BobORama wrote:
You can do 1:1 macro with that setup without any accessories.
With internal focus, i.e. modern lenses, the result of using extension tubes can be not great, as the spacing of the fixed rear elements to the sensor is more critical. Same is true for rear doublers not engineered to work with a specific lens.
Older design helicoid macro lenses are essentially a fixed conjugate on a variable extension tube - so additional extension is usually OK.
How old is an "older design"? I have one of the Nikon 55mm f/2.8 Ai-S Micro Nikkors that has a floating rear group. That design was introduced in 79. Many years ago, I took a physically damaged on, separated it into two optical capsules, mounted one in a short helicoid, put an iris between the two groups, and the whole thing in a short tube for use on a bellows. The helicoid had 4x the range of Nikon's original setup, and set the compensation from infinity to about 2x in forward mode, or 0.5x to maybe 6x in reverse mode.
(Speaking of "how old is older?", Wow! You're still alive! Hadn't seen you post in a while, and feared the worst. There aren't that many of us old geezers left).
However the length of the tube gets to be rediculous. Either way, this is where front dipoters ( like the Raynox series ) help.
Nah. The Raynox are far more useful behind a lens than in front of it. Seriously.
If you are interested in doing studio / bench work, and can deal with longer exposures, you can construct a very nice 4x close focus lens with a flatbed scanner lens and a cheap helicoid extension tube. Its basically $0 and the results can be amazing. They were engineered to do 4x on a digital sensors.
Or a 4x AmScope Plan Achro objective. They're around $29, and what all the cool kids are using these days.
Anyway, I think you have a fine starting point, and you have some cropping latitude. If you find yourself wanting higher magnification, add dipoters. For 4x or above, fixed conjugates some of which can be free from the dumpster.
Tell me about it. My current 50mm f/2.8 EL-Nikkor came off an enlarger I spotted on the curb one day about 15 years ago. Fine lens at 2-5x on a bellows.
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The term "mirrorless" is totally obsolete. It's time we call out EVIL for what it is. (Or, if you can't handle "Electronic Viewfinder Interchangeable Lens" then Frenchify it and call it "LIVE" for "Lens Interchangeable, Viewfinder Electronic" or "Viseur électronique").
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