Lens Text: Luminar at 11-12x Magnification

[Cactuspic]

One of the treasures from my recent travels, a 25 mm Luminar, was burning a hole in my pocket. I just had to try it out on some tiny spines to see how much fine detail it can resolve. At 11-12x magnification, 3.1 mm (about 1/8 inch) will fill a 35 mm frame. At that magnification, it is very difficult to see the subject without additional light, even a white spined cactus appears nearly black in the viewfinder. I cropped this focus stack slightly to change the aspect ratio. Hope you enjoy.

Irwin

[LordV]

Looks like a coral - lovely shot.
What are you doing with the lens- using it on bellows or reversing it ?
Brian V.

[dreamline]

Now that is nice Irwin. Looks like thistledown at that magnification.

Must have been pretty hard to get anywhere near the focus.

[Cactuspic]

Looks like a coral - lovely shot.
What are you doing with the lens- using it on bellows or reversing it ?
Brian V.

Thank you Brian for you kind thoughts and comments. It struck my sense of irony at how often plants from the desert, once they are stripped of their contextual clues, resemble sea life.

The Luminar has the same RMS threads as a microscope objective, from which it was derived. To get that much magnification, I screw it into an adapter that will attach to anything with m42 threads (the old pentax screw mount). I attach my camera to an old Novoflex bellows unit and then attach various m42 tubes , cheap on Ebay. My total extension was about 10 inches (25.4 cm). To calculate magnification, I take a picture of a ruler and set up my ratios.

This Luminar has an optimal magnification range of 6.3-25x. Since it is meant only for high magnification macro, it is not reversed. Curiously it is often used by medium format and large format shooters.

Irwin

[Cactuspic]

Now that is nice Irwin. Looks like thistledown at that magnification.

Must have been pretty hard to get anywhere near the focus.

Thank you for commenting Bernie.

I cheated on focusing. Since I shoot digitally, I get as close as I can by the dim light in the viewfinder, snap a shot, then I check the focus on my camera's display at its highest magnification. I then tweak the focusing rail, snap again and continue until I am satisfied that focus is dead on. Don't you love digital?

The hardest part is to make minor changes in composition. Since any change in camera or plant position is so magnified (the complete filed is only 1/8 inch--3 mm) it's difficult to make adjustments that are small enough.

Irwin