[oneill]

I recently purchased a close-to-mint copy of the smc Pentax 67 500mm F5.6 for well below "market" price. Its optical design is circa 1971 and I got the newest of three versions which was introduced in 1989, but the optics have remained unchanged since its introduction.

I assumed that judging from the cut away view of the amazingly few and unsophisticated elements it contained, the age of the design, and that all the copies for sale were at “bargain” prices, that it was an “old dog” of a lens and not up to modern standards, but I had to look for myself.

I received the lens and it was indeed as good looking as its pictures, so I did some serious “studio” testing with it. I relearned quite a bit:

(1) Don’t judge a book by its cover!
(2) Don’t judge performance by age! (that goes for people as well)
(3) Don’t make assumptions not based on fact!
(4) Don’t misjudge the versatility of accessory hardware.

You have probably assumed by now that I was pleasantly pleased with my purchase. While it is not in the same class as the SMC Pentax-M* 67 series lenses, such as the 300 & 400mm, does not contain ED glass, is not internal focus, but is not as expensive, and is sharp. It has very minimal (barely noticeable) CA, at least under studio lighting. It remains to be seen if contrasty outdoor lighting shows more aberrations.

I will be field testing it in the coming months and will post a full review. Tripod mounting and attaining balance of mounted equipment are serious physical design issues, but I was able to overcome these and will include details in the review.

The minimum focus distance at 8 meters, or 26 feet is dismal, and the lens is not listed in the lens specification tables of the Pentax 67 Auto Extension Tube manual so I tested it using a 645Z and using all possible combinations of Auto Extension Tubes and documented the results. The results are included in the following supplemental table.

I used a size recognizable subject for testing, a smc Pentax 67 135mm F4.0 Macro, and although I knew there would be a considerable magnification effect, I was not prepared for the substantial graphic impact when I was done. I have not seen it presented this way so I thought I would share. The shallow depth of field is apparent at minimum focus distances.

Murray

Attached Images

   

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Last edited by oneill; 03-09-2022 at 09:16 PM.

[bwgv001]

congratulations. Sounds like you are a happy camper right now.

[TDvN57]

congratulations. Sounds like you are a happy camper right now.

Very interesting results you got. Did you perhaps measure the maximum focussing distance as well, where practical?

I found when playing around with similar tests on other lenses that although the min focusing distance gets closer, the maximum focussing distance also creeps closer real fast. Sometimes to such an extent that the combo would not be practical in the field.

[willdmo]

It's not exactly a compact handheld lens but congrats on leading it out of its comfort zone

[Paul the Sunman]

Great lens bargain, and lots of fun with the tubes!

[Michail_P]

Great catch. Enjoy your lens.

[FozzFoster]

sounds like a bunch of fun! well done!

[oneill]

Very interesting results you got. Did you perhaps measure the maximum focussing distance as well, where practical?

I found when playing around with similar tests on other lenses that although the min focusing distance gets closer, the maximum focussing distance also creeps closer real fast. Sometimes to such an extent that the combo would not be practical in the field.

Hi Theuns,

Testing maximum focus distance with various extension tubes is not practical in my opinion as this is not a lens that would be used for "landscape", and if for some reason you would, you would need another venue. Focus stacking would be the only method that would produce reasonable results and additional images required would probably need to have the extension tube not mounted.

Evaluating precise focus of distant objects is far more difficult than near ones .

Murray

[RICHARD L.]

I purchased a like-new copy of this lens exactly one year ago for a similar price (peanuts, really) and posted an evaluation in the "Lens Review" section. It is true it is surprisingly sharp for such an old, simple 4-element design. One problem is handling such a gigantic lens (I learned the hard way ...). You need a Gimbal support with an Arca-Swiss quick-release plate if you do not wish to sweat profusely during an unwieldy mounting on a tripod ordeal. Finding critical focus is another problem as the viewfinder image is a little dark and the image is difficult to judge adequately. But when you nail it correctly, images are splendid on a 645Z. The diaphragm must be closed at least one stop (i.e. @ f/8) as images look a little "flat" wide-open. It accepts the P67 1.4X converter without any vignetting on the small 645Z sensor.

Best Regards

P67 500 mm @ f/16

[TDvN57]

Hi Theuns,

Testing maximum focus distance with various extension tubes is not practical in my opinion as this is not a lens that would be used for "landscape", and if for some reason you would, you would need another venue. Focus stacking would be the only method that would produce reasonable results and additional images required would probably need to have the extension tube not mounted.

Evaluating precise focus of distant objects is far more difficult than near ones .

Murray

Hi Murray,
Enjoy and have fun. Having a new lens is a highlight with new inspiration. I've had my eye on that 500mm for a while now.

Theuns

[RICHARD L.]

I've had my eye on that 500mm for a while now.

Prepare to go to the Gym,Theuns ... lol !

JK, Best Regards

[TDvN57]

Prepare to go to the Gym,Theuns ... lol !

JK, Best Regards

Darn.... And there I was trying to get a lighter more portable solution than the 645 A* 600mm.

[oneill]

I purchased a like-new copy of this lens exactly one year ago for a similar price (peanuts, really) and posted an evaluation in the "Lens Review" section. It is true it is surprisingly sharp for such an old, simple 4-element design. One problem is handling such a gigantic lens (I learned the hard way ...). You need a Gimbal support with an Arca-Swiss quick-release plate if you do not wish to sweat profusely during an unwieldy mounting on a tripod ordeal. Finding critical focus is another problem as the viewfinder image is a little dark and the image is difficult to judge adequately. But when you nail it correctly, images are splendid on a 645Z. The diaphragm must be closed at least one stop (i.e. @ f/8) as images look a little "flat" wide-open. It accepts the P67 1.4X converter without any vignetting on the small 645Z sensor.

Best Regards

P67 500 mm @ f/16

Hey Richard,

I actually read your review and that is what made me push the button on the purchase . I have tested it with both the 1.4x and 2X 67 converters and it performs well. I think what I did with the lens mount makes a huge difference. I was going to post this in my lens review but with the weather we are getting it may be a while for field work. Here is what I did and in my opinion it took the "handling" from a score of 5 to a score of 8.5

While there are a few design “short comings” affecting the usability of this lens, the main problem being the balance of camera & accessories, but it is well worth accommodating these. Using it with a full size gimbal head (not a side mount) and fabrication of a “lens foot” makes it into a valuable medium format telephoto.

As this lens is not internal focusing, almost everything forward of the aperture ring is moving. This makes the addition of “stabilizing” hardware not an option. In testing I used every accessory combination (extension tubes/extenders) and found that to be able to balance the various configurations, there needed to be a mounting rail of a minimum of 6 to 7” long. It goes without saying that it needs to be a quick release rail to be able to slide the lens back and forth safely.

The lens rotating/mounting collar, while being generously long and supportive, and quite wide on the bottom, only extends down 3/8” below the barrel of the lens and the focusing collar. Mounting a 7” rail extends almost half way along the focusing collar making it impossible to get your fingers between the rail and the collar for focusing.

The solution is to use a fabricated “lens foot” for mounting, to allow finger space to access the focusing collar and also to move the center of the lens barrel up higher on a gimbal cradle arm, providing better balance being closer to the swing arm pivot point. An added benefit of a “foot” is that it allows you to carry the lens with one hand rather than cradling it in your arms (an important feature in the field).

Procedure to fabricate a Lens Foot:

(1) Mount the lens plate across the bottom of the lens collar tripod flat, not longitudinally (which is normal).
(2) Using a ½” thick base rail is better than a 3/8 one, and a 6” long rail is OK, but a 7” gives a little more adjustment if you don’t mind the additional length.
(3) Use a clamp (2.375”) that is almost as wide as the lens plate is long, orientate the jaws of the clamp to be crossways on the base rail, with the knob at the rear, and use two anti-twist pins between the clamp & rail.
(4) Because this foot will be semi-permanent it is advisable to use Loctite Threadlocker Blue 242 on the lens plate and clamp mounting screws. Blue 242 is designed for the locking and sealing of threaded fasteners which require disassembly with standard hand tools.

Lens Foot Bill-of-Materials

Hejnar Photo C1-275 Lens plate
http://www.hejnarphotostore.com/product-p/c1-275.htm

Hejnar Photo E030-60 6” x ½’ Rail
6.00 x 1/2 Inch Base Rail

Hejnar Photo E030-70 7” x ½’ Rail
7.00 x 1/2 Inch Base Rail

Hejnar Photo F62AB 2.375’ Wide clamp (request 2 only anti-twist pins)
2.375 Inch Jaw Length Clamp

I had an old Kirk Enterprises one in my "spares" drawer so that is what i used.

Murray

[RICHARD L.]

Your wisdom is always appreciated, Murray. I'm glad my review could help a little. This lens needs careful handling but is capable of surprising results.

Receive my Best Regards

[RICHARD L.]

I have tested it with both the 1.4x and 2X 67 converters and it performs well.

On a Pentax 67 or 67 II, the P67 500 mm f/5.6 is said to vignette with P67 teleconverters and their use is not recommended. But on the 645Z only the central portion of the aerial image is exploited and you can use converters without fear of having dark corners. A 500 mm + P67 1.4X converter gives 700 mm in Focal Length (560 mm FF equivalent FOV) and the results are very sharp indeed.