOF you might open the aperture 2 stops going from f/8 to f/4. This would decrease the DOF, but also allow in 4 times as much light as we need (a stop is a halving or doubling so 2 stops is 4 times as much or less light, 2×2=4, 3 stops is 8 times, 2×2x2=8, etc…). To get the exposure back to what we want we need to decrease the amount of exposure by either increasing the shutter speed, decreasing the light sensitivity (lower ISO), or a little of both. All of the following combinations are exactly the same amount of exposure.

ISO 400 @ f/8 @ 1/125

ISO 400 @ f/4 @ 1/500

ISO 100 @ f/4 @ 1/125

ISO 200 @ f/4 @ 1/250

ISO 200 @ f/5.6 @ 1/125

and so on…

As you change the exposure with one or two settings, the other setting(s) must be adjusted to compensate to stay at the correct exposure. This relationship is called reciprocity (in particular aperture and shutter, but the way digital functions ISO is effectively the 3rd control).

ISO stands for International Organization of Standards. I don’t know why it’s not IOS, but what it refers to in photography is the level of light sensitivity of the sensor or film. It’s often called “film speed“, even when talking about digital cameras.

A higher ISO number means more light sensitivity; more sensitivity means less light is necessary to get a good exposure. Besides shooting a low light scene, a photographer might need to use a very fast shutter speed to freeze action, or a small aperture (large f/#) to get a very deep DOF. These situations may require getting the exposure with less light.

ISO 100 is typically used for bright, well lit scenes such as outdoors on a sunny day.

ISO 400 would be used in situations with less light, when photographing action, and/or with flash.

ISO 1600 would be used in very dim situations or with extremely fast moving subjects.

Generally higher ISO settings mean the photos will have more noise with digital or more grain with film. Whether noise is going to be an issue depends on how much magnification or enlargement the finished photograph requires. Noise won’t show as much in small prints or web friendly sized photos. On the other hand it becomes much more evident in large prints.

Currently available DSLRs have extremely low noise if the exposure is good. The difference between ISO 100 and ISO 400 is barely noticeable if at all, and even at ISO 1600 the noise is comparable to the grain of ISO 400 film. Underexposure is usually the culprit for excessive digital photo noise.

It also depends on the photographer’s opinion and vision of the finished photograph. For instance I think coarse noise/grain often works well with the subject of live music. Noise/grain is sometimes assumed to always be undesirable, but as my Photo 101 professor said “Grain is not evil. It’s just grain” (at least it was something like that). It is true that people do like sharp, smooth grained or noise free photos, but there are plenty of examples of great photos that have extremely coarse noise/grain. I think the detrimental effects of grain and noise on photographs are often over-emphasized in discussions among photographers. The rest of the world is mostly concerned with content.

Here’s a photo taken at ISO 100 or 200

Here’s one taken at ISO 3200 (no noise reduction used)

At these sizes it’s pretty hard to see the difference, but they would be obvious in an 8″x12″ print.

There are ways to decrease noise and grain. Film photographers can choose tabular grain films and fine grain developers. Digital photographers can use noise reduction software. With both there are exposure and processing techniques that can be used by the photographer to decrease or increase grain/noise.