[leping]

There have been recently quite a few messages asking how did I do the tilt modification on the Pentax 67 55mm/f4 late model lens, after I had it mentioned in at least one of my posts, so I am here to share my successful and unsuccessful stories.

The following URL describes one way to do it, not exactly my originally way (the author did not thoroughly understand me), and by this along it is hard to get the down tilt up to the desired ~1 degree range:

Effeunoequattro - Il Portale Della Fotografia analogica e digitale

However, after seeing his method, I recently re-worked my sample to include his mod, in additional to my original one, which went much deeper into the lens, with much more risks. It is really hard to describe, but maybe one day I should shoot a series of instruction pictures if there are enough interests, taking the risk that I can be unable to put things back one more time or break something. With now two spacers in stead of one inserted into 2 gaps, I am getting about 1.2 degrees overall, which fits my need pretty well.

Nevertheless, I volunteered to mod another copy of the same lens for a forum member, but could not loose the three inner screws no matter how hard I tried, so that I could only complete the easier "outer" mod, as documented in the web link.

Also, remember that, after the mod(s), the lens become a fixed tilt lens for only the vertical shots (unless you need a horizontal swing, and it happens to be along the right direction, i.e., the close subject is on the left side of the frame). It is fine with me, because the purpose is to help the near-far kind of composition and the down tilt is mostly needed shooting vertical. Another problem is, the original lens structure of course was not designed with such gap(s) created in mind, so the aperture ring will become very stiff, and can be adjusted only with little force.

I examined the structure of almost all the other P67 fixed focusing lenses, but found only the 55mm/f4 late has the room for mods like this, looking at the components from the rear.

Need not to say it is not a easy, a readily practical, or a perfect mod of any kind, and anyone trying this takes his/her big risks, even I managed to get one copy working great, selfishly for myself.

Unfortunately, 55mm is no longer a true wide angle on the much smaller 645D sensor (becoming 40mm in 35mm term, using the short side equivalency which makes sense to me as I print 4:5), so that the value of such tilt mod becomes much less significant in the digital age. Needless to say, a shift/tilt P67 to P45 lens adapter is what we are all really waiting for.

---

Last edited by leping; 04-08-2011 at 10:09 PM.

[Royalan]

I'd love to see some examples from this lens mod. I have played around tilting my 45mm lens just inserted into the body but not rotated and locked. What is the near distance you can focus at and still keep infinity reasonably sharp?

[desertglow]

Hello, I am the author of the "light" version of the mod.

If I remember well I could reach more or less from 1 meter to infinity.

It would be really nice to modify the 45mm, I will try and do that one day or another.
The 45 has a nicer "superwide" look and I would rarely miss the need of shooting horizontally, more rarely than the 55.

.... and to be honest I haven't used very much the modified 55....

[rlj]

I recently modified a late P67 45mm lens (not 55). It was actually very easy. I followed Leping's suggested method for the 55mm lens (see above links). I removed the center black plastic cover and then unscrewed the mounting plate. It does not have to be completely removed, simply lifted off about 20 degrees over the 2 mounting screws where you wish to place the shim. The shim can then be slipped in, between the chosen 2 screws, and the mounting ring re-positioned, followed by replacement of the black plastic shield with it's 3 screws.

I chose to shim opposite from the vertical tripod mount position (so tilts are vertical---portrait style). I placed a 1.65 mm thick plastic fragment (about 3 x 4 x 1.7mm) between the pair of mounting ring screw holes. Care must be taken to not over-tighten these screws, esp the ones away from the shim position. If you over-tighten, the mounting ring distorts and you cannot mount the P67/P645 adapter.

The 1.65mm shim gives about 1.2 degrees of tilt when using the 45mm lens on the P645D (an effective focal length of about 35mm). This is exactly what is needed for Scheimpflug tilts when the camera/lens is 6 feet off the ground and the subject is the ground receding to infinity.

If the subject is 1.5 feet off the ground (say a field of flowering plants) and the camera is still at 6 feet, the subject plane difference is now 4.5 feet, and the required tilt is 1.6 degrees, not so far off (and besides, you want to use at least f11, which will overcome slight tilt errors, and to focus about ~2/3 into subject matter to maximize the correction).

Thus, this fixed 1.2 deg tilt is very practical for landscape work (however, it is not useful for table top photography, which requires much greater tilts).

Attached Images

 

---

Last edited by rlj; 06-14-2011 at 06:33 AM.

[desertscape]

......or instead of modifying the 55mm, one can use the 55-100 zoom at 55mm at f/32 and get a DOF of 42 inches to infinity.

[desertglow]

I recently modified a late P67 45mm lens (not 55). It was actually very easy. I followed Leping's suggested method for the 55mm lens (see above links). I removed the center black plastic cover and then unscrewed the mounting plate. It does not have to be completely removed, simply lifted off about 20 degrees over the 2 mounting screws where you wish to place the shim. The shim can then be slipped in, between the chosen 2 screws, and the mounting ring re-positioned, followed by replacement of the black plastic shield with it's 3 screws.

I chose to shim opposite from the vertical tripod mount position (so tilts are vertical---portrait style). I placed a 1.65 mm thick plastic fragment (about 3 x 4 x 1.7mm) between the pair of mounting ring screw holes. Care must be taken to not over-tighten these screws, esp the ones away from the shim position. If you over-tighten, the mounting ring distorts and you cannot mount the P67/P645 adapter.

The 1.65mm shim gives about 1.2 degrees of tilt when using the 45mm lens on the P645D (an effective focal length of about 35mm). This is exactly what is needed for Scheimpflug tilts when the camera/lens is 6 feet off the ground and the subject is the ground receding to infinity.

If the subject is 1.5 feet off the ground (say a field of flowering plants) and the camera is still at 6 feet, the subject plane difference is now 4.5 feet, and the required tilt is 1.6 degrees, not so far off (and besides, you want to use at least f11, which will overcome slight tilt errors, and to focus about ~2/3 into subject matter to maximize the correction).

Thus, this fixed 1.2 deg tilt is very practical for landscape work (however, it is not useful for table top photography, which requires much greater tilts).

NICE work, very interesting!

[Thomas]

For use on the 645D, I wonder if it would be possible to modify the 67/645 adapter for tilt? No risk to the lens and the adapter could be used to supply tilt to any lens. The mounting flange of the adapter is held to the adapter body by six screws; it might be possible to insert a shim between the mounting flange and the adapter body. I might try it when I have some time.