I have a Fujinon 240A and have used it a lot for close subjects.
Getting down near 1:1, I find that the depth of field is rather limited with that length. I figure I'd do better with a 15o or 180. As I say, I presume the 120, while giving even more depth of field, might introduce foreshortening.
Vijay, a little background information. Lenses are either asymmetrical, like a Tessar, in which the rear cell is nothing like the front, symmetrical in which front and rear cells are identical, or near-symmetrical, the cells resembling each other but not being the same. An asymmetrical lens definitely must be turned around to give decent reults when the image is larger than the subject. A true symmetrical lens doesn't care which way it faces the subject. The Apo-Sironar-S is near symmetrical. It probably is at its best when the subject is from ten to an infinite number of times larger than our image. It probably would perform decently down to a reduction ratio of 5:1. This means that it should work well magnifying more than five times if reversed, better at 1:10 and up. O.K., lets do it. WE take a small one, the 135mm, and set up for 1:5. This means extending the bellows to 810mm. Oops, that's almost 32", Maybe our camera doesn't have that length. Higher magmification ratios and/or longer focal length lenses would make matters still worse, of course. In addition, those lenses in number 1 shutters can't be reversed because the mounting threads are different fron and rear.
Ken, what aperture did you use for that example photo of the orchid?
A macro lens should do better than a lens optimized for distance, but I suspect that for your botanicals you will usually be stopping way down for depth of field. This may create enough diffraction to wipe out the improved performance for macro work of the macro lens compared to lens optimized for distant subjects. So if you are stopping way down, don't be surprised if you don't notice an improvement after buying a macro lens.
(Thank you for your contributions to this forum. Dunno what you do for a living, but your knowledge of optics and lenses, and your ability and willingness to clearly articulate it, is stunning).
That shot was made at f/32, which I figured was around as small as I could go before diffraction effects set in.
In shots such as these, having some out-of-focus areas can be visually pleasing, giving a greater sense of depth, and can emphasize the sharp areas. But it would be best if I could get more than necessary, and open the lens to remove depth of field, according to taste.
To get the same reproduction ratio, we need to move closer or further away, according to the length of the lens. That makes sense.
By moving closer with a short lens, are we, in effect, tossing out whatever increase in depth of field that we would otherwise get due to a shorter lens ?
When we read that shorter lenses give greater depth of field, is this statement based on "normal" subject distances only ?
"By moving closer with a short lens, are we, in effect, tossing out whatever increase in depth of field that we would otherwise get due to a shorter lens ? "
essentially, yes. To get the same sized image on the film, if you use a wider lens and move in closer, the DoF is basically the same at with the longer lens from further away
(see some of the discussion in the link I posted).
There is all sorts of fancy maths around this, but in actual practice, this is the case
You'd be amazed how small the demand is for pictures of trees... - Fred Astaire to Audrey Hepburn
Ken, I would doubt that you would see any difference when making contact prints between any high quality lenses regardless if the lens was optimized for 1:1 or infinity. Here are a few general rules of thumb for macro work.
1. You will require more magnification for larger formats. An image that is 1:1 for 35mm would require 5:1 or greater for 4x5 to make an equivalent image. That is why I only work with 4x5 for macro photography. 8x10 would tend to require extreme magnification unless you are shooting big flowers that are close to 8" in size.
2. The DOF is the same for any focal length lens for a given image size. Thus, a flower 2" big on the ground glass will require the same DOF whether you shoot if with a 120mm lens or a 500mm lens.
3. For a given image size, say a flower 2" on the ground glass, a change in focal length will alter the scope of the background. Shorter lenses will have a broader background while longer lenses will have a restricted background. In most cases the this is not an issue because the background is severely blurred to begin with.
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