Macro Photography - Part 1

Thursday, 3 September 2009 22:22 by RanjanBanerji

This is going to be interesting.  As I mentioned in my first post I am no pro.  I like photography and I try to keep learning and improving my skills.  Unfortunately, I am not much of a reader.  So I end up learning by scanning a few blogs rather than reading a big fat book on photography.  I also realized, rather fast, that photography is not a cheap hobby.  This thing is one huge money pit.  So I scan blogs and then try out ways to keep my cost low.  This is not necessarily a great way to go.  Sometimes being cheap is just not a good idea.  Anyway…

Macro photography is something that I really enjoy.  Specially when it comes to bugs, insects, and other weird little critters.  There are various techniques one can adopt to take these pictures.  If you search the web you will find some absolutely incredible pictures.  Mine?  Not so good…  lol.  Great! what a wonderful way to get started reading about someone's experiences and hoping to to pick up a tip or two.  Well this is where you can see some of my macro pictures and judge for yourself.

Macro photography is when the size of the image on film or sensor is almost the same size as that of the subject or perhaps even larger.  For example a 35mm film SLR takes a film that is 35mm wide per frame.  Most DSLRs have a sensor that is around 23mm.  For example the Nikon D80 CCD is 23.6mm wide.  So imagine taking a picture of an insect that is 20mm long.  If you have a 1X or a 1:1 macro lens then the image of the insect will take exactly 20mm on the sensor.  So on a Nikon D80 the insect will take 20/23.6 or about 85% of the length of the sensor.

Why is this a good thing?  Well now its time for you to print your insect picture.  Let’s say you decide to go with a 4x6 printout.  Now your insect will be about 5” wide.  So what you have is this awe inspiring insect picture or for some this really creepy picture.   With most normal lens this 20mm insect would probably not even be visible on a 4x6 printout.  For example a Nikkor 50mm f1.8 offers a magnification of 1:6.6.  So the 20mm insect will take only 3mm on the sensor and only 0.72” on a 4x6, not very impressive is it?

Most macro pictures are 1:2 or better.  A true macro picture is usually considered to be at least 1:1 or 1X.  A 2:1 or 2X is when image of the subject on the sensor is twice the size of the subject itself.  So in our 20mm insect example the entire insect would not even fit on the sensor.  In cases like this you can take a picture of the head of an insect to fill the entire frame.

Please do not confuse the 1X, 2X terminology in Macro photography with the often used marketing terminology of 10X or 20X zoom lens.  These are two different concepts.

 

The picture above was taken by reversing a Nikkor 50mm on a 85mm lens.  The resulting magnification is 85/50 = 1.7X

What Do I Need?

Macro Lens:  There are several techniques that can be used to take macro images.  The simplest, easiest, but most expensive way to do so is to purchase a Macro lens.  Just make sure the lens specifications state 1:1.  There are lens out there that have the word Macro on them but they do not offer 1:1.  Also, I have a preference for a Macro lens that is at least 100mm.  This way you get some working space.  With a shorter focal length you will have to come very close to the subject to get pictures at maximum magnification.  If you don’t like bee stings then go for at least a 100mm lens.

Diopter Lens:  These are lens that look like filters and screw on to a regular lens.  They let you move closer to the object and thereby get some magnification.  The magnification you achieve from a diopter lens can be computed as follows:  Focal Length of the lens you are putting the diopter on/(1000/Power of the diopter lens).  So a 4T diopter lens on a 70mm lens will give you a magnification of 0.28X, i.e., a 10mm insect will take 2.8mm on your sensor/film.  This is no where close to a 1X but is not bad considering the fact that a cheap diopter lens can be obtained for $10 and a 1:1 or 1X Macro lens will cost you at least $500.

The problem with diopter lens or at least the cheap Tiffen ones I bought is that the optic quality is not all that good.  They are great for initial experimentation but after a while you find yourself wanting better quality images.

Reversing Lens: This is a technique that can get you incredible magnification (maybe too much).  Instead of using a diopter lens you can reverse a lens onto another.  The resulting magnification is focal length of prime/focal length of the reversed lens.  For example the Cicada picture above was taken by reversing a 50mm on a 85 mm giving me 1.7X.  One problem with most macro techniques is that you get a very shallow depth of field.  So if you focus on the front of an insect you rear is a blur.  As you go to higher levels of magnification the depth of field gets shallower.  In order to reverse a lens directly on to your camera you will have to purchase a reversing ring (BR2A for Nikon).  In order to reverse a lens onto another you will need coupling rings.  The reversing or coupling rings screw onto the front of your lens like a filter and then attach to your camera or another lens.

A step down coupling ring for reversing a lens onto another and a BR2A with a step down too.

A Nikkor 50mm with a BR2A so it can be mounted reversed onto the camera.

Extension Tubes: Like reversing lens you can mount an extension tube onto your camera and then the lens to the tube.  Since the tube is just a tube, i.e., no optics, this approach does not impact the optic quality like a diopter lens does.

More about macro photography later…..

 

Categories:   Photography | Photography | Macro | Macro
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