Lens: Spiratone 35 mm f/3.5 enlarging lens
Vintage: uncertain - 60's or 70's?
Lens Mount: M39
Needed Adapters: This lens is easy to adapt to most cameras and just requires an M39 adapter. I
just screw the lens into the backside of the adapter. This does make adjusting the aperture a little
more difficult (since it will be inside the bellows when the lens is mounted. Just have to do it before
you mount the lens onto the bellows.
just screw the lens into the backside of the adapter. This does make adjusting the aperture a little
more difficult (since it will be inside the bellows when the lens is mounted. Just have to do it before
you mount the lens onto the bellows.
Preferred Mounting: Reversed.
Filter Thread: about 27 mm (I don't have an adapter and didn't use them).
Controls: This lens only has an aperture control.
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Resolution vs Aperture:
The sharpest aperture is f/4 and the most
resolving aperture is f/4. I prefer to use f/4 for
most images because of the sharpness and
resolution. You could also argue for using f/5.6
(at least at lower magnification) because of the
improved corner sharpness with little loss in
resolution (see next section).
The sharpest aperture is f/4 and the most
resolving aperture is f/4. I prefer to use f/4 for
most images because of the sharpness and
resolution. You could also argue for using f/5.6
(at least at lower magnification) because of the
improved corner sharpness with little loss in
resolution (see next section).
Corner Sharpness vs Aperture:
The corner performance of this lens is only so-so
at the sharpest aperture of f/4. At higher
magnification, f/4 improves enough to not be a
problem. If you want improved corner sharpness,
f/5.6 is a good compromise.
(Testing done at 1.7:1 magnification. Numbers at
each aperture setting will tend to improve as the
magnification is increased and worsen as the
magnification is decreased.)
The corner performance of this lens is only so-so
at the sharpest aperture of f/4. At higher
magnification, f/4 improves enough to not be a
problem. If you want improved corner sharpness,
f/5.6 is a good compromise.
(Testing done at 1.7:1 magnification. Numbers at
each aperture setting will tend to improve as the
magnification is increased and worsen as the
magnification is decreased.)
Sharpness and Resolution vs Magnification:
This lens shows decent sharpness and resolution
across its usable magnification range of 1.7x -
5.7x. Compared to other lenses in its
magnification range - better quality enlarging
lenses, bellows lenses - this lens does not tend
to produce as good sharpness and resolution.
This lens has so-so corner performance at f/4,
but it does improve as the magnification
increases.
At maximum magnification, this lens can resolve
details down to about 2um.
This lens shows decent sharpness and resolution
across its usable magnification range of 1.7x -
5.7x. Compared to other lenses in its
magnification range - better quality enlarging
lenses, bellows lenses - this lens does not tend
to produce as good sharpness and resolution.
This lens has so-so corner performance at f/4,
but it does improve as the magnification
increases.
At maximum magnification, this lens can resolve
details down to about 2um.
Street Price: ~$5 in good condition (mine was new old stock).
Chromatic Aberration: This lens show minimal color fringing in the center and even better on the periphery
(0.010 - 0.040%). Less than 0.04% is considered insignificant. This lens shows minimal longitudinal CA on out
of focus details and no significant long CA at the focus plane (see image below). Not bad for $5.
(0.010 - 0.040%). Less than 0.04% is considered insignificant. This lens shows minimal longitudinal CA on out
of focus details and no significant long CA at the focus plane (see image below). Not bad for $5.
Image Contrast: Image contrast is not the strong suit of this lens. I think that this may be the price of a $5 lens.
The lenses don't appear to be coated like higher quality lenses will be. this problem can be mostly fixed in
post-processing.
The lenses don't appear to be coated like higher quality lenses will be. this problem can be mostly fixed in
post-processing.
Flare: There is mild flare present with this lens during testing. Again, probably the result of no lens coatings.
Careful masking of stray light is essential.
Careful masking of stray light is essential.
Conclusion:
This is a fairly easy to find lens that tends to be cheap (I paid $5, free shipping). For the price, you
can't do much better. If you are willing to pay a little more, a good quality used short focal length
enlarging lens will perform significantly better in terns of resolution, sharpness. It is easy to adapt to
a bellows with an M39 adapter.
This lens has so-so to good corner performance at the sharpest aperture of f/4, although stopping
down to f/5.6 will improve the number significantly with little loss in resolution. This lens has
extremely good CA performance in the corners. It has very little longitudinal CA on out-of-focus
details - better than I was expecting.
The main two flaws of this lens are probably both related to the lack of lens coatings - a little flare
and relatively low contrast. The contrast is mostly correctable with post-processing. The flare can
be lessened with careful lighting and masking of stray light. This lens has a magnification range of
about 1.7:1 to 5.7:1 on a bellows. That means a narrow depth of field and will generally require
focus stacking.
Despite the flaws, the images that you can produce with this $5 lens are perfectly acceptable. If you
have a few more dollars (say $25 - $35), a used 35 mm Schneider enlarging lens will significantly
outperform this lens.
This is a fairly easy to find lens that tends to be cheap (I paid $5, free shipping). For the price, you
can't do much better. If you are willing to pay a little more, a good quality used short focal length
enlarging lens will perform significantly better in terns of resolution, sharpness. It is easy to adapt to
a bellows with an M39 adapter.
This lens has so-so to good corner performance at the sharpest aperture of f/4, although stopping
down to f/5.6 will improve the number significantly with little loss in resolution. This lens has
extremely good CA performance in the corners. It has very little longitudinal CA on out-of-focus
details - better than I was expecting.
The main two flaws of this lens are probably both related to the lack of lens coatings - a little flare
and relatively low contrast. The contrast is mostly correctable with post-processing. The flare can
be lessened with careful lighting and masking of stray light. This lens has a magnification range of
about 1.7:1 to 5.7:1 on a bellows. That means a narrow depth of field and will generally require
focus stacking.
Despite the flaws, the images that you can produce with this $5 lens are perfectly acceptable. If you
have a few more dollars (say $25 - $35), a used 35 mm Schneider enlarging lens will significantly
outperform this lens.
Basic Function: Requires extension tubes or bellows to focus.
Appearance:
Aperture: 5 blades.
Image Samples:
About 2.5:1 magnification, f/4, focus stack of 25 images, resized:
About 2.5:1 magnification, f/4, 1 to 1 crop of a
single source image from above:
OK pixel level detail for the magnification, but a little
softness is present.
single source image from above:
OK pixel level detail for the magnification, but a little
softness is present.
About 5:1, f/4, focus stack of 29 images, resized:
About 5:1 magnification, f/4, 1 to 1 crop of a
single source image from above:
Getting quite fuzzy at the pixel level. Doesn't look bad
when resized to a normal size image.
single source image from above:
Getting quite fuzzy at the pixel level. Doesn't look bad
when resized to a normal size image.
Distortion: There is no visible distortion with this lens.
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 Spiratone 35/3.5 shows sharpness
performance varying from good at low
magnification to poor at its higher end. Especially
at higher magnification, other lenses will perform
significantly better.
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 Spiratone 35/3.5 shows sharpness
performance varying from good at low
magnification to poor at its higher end. Especially
at higher magnification, other lenses will perform
significantly better.
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 Spiratone 35/3.5 shows resolution
performance varying from very good at low
magnification to fair at its higher end. Especially
at higher magnification, other lenses will perform
significantly better.
The slight bump in the ratings from sharpness to
resolution is likely related to this lens being at its
best at f/4. That's a pretty large aperture and
that tends to improve resolution compared to the
sharpness.
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 Spiratone 35/3.5 shows resolution
performance varying from very good at low
magnification to fair at its higher end. Especially
at higher magnification, other lenses will perform
significantly better.
The slight bump in the ratings from sharpness to
resolution is likely related to this lens being at its
best at f/4. That's a pretty large aperture and
that tends to improve resolution compared to the
sharpness.