focus lock

Macro Lenses for Micro 4/3

Posted on by in philosophy, underwatermacro and tagged , , , , , , , .

Very good comparison video of macro lenses for M43.  Makes me think a little bit more than usual….

I think that just about everybody doing underwater macro with a M43 (Panasonic G9, GH5, etc and the Olympus OMD-EM1/5/10) is using the Olympus 60mm Macro.  I haven’t seen any debate about this at all.

The reason that we all use the 60mm is because more magnification is good and the image quality of this lens is good.  And hey, that’s what everybody else uses, so why not?  However, I wish there were other good M43 macro lenses: a 100mm or 120mm would make me very happy although it might not be useable underwater.

But, we also have wet diopters (wet lenses), and they change the lens game considerably.  I myself have both a Nauticam Supermacro converter SMC-1, a Saga +5, and an Inon super-wide macro (bug-eye).  I’m have the additional magnifier for the SMC-1 coming next week for even better supermacro, although for the past 18 months I’ve been a heretic and stacked the Saga +5 on top of the SMC instead because the price is right.

My thinking goes like this:

  • It’s harder to focus underwater because of less light.  This means less contrast for autofocus.
  • It’s harder to focus underwater because current and surge: you and your subject are constantly moving in large and small amounts.
  • It’s harder to focus underwater because well, you’re underwater and breathing through a hose.
  • A 30mm or 45mm macro lens plus wet diopters is an interesting option, especially if they have a faster autofocus.  If you can shoot closer and/or use wet diopters, then you can even get to supermacro.
  • A macro lens at a wide F-stop (F2.8 for most macro lenses) means a thinner plane of focus.
  • Adding a wet diopter makes a thin plane of focus.
  • Stacking wet diopters makes a very very thin plane of focus.
  • I usually end up shooting at F22 with stacked diopters to increase my plane of focus as much as I can.  Obviously, this changes my exposure so I have to compensate in shutter speed, strobe power, or ISO.
  • It is very common for the lens to be able to focus in front of and beyond what the wet diopter is capable of.  IE, the focus range of the lens exceeds the focus range of the diopter.  This adds to difficulties in autofocus because the lens hunts in places where it cannot focus.  Using a limiter switch on the lens (the Olympus 60mm has one) helps because it eliminates the hunting in the longer ranges.
  • Focus lock helps a ton with wet diopters because it almost eliminates out-of-range situations unless you’re setting a new focus.
  • For larger subjects (shrimp gobies, garden eels, larger crabs, scorpionfish, etc), diopters can also be unscrewed or swung out of the way with a hinge.  I use a hinge for the SMC-1.  I screw the Saga +5 on and off because it doesn’t have a downsize threads to fit the front end of the SMC-1.  Screwing on and off is not a quick process.
  • If you remove the diopter, then the focus is further away, so using a limiter switch on the lens means that you maybe can’t focus at that longer length.  So really, using the limiter switch is a tradeoff between autofocus speed and being able to take pictures of larger subjects.
  • You absolutely need to try all of the options available to you before you do it underwater.  Dry-land training is huge.

What’s the point of all this?  Well, everything in photography is a tradeoff.  The more you understand what decisions you’re making, the more you can adjust when things don’t work out the way you intended.  And I’m a huge believer in being able to adjust to conditions and just keep shooting.

 

See You Underwater!!!

–Mike

Dry Land Training: Focus Distance

Posted on by in underwatermacro and tagged , , , , , .

Finding your minimum and maximum focus distance is a critical skill in underwater macro.  This is because if you can’t focus, you can’t take pictures that you’ll like.  In supermacro, most of the the time you can’t even see your subject because the depth of focus is so thin.

I test for maximum and minimum focus distance every time I have a new camera, lens, or wet diopter.  I’ll even test combinations of these 3 to see what I like.

Given:

  • A well-lit room
  • One camera with lens
  • One housing with appropriate port
  • Series of wet diopters
  • A subject (can be a nudie replica or something as mundane as the screw on a tripod head)

Process:

  1. Mount camera and lens in housing with port.
  2. Find minimum focus distance first.
  3. Put the glass of the port up against the subject.
  4. Try to gain focus with the auto-focus–back-button or half-press on the shutter.
  5. When you have the closest focus point, measure the distance from the end of the port to the subject.
  6. Check for farthest focus point.
  7. Move the camera back from the subject while you are trying to gain focus.
  8. When you can’t focus anymore, go forward just a bit and get a focus.
  9. When you know the furthest focus point, measure the distance from the end of the port to the subject.

Tricks:

  • Put the camera in constant focus mode:
    • Panasonic: AFC
    • Canon: AI Servo
    • Nikon: AF-C (Continuous-servo AF)
  • Us manual focus to set the minimum and maximum focus distance.
  • Put the subject on a ruler so that you can easily measure the distances.
  • Try stacking wet diopters.  I sometimes use a Nauticam SMC-1 with a Saga +5.  Different diopter combinations have different focus ranges.
  • Once you have a focus lock, move the camera in and out to see how deep the focus is.  Try it with maximum and minimum aperture.

 

See you all underwater!!!

–Mike