Macro photography - true macro lenses
Here is the next post about Macro photography series. This post is about true macro lenses. I will try to help you choose the best lens for your purpose.
True macro lenses differentiates from the usage point of view. If you ask me I will classify the lenses from the focal length, magnification ratio and internal focus point of view.
There are some old macro lenses that are still used today altough they are not true 1:1 lenses. But first let me answer a question... Why is so important the focal length since the DOF is the same at the same magnification ratio?
Well, the focal length gives you the Working Distance. Let's take for example short focal length lenses like 35mm Tokina F2.8, 40mm Micro Nikon 2.8, 50mm Canon F2.8, 50mm Sigma F2.8, 60mm Tamron F2.0 etc. They all have in common at least one thing... very short working distance. You can achieve 1:1 magnification ratio at around 4-6cm distance from your subject.
This pose one big problem... the diffusion of light. With natural light sometimes the lens will most probably cast a shadow onto your subject. Most of the critters will never let you approach so much when they are active. These lenses are used mainly at product photography.
In the next category I include medium length lenses, which I prefer. I will list some of the most common used lenses beginning with Tamron 90mm F2.8, 100mm Tokina F2.8, Canon 100mm F2.8, Sigma 100mm F2.8, Nikon 105mm F2.8.
These lenses have a working distance of about 14-15 cm. You have a generous distance between the lens and the subject and you can use these lenses at almost all kind of critters. The distance is perfect for light diffusion. You can use this kind of lens for product photography, wild macro and they are very good at portraits.
The last and the best lenses for a true wild macro photographer are the long focal ones. I will enumerate only some of them like 150mm Sigma F2.8, Tamron 180mm F3.5, Canon 180mm F3.5, Nikon 200mm F4. The working distance is huge, around 25cm. You can approach any kind of critter with this working distance. The only problem I can see with these lenses is the diffusion of light. Even with off camera flash strobes you will find it hard to correctly diffuse the light.
If you remember my previous post Macro photography - the alternatives to the macro lenses then you can figure it out how to use extension tubes or even converters along with these lenses to best suit your purpose.
Another aspect is High Magnification. Let's suppose that you want more than 1:1 magnification ratio and you will use some extension tubes to achieve this. If the lens is NOT true IF, when you attach extension tubes you will decrease drastically the working distance. The best example is Tamron 90mm F2.8. A very good lens at 1:1 or less magnification ratio. With 68cm extension tubes you have some 2:1 magnification ratio but the working distance of only ~5cm. Fortunately, when using a true IF lens you preserve a good working distance. Let's take 105mm Nikon F2.8. With 128mm extension tubes attached you achieve around 3:1 magnification ratio and still have around 11cm working distance.
If you want a true high magnification lens you can't go wrong with Canon MP-E 65mm. This lens will give you a magnification from 1:1 till 5:1. Basically is the same as adding one variable extension tube to your existing macro lens.
The problem with working distance remains... so personally I prefer something like 100mm with extension tubes. My biggest magnification ratio is 3.6:1 and I think that's enough. If I want more I can always use a microscope.
There is one (it won't go at true 1:1 but close) zoom lens. This is NIKON AF MICRO NIKKOR ED 70-180mm f/4-5-5-6D. This lens is very expensive and I personally don't see why... same thing can be achieved with a banal 55-200mm lens and some extension tubes.
There are some 1;2 lenses that are still considered macro lenses like 55mm AI-s Nikkor, Canon 50mm F2.5, Olympus 50mm F2 etc.
If you ask me, all the lenses are more or less the same at F11. No matter if they are true macro lenses or not. I personally sold the 105mm Nikon and I currently use 55-200 with extension tubes with the same great results.
More important than the lens is the light diffusion, so stay tuned for my next post about macro photography.
Photo credits: Bogdanzagan.