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I was unimpressed by the first advertisements and reviews of the Contax AX
body, which autofocuses by changing the lens-to-film distance. Contax seemed like
a niche player desperately trying to tack a convoluted AF system onto their
manual focus lenses. However, I was interested in high quality construction and I
did some research on Contax equipment. I became impressed, not only by the
quality of the Carl Zeiss T* lenses, but by the cameras themselves. As a result I
added a Contax system to my Canon EOS. Here are my thoughts on the AX.
Construction
The AX is a solid camera. It is heavy and big. It weighs 1080 grams without
the battery. Particularly, it is deep (72 mm from front to back) in order to
accommodate the camera within the camera that must move back and forth to
accomplish autofocusing. It is well constructed with high quality materials. The
finish is beautiful and smooth. The controls have a very solid feel with just the
right amount of resistance for me. It operates positively with good feedback to
the photographer. There is no doubt about what the camera is doing. All of the
controls (mostly conventional knobs and levers) are really electronic rather than
mechanical. There are no loose levers and no free play or wobble in the knobs.
The construction is positive and solid throughout. To achieve this Contax starts
with aluminum alloy chassis that is quite rigid. The top cover is titanium.
Autofocus
Even without autofocus, the AX would be an excellent camera. The autofocus
system is the center of attention because of its unique approach to focusing in
35 mm photography. Adjusting the distance between the lens and the film plane by
moving the film plane is old hat to large format users, but the AX is the first
application of this method to the 35mm format. The principle is simple, in order
to focus on a subject, one can either use the lens to focus or one can move the
film plan. In the AX the body does most of the focusing work, not the lenses.
It works like this. In order to focus, the film plane moves back and forth.
But for the system to work, the film plane must be accompanied in its travels by
the mirror box and the prism/viewfinder assembly. The distance that the film
plane moves must be very precise.
There are two big problems Kyocera had to master: (1) how to move the assembly
precisely enough; (2) how to move the assembly quickly enough. Relying on its
extensive expertise with ceramics, Kyocera developed a ceramic guide rod for this
inner assembly to ride on. A ceramic tube slides along the guide rod, providing
the necessary precision. Ceramics are almost as hard as diamond, ensuring long
life and continuing precision. Thus, the assembly can move precisely enough.
The second big question that strikes almost everyone is how in the heck can
you move the weighty assembly fast enough for effective autofocus? The assembly's
movement back and forth along the guide rod is powered by a USM (ultrasonic)
motor. Being a Canon user, I am familiar with Canon's use of ultrasonic motors in
its lenses. They are noted for high torque and very precise placement. The AX AF
motor is low-rotation motor that requires only 1.5 rotations of the motor shaft
to move the assembly from its front to back positions.
Still, the fact is that an autofocus lens need only move a few lens elements
or maybe a couple of lens groups. These weigh far less and have to travel much
smaller distances than the heavy film plane / mirror box / pentaprism assembly
insider the AX. No matter how well engineered, how can such a system really
operate quickly and precisely enough to be effective?
I was a doubter. When I bought my AX, I thought that the autofocus would only
be useful in a few selected situations where little fast action was necessary -
scenic and still life photos. After having used the AX, I am amazed that it is as
fast and accurate as it is. It is not as fast as my Canon EOS 1N, but it is
surprisingly close.
The British photography publication "Photon," compared the AX to a Minolta
Dynax 9xi and found that the AX performed as well as the Minolta. The review
stated that the AX proved just as capable of tracking action, catching suddenly
framed images and selecting the correct focus setting.
Special Focus Operations and Limitations
The AX has special advantages and limitations regarding autofocus. Both the
advantages and limitations are related to the 10mm of travel through which the
film plane moves back and forth.
For macro work, the 10mm movement is like having a 10mm extension tube
available at the flick of a lever. This means that normal lenses can operate like
close focusing lenses and that wide angle lenses can act like macro lenses. Even
with the Carl Zeiss macro lenses, there is an advantage because the 10mm
extension can result in even greater than normal magnification.
One limitation is that the 10mm movement of the film plane limits the amount
of focusing travel available. The longer the lens, the more travel is required to
focus at close distances. So, for example, the 10mm travel is used up before the
180mm lens can focus to its normal closest focusing distance.
The solution is one of those things that sounds much more complicated on paper
than in practice. To focus close with longer lenses, it is necessary to rough
focus first. This is not a big deal (particularly to someone used to focusing
manually), but it is less convenient than other autofocus systems.
The second limitation is a little more complex - the use of lenses with a
floating group. Lens designers developed the use of floating groups to maintain
sharpness at close focusing distances. As the subject to camera distance
decreases, and the lens is rotated to a closer focusing setting, the floating
group moves to maintain sharpness. Remember that with the AX, the lens is
normally set to infinity, so that the floating group does not have a chance to
move to maintain sharpness at closer focusing distances. So.... a lens with a
floating group must also be rough focused before allowing the AX's AF to take
over.
The viewfinder contains a display that shows the position of the film plane -
whether it is in its base position or the degree of extension along its 10mm
travel. This is quite useful, so that the photographer knows the amount of
extension. This is helpful for close focusing and with lenses having a floating
group. The viewfinder also has an in-focus indicator.
Autofocus control is flexible. On the back right side of the camera there is
an AF button surrounded by a switch. The switch determines whether the AF is
active when the shutter button is partly depressed or when the AF button is
pushed. On the top right side of the camera is a lever that determines AF mode -
either single shot, continuous tracking, manual focusing or locked at the full
10mm extension for macro work. The camera also uses an AF aid light for dark
situations.
Operation
With the exception of the autofocus system, the operation of the AX is modern
in function but classic in control layout. There is a shutter speed dial for
exposures from 4 seconds to 1/4000. The shutter speed extends from 32 seconds to
1/6000 in Av and P modes. Flash sych speed is 1/200. There is a mode level that
selects Av, P, M, Tv modes and is also used to select the ISO and custom
functions control.
Either 5mm spot or center weighted TTL metering can be selected. There is a
separate exposure check button for those who prefer it to partly depressing the
shutter button. There is an AE lock switch. With a custom function, AE lock may
also be achieved by partly depressing the shutter button or the exposure check
button. Exposure compensation is handled by a dial on the top right side of the
camera with +/- 2 EV compensation in 1/3 EV increments.
The viewfinder is bright, relying on a large pentaprism. It shows 95% of the
actual field of view at .7x magnification. The viewfinder shows lots of
information including focus indication, film plane position, aperture, shutter
speed, exposure warning, flash indicator, exposure compensation and exposure
counter.
There is no mirror lockup but there is multiple exposure capability. There is
also a depth of field preview button. The camera relies on a single 2CR5 lithium
battery. A data back is available that can print information on the first two
frames or in between frames. There are also eight custom functions that change
operations like auto film rewind and leader in/out. There is a self timer,
dioptric adjustment with optional lenses, inter-changeable focusing screens.
Autobracketing is either +/- .5 EV or +/- 1 EV.
For flash photography there is 5 pin communication with the dedicated Contax
flash units. The Contax flash units are excellent - particularly the TLA 360.
Conclusion
I have small hands, so the AX feels like a big package to me. The most
particular difference is that the camera is thick from front to back. After using
it for a while I no longer notice this, but the initial feel is different than
most SLRs. The camera balances and moves very well. The weight and size is not an
issue for one used to heavier SLRs. It does not seem much different in these
respects than an F4, 1N or RTS III. It is a very comfortable camera to hold and
the placement of the controls is quite good. Contax has standardized the general
layout of most of the controls on its more recent cameras. This is smart idea and
is quite different than most manufacturers whose cameras differ from each other
so dramatically in the layout of their controls (Compare a Nikon N70 to an N90 or
Canon 1N to Elan IIe).
The general capabilities of the camera are similar to most modern SLRs. The
advantage is the design philosophy of its creators. Like all Contax cameras, the
AX is solid and straightforward. What it does is similar to its contemporary
competition from other companies. How it does it is pure Contax.
To me this review of the AX is excellent and
accurately mentions all that needs to be said
about this camera, but....
The spot meter works differently than that of the
RTSIII and 167MT, the only other current Contax
cameras that I'm familiar with. When digging
through the AX's manual you'll find that Kyocera
does say that with lenses slower than f5.6 or
when the actual exposure is slower than f5.6 with
a Mutar or close-up accessory attatched that an
error will occur in the spot metering. This is
only partially correct. The spot meter
overexposes between one and two stops with the
following :
100-300 Vario-Sonnar, even at 100mm, where it's a
f4.5 lens
180f2.8 + any Mutar (even MutarIII where it's an
f4 lens)
The 300f4 works fine alone with the spot meter,
but not with the Mutar III
The 100f2.8 works with the spot meter near
infinity, but increasingly differs from the
center-weighted metering as the lens is focused
closer.
If you're like me and find spot metering most
useful for telephoto photography, then this is a
disadvantage. On the positive side, it is easier
to use the exposure compensation dial in the
center-weighted mode on this camera than on the
RTSIII. The value of exposure compensation is
displayed in 1/3 stops (eg. +0.3, +0.7, etc.) in
the viewfinder vs. only the + or - that shows
with the RTSIII.
Oh dear. I just had a play with the Contax AX on
a serious basis after borrowing it from a friend
who had gone out of town for business. It is big,
really big, but it's good, really good.
Tom has done an excellent balanced review (as
usual), here are my additional thoughts:
1. The AX is quiet. I use a Minolta 800SI as my
AF workhorse. Perhaps not the very fastest, but
certainly no slouch. The only problem which I
have is that with certain lenses (old minoltas,
3rd party lenses), the AF is noisy. The AX,
because standard focussing regardless of lenses is
via film plane/mirror box movement, is driven by a
USM and ceramic rods, is really very smooth and
quiet. As Tom says, maybe not as quick as the
quickest, maybe even a touch slower than my 800,
but surprisingly quick for what it has to do, and
creamy smooth. It is also consistent.
2. AF/manual flexibility - The drawback that
for the lenses below 100MM u have to set the
lens at infinity is a chore, but easily gotten
over. On the other hand, one of the nice things
about the AX is that u can either AF and then fine
tune manually(in SAF,CAF mode) or manual focus and
then fine tune with AF (manual focus)mode. This
makes the photo taking and image making process
much more personally involving, and , IMO, more
interesting. The one thing which I really
appreciate is the standard split prism focussing
ring in the viewfinder. This is a rarity in any
AF camera as standard equipment, and with the
Contax, reinforces the impression that the camera
is a high quality precision instrument. With the
collar/ring, it is so much easier to fine tune
point of focus. This is also facilitated by the
(very) bright and excellent viewfinder.
3. The AX is a monster of a camera, especially
depth wise, but it's true, after a while the bulk
feels reassuringly solid in your hand, and coupled
with the excellent rubber body coverings, ends up
being quite comfortable to hold. All other
controls are well placed and intuitive, and also
work with the usual Contax precision. What was a
little surprising though was the shutter action.
IMO, not as smooth or progressive as the AX or
even the 167MT. In particular, mirror damping was
not substantial, with mirror slap making quite an
uncharacteristically loud noise. One would also
expect less feel of the impact cos of the mass and
size of the AX. This is unusual for COntaxes, and
may be sample specific. Or it could be because of
compromises they had to make when making the body
within the body so that they could move it around
fast enuff.
Overall though, very impressive. Coupled with the
CZs, worth saving up for. I want one.
When I looked over the Contax line, the AX looked like a great choice. My Contax dealer stocked most of the cameras, and I was able to try the AX and several other models. In the end, I chose the RX for these reasons: 1.The focus indicator on the RX worked extremely well, even in low light. No, it's not autofocus but I found it to be almost as fast. 2.The depth of field indicator is a great aid I haven't seen on any other camera. 3.The RX is smaller, lighter, and much easier to handle than the AX. It also costs a lot less than the AX. I saved enough money to buy several of the excellent Zeiss lenses for the RX. 4.The RX is much simpler than the AX and I suspect it will be much more robust and durable over time, and it still has the typical Contax quality look and feel. 5.I found the RX much easier to operate than the AX
One aspect that is rarely mentioned in US reviews of the Contax AX is that is autofocusses with Novoflex equipment (bellows and 400 mm follow focus lenses). This makes the 400 mm Novoflex one of the fastest telephoto available and a much cheaper combination then the new Contax N1 with 4/400 mm N lens.
Jan
After using this excellent body for 2 years, some things should be mentioned:
- the autofocus works, but only in good light conditions. Maybe my body is unique in this, but in overcast conditions it is slower, during the night almost impossible to focus fast enough to catch the moment.
- so, the only 2 things the film-moving plane is good for: macro and sometimes very fine and accurate focus (my eyes ain`t what they used to be)
- multiple exposure: excellent
- +- 2 EV correction on rotary knob : sometimes +-3 is needed, which is only available by setting the iso-speed of the film.
- TTL metering accurate in most of the situations, 1 out of 20 pictures is wasted, because of too dark or too white centerpoint (you don`t see it in dark), there is no pre-flash option (i don`t even know what is it used for ;-)
- too heavy for travelling, it really is a heavyweight for carrying on the neck or backpack
- sometimes I forget and let the 2s or 10s delay selected, after pressing the button, nothing happens, but suddenly the surprised face is on the picture as i look what`s wrong with the camera. Of course it is visible on the knob and inside in viewfinder, but you usually forget that (acoustic indicator could be handy)
- Dioptry selection in the viewfinder is not marked with numbers.
Otherwise I`m very pleased, it works well under dryland or rainforrest conditions, sand, dust, snow ... Very intuitive and excellent for macro.
mosi [at] pobox.sk
My primary body is an RTS III (second one stocked away in the closet) and I have an AX that I intended to use for quicker action shots. Specifically, I wanted to catch some whales in Hawaii with the 100-300 CZ zoom. The problem is, that AF does not work with that lens. That was a real bummer.
However, I like to use the AX close-up feature with wide-angle lenses, which overcomes some issues with extension rings. The 13 mm extension ring used with the 21 mm lens produces a focal point inside the lens. So here a few mm of "virtual" extension ring from the AX does the trick.
On my body, the AF/AF-lock button has its contacts inversed. Took me a while to figure that out, but now I know. It is also unfortunate that it takes a specialized lithium battery, and cannot be used with regular rechargeables as on the RTS III.
I do admire Contax's ingenuity of getting AF without AF lenses. It is a very interesting engineering piece, and I also like it for that.
What a wonderful bargain these Contax cameras are. Especially these AX units! Having engineered a camera that can apply Pentax screwmount, Yashica or Carl Zeiss etc., and use them as Auto-Focus lenses is amazing!
There is a "mirror slip" issue which is common to many cameras including this one. Those with manufactures that used "double stick tape" to hold their mirrors in place. Unfortunately with age coming into play with this adhesive, the weight of the mirror in conjunction with gravity, allows for a position change of the mirror. To lessen the down-force:
Store the camera with the mirror locked up or
Store the camera upside down or
Support & lock; apply a 1/2 drop of clear nail polish to the middle front edge of the mirror and it's base holder.
Either use the mirror lock-up, or hold the shutter release button down on "Bulb" to best expose the bottom edge of the mirror and it's base. (Of course don't be sloppy, use caution as you apply the half drop)
