The color balance is off a bit in this one. I had a small 4x6 made from the slide and flatbed scanned the print. The minilab that made the "quick and dirty" print either cranked down the yellow or didn't add enough. Didn't catch it until I projected the slide again and compared it to the print.

Yes, it's not easy. Spent several hours doing the shoot. I don't usually work with this much magnification in making macros. Some of the details of the technical aspects of making this one after visualizing the composition and lighting I wanted:

There were a couple of challenges working with the high magnification ratio:

(a) When using studio monolights with lens extension for macros it must metered using a flash meter and then compensated for the falloff caused by the high magnification (how much depends on magnification). Compensation for this one was two f-stops. The approximate magnification ratio is figured by using a ruler to measure the field of view on the subject. 35mm film is roughly 1x1-1/2 inches (close enough for macro exposure compensation). Medium format 645 is roughly 1-3/4x2-1/4 inches (also close enough to work well).

(b) Depth of field is extremely shallow at high magnification. Not having a very good feel about what would actually be needed for enlargement . . . DOF shrinks some with enlargement; it's a visual effect . . . this is one of several using combinations of different lens apertures with exact location of critical focus point. A 2.5X magnifier on the viewfinder was used to aid critical focusing. Stopping the lens down to increase DOF requires greater power from the lighting. Combined with the two f-stop light loss from high magnification (using lens extension), f/11 on the lens must be flash metered as f/22. That's quite a bit of light power from a single monolight when a louvered softbox is added to it.

Purple in itself can be problematic when desiring great enlargement for printing. The color is a challenge to lens design as it's red and blue at the opposite ends of the spectrum. Different colors refract at different angles; it's why rainbows and prisms produce their spectra. If a lens isn't chromatically well corrected, it can show fringing at sharp color and contrast edges when the photograph is greatly enlarged. It requires very close scrutiny at edges of things to see the fringing, but the overall visual effect is a loss of apparent sharpness that can limit print enlargement. Purple is the most demanding of the chromatic correction in a lens and has one of the greatest risks of producing fringing. The lens used had revealed its excellent chromatic correction in past photographs . . . along with excellent bokeh . . . and is why I selected it versus a couple others that could have been used.

-- John Lind #1432628

Susan #1433140

The higher the magnification (size of subject versus size of film or CCD/CMOS sensor) the shallower the depth of field. High magnification photography can be quite difficult if the subject has depth to it that one wants to be clearly within the depth of field. Some subject material I've dealt with has depth that exceeded capability to stop the lens down further to attain enough depth of field for the originally desired composition even when I could add more light, forcing the need to do something different than what was originally visualized.

Depth of field in a photograph also shrinks some as print size (or projection size) is increased because depth of field is a visual perception related to the acuity of the human eye (ability to see that something is out of focus). Increasing print or projection size increases the "fuzziness" at depth of field boundaries, enhancing ability of the human eye to detect it resulting in a shrinkage of the region that does appear to be in focus. This shrinkage is limited some by the increased viewing distance to take in the entire photograph with very large prints, but one must also anticipate the closer scrutiny a large print will likely receive if it's destined for gallery use. I wouldn't enlarge this Iris photo beyond an 11x14 as the very front of the lower petal will "lose it" too much beyond that size.

If you have a very hi-res of your Eubie photo, try viewing the portion around the sharp focus area on his eye at various enlargement levels on your computer monitor. I'm thinking you should be able to see the effect enlargement has on apparent depth of field.

I'll post something later about exposure compensation required for using off-camera studio lighting to make macros.

-- John Lind #1433449

If you are using ambient lighting, or a dedicated TTL flash or strobe, the output of which is controlled by the camera (its metering), your camera's internal TTL metering will handle everything.

Studio lighting . . . strobes or monolights . . . that are not under control of the camera's internal metering are another matter. The camera only triggers the lights, it doesn't control the amount of light they produce. Exposure is controlled by lens aperture and light power. Camera shutter speed is set to one that will properly X-sync the light triggering. Light output is measured using a flash meter which gives lens aperture.

Macros made closer than a "normal" lens will focus are done in one of three ways: auxiliary "close-up" lenses that screw onto the front of a lens (sometimes mislabeled as "filters"), true macro lenses, and lens extension tubes or bellows added between a "normal" lens and the camera body. Aux "close-up" lenses and modern design *true* macro lenses need no compensation. A true macro lens is not a zoom with "macro" or "close-up" feature; it's a special prime lens designed to focus much, much closer than a normal lens of same focal length would allow using the same focusing mechanism. The shorter ones usually allow life-size on film; longer ones typically are 1/2 life-size.

Extension tubes and bellows added between a normal lens and camera body move the lens forward making its image circle bigger and reducing the amount of light reaching what will record it (film or CCD). The farther forward the lens is moved, the bigger the image circle. Exposure compensation for this is required when magnification is greater than about 1:8 (image on film or CCD is bigger than 1/8th life-size) as the light loss reaches about 1/3rd f-stop.

With lens extensions, the camera's TTL metering will automatically compensate if it's used with available light or controlling a dedicated TTL flash. Studio strobes or monolights with fixed output set on the light(s) must be flash metered for setting exposure, and the compensation required to prevent underexposure is roughly as follows:
1:8 = +1/3 f-stop
1:4 = +2/3 f-stop
1:2 = +1 f-stop
3:4 = +1-2/3 f-stop
1:1 = +2 f-stop

While this is a PITA, extension tubes or a bellows used with a good prime lens are optically better than using close-up aux lenses on the front of one. The optics of nearly all but the most expensive close-up aux lenses (aka filters) are mediocre at best and prone to flare. Good ones are more costly than a set of extension tubes. Monolights have great advantage over using a dedicated TTL flash (on a remote cord). Their modeling lights allow seeing what the lighting setup will create. A true macro lens, is quite expensive. I don't make enough of them to justify the cost of one.

-- John Lind #1434938