Reproduction ratio vs zoom lenses

Augie

Is there any documentation that explaing the reproduction ratio of a lens vs magnification.

I work with microscopes, both optical and scanning electron. My boss wants me to buy a lens for some work here with a camera. My recomendation was a Nikon 105mm macro, Somewhere she got the idea that the longer the lens IE: 200mm will give more magnification than a say a 50mm lens. I know that magnfication related to microscopes is totally different than the lenses, AFIK all a longer lens will do is focus on a distant object to fill the frame but there will ne no magnification change which I soppose in essance is a form of magnification. but not the same thing. I do know that the minimum focus for lenses will vary but the magnification will not.

Thanks

Qarik

basically the facor you should key on his how much of the sensor the image will occupy..macro lens terminology often use pharases like 1:1 reproduction whcih means that an object that is 2 cm in length will occupy 2cm of space on the sensor. There are basically only 2 factors..the zoom strength and min focus distance of which min focus distance is the key in a macro lens. As you noted 200mm lens with 10 in min focus distance may give inferior reproduction value to a 100mm lens that can focus to 4 in for example. Depending on what you are shooting though..you may need or want the 10 in of space if the subject matter or lighting does not allow you to shoot at 4 in.

ziggy53

In photography, when working with a "true macro" lens, or a Nikon "Micro" branded lens, and if the lens is rated to 1:1, that means that the lens is capable of a 1:1 magnification at full extension, i.e. the lens is capable of recording at lifesize, and 1mm of the subject will be represented by 1mm on the focal plane. (At less than full extension the magnification will be correspondingly less than lifesize, depending on the particular lens and extension.) Working distances, including minimum working distances, will vary by focal length and lens construction.

Extension tube sets and bellows will allow respective different magnifications, and generally more magnification. (The exception being lenses designed for bellows use may allow more or less than lifesize.)

There will be additional magnification during the presentation of the image, either on a computer screen or when the image is printed. There are visual scale aids available which can help to determine exact magnifications, if that's required. (Micron Scale, etc.)

---

Most optical microscope users are familiar with the magnifications available to the naked eye (virtual image); generally calculated as at the following page:

http://hyperphysics.phy-astr.gsu.edu/hbase/geoopt/micros2.html

The real image formed on the image plane of a camera is quite a bit different, however. It is best to use empirical methods to determine total magnification, when possible.

puzzledpaul

What size (range) are the likely subjects and are you using a FF or crop body?

A site that might be of interest...
http://www.photomacrography.net/forum/


pp

Augie

Thanks all,

Now I can talk to her and provide an reasonable explanation.