BetterPhoto Q&A
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getting top quality from lenses

Canon EOS Rebel 2000 body
Canon EF 28-80mm f/3.5-5.6 II zoom lens
Canon EF 75-300mm f/4.5-5.6 III zoom lens
Canon EF 100mm f/2.8 macro (non-USM used via eBay)

I have a serious interest in landscape, night/low-light photography, macro & still-life, and stock photography. This is where my main concern is. If I want to get into stock photography and (hopefully) make some money, I understand that the final quality must be "razor sharp". In reading various newsgroups I've learned that the two critical factors (as far as equipment) in getting top quality results is the film and lenses. That's why I bought the 100mm macro, for example. 90% of my shots are from a tri-pod and I have just started using slide film. I consider the Rebel 2000 body as just a light-tight box. It has many features that allow me to grow and and experiment and does just fine for now, though I do plan to buy a second body by the end of the year and will probably buy something a little more solid and durable.

Lenses:
I've read disparaging remarks about zooms and my 75-300mm has been mentioned specifically. Part of me wonders how much of this is "photo snobbery", and how much is real. I think to my experience in high-end stereo equipment and all the garbage about how you just have to have that certain vaccum tube CD player or the vaccum tube dual mono power amplifiers if you want to hear the music just so. I'm sure the same happens in every field, even photography. Any endeavor can be taken to the nth degree of absurdity. Having said that, can I get the quality I need out of my two zooms? When I say "need" I realize that my own judgement won't be enough, but also the judgement of potential clients, photo libraries, etc. I am definitely open to buying Canon's 100-300mm f/5.6L zoom, as it seems to be very reasonably priced and well-regarded. I could then sell my 75-300 on eBay and get some of my money back. Did someone mention that this lens is being phased out, meaning that I should get one soon?

Now for the 28-80mm zoom. I've gotten some VERY nice photos from this, though 8x10 seems to be about the limit. I was using cheap Fuji Super HQ 100 which probably explains alot. In this range I would be willing to go with primes instead of a zoom, although I'd probably keep my 28-80mm as I like its light-weightness and ease of use for non-critical work, generic snapshots, etc. I want to get Canon's 50mm f/1.4 prime lens. I've also thought about the 24mm f/2.8 and 85mm f/1.8 USM. I've heard conflicting comments about their two 28mm primes. I'm also intrigued by the 20-35mm f/3.5-4.5 USM zoom.

As you've no doubt noticed I am at the lower half of the price scale. I simply cannot afford the higher priced stuff, at least not right now. I do need to get the most bang for my buck while still getting the results I desire. That's part of why the 100-300mm f/5.6L is so appealing. Most of these will be bought over the next year or so, though I'll probably buy the 100-300mm and the 50mm within the next two months. I have always been the type to buy beyond what my immediate needs are, knowing that I will grow and not have to spend more money to upgrade later. I just hope that last sentence doesn't conflict with my budget.

USM versus non-USM. Is there any real difference other than the motor?

I am not a Canon groupie, but that is what I have started with and compatability is important to me. I am open to third party equipment, but am not familiar with their specs, etc. I understand Tamron is good. Sigma can be, but campatability may be a problem in the future, so I'd rather stay away.

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October 21, 2001

The other type is ring-USM. In these lenses the USM motor moves the focus elements directly. These lenses have full-time manual focus, so you can override the autofocus without using the MF/AF switch. This is not necessarily useful with the Rebel 2000, as the camera will try to autofocus everytime you press the shutter button. On the Elan II/7 and higher model EOS cameras, a custom function setting can move autofocus-start from the shutter button to a thumb button. Thus you can manually focus and hit the shutter button without activating autofocus again, and autofocus is still instantly available from the thumb button.

Ring-USM lenses are in Canon's middle and upper lens lines. Along with USM these lenses also have more durable construction with metal lens mounts, a focus distance scale, and non-rotating front elements.

I agree with you thinking on the other lens choices. In my opinion, the EF 75-300 f/4-5.6 is no better or worse than Tamron's 70-300 LD and Sigma's 70-300 APO. All three of these lenses are very good from 70 to about 200, but sharpness and contrast fall off noticably out to 300. They're acceptible for 4x6 prints, but for not real critical work or enlargements.

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October 22, 2001

I'm probably one of those that you might call "Photo Snubbery" but I do demand the highest possible quality from my camera, film and processor. My photographer friends and I can see graininess and unsharpness where other people can't. In reality, it doesn't change their appreciation of the photo, but it bugs me that it wasn't the "best".

Let me start off by giving you the statistics from the canon EF lenswork book.

Lenses are rated using a phrase called "Modular Transfer Function" or MTF. A lens with a rating of 1 means that light is perfectly transmitted with no loss of contrast. The only such lens I know of is vacuum. Even air will lower this rating (But not by much)

At f/8.0 your 24-80 has a MTF of 0.95 and 0.88 at the 24 and 80mm end respectively. This is very impressive for a lens. However, at the 80mm end, the edge of the photograph falls to about 0.75 This is still very good.

At maximum aperture, your lens has a rating of 0.80 at 24 and 0.80 at 80mm. Towards the edge of the photo though, it falls to about 0.50 This is considered as "unacceptable" quality (Most people should notice unsharpness)

To speed things up, I'm only going to give the stats at the middle of the lens.

75mm - f/8 = 0.92 Max = 0.75
300mm - f/8 = 0.82 Max = 0.75

At 300m, you're pushing the edge of "professional" into "good" Both of them held at max aperture are still good, but some softness will be noticed by professionals. Once enlarged, softness will probably be noticed by anyone.

100mm 2.8 f/8 = 0.92 Max = 0.85

As you can see non-professional primes tend to perform better than non-profesisonal zooms.

To give you an idea the 70-200L f/2.8 (professional) series lens at f/8 is 0.99 at both 70 and 200mm. At max aperture though, they are not much better than standard zooms, coming in at 0.85 and 0.90 respectively.

What does this teach us? In every case, f/8 is the clearest aperture setting. Why? Because there are two opposing needs for sharpness. By stopping down the aperture, light is coming more directly from the source and so sharpness is improved. (I wish I could draw a diagram to explain this, but I don't have the time)

ON the other hand, shine a light through your thumb and forefinger onto the ground. Move your fingers closer together until the SHADOW looks like it's touching. Is your fingers touching? Chances are no. Light bends when the space for it to go through gets smaller. So as your aperture gets smaller, the sharpness decreases because of this light bending.

It just so happens that the sharpest point is about f/8 (some people also say 2 stops above max aperture). So, if light is no problem, shoot at f/8 unless you are going for low DOF blur.

Other things to keep in mind:

Are your lens elements clean?
Are you using good quality clean filters?
Are you using filters you don't need?

Finally, is your processor using good lenses during the printing process? If not, then the top quality photos you're taking are being ruined by him.

Also, I recommend that you try something like Reala, as the grain on that is incredibly fine.

Good luck! I know the need for perfection - you don't necessarily need to spend up big, but you do need to understand how to get the most out of what you have.

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October 27, 2001