Looking for a "cheap" MD/MC macro lens.

Started Mar 7, 2013 | Discussions thread
Letsgokoulos
Senior MemberPosts: 1,465
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Re: Looking for a "cheap" MD/MC macro lens.
In reply to JoeyCF3, Mar 8, 2013

JoeyCF3 wrote:

Understood.. now things are becoming a little clearer to me. I want it for flowers and shots of insects on flowers and branches.
What exactly is "cropping"? Is there an image where you can show me an example?

Also, what would be the real difference between a f3.5 and a f4.5 70-210mm Vivitar? Am I sacrificing a lot by getting the cheaper f4.5?

How close would you like to get to insects ? The closer you need to get the longer the focal length you will need. Insects are easily scared, so you need to shoot from a distance. This distance is set by the focal length and the magnification ratio you expect to obtain. If you want an ant to fill your frame, then we are speaking of ratios higher than 2:1. If you want a butterfly on a branch, the ratio is closer to 1:2. And of course, the higher the ratio, the more expensive the lens...

A crop is the selection of a part of your picture. Here is an example, with a small jumping spider that must measure about 2.5 mm in width :



Uncropped, this is the original picture (with a magnification ratio of about 10:1)

The magnification ratio is around 10:1 in this case, because the spider of 2.5mm in width would need to be multiplied by a factor of 10 to fill the entire width of the sensor, which is 23.4mm

Cropped. I selected a part of my picture which is now enlarged (the magnification ratio now is closer to 5:1) to fill the same area. This means that I am loosing some pixels and therefore the resolution of the picture is lower that the original uncropped picture

With regards to the minimum aperture, this is important for regular photography for influencing the depth of field, i.e. controlling the in- and out-focus areas. The higher the aperture value the smaller the aperture is (f3.5 is larger than f4.5). And larger the aperture is, the deeper the depth of field (DoF). I hope I am not teaching something you do not know, but if i do, I strongly recommend you read some books on the basics of photography.

In macro photography, you never use aperture values of f3.5 or f4.5, since the DoF is then far too shallow, you usually go to f8 up to f22 or even higher. If you look at the example above, the tiny spider is not fully in focus. This means the DoF (the area in focus) was under 1mm, although the aperture used was f11.

And when you use small apertures like f11, there is not much light coming on the sensor, therefore your shutter speed drops tremendously. And when shutter speed dicreases, you risk having blurred pictures, particularly with moving insects...

So, to conclude: define the type of macro photography that you would like to achieve, let us know (there are many other experts in this forum who can provide you with good advices) and tell us what your budget is. If you are starting and are not sure of what you want to achieve, a 50mm macro prime could be a good idea. You can find some high-quality 50mm like a Minolta Macro-Rokkor-QF 50mm f3.5 or a Canon FD 50mm f3.5 macro for around 100$, maybe less if you are patient and lucky. There also are other brands, but I cannot list them all.

There are, otherwise, many other possibilities to get started in macro, such as extension tubes, close-up adapters, reversing rings, etc... Keep in mind that macro usually is manual focus because of the shallow depth of field.

Marc

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