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02-01-2008, 01:37 AM   #1
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difference between macro and zoom

i am told that you use macro lense for a really close shot of a bug or insect or flower or something...

but isnt that zooming in ???

so can someone explain to the super noob just what the difference is please

02-01-2008, 02:06 AM   #2
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A zoom lens allows you to use multiple focal lengths with one lens. For example 16-45mm. A true macro lens will allow you 1:1 magnification. 1:1 means that if you are taking a picture of something the same size as the sensor then it will fill the frame. This is achieved by allowing a smaller minimum focusing distance.
02-01-2008, 02:39 AM   #3
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best thing to do is to check how close you can focus on a subject with your existing non-macro lenses. Most likely if you're using, say, a 50mm non-macro lens, you'll need to be at least half a meter away from your subject for it to be in focus. It simply can't focus on anything closer.

You might be able to get closer with a wide angle lens (say to within 20cm when you're using a 28mm lens) but on the other hand, you'll need to be even further away with a longer lens.

For example, I need about 1.2meters before anything will be in focus with my 135mm lens.

The dedicated macro lens will let you get really close to your subject.

I'm sure there's been a thread on this forum in the past comparing 50mm MACRO to a 100mm MACRO lenses - can anyone help? Also worth investigating how these babies compare to 'macro' zoom lenses.....
02-01-2008, 02:59 AM   #4
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Macro photography by definition means photography where the subject is reproduced on the film or sensor at ratios between 1:1 (life size) and 10:1.
Greater magnifications are referred to as micro photography.

A zoom lens is on where the focal length can be varied and the subject remains in focus.

One is not related to the other, some zooms do offer macro capabilities.

02-01-2008, 04:52 AM   #5
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Even if a zoom can offer 1:2 magnification , a true macro lens will offer much better quality at the same magnification rate
02-01-2008, 05:47 AM   #6
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let's all be clear on the difference.

as some have stated, "zoom" means changing the focal length of the lens, and while image size changes, and as you zoom in things get bigger, this is not macro photography.

again as some have stated, macro photography is in principle dealing with images that are magnified, i.e. bigger on the sensor than they are in real life. True macro photography is with image sizes between 1:1 (life size on the sensor) to 10:1 (10 times life size on the sensor), beyond 10:1 is Micro photography.

Now lets look at how you get life size and beyond:

any lens can produce life size images. Life size occurrs when the distance between the object and lens is equal to the distance between the lens and image sensor or film

How do you get to 1:1? you need two things, first, you need to get close to the image, and second you need to be able to move the lens further from the sensor.

There are 2 ways to do this, 1 is with lens extension, either with extension tubes or a macro lens that permits a long extension, described below:

You will notice true macro lenses extend a long way out, compared to a normal lens. for example, my 50mm lens when focused to the closest distance extends out 7mm. a 50mm macro lens may extend 25 or 50mm. at 50mm extension a 50mm lens will focus on an object 100mm away and the magnification ratio will be 1:1

Many "macro zooms" have the ability to close focus, but this is usually limited to the minimum focal length, and ratios of 1:3 or 1:4 because it is what is within the practical limit of the lens body.

the second way is to put close up lenses in front of your lens, in order to shorten the focusing distance. Close up lenses are measured in dipoters, where 1/diopter = focal length in meters.

By placing a 1 dipoter close up lens, what you actually do is to modify the focal length of your lens, (making it shorter) and also limiting the maximum focusing distance, to 1 meter. by permitting closer focusing you get bigger images because the ratio of distance between lens and sensor divided by the distance between lens and object is increasing.
02-01-2008, 06:07 AM   #7
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So Lowell, if I understood you: If you have 50mm lense and you are able to focus on a distance of 50mm to a subject, you will get a 1:1 macro? If you have a 135mm lense and you are focusing at at 135mm from the subject, you also get a 1:1 macro?
02-01-2008, 06:19 AM   #8
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QuoteOriginally posted by pentagor Quote
So Lowell, if I understood you: If you have 50mm lense and you are able to focus on a distance of 50mm to a subject, you will get a 1:1 macro? If you have a 135mm lense and you are focusing at at 135mm from the subject, you also get a 1:1 macro?
no, not quite, a 50mm lens at infinity is 50mm from the film/sensor add an additional 50mm extension, and you focus at 100mm away, this gives you 1:1 and a working distance of 100mm from the subject.

1:1 occurres at a distance of 2x the focal length.

02-01-2008, 06:29 AM   #9
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I really am a noob....
I need some serious reading to do on this subject. I still don't understand that. Some sketches out there?
02-01-2008, 06:36 AM   #10
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Think of it this way with extension tubes or a bellows. If the lens is fixed at 50mm and you add 50mm of extension, you get 1:1 macros. If the lens is 100mm then add 100mm of extension to get 1:1 macros and so on. Just match the extension to the lens length to get the 1:1. With a bellows you can get greater than 1:1 with a 50mm since the bellows can go from about 20mm to as much as 290mm. You can also stack extension tubes as well to get better than 1:1.

The main disadvantage with extension or bellows units is, that you loose light as you extend the lens further out. But with a fast lens that is not a huge issue.

Last edited by Peter Zack; 02-01-2008 at 07:06 AM.
02-01-2008, 06:38 AM   #11
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So OK, I can add a 50mm to my 50mm lense and I will get 1:1. But at which focusing distance? 100mm?
02-01-2008, 06:39 AM   #12
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You might find this helpful as well. It's a thread I started a few months ago in an attempt to answer a few similar questions.

https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/11161-answer-macro-question.html
02-01-2008, 06:45 AM   #13
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Thanks everyone. Now I think I'm getting somewhere.
02-02-2008, 07:16 PM   #14
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Many many thanks.

I am off doing more and more every day and loving it - very tempted by the idea of getting a new lense but think its important to get the hang of what this one can and cant do properly - this has been a matter of great intrest to me since getting the camera and i really appreciate the advice

thankyou once again
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