Ken I have done the side-by-side test with three lenses: a 180 Apo Sironar N/180 Macro Symmar HM/Apo Macro Sironar S. I measured my magnifications carefully on the rail of my Horseman LS and right up to just a few mm shy of 1:1 there was no discernible difference between the three lenses. The moment I hit 1:1 the differences between the macro lenses and the standard 180 were clearly evident, especially as you moved toward the edges and corners of the image. The test subject was a long silver necklace made up of thousands of small (2 mm across) links and it was heaped to check both depth of field and resolution.
Thank you all, for clarifying the various issues. As Tim has pointed out, the mathematics involved is fancy - so I appreciate the 'nutshell' version.
There seem to be 3 variables in the game: image size, aperture, and focal length. You get to keep any two the same, but the third one varies accordingly.
This reminds me of what we say in the software business. High Quality, Fast Implementation, Low Cost: you get to pick two. You can't have all three.
On second thought, please excuse my lame attempt at simplification. I overlooked lens-to-subject distance, and probably a few other variables.
You saved me some money, time, and vexation: No need to get a shorter lens.
Since I already have a Fujinon 240A, and my camera has enough bellows draw to accommodate it all the way to 1:1, I can use it, without missing any depth of field.
Bob Hale, It's all a matter of lens design. Very subtle variations will affect the subject/image range the lens works best at. Highly asymmetrical lenses are very picky regarding optimum range, so most newer ;enses are symmetrical, or nearly so. This is why thr G-Claron for example, is usable at small stops even at landscape distances, even though designed for close work.
When used at magnification ratios, a short focal length lens will cover a format for which a much longer lens is needed in landscape work. This is why the shorter (17mm to 75mm) MP-4 lenses, for another example, are usable in macro work. Longer lenses demand too much bellows extension when used for magnification.
Rob - Sorry, I thought at the time that my response was funny, but now that I read it, it comes off a little sarcastic, which was not my intention. Please accept my apology.
I have updated the first photo with another taken at the same time with the same lens, the 150 Sironar S. By the way, these are my first photos using Sandy King's Pyrocat P formula.
Pyrocat P seems to work very nicely, and the stain is more neutral-colored, which is probably a good thing for those of us who print on VC Silver paper. There has been a nice discussion of some initial testing results here.
Ken, I'll throw a wrench in the gears here. I've been playing with macro on 8X10 with the big 9a Century studio camera. 36+ inch bellows. Since with LF you WILL have to live with sharpness fading to unsharpness somewhere, think about that transition. Most any lens can make the sharp areas look nice in a print. But the smooth transition of an antique petzval or Heliar does good things to my psyche. The attached was done with a 9" darlot Magic Lantern lens
All wrenches are welcome and much obliged. You're right.
Oren's words have come back to haunt me, and now I can't help but wonder if my 150 APO Sironar-S does render the out-of-focus areas in an especially "creamy" manner, in close images of orchid blossoms, such as this one.
I really will have to do some side-by-side comparisons at close range.
Better yet: Perhaps Christopher Perez can repeat his recent bokeh tests... on a set of model trains this time !
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