Sony SAL100M28 macro: problems photographing insects

I would like to be able to photograph insects (e.g., bees) up close
with my Sony A33 and Sony SAL100M28 macro and also get the entire
insect to be in focus. With this lens, in order to get depth of field
that will enable me to get the insect body in focus, I have to move
several inches from the insect. DOF is virtually nonexistent at
minimum focus distance (.352 meters). At that focal distance, the DOF
is zero up thru f11. At f16-f32 DOF is only 1 to 2 mm, which is not
enough DOF to get enough of the insect in focus.

Do I have an appropriate lens for what I want to do, or would I be
better off with the SAL50M28?

Thanks.
Don
(a rookie)

On 2011.01.15 13:36 , Don Tuttle wrote:
I would like to be able to photograph insects (e.g., bees) up close
with my Sony A33 and Sony SAL100M28 macro and also get the entire
insect to be in focus. With this lens, in order to get depth of field
that will enable me to get the insect body in focus, I have to move
several inches from the insect. DOF is virtually nonexistent at
minimum focus distance (.352 meters). At that focal distance, the DOF
is zero up thru f11. At f16-f32 DOF is only 1 to 2 mm, which is not
enough DOF to get enough of the insect in focus.

Do I have an appropriate lens for what I want to do, or would I be
better off with the SAL50M28?

The 50mm will need you to be even closer to the insect. I don't think
the DOF will change enough to matter much.

Insects are challenging - I'm hopeless at it...

Using the same lens as your 100 f/2.8 (the Minolta version - same thing
optically):
http://gallery.photo.net/photo/9256748-lg.jpg

Note this was not at 1:1. The DOF, as you can see does not make the
entire insect in-focus.

This guy's pretty good (!) at insects. Still not totally in focus:
http://photo.net/photodb/folder?folder_id=768656
He uses a 65mm lens.

--
gmail originated posts filtered due to spam.

On 01/15/2011 07:36 PM, Don Tuttle wrote:
I would like to be able to photograph insects (e.g., bees) up close
with my Sony A33 and Sony SAL100M28 macro and also get the entire
insect to be in focus. With this lens, in order to get depth of field
that will enable me to get the insect body in focus, I have to move
several inches from the insect. DOF is virtually nonexistent at
minimum focus distance (.352 meters). At that focal distance, the DOF
is zero up thru f11. At f16-f32 DOF is only 1 to 2 mm, which is not
enough DOF to get enough of the insect in focus.

Do I have an appropriate lens for what I want to do, or would I be
better off with the SAL50M28?

In macrophoto the DOF is about independent from focal length and is in
practice related to the size ratio between the subject and its image on
the sensor(*). In other words, with a shorter lens, you'll have to get
closer but it won't improve your DOF. You can interpret that as having
your in-focus subject within a parallelepiped with a fixed aspect ratio
(once you have set aperture): it will become thinner as you reduce the
height and width when closing in.

The concept of DOF is however a bit blurry nowadays. It used to be based
on a circle of confusion equal to 1/1780th of the sensor diagonal, but
now with pixel peeping the circle of confusion for many people is one
pixel on the sensor which is, on current cameras, 3 to 4 times smaller.
Your pictures may look out of focus when pixel-peeping but OK when
looking them from far enough to see the full frame.

From what has been said above, you can infer that if you don't try to
get too close you can get your insect in acceptable focus. My personal
technique is to keep the insect to at most 1/3 of the frame and shoot it
centered. This gives more DOF and lets the camera use its most accurate
AF point. I reframe in post-processing to make a more aesthetically
pleasing photo (with 14 Mpixels, you can crop a lot).


(*) a corollary is that since, to produce a picture where the insect
fills the whole frame, you need a bigger image on a 24x36mm sensor than
on an APS-C one, and a much bigger image on an APS-C sensor than on a
compact camera, you have very little DOF on full-frame cameras, slightly
more on APS-C cameras, and a very deep one on compact cameras.

--
Bertrand

Don Tuttle wrote:

I would like to be able to photograph insects (e.g., bees) up close
with my Sony A33 and Sony SAL100M28 macro and also get the entire
insect to be in focus. With this lens, in order to get depth of field
that will enable me to get the insect body in focus, I have to move
several inches from the insect. DOF is virtually nonexistent at
minimum focus distance (.352 meters). At that focal distance, the DOF
is zero up thru f11. At f16-f32 DOF is only 1 to 2 mm, which is not
enough DOF to get enough of the insect in focus.

Do I have an appropriate lens for what I want to do, or would I be
better off with the SAL50M28?

I don't want to get involved in the DSLR / ultrazoom flame wars, but if
you want more DoF for macro, the smaller sensor of the bridge camera can
be an advantage. Although the built in macro mode can be limited to
wide angle, if you use a supplementary close up lens that screws on the
front like a filter, e.g. Raynox, you can get more visible DoF for the
same print magnification at a reasonable working distance. If the
light's good, you can keep low ISO, and noise isn't too much of a problem.

Another technique is focus stacking - take multiple shots, varying the
focus slightly, and blend them in PP - you need the insect to keep still,
though I've heard of people putting them in the freezer for a few
minutes to chill them out!

Don Tuttle wrote:
I would like to be able to photograph insects (e.g., bees) up close
with my Sony A33 and Sony SAL100M28 macro and also get the entire
insect to be in focus. With this lens, in order to get depth of field
that will enable me to get the insect body in focus, I have to move
several inches from the insect. DOF is virtually nonexistent at
minimum focus distance (.352 meters). At that focal distance, the DOF
is zero up thru f11. At f16-f32 DOF is only 1 to 2 mm, which is not
enough DOF to get enough of the insect in focus.

Do I have an appropriate lens for what I want to do, or would I be
better off with the SAL50M28?

Interesting lens the way it extends:
http://www.photozone.de/sony-alpha-a...78-sony_100_28
You'll have to stop down to f/32 for more DOF although that will lose
critical sharpness from diffraction, that's your goal as stated. Adding
a 1.4x teleconverter with give f/64 and increase your working
distance... and impact image quality, plus you'll probably need flash to
get usable shutter speeds. Check out what happens to mtf at f/22:
http://www.photozone.de/sony-alpha-a...100_28?start=1

Another thing to check is whether the minimum aperture changes at close
focus. If it still allows an f/2.8 setting, that means the real aperture
numbers will be larger per this formula: f-number(mag+1).

32 (1+1) = f/64

Now, if you want to try focus stacking, then you can use an optimal
aperture of f/11, and if that calculation needs to be added, you'll want
to use about f/5.6 to get a final f/11 and it will take probably 50
frames to capture the maximum detail. It is sometimes possible to take a
quick succession of hand held focus stacks, although very difficult!
because you'll want to be stopped down a fair bit and shutter speed will
be a problem plus most insects will fidget unless you catch them
sleeping in the morning when it's cold.