About 5:1 magnification, f/4, 1 to 1 crop of a
single source image from above:
Good detail but starting to show the effects of
diffraction.
single source image from above:
Good detail but starting to show the effects of
diffraction.
Lens: Olympus 38 mm f/2.8 auto bellows lens
Vintage: 1980 - ??
Lens Mount: Olympus OM mount
Needed Adapters: To make this lens work on a non-Olympus lens mount, you will need a
couple different adapters. First, I use an OM to 4/3 adapter. That will allow one to use an OM
lens on new Olympus 4/3 mount dSLR's. Second, I use cheap (5-piece) extension tubes from
eBay. These have screw-on lens mounts on the front and back. If you buy one for a 4/3 mount
and one for your camera's lens mount, you can take the female 4/3 mount and screw that to
the male lens mount for your camera. hook them all together and you are ready to go. The
only problem is that some of the cheap extensions have the opposite threading and you may
end up both pieces having a male thread. I would suggest that you buy them from the same
supplier (and keep your fingers crossed). If that happens, all is not lost. I have found a 57mm
step-down ring that will fit into the female adapter and that can be adapted to a reversing ring
(I had to do this to make a Minolta adapter, so I know it works).
couple different adapters. First, I use an OM to 4/3 adapter. That will allow one to use an OM
lens on new Olympus 4/3 mount dSLR's. Second, I use cheap (5-piece) extension tubes from
eBay. These have screw-on lens mounts on the front and back. If you buy one for a 4/3 mount
and one for your camera's lens mount, you can take the female 4/3 mount and screw that to
the male lens mount for your camera. hook them all together and you are ready to go. The
only problem is that some of the cheap extensions have the opposite threading and you may
end up both pieces having a male thread. I would suggest that you buy them from the same
supplier (and keep your fingers crossed). If that happens, all is not lost. I have found a 57mm
step-down ring that will fit into the female adapter and that can be adapted to a reversing ring
(I had to do this to make a Minolta adapter, so I know it works).
Preferred Mounting: Normal (not reversed).
Filter Thread: 49 mm, but recessed fron the front of the lens and only useful for mounting
the lens cap.
the lens cap.
Controls: This lens has two controls - aperture setting and an a focus ring that allows you to
adjust the extension for fine adjustment of focus. This lens has the capability of having
automatic aperture control with an Olympus body, although it loses that ability when adapted to
other lens mounts.
adjust the extension for fine adjustment of focus. This lens has the capability of having
automatic aperture control with an Olympus body, although it loses that ability when adapted to
other lens mounts.
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Resolution vs Aperture: This lens is at its
sharpest at f/4. For the focal length and expected
magnification range, The relatively large
sharpest aperture will provide sharp and detailed
images.
The most detailed aperture is f/2.8 although the
resolution is only minimally greater than that at
f/4. I don't see any real advantage of using f/2.8
because of this.
sharpest at f/4. For the focal length and expected
magnification range, The relatively large
sharpest aperture will provide sharp and detailed
images.
The most detailed aperture is f/2.8 although the
resolution is only minimally greater than that at
f/4. I don't see any real advantage of using f/2.8
because of this.
Corner Sharpness vs Aperture: There is a
moderate amount of peripheral fuzziness seen at
f/2.8. At all apertures above this, the field is
commendably flat, about 15% at f/4 and less than
10% above that.
This testing was performed in the worst case
scenario at the lowest magnification I can make
with this lens, about 2:1. These numbers will tend
to improve for all apertures as the magnification
increases.
moderate amount of peripheral fuzziness seen at
f/2.8. At all apertures above this, the field is
commendably flat, about 15% at f/4 and less than
10% above that.
This testing was performed in the worst case
scenario at the lowest magnification I can make
with this lens, about 2:1. These numbers will tend
to improve for all apertures as the magnification
increases.
Sharpness and Resolution vs Magnification:
This lens produces very sharp and detailed
images from a magnification of 2:1 to 7:1. At 2:1
there are very few lenses that outperform this
lens and those that do, only by a relatively small
margin.
At 7:1, this lens will resolve details down to about
2 um at the higher end of its magnification range.
This is good, but can be outdone by shorter
focal length bellows lenses and microscope
objectives. The increase in resolution with these
other lenses will come at the expense of shorter
working distance.
The corner sharpness is extremely good across
the usable magnification range.
This lens produces very sharp and detailed
images from a magnification of 2:1 to 7:1. At 2:1
there are very few lenses that outperform this
lens and those that do, only by a relatively small
margin.
At 7:1, this lens will resolve details down to about
2 um at the higher end of its magnification range.
This is good, but can be outdone by shorter
focal length bellows lenses and microscope
objectives. The increase in resolution with these
other lenses will come at the expense of shorter
working distance.
The corner sharpness is extremely good across
the usable magnification range.
Street Price: $300 - $700 in good used condition. Prices vary a lot online, shop around.
Chromatic Aberration: This lens shows minimal color fringing in the center
(about 0.30 - 0.60 pixels) and mild in the periphery (0.20 - 1.2 pixels). On the
periphery, it stays below 1 pixel at all but the highest magnification. Anything
below 1.0 pixel is good and only minimally visible.
(about 0.30 - 0.60 pixels) and mild in the periphery (0.20 - 1.2 pixels). On the
periphery, it stays below 1 pixel at all but the highest magnification. Anything
below 1.0 pixel is good and only minimally visible.
Image Contrast: Image contrast is very good, typical for high-quality bellows
lenses.
lenses.
Flare: No significant flare is evident during lens testing.
Conclusion: This is a bellows lens that performs well from 2:1 to about 7:1. Its combination of high resolution,
flat field, and relative lack of chromatic aberration make it hard to find a lens that will outperform it in the lower
magnification range. In the higher magnification range, you will have to go to shorter focal length bellows lenses
or microscope objectives to significantly outperform it ( at the expense of less working distance).
It is a strong all-around performer that I highly recommend. It is also commonly available on the internet (used
camera stores and eBay). The only problem that I can see is that it can be a little tough adapting this lens to other
lens mounts, but one that is not insurmountable with the right equipment.
flat field, and relative lack of chromatic aberration make it hard to find a lens that will outperform it in the lower
magnification range. In the higher magnification range, you will have to go to shorter focal length bellows lenses
or microscope objectives to significantly outperform it ( at the expense of less working distance).
It is a strong all-around performer that I highly recommend. It is also commonly available on the internet (used
camera stores and eBay). The only problem that I can see is that it can be a little tough adapting this lens to other
lens mounts, but one that is not insurmountable with the right equipment.
Basic Function: Requires a bellows for setting focus and magnification. Fine focus can be
had with the focus/extension ring on this lens.
had with the focus/extension ring on this lens.
Appearance:
Aperture: 6 blades.
Image Samples:
About 2:1 magnification, f/4, focus stack of 18 images, resized
About 2:1 magnification, f/4, 1 to 1 crop of single
source image from above:
Good pixel level detail at 2:1. No problems here.
source image from above:
Good pixel level detail at 2:1. No problems here.
Performance: Sharpness vs Magnification:
This is a new graph that I recently constructed. I
have 4 lines that represent levels of performance
from outstanding (top) to fair (bottom). This
shows where this lens fit into the hierarchy that I
have created.
The Olympus 38mm shows sharpness
performance that varies from very good at the
low-end to good at the high-end of its
magnification range.
This is a new graph that I recently constructed. I
have 4 lines that represent levels of performance
from outstanding (top) to fair (bottom). This
shows where this lens fit into the hierarchy that I
have created.
The Olympus 38mm shows sharpness
performance that varies from very good at the
low-end to good at the high-end of its
magnification range.
Performance: Resolution vs Magnification:
This is a new graph that I recently constructed. I
have 4 lines that represent levels of performance
from outstanding (top) to fair (bottom). This
shows where this lens fit into the hierarchy that I
have created.
The Olympus 38mm shows resolution
performance that varies from very good at the
low-end to fair/poor at the high-end of its
magnification range.
This is a new graph that I recently constructed. I
have 4 lines that represent levels of performance
from outstanding (top) to fair (bottom). This
shows where this lens fit into the hierarchy that I
have created.
The Olympus 38mm shows resolution
performance that varies from very good at the
low-end to fair/poor at the high-end of its
magnification range.
About 5:1 magnification, f/4, stack of 24 images, resized: