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Pentax 645N AF
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Pentax 645N

Pentax 645N and 75mm f/2.8. enlarge. You can find these used at these direct product links to Adorama and eBay. It helps me keep adding reviews of this old stuff when you use these links to get yours, Thanks! Ken.


April 2009            More Pentax Reviews


Introduction          top

Intro   Specs   Performance   Usage   Recommendations

The Pentax 645N is an autofocus medium-format SLR. It is completely compatible with all Pentax 645 film backs and 645 lenses, both manual and auto focus.

This is Pentax' second medium format 645 camera. It replaced the manual-focus Pentax 645, and was later replaced by the very similar 645N II.

The Pentax 645N is a real camera. Everything just works. Pick it up and you're shooting. Forget reading the instruction manual; it's awful. There are no menus; everything has its own knob, as it should.

The Pentax 645N is a huge step forwards from the earlier Pentax 645. The Pentax 645N adds autofocus, matrix metering, a shutter-speed knob, an exposure compensation knob, a self timer, a much brighter and sharper viewfinder with far more displayed information and film-edge data imprinting! The finder's diopter control clicks in nicely and doesn't move around as it does on the older 645 and other cameras.

The 645N has none of the glaring omissions of the original 645. The 645N allows exposure compensation in third stops, has an auto exposure lock and manual metering reads to thirds of a stop with a six-stop range bar graph! This outdoes anything from Nikon or Canon.

Pentax 645N

Top, Pentax 645N. enlarge.

The 645N is even easier to use than today's Nikons, and a lot easier to use than today's Canons.

The Pentax 645N is so well designed that Leica copied its shutter speed knob five years later in the Leica M7. The Leica M7 has exactly the same settings in the same locations, with the only difference being that the Pentax 645N has its X-sync setting between B and A, while the Leica M7 has a slower sync speed and leaves its setting between 60 and 30.

To set the various exposure modes, just move the aperture ring and shutter dials. If a dial is set to a shutter speed or aperture, you get what you set. If one of the dials is set to A, the Pentax 645N sets that automatically. If both are set to A, you're in Professional (previously called Program) mode. If both are set to speeds and apertures, you're in manual mode. There is no need for an old-fashioned mode selector as Nikon and Canon still have to use.

Green means GO! Check the five green marks above, and you're ready to shoot. From the top left, the green settings are A on the lens aperture, 0 exposure compensation, 0 exposure bracketing, A on the shutter speed dial (which gets you the Professional exposure mode with the A setting on the lens), and [*] below the shutter dial to set Matrix metering. Don't forget to turn on the power, which shows in red.

When new, the Pentax 645N was an expensive camera. In 2001, B&H got $1,890 for the stripped body. You had to buy at least one film magazine for $175 and at least the 75mm AF lens for $420, bringing the cost for this camera new to $2,485, which is over $3,000 in 2009 dollars. Today, you can buy one of these used for about $350 for the body with a film magazine, and about $100 or less will get you the manual-focus 75mm lens as shown. You can use manual or auto focus lenses, all of which are very inexpensive used today.


Specifications         top

Intro   Specs   Performance   Usage   Recommendations



B&H Photo - Video - Pro Audio

Ritz Camera

I personally buy from Adorama, Amazon, Ritz, B&H, Calumet and J&R. I can't vouch for ads below.



645 medium-format SLR.


Image Size

56 x 41.5mm, or roughly 6 x 4.5 cm, or "645."


Crop Factor


645 film has 2.6 times the area of full-frame 35mm.

In other words, a 100mm lens on 645 has about the same angle of view as a 60mm lens does on 35mm film.

Here's the chart:


35mm Equivalent



You have to buy different backs, called inserts, for each kind of film. Don't presume that a camera will come with one; they were sold separately. They're compatible with the older 645 camera, too.

Film backs come in sizes for 120, 220 or 70mm film.

You'll get 16 (120), 33 (220) or 95 (70mm) exposures.


Compatible Lenses

All autofocus (Pentax-FA) and manual-focus (Pentax-A) Pentax 645 lenses.

No, don't expect manual-focus lenses magically to autofocus, but all finder displays and edge-imprinting (except for focal length) works fine.

Pentax 67 lenses fit with an adapter.



Modern bright laser-cut screens, interchangeable.

92% coverage vertical, 94% horizontal.

0.76x magnification with 75mm lens.

-3.5 to +1.0 diopters with nice, solid click stops that won't get knocked.


Finder Screens

Optional grid, microprism or split-image screens were available.

There was never a combined split-image/microprism screen; you could get either one or the other, but not both on the same screen.

The screens are:

AS-80: Standard screen: Matte everywhere.

AB-82: Adds split-image (only) in center for manual focus lenses.

AA-82: adds microprism (only) in center for manual focus lenses.

AG-80: 9mm grid over matte screen.


Finder Indicators

Pentax 645N Finder Display

Pentax 645N in-finder display.

Compensation warning

± 3-stop bar graph with 1/3-stop segments. Nikon users beware: the bar goes in the correct direction, which is backwards from Nikon.

Focus confirmation dot (and beeper if you set it on the power switch)

Shutter speed and aperture

Exposure lock (*)

Flash bolt


Top-of-Camera LCD

Pentax 645N Top LCD

Pentax 645N Top LCD.

Shows [D] icon in top left when edge data imprinting is on.

Low battery warning.

The ISO is displayed anytime the power is on, which you can leave on for weeks at a time. It goes off when power is turned off.

The frame counter is always displayed, power on or off. With no film, there is no display.


Depth-of-Field Preview Lever

This is the lever next to the lens near the grip. Pull it towards you to stop down the lens.

It only works if you've chosen an aperture on the aperture ring. If you have the lens set to Auto, the preview lever stops the lens all the way down.



TTL Matrix (evaluative), center-weighted and spot.


Meter Range

LV 2 ~ 21 with f/2.8 lens.

ISO 6 ~ 6,400.


Exposure Modes

Professional (previously called program), Aperture-Priority, Shutter-Priority and manual.

No shift in Professional (program) mode.



Electronic vertical-travel cloth focal plane.

1/1,000 ~ 4 seconds in full-strops in manual mode.


As long as 15 seconds in Professional (program) mode and up to 30 seconds in aperture-priority mode.


Fastest Shutter Speed with Flash (sync speed)


But wait: Pentax makes some "LS" lenses with leaf shutters designed to sync at 1/500. They come in 135mm and IU think 75mm, if you shoot with fill in daylight as wedding shooters do.



Six AA, alkaline or lithium.

Battery life: 130 rolls of 120, or 100 rolls of 220 (per Pentax).



5.9 x 4.4 x 4.6" (150 x 111 x 117mm) WHD, no lens.



60.245 oz (3.76 pounds or 3 pounds, 12.245 oz. or 1,707.85g) as deployed with six AA batteries, 75mm f/2.8 manual lens, 120 film back, film and strap lugs (but no strap).

50.885 oz. (3.18 pounds or 1,442.5g) without lens or film, but with batteries, strap lugs and film back.

Pentax specifies 45.2 oz. (1,280 g), stripped.


Performance         top

Intro   Specs   Performance   Usage   Recommendations

The Pentax 645N works great.

The Matrix meter is always right-on, and more impressively, the system is good enough so that auto exposures made with different apertures all match.

The finder is wonderful. It's worlds better than the fuzzy dim thing on the older Pentax 645. The click-stop diopters mean that the finder is always sharp without having to twiddle the adjustment each time.

I only have manual focus lenses. They're easy to focus looking at the matte screen, looking for the green finder dot, or if you turn the power switch to the middle position, with a beep.

As you'd expect for a big SLR with a big focal plane shutter and mirror, it makes a lot of noise going off and winding film.

There's no light for the top LCD; you'll need a flashlight to check your exposure counter. There's no ISO or frame count display in the finder.

The outer body is plastic, but tough plastic.

The matrix meter knows to light the in-finder flash bolt in harsh light to ask you to use fill-flash. Good luck, with only a 1/60 sync speed.

The grip is man-sized. Unlike the Canon 5D Mark II, you don't have to worry about your big American hands being too large for this Oriental camera.


Usage         top

Intro   Specs   Performance   Usage   Recommendations

Pentax 645N

Pentax 645N and 120 film back. enlarge.

It's simple: pop out the film holder, load to the red index, set the ISO by pulling the top left lever to ISO and pressing the up and down buttons below the shutter release, and go.

Unlike the original Pentax 645, the Pentax 645N dry-fires without film in the camera.


Auto Focus

There are two slide switches on the top back.

The left one selects either continuous (servo) or focus-and-lock (single) modes. These are the same as Nikon's AF-C and AF-S, or Canon's AI Servo or One Shot.

The slide switch on the top right selects either the central spot only, or the entire central rectangular area for the AF sensor.


Manual Focus

Look at the screen, or look for the in-focus dot at the bottom. Slide the power switch to the middle position, and the beeper goes off when you're in focus.



The top right lever selects spot, center-weighted, or Matrix (evaluative).


AE Lock

Pentax 645

Pentax 645N. enlarge.

AE Lock is the "ML" button under your right thumb, at the top right of the hand grip.

When set, it lights the * in the finder.

AE lock stays set until you hit it again, or until the meter turns off.

Once you've locked the exposure, you can change the exposure compensation and exposure will vary along with it.

If you change your shutter or aperture setting in aperture or shutter priority auto, the other setting will change automatically to maintain the same overall exposure once locked.

For instance, if you set the shutter to A, set the lens to f/8 and lock the exposure at 1/125, set the lens to 5.6 and the shutter will shift to 1/250. Play with this all you want; just remember that the memory goes away if the meter turns off.

AE Lock ignores you in manual mode.

When the meter has gone to sleep, tap ML once to wake the meter, which locks in that instantaneous reading. Tap it again to unlock the meter.

Tap the ML button twice to wake the meter and let it free run. You still have to hit the shutter halfway to wake up the AF and focus confirmation system.


Exposure Compensation

Exposure compensation works great: press the center release button and spin the knob.

Pentax 645N TOp Controls

Pentax 645N Top Controls.

The big bar graph lights up in the finder when you've set it, so you won't forget it. You can set it without taking your eye from the finder.


Auto Bracketing

If you set AE Bracketing on the left control under the compensation dial, you automatically get N, - and + exposures.

The finder bar graph shows the three exposure levels, and blinks the bar corresponding to the next shot.

In AE bracketing mode, hold the shutter down and you'll get three continuous shots, after which the 645N stops. It doesn't matter if you've chosen single or continuous advance mode.

In self timer, you only get one shot. Tough; it ignores bracketing.

AE bracketing never cancels until you move the lever back to 0. If you only make two shots of the sequence, your next first shot will be at the + exposure.

Exposure Compensation works at the same time. If you set anything, you'll see the three bars for AE bracketing move up and down with it.

You can reset the bracketing sequence to start from N by turning off the power. You can't change the order; its always N, - and +. Since exposure compensation works at the same time, you could dial in + and then the sequence would be +, N and ++. If you only made two shots in the sequence and cycled the power, you could be shooting at + and N for each scene, instead of N and - by default.


Self Timer

The self-timer is easy to set: just spin the dial around the shutter release.

It's fixed at 12 seconds.

To cancel, spin the knob back to either other setting.

Unlike most cameras, there is no default AE lock when you hit the self timer. If you need to lock a reading, for instance, a shot with a light shining into the lens which you'll block while locking your exposure, you need to use the dedicated memory lock (ML) button.


Night Exposures

The 645N is only so-so for use at night.

Use the aperture-priority mode and auto exposures go out to 30 seconds.

Exposures only go to 15 seconds in program or 4 seconds in manual.

The finder display blinks if the light level is below what the specifications say is the lower limit of the meter, but like most cameras, so long as you haven't exceeded the time limits of 4, 15 or 30 seconds, you're OK.

Bulb exposures are fine. Like most cameras except the Leica M7, there are no automatic counters timing for you.

Pentax says a new set of batteries will last you for an 8 hour bulb exposure. The old Pentax 645 goes about 40 hours if star trails are your thing.


Multiple Exposures

Pentax 645N

Pentax 645N. enlarge.

There is a multiple exposure button on the side, next to the strap attachment seen on the right above.

Good luck; I never use these.

The funny tripod hole is a second tripod hole for dedicated vertical shooting.



The Pentax 645N has no strap lugs.

Instead, there are two little nubbins which mate only to the special hardware you see above, which comes with Pentax' straps.

If you get a camera without the Pentax strap, no problem. You can get this special Op/Tech strap which includes its own special ends for $20.

Bottom, Pentax 645N

Bottom, Pentax 645N. enlarge.


Recommendations         top

Intro   Specs   Performance   Usage   Recommendations

The Pentax 645 system was designed for amateur wedding shooters. Today, this system is a bargain for people who want to shoot film for serious landscape, nature and fine art.

The 645N is a far better camera than the older 645. Except for mirror lock-up and custom functions I don't need, I see no reason to pay the big bucks for a 645N II.

Pentax' 645 lenses are fine, but not as stellar as the Hasselblad or Mamiya 7 systems if you like to shoot flat landscapes at infinity at full aperture.

If you don't mind optics which prefer to be stopped down a little, the Pentax 645N is a much faster and more fun camera to shoot than the other more manual Hasselblad or rangefinder Mamiya systems.

With this 645, you can pay attention to your subject and composition and just press the button for great results. You don't have to distract yourself with metering as you do with other cameras.


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Thanks for reading!


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