
Why Leaf Shutter Lenses Matter (2013) - Lio
http://www.kern-photo.com/2013/01/why-leaf-shutter-lenses-matter/
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haikuginger
Quick explanation of the groundwork for this piece:

Typical DSLR shutters are focal-plane shutters, which mean they open and close
directly above the image sensor. They are mechanically primed, and when
triggered, the "first curtain" opens across the sensor, followed by the second
curtain after a brief delay corresponding to the relevant exposure time.

In the case of very fast shutter speeds (depending on the camera, typically
1/250s or faster), the second curtain begins its traversal of the sensor
_before_ the first curtain is fully open. This means that every portion of the
sensor is exposed for the appropriate amount of time, but that not every
portion of the sensor is exposed _at the exact same time_. This is due to
mechanical limitations, and is hard to get around.

In general, this isn't an issue. However, flashes and studio strobes are of a
very short duration - often 1/10000th of a second or less. In the case of a
focal plane shutter, this can mean that not the entire sensor will be exposed
to the flash's light, causing a stripe in the final image.

There have been various ways to compensate for this - for example, high-speed
flash synchronization that fires the flash at lower power levels several times
during the exposure such that each portion of the image sensor is properly
exposed.

In earlier DSLRs (Nikon D50 and D70 models with the 6MP Sony CCD), a "digital
shutter" was used, which allowed for native flash syncing at high speeds - the
mechanical shutter only operated up to its "sync limit" of 1/250, and the
digital shutter took over at speeds higher than that.

In comparison, leaf shutters always open fully, which means that there's a
period where, if a flash is fired, the entirety of the sensor will be exposed
evenly to that flash. Because of the very short duration of the flash, shutter
speed does not affect how much of the flash's light falls on the sensor, and
can be used to control for background light instead, as compared to aperture
and ISO controls that would affect both background light and the impact of the
flash's light in the overall image.

~~~
maxxxxx
I could never figure out why we generally focal plane shutters now. I suppose
there must be some advantage to them.

Edit: Thanks a lot for the explanations

~~~
stan_rogers
It boils down to higher effective shutter speeds. Barring a global electronic
shutter (such as was in the Nikon D100 and D70 CCD cameras), you can get much
faster shutters (or, really, lower exposure times at the sensor) with a focal
plane shutter than you can with a leaf shutter. The limiting factor is not how
much stuff you can move how far in how little time, but how narrow you can
make the moving slit. Not only does a leaf shutter need to fully open and
fully close to create the exposure, it needs to do it quickly enough to have a
negligible effect on the len's aperture (both for exposure and for depth of
field control reasons).

That speed does come at a cost, though, since there is a point at which you
cannot expose the entire sensor at once. (That's also true of rolling
electronic shutters, by the way.) Flash needs to be worked around in various
ways, and anything moving in the frame will suffer distortion.

I still have good reasons to use an old Nikon in some circumstances (lower
resolution requirements, high ambient light levels and flash). While they do
have focal plane shutters, they only go up to 1/250 of a second. Faster than
that and you're using a global electronic shutter, which doesn't reduce
effective aperture when the lens is wide-open or nearly so, but still expose
the entire sensor in one go. That means I can use a higher shutter speed to
control the ambient exposure while using very low flash power. That means no
waiting for recycling or carrying around large amounts of lighting equipment.

~~~
mark-r
Aren't there modern sensors that have electronic shutters? Why isn't this
capability found on newer cameras?

~~~
maxxxxx
Electronic shutters don't work well with fast moving objects. You can get
distortion. I think they don't read out the whole sensor at once.

~~~
stan_rogers
The global shutter on the Nikon 6MP CCD sensor was really global, not like the
rolling electronic shutter on a CMOS sensor. You got an all-at-once still, the
electronic equivalent of a leaf shutter; the current scanning versions are
basically a "no moving parts" version of a traditional focal plane shutter.

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michrassena
The other comments have done a good job of explaining what leaf-shutters are
and the differences between leaf shutters and focal plane shutters.

Flash photography is a balancing act between the light that comes from the
flash strobes and the light of the environment. It's very popular these days
to take portraits where the background is blurred, often significantly, but
the subject is still in sharp focus. Background blurring is a product of the
physical aperture of the lens and the distance to the subject. Opening the
lens up to create more blur in the out-of-focus areas requires that the
shutter speed be increased to compensate for the additional light entering the
camera. A typical sunny day outdoor exposure might be f/2.8 at 1/3200s. This
is far beyond the typical sync speed of a focal plane camera.

One alternative method is to place neutral density filters (darkening filters)
over the camera lens (limiting the light entering the lens, but not increasing
the depth of focus). The disadvantage is this method requires more light be
generated by the strobes, shortening battery life, and generating more heat,
and possibly more discomfort for your subjects.

As an aside, leaf shutters used to be quite commonplace until SLRs became
popular (Leaf shutter SLRs were complicated and hard to repair). Even some of
the most rudimentary leaf-shutter cameras from the 1950s could sync at higher
speeds than the latest high-end SLRs.

~~~
freetime2
> Flash photography is a balancing act between the light that comes from the
> flash strobes and the light of the environment. It's very popular these days
> to take portraits where the background is blurred, often significantly, but
> the subject is still in sharp focus. Background blurring is a product of the
> physical aperture of the lens and the distance to the subject. Opening the
> lens up to create more blur in the out-of-focus areas requires that the
> shutter speed be increased to compensate for the additional light entering
> the camera. A typical sunny day outdoor exposure might be f/2.8 at 1/3200s.
> This is far beyond the typical sync speed of a focal plane camera.

I found this to be a very helpful explanation of why I would want to use a
leaf shutter. TFA explains it in terms of your flash "competing with ambient
light", and shows a lot of sample pictures of a properly exposed subject over
an underexposed background. While visually interesting, it's probably not an
effect I would want to go for when taking pictures of my kids.

Putting it in terms of being able to use the largest aperture possible in
broad daylight makes more sense. There have been plenty of situations where I
have been shooting in harsh daylight at f/1.7, and would have liked to use my
pop-up flash to soften the light a bit, but the camera doesn't allow it due to
max sync speed limitations.

Unfortunately it doesn't sound like leaf-shutter lenses are the solution for
me, as the $1800 minimum for a single leaf shutter lens is more than I am
willing to pay for an entire camera + lens setup.

~~~
michrassena
If you really wanted to use a leaf shutter lens on a digital SLR, the price
point isn't quite so high. I've adapted a Mamiya 645 leaf shutter lens to
Nikon full frame using a cheap third party adapter. A small selection of leaf
shutter lenses were made for the 645 (standard lenses used the body's focal
plane shutter with a sync of 1/60s). The 55 f2.8, 70 f2.8 and 150mm f3.8 were
all made with an integrated shutter for full flash sync at up to 1/500s. I see
the 70mm selling for around $115 these days.

That said, they're a real pain the neck to actually use, since you have to
compose and focus, cock the shutter on the lens, release the shutter on the
camera body (bulb mode or a long exposure), then fire the shutter on the lens
using a cable release, then after the body is finished, open up the lens
again.

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huy-nguyen
I take casual snaps of people in daylight with fill flash a lot. I used to
have an interchangeable lens camera (which is limited to roughly 1/200 sync
speed) but I sold them all to switch to Fuji's X100 camera line because of its
leaf shutter. The X100's leaf shuter allows you to sync at 1/1000s at f2.
That's a 2- to 3-stop advantage over a focal plane shutter in the typical
interchangeable lens camera so you can have a much smaller and portable flash
and still have the same illuminating power.

~~~
Lio
I have both an original X100 and an X100F for this reason. Probably my
favourite camera.

The X100F is interesting for having both a leaf shutter and an electronic
shutter.

Also good for high speed flash are the old Nikon 6MP cameras. I have an old
D70 somewhere that I've used for high speed sports portraits.

Apart from the small image size it's a great camera. You can sync from the hot
shoe at any speed, although practically this is limited by the t.5 time of
your flash gun. For a Nikon SB-800 and the sort of power I was using that was
about SS 1/2000.

~~~
stan_rogers
For anyone considering this, please note that if the flash is iTTL-compatible,
you'll be limited to 1/500s. (This is because of the flash duration at full
power of the Nikon iTTL flashes of the same vintage.) A "dumb" flash will sync
at all speeds since the centre pin is live at all times and the flash doesn't
talk to the camera through any other pins; your t0.5 and trigger become the
limiting factors. (Many radio triggers will not work reliably above 1/500, and
only a very few are usable above 1/1000\. A shoe-mounted flash or a cable
connection doesn't have a trigger-speed limitation as such.)

If only that 6MP sensor had a broader ISO range. If you're not shooting for
the big print, 6MP goes a long way.

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klodolph
I have owned a number of leaf shutter lenses over the years, most on cheap
rangefinders like the Canonet. There was a short period of time where you
could ditch the SLR, ditch the interchangeable lens, and pay very little money
for beautiful 1/500 flash sync. It really does open up an entire world. I went
around outside with some gels and complementary filters. I had no idea that
leaf shutters had gotten three times faster.

That said, 1/500 is actually very good at close-ish portrait distances, like 3
meters or so. Take a typical flash unit with GN 36 and ISO 100 sensitivity.
Underexposing ambient light by one stop in direct sunlight means about 1/500
at f/11, so you need a guide number of (3 meters) x (11 f-number) = 33.

Incidentally, digital cameras with electronic shutters can do this much
cheaper, but for various reasons nice cameras do not generally use electronic
shutters.

And you can get leaf-shutter lenses for fairly cheap. You can even get
fantastic, beautiful leaf-shutter lenses with sharp images and big apertures
for cheap. Old photo studios have been getting rid of them in the switch to
digital. These lenses are amazing, they just don't work with the camera system
you want to use them with.

~~~
Finnucane
>Incidentally, digital cameras with electronic shutters can do this much
cheaper, but for various reasons nice cameras do not generally use electronic
shutters.

I admit that I haven't thought about this for a while (I don't actually use
flash a lot) but my impression was that most focal-plane shutters are rolling
shutters or moving slits of some sort; at high speeds there's no point where
the frame is completely open. Whereas leaf shutters have that at all speeds.

Most of the leaf-shutter lenses I have are for my old MF and LF film cameras.
He's right about them being like watches. One real issue with using older
lenses is that there aren't a lot of good repair folks left who know how to
service them. I've got a real nice vintage Konica rangefinder with a busted
shutter and there's literally one guy who might have the parts.

P.S. see above comment for better explanation.

~~~
klodolph
Some electronic shutters are global, and they work like leaf shutters. The D40
is like that and you can officially sync at 1/500, but I have used flash at
much higher speeds like 1/2000.

The D40 sensor is not great by today’s standards, though.

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dmourati
I learned this trick from @strobist, David Hobby. I used it to great effect in
skateboarding photography during mid day. Turning day into night.
[https://www.flickr.com/photos/dmourati/6649727333/in/photoli...](https://www.flickr.com/photos/dmourati/6649727333/in/photolist-
aqid3C-8GwQPZ-b8BAgg-apYZU1-apYZqs-apYZ6G-aqixLE-aqizzJ-aqfV3V-apTrsG-
apQq8p-apMZS1-aqisXW-aqfFuM-aqiqC5-aqfAr6-aqfxKc-aqfD3P-8GwPRc-8GwQaX)

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mikeytown2
Surprised I don't see any comments about High Speed Sync. The tech behind
pulsing the strobe to match the shutter is spot on these days. Most modern
flashes have HSS which solves this issue, I don't see the need for a Leaf
Shutter when your flashes support HSS.

~~~
Lio
Well, one problem with HSS used to be that it reduced the effective
power/range of the flash gun.

The strobe has spread the energy stored in its capacitors across a series of
small flashes instead of one large one.

Has that been solved now for small strobes (flash guns)?

By using a leaf shutter and a real high sync speed an X100 can use a tiny on-
axis fill to do the work of a larger pulsing HSS system.

~~~
mikeytown2
All true points. The x100 is a fixed lens camera though. HSS flashes are
fairly cheap these days; I have 3 Flashpoint ones (low cost Chinese), but I
usually only need one. Nice thing is the same flash works (TTL & HSS) with
Canon, Nikon, Sony, Fuji, Olympus, and Panasonic. Leaf shutters are nice but
the added cost is too high :/

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ape4
So I guess the interface (API) between the lens and camera has a way of
saying: I'll take over the shutter function? Would like to know.

~~~
jzwinck
There is often an interface between the lens and camera. It's different for
each camera maker usually. It may be mechanical, electronic, or both. It may
provide significant power to the lens, a data path for firmware updates
(Olympus), or even mechanical rotation to drive unpowered focus mechanics in
the lens (Nikon).

Various lens parameters can be communicated to the camera, including static
lens capabilities but also dynamic factors such as the current manual focus
distance, current manual aperture, or focus mode.

So yes, they could do that. But some systems would be designed with the
assumption that all lenses will have shutters, or that the user of lenses with
shutters will set the camera shutter to remain open.

Sometimes the shutter release "button" is part of the lens instead of the
camera.

