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Pentax 67 600mm f/4
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— Using Big Lenses in the Field —

  This subject is featured in Issue #4 of  The Luminous Landscape Video Journal.

Big Lens — Big Issues

Pentax's 600mm f/4 lens weighs 13lbs. It's 14.5" long and has a front element diameter of 170mm. This is a big lens. Together with a Pentax 67II body the combo weighs in at nearly 17lbs. Why would anyone subject themselves to this, and how on earth does one use such a lens? 

The simple answer to the first part of the question is a desire for exceptional image quality. The answer to the second part is, to use the right support equipment when dealing with the challenges of weight, bulk and stability. But, to tell the story properly let's start at the beginning.

Be advised though — this is a long and involved dissertation, (big lens — big story). Also, this page has a lot of illustrations and therefore will load slowly. But if this particular lens, or the issue of big fast lenses and how to use them interests you, then this is the article that you've been looking for.

The Need & The Desire

During 2000 and 2001 I found myself shooting more and more wildlife in addition to my landscape work. Probably 95% of wildlife photographers shoot 35mm, for a variety of reasons. These include the availability of autofocus, high-frame motor drives, Image Stabilization and in large measure the availability of fast long lenses. If you visit popular wildlife sites like Bosque del Apache you'll see that 400mm f/2.8 and 600mm f/4 lenses are de rigueur with serious photographers, along with their large size and larger price tags. 

I own a Canon 300mm f/2.8L IS super-telephoto, and on my late 2001 Bosque shoot enjoyed using Canon's exciting 400mm f/4 IS DO lens, which was loaned to me by Canon for testing. As much as I enjoy using these lenses, and also my Canon 100~400mm f/5.6 which I've used when portability is paramount,  and as pleased as I am with some of my wildlife images,  I still missed medium format quality. 

Because I'm a fanatic for image quality I only shoot 35mm when the use of medium format is out of the question. Don't get me wrong — I own a lot of 35mm gear, and enjoy using it, but in my experience when it comes to image quality, poor medium format is better than good 35mm. So, the challenge was, could I use medium format successfully for long-lens wildlife work? Not many people do, and that's one of the things that made this challenge exciting.

Which Medium Format System for Long Lenses?

My medium format Rollei 6008 system has been the mainstay of my landscape work since the mid-90's. Some 90%+ of the images in my Monograph of 2001 and subsequent 2002 exhibitions were done with the Rollei. But, the longest lens I have for that system is 300mm, which is only 180mm in 35mm terms. Not long enough for serious wildlife work even with a 1.4X extender.

In late 2001 I purchased a Pentax 67II system, primarily for use when hiking, as well as in situations where the Rollei's battery dependence and aversion to damp conditions were problematic. With wildlife work in mind what also appealed about the Pentax was, that of all the medium format systems on the market the Pentax has the most really long lenses, and several have relatively fast maximum apertures. 

These lenses include a 400mm f/4, 500mm f/5.6, 600mm f/4, 800mm f/4, 800mm f/6.7 and 1000mm f/8 mirror lens. (You need to divide the focal length by 2 to get the 35mm equivalent. Twice the focal length for the same magnification but you get 4 times the film area.)

I figured that the 400mm was too close to the 300mm f/4 that I already own. The 500mm seemed too slow, the two 800mm lenses way too big and expensive, and the 1000mm mirror likely deficient in terms of image quality.

That left the 600mm f/4. It's big and it's expensive. Should I get one?

Good & Bad Vibrations

I eventually decided to take up the challenge and purchase the 600mm f/4, but there wasn't a single dealer that I could find that had one in stock. (Why am I not surprised?) Not even Pentax Canada had one for me to see, let alone test. This purchase was going to have to be done on faith, and comments by current owners.

I checked all the online resources and found very few people that owned the lens. Of those that have their comments were that the lens was difficult to use because of its weight and bulk (I was prepared for that), and that vibration was the most prominent potential issue. (There was also mention about colour fringing at wide apertures — more on this later). I was not at all surprised at the vibration discussions, given the shutter vibration issues that I'd uncovered when using a less than robust tripod during my initial experiences with the Pentax 300mm f/4.

But, the appeal of being able to produce very high quality environmental wildlife photographs pushed me over the brink and I decided to buy the lens, regardless of the challenges. Now, fast high-quality super-telephoto lenses are expensive — really expensive. Most start at around $5,000 and range to about $10,000. The really exotic stuff is special order from the factory and costs as much as a small car. Such buying decisions aren't made lightly.

At a typical retail price of about USD $4,000 the Pentax 600mm f/4 lens is a relative bargain. (List price is close to $6,000). By way of comparison, a Canon 600mm f/4 IS lens is twice as expensive at a retail of USD $8,000.

As we've already seen the magnification factor for the 6X7cm format over 35mm is 2X. This means that a 600mm lens in 6X7 gives the same magnification as a 300mm lens does on 35mm. Such is the penalty of using a larger format. A four times larger image but with half the magnification. Since 600mm is about as long as it gets in medium format I was ready for the challenge. (Long-lens location wildlife photography with large-format isn't my cup of tea, (Is it anyone's?), so this was as challenging as I was prepared to take on.)

But before placing an order with my preferred Pentax dealer, Harry's Proshop, I decided to check Ebay, just for fun. I knew the odds of finding this relatively obscure lens on the same day that I just happened to be looking were really remote — but what the hell. To my complete amazement, and delight, a used 600mm f/4 had just been listed 24 hours before, and I was able to buy it for $2,000 without waiting for the auction to conclude — at half the price of a new lens. 

This was my first Ebay experience and it went smoothly. When it arrived the lens was found to be optically and mechanically perfect. Just some nicks and scratches on the barrel. Well worth the 50% saving. I got lucky, and the omens appeared to be good.

Optical Performance

   

 F/8

This is a stunningly sharp lens. Resolution and contrast are very good starting at f/5.6, and excellent by f/8, though wide open at f/4 it is  soft. Unfortunately there's a fly in the ointment — longitudinal chromatic aberration. This can be seen in the 100% close-up at right above as the reddish fringe on high-contrast vertical white lines. It's pretty bad at f/4, and a bit better at f/8, but never really goes away. At f11 and beyond it is still slightly visible, though it would take a 3 foot by 4 foot print to be of concern.

(The location of his enlargement can be found by looking for the building corner at the far right-hand of the red building).

The reason for this optical flaw is that this lens is an older design (mid-80's) that does not feature fluorite or ED glass. If it did it would easily cost double what it does, if not more. If a replacement for this lens were to appear today, using ED glass, I would expect it to cost USD $12,000.

Is this fringing a fatal flaw? Not at all, and you shouldn't read too much into this. I deliberately chose a test subject that would show this problem at its worst — an extremely high-contrast white subject against a dark contrasting background. While there may be some wildlife and landscape situations with high contrast vertical white lines, there aren't really that many, and in the vast majority of test images that I've taken this aberration is simply not visible.

Time will tell if this becomes a real issue in the field, but I was aware of it beforehand and don't consider that it will be a problem for my type of shooting.

I have discovered a wonderful software program that can lick chromatic aberration. Problem pretty much solved.

The Lens is Not Enough

Anyone considering the use of a really large lens like this needs to be prepared to purchase, or must already own a number of associated items that are absolute musts. Foremost among these are a large stable tripod. I already owned a Manfrotto 028 which I've used over the years for large format work. A proper mount is also a must, and no ballhead will do. This much weight is impossible to handle in any reasonable way with a ballhead, even the biggest. A Gimbal mount is therefore mandatory, particularly for wildlife work. I already own a Wimberley Sidekick for use with my Canon 300mm f/2.8L IS, but the Pentax 600mm — any 600mm, needs the full-sized Wimberley Gimbal Head.

Briefly, a gimbal head allows a large and otherwise unwieldy lens and camera to hang over the tripod rather than balance on a single point, the way that it would on a ballhead. When adjusted properly a 20lb lens, camera, head combination literally floats into any position, and stays there. Great for tracking wildlife that's on the move.

  

I've read some comments on the Net that the Pentax 67 / 600mm f/4 combination needs the use of two tripods for proper vibration-free stability. This strikes me as the comment of someone who has never taken a photograph on location in the real world. In fact the lens' manual suggests this as a vibration solution, and is likely the original source of the idea. Maybe this makes sense when testing at the factory, but this approach is simply a non-starter in the real world. Bad advice. Ignore it.

There's a much simpler yet equally effective solution, the Manfrotto #359 Long-lens Camera Support. This is an inexpensive telescoping arm with a small ballhead at one end and a C-Clamp at the other. With the lens attached to the gimbal mount on the tripod, you then attach the small ballhead at one end of the arm directly to the camera. The C-Clamp at the other end of the arm attaches to one of the tripod legs. 

  

Voila. Essentially the equivalent of two tripods in terms of stability, yet a system that hardly restricts motion and versatility. The telescoping aspect of the arm along with the swiveling ability ballhead allows you to swing the lens though a wide arc of motion, horizontally and vertically. When your shot is framed just tighten two knobs on the arm and the system has full rigidity. With two separate points of attachment for the combined body / lens combination, rigidity is much enhanced, and there is no danger of a pendulum effect from having a heavy body hanging off the end of a large lens. (Assuming that you use Arca-style quick release plates be sure to buy a Kirk QR1 mount so that the ballhead can attach and detach easily to your camera's plate).

Finally, and specifically for the Pentax, the wooden handgrip is a very good idea. The 67II with its integrated right-hand grip doesn't normally need this, except as a convenient mount for a TTL flash. But, I've found that manipulating this large lens and body combination is really enhanced with the addition of the grip. If you're going to use projected daylight fill-flash with something like the Better Beamer you'll need this to attach the flash in any event.

The grip is also useful as a place to hold onto the lens to further help reduce vibration. This can easily be seen with a simple test. Tap the lens while looking through the viewfinder and watch how long it takes to stabilize. Now hold onto the lens and body with the grip while tapping the lens. Much faster recovery.

Vibration Test Results

Some extensive testing has shown that using the setup described above I can shoot with the 600mm f/4 at 1/125 second almost 100% of the time, and at 1/60th second about 50% of the time. (This is with mirror lock up). That's pretty good for a lens this long on any camera let alone the Pentax 67 with its huge focal plane shutter. 

In fact during my initial testing I had very good luck with the lens at 1/125 sec using the Pentax 1.4X extender as well. This extender has proven to be very sharp, and there is no significant image degradation if the lens is stopped down a couple of stops from wide open. This makes the 600mm f/4 an 840mm f/5.6 lens, (420mm in 35mm terms). Excellent for wildlife, and still quite usable.

 
1/125 sec @ f/5.6 — f/8

This frame is from a 100% enlargement taken with the Pentax 1.4X extender. The print at this size would be 3 feet across. Remarkable performance. (This is the horn of the satellite dish at center fame above).

Traveling with The Monster

Given its size and weight, traveling with such a lens should be an issue, but strangely it isn't. Remember, not only do you need the lens but also a large tripod, the Wimberley head, support arm, and of course the Pentax body and other lenses.

By car this is never an issue. The Pentax 600mm f/4 lens comes in a fitted aluminum case and there's always room in the trunk of the car for more. But when flying there most certainly are issues, particularly in the shadow of 9/11/01.

Lowepro has an excellent solution — the Lens Trecker 600AW. This case will comfortably handle a 600mm f/4 lens (Nikon and Canon included) with a large body (such as the Pentax 67, or an F5 or EOS 1V) attached. What's more it easily qualifies as airline carryon. It comes with a shoulder strap but can be fitted with an optional shoulder harness, making it suitable for hiking. Frankly though, the only hiking that I plan on doing with this lens is through airports.

What I also like about this case is that it's part of Lowepro's Street and Field system. They make a range of different sized lens and accessory pouches which attach to the outside of the case. Even with these attached the case will still fit through the airline's carry-on template, making this the solution for flying to location with a super-telephoto system.

In Operation

This is easier to see in action than to write about. The use of this lens on location and a full explanation of the workflow is to be featured an upcoming issue of The Video Journal.

There's no question that an auto-diaphragm, autofocus, Image Stabilized 600mm f/4 lens for 35mm cameras is easier to use. But strangely, for doing the type of wildlife photography that I do, the compromises necessary to work in medium format aren't that bad. 

Certainly any lens of this size and focal length needs a very large and sturdy tripod. A mount like the Wimberley is also de rigueur. On my recent trip to Bosque every single photographer there (and there were dozens seen over several days) used either a Wimberley or Kirk King Cobra gimbal mount with their ultra-long 35mm telephoto lenses.

NB: The Wimberley Sidekick and the Kirk King Cobra require the use of a rotating tripod mount. The Pentax 600mm f/4 doesn't have one and so only the full-sized Wimberley head is suitable for this lens.

This means that the only real differences encountered by using a Pentax 67 and this lens, rather than 35mm, is the fact that you loose some automation. Surprisingly, this isn't so bad. Here's the workflow.

With the knobs on the Wimberley mount and the Manfrotto #359 tripod support all slack, frame the photograph. Once the framing is achieved, lock all of the knobs (5 in all). With the aperture wide-open at f/4 focus the lens. Now, close down the aperture so that you achieve a shutter speed and aperture combination that's suitable for the shot being taken. 

Flip the mirror lock lever, wait a few seconds for any vibration to die down. While holding the camera firmly with the wooden grip in the left hand and the right-hand grip in the right hand, press downward slightly for some additional stability and then release the shutter.

Sounds slow and complicated, but for the first frame of a new set-up this needn't take more than 20 seconds or so. With some practice I've found that it's no impediment to shooting typical wildlife subjects and every single shot at 1/125sec or better is tack sharp. Vibration with this monster setup has been licked.

The News

The Good News

Though this is an older design, and it doesn't feature the latest in ED or Fluorite lenses, it is an exceptionally sharp and contrasty lens. Any degradation of resolution seen is either the result of using the lens wide open (f/4 is soft) or was caused by vibration.

The price is right. At less than USD $4,000 new, this is one of the long lens bargains around. Certainly there's nothing in medium format that comes close, and little in 35mm 

No, it doesn't have auto-diaphragm, autofocus, Image Stabilization or ED glass. But at a saving of some $4,000 over it's Nikon or Canon counterparts, and with it's ability to produce a transparency that's 4 times the size of what's available from 35mm, the equation isn't quite as lopsided as one might at first think.

Filters: The 170mm lens diameter makes front mount filters out of the question. (You thought 95mm filters were expensive?) Instead the 600mm lens uses 77mm filters that screw into the rear element. (This gives you some idea of how large the rear mount of this lens is). This is reasonably convenient, though of course you have to remove the body to install and remove a filter. The use of a polarizer is awkward, though not impossible.

If you're using a meter prism on the 67II it works just fine, at stopped down aperture. Set the camera to Automatic and the lens to the aperture that you want to use, and the camera automatically sets the shutter speed. Match-meter setting in the viewfinder is also possible if preferred.

The Bad News

The rack & pinion focusing system while robust and of precision design and construction does not have a locking mechanism. This means that when the lens is pointed sharply upwards or downwards there is some focus creep. Also, when the lens is being carried face downward the whole focusing mechanism racks open due to the lens' weight, sometimes with a thunk. If Pentax is planning a re-design at some point this is #1 on my must-fix list.

The longitudinal chromatic aberration can be an issue with some images, though by no means should the lens be disqualified from your consideration because of it. In fact in 95% of all images it's a non-issue.

There is no automatic diaphragm. You set the aperture manually. Wide open for focusing, and then manually stopped down to the shooting aperture desired. Slow, but not a serious impediment.



Speaking of manual aperture — this is a big sucker. No whoosy little knurled knobs for the Pentax 600. When you set the aperture on this lens you feel like you're dialing in a huge rheostat on a 19th century Van de Graf generator.

Because the lens does not have an auto-diaphragm coupling you lose matrix metering. The camera therefore reverts to center-weighted metering. Not a serious issue at all. Spot metering also works just fine.

There is no rotating lens mount. This means that to take vertical shots you need to remove the camera from the lens, rotate it and remount it. Since this lens uses the larger outer-bayonet mount (which is an awkward design in the first place), this can be a frustrating experience when trying to work quickly, especially in the cold and with gloves on.

A Comparison With the Canon 300mm f/2.8L IS

I approached this comparison with some trepidation. The Canon 300mm f/2.8L IS lens, from its original FD-mount incarnation through it's current IS version, is regarded by some as being one of the sharpest super-telephoto lenses available for a 35mm camera. My own experience with it during two years of use prior to this comparison test has been that it is an awesome lens that always delivers the goods. 

How would the Pentax 600mm f/4 compare? Notwithstanding format aspect ratio differences, these lenses have roughly the same angle of coverage for their respective formats. The Canon is an f/2.8, while the Pentax is an f/4, but this makes them both class leaders for their formats. Their prices are also not all that much different. 

Certainly the Canon would win-out in terms of lower weight, (though it's no lightweight itself), smaller size, and automation. No doubt about it — auto-diaphragm, autofocus and Image Stabilization are very nice to have. But ultimately, what about image quality?

Given that I had made a considerable investment in the Pentax 600mm f/4 based solely on a series of assumptions about image quality, would my decision be vindicated? I knew it would be an interesting comparison.

Film Size

I spent a cold and blustery late December afternoon shooting several comparison rolls down at the Toronto docks. Not the greatest wildlife location, but lots of interesting subject matter with fine detail.

  

Here are examples of the test frames from these two systems. I needn't tell you which is which. They are to show you the relative sizes of these two formats.

They were both scanned at 3200ppi with an Imacon Photo scanner. The Pentax's 6X7cm frame produced a 169MB file. The Canon's 35mm frame produced a 34MB file. Both were in 24 bit mode.

Full Frame

Both cameras were tripod mounted, as seen above. IS mode was turned on with the Canon and the extra body brace was used with the Pentax. (Fair is fair). Aperture was set to f/8 on both cameras and Aperture Priority mode was used. The Canon took the shot at 1/250 sec and the Pentax at 1/160 sec. Both transparencies (Provia 100F) looked almost identical. Differences in metering style, I imagine, but not enough to matter. 

Here is the Pentax frame in a more legible size so that you can orient yourself to the frames below. Those enlargements are of the white wall just to the left of the center brown doorway.

Enlargement Size

  

Here's one way of making the comparison. These two frames are the largest views that can be made from same-resolution scans (3200ppi). What tells the tale is that the lettering under the lamp in the Pentax frame is quite legible. The same lettering in the Canon frame is not. This is what it's all about — high image quality combined with large film size.

Because of the high contrast some chromatic aberration is visible in the Pentax frame, (look at the top edge of the valve), even at f/8, while the Canon frame has none, as was to be expected. 

While I judge the Canon frame to be slightly sharper (it just may be that it has a bit more contrast), you certainly can see more detail in the Pentax frame. Any enlargement of either frame beyond this size would simply become pixilated. Because identical film was used grain is the same, but it is more noticeable in the Pentax enlargement because the magnification is significantly greater.

I did this and other shots at various apertures. As I have experienced in the past the Canon lens is tack sharp at every aperture — even wide open at f/2.8. On the other hand the Pentax 600 is soft at f/4, its widest aperture, and only becomes usable starting at f/5.6; with f/8 to f16 being optimum. The Canon has a clear 2 stop advantage in this area.

It's worth noting that if printed at 240 ppi (the lowest resolution needed for a decent print with an Epson Photo printer), the Canon print would be roughly 12" X 16". The Pentax frame would be 28" X 36". 

As Godzilla liked to say, "Size matters!"

Many test prints and loupe examinations later I feel vindicated. The Pentax 600mm f/4 is going to provide me with images that are every bit as good as I want, and superior in quality to the best that I could get from 35mm. (Remember, on a same-sized print the Pentax will offer greater resolution just based on image size alone, ignoring its optical characteristics). Since these characteristics have proven out to be excellent, I'm going to achieve what I want from this lens. 

Grain, though very low with a film like Provia 100F, is noticeable in a 13X19" print from a 35mm frame. In a similar sized print from 6X7 grain it is essentially non-existent.

In summary, the price I'll pay for these advantages is weight, bulk, the loss of a couple of stops of usable aperture and the lack of automation and stabilization features.

Will the trade offs be worthwhile. I believe so, but time will tell.

In The End 
Feb, 2002

After some small-scale test shoots with the 600mm I concluded that it had defeated me. It turned out to simply be too big and too heavy for the kind of location wildlife shooting that I had anticipated needing it for. Though I'm pretty fit, I'm also middle-aged and have intermittent back problems. The 600mm simply was too much lens for what I hoped to do with it.

Ultimately I was able to sell it for what I paid, and ended up putting the money towards the newer, lighter and sharper (though more expensive) Pentax 400mm f/4 ED(IF). For some other photographer though this lens may well turn out to be just what's needed. For me it was better to chalk this up as a learning experience than to be saddled with an unproductive tool and more visits to the chiropractor.

A good general article on the use of long lenses can be found at 
Nature Photographers Online Magazine

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Concepts: Camera, Single-lens reflex camera, Telephoto lens, Focal length, Aperture, Photography, Lens, Photographic lens

Entities: Toronto, this lens, optimum, the Rollei, Nikon, Ebay, Pentax., Canada, airline, sec, Michael Reichmann, Bosque, Wimberley, Lowepro, Harry, Grain, Kirk King, Aperture, The Video Journal

Tags: Pentax, aperture, image, medium format, 35mm, wildlife, cameras, large, image quality, Pentax frame, large lens, chromatic aberration, long lenses, big lens, wildlife work, Pentax 1.4X extender, Wimberley, vibration, gimbal mount, longest lens, focal length, wide, different sized lens, longitudinal chromatic aberration, particular lens, Canon frame, mirror lens, Canon lens, ED glass, sharp lens, Image Stabilization, medium format systems, 20lb lens, long lens bargains, unwieldy lens, Pentax 67II body, new lens, Lens Trecker, lens mount, obscure lens