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Photography Question 
Tobie A. Abbajay
 

Which lens??


I am currently shooting a Nikon D80 with either the Nikkor 50 1.8 or 18-135 lenses. I'm doing mostly portrait work with children.

I want to upgrade, but not quite sure which direction to go.

1. 70-200 2.8 VR
2. 18-200 3.5-5.6 VR AND 105 2/micro (I would sell my 18-135, but keep the 50 prime)
3. Possibly even stretch the budget a tiny bit further and get the D300 with 18-200 VR sell the 18-135 keep the 50 prime).

I'm sure there are some other options out there, but this has my head hurting as it is. I'm also aware that Sigma and Tamron make good 70-200 2.8 glass for much less $$$, but not sure if they have VR equivalent.

Anyone want to give me their valued opinion it would be greatly appreciated.


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5/23/2008 10:02:53 AM

 
Alan N. Marcus   Hi Toeib,

Photography combines both art and science. When it comes to which lens to use, often you can throw away the book. However, science has an opinion.
What lens to use? What focal length for portraiture?

Conventional wisdom advises you to lengthen the camera-to-subject distance. This act solves the problem I will describe below but likely you like the rest of us have a compelling tendency to compose tight in our viewfinder. Often this behavior will result is an exaggerated prospective. Allow me to explain.

Things close to the camera are reproduce larger than life and things distant are reproduced smaller than we might expect. This is likely very important when we photograph the human face, When working in too close the lens likely will microscopically enlarge the nose and reproduce the ears too small. The results are likely a slight distortion of the human face. The will be inconsequential to you but the subject and/or mom and dad often say the camera lies or he/she doesn’t photograph well.

The counter measure is simple, just back up. This act simply solves the distortion but because we do like to compose in the viewfinder, we can’t do this easily if we are working with a “normal” lens. What is “normal” Your camera sports a sensor chip that measures 15.8mm by 23.6mm. A “normal” lens for this format is one with a focal length about the same length as the diagonal measure of the rectangular shaped sensor chip inside the camera. This works out to 28mm. What I am saying is, setting your current zoom lens to about 28mm replicates a normal view. For portraiture we want to use a longer than normal lens. The rule of thumb is one that is about 2.5 times longer than normal or in this case 28mm times 2.5 = 70mm. This forces us to step back solving the prospective error. Also you need to know that a lens that is a little longer won’t do harm, and maybe some good.

I am thus advising you to set you zoom at or about 70mm to achieve the ideal portrait prospective. Also, you should know that Hollywood, takes this one step further, they would use about 3 times normal for close-up work. That equates to about 85mm focal length. Also, these values are not etched in stone. All I am trying to say is your current 18mm ~ 135mm zoom encompasses all you could ever need to pull off this type of work. Stated another way, don’t expect miracles if you fork out big bucks for another lens.

Another look from a different slant. Your camera has a smaller imaging chip than the standard format which is the full frame 35mm film format 24mm by 36mm. Your camera is 65% of that size. Stated another way you camera’s crop factor is 1.5. The venerable old portrait lens focal length for the 35mm is 105mm. So to make a comparison we take your ideal portrait focal length and multiply by 1.5 thus 70mm times 1.5 = 105mm. Stated another way, your zoom set to 70mm delivers the same prospective as a 105mm on a 35mm format.

OK to disregard everything I have written above and listen to other wiser chaps. After all, I am known to dispense only marginal technical nonsense anyway.

Alan Marcus
Ammarcus@earthlink.net


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5/23/2008 3:00:21 PM

 
Tobie A. Abbajay   Thank you for taking the time to respond. Ultimately I already understood the information you stated.

I think the 18-135 lens is ok. It's not the sharpest lens out there nor is it the fastest. I do really love the color saturation and sharpness of my 50mm 1.8, but it's just too in the face for kids for a tight crop.

When shooting children in natural light mostly outdoors they are constantly in motion and hardly stay at the same spot for more than a few seconds at a time. I also have a studio set up with limited space for depth.

I am looking for something to grow with, not expecting miracles if ya kwim.


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5/23/2008 3:14:51 PM

 
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