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Forum: Mini-Challenges, Games, and Photo Stories
07-26-2009, 03:12 AM
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I hadn't played with my reverse ring and bellows etc for a while, but the fantastic photos everyone has been posting have inspired me to dig it all out again and have another go.
The first photo was taken using a reversed Super Takumar 50 f/1.4 and the sencond two with a reversed Super Takumar 55 f/1.8. In all cases the lenses were reverse mounted on a pentax auto bellows and for the second photo a full set of extension tubes was used in addition to the maximum bellows extension to magnify an area only 3mm across. All pictures taken at f/16 to get the depth of field and all lit by a tungsten spot lamp.
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Forum: Mini-Challenges, Games, and Photo Stories
07-19-2009, 04:08 AM
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There are some fantastic photos in this thread, way better than I have achieved. However there are a lot of misconceptions about the purpose of reverse rings and how to use them to best advantage. I will try to explain.
Firstly, macro shots (beyond what the focus travel allows) can be taken with any lens if it can be moved further from the film / sensor somehow (extension tube or bellows normally). This generally works better with primes than zooms as they will generally have less glass in the way and so introduce less aberrations when used outside what they were designed for. When the length of the extension tube or bellows is equal to the focal length of the lens you have achieved 1:1 magnification i.e. the image on the sensor / film is the same size as the object.
Lenses are optimised (designed) to work over a defined range of object distances which will be the range over which the focus ring allows you to work. If you use a normal prime lens with extension tubes to achieve 1:1 magnification, it is being used outside what it was designed for and so it will not perform at its best. In addition to having a significantly longer focus travel, macro lenses are also optimised to work closer to the object (so a 50mm macro will NOT be as good at taking landscape images as the equivalent 50mm normal lens).
For normal photography the distance between the object and the lens is greater than the distance between lens and the sensor. If you want to achieve a magnification greater than 1:1 the distance between the object and the lens will be less than the distance between the lens and the sensor. In this case the lens is being used well outside of what it was designed for and the performance will be reduced. If the lens is used reversed for high magnification macro (long extension tubes of bellows) then it is as if it were being used the right way round for a distant object i.e. it is being used how it was designed for. The higher the magnification the better the lens should work reversed (but the harder it is to illuminate the subject well)!
Now it just so happens that if a short focal length (maybe 50mm or bellow) lens is reversed then it will generally give a closer macro than if it were used the right way round. If a long focal length lens (maybe 80 mm and above) is used reversed without an extension tube or bellows then it will be IMPOSSIBLE to focus at ANY distance (the lens it trying to focus beyond infinity).
So in summary, if you want a low magnification then use the lens the right way round, with an extension tube / bellows if necessary. If you want something around 1:1 macro the a purpose designed macro lens will give the best results but a lens either the right way round or reversed will work with extension tubes. If you want a magnification greater than 1:1 then a reversed lens on extension tubes should work best. I hope that this helps and is not too confusing (it is difficult to explain without using terms like conjugates and numerical aperture).
Bellow is a picture I took with a reversed lens (I can’t remember if it was a Helios M44-2 or a Takumar 55 f/1.8) at about f/11 on a long bellows extension. The image is of some Vanadinite crystals and the area of the image was about 5mm across.
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