Vignetting from the P67 45mm lens with filters?

[Photopathe]

I am sometimes getting quite a bit of vignetting from one of my two favorite lenses, the 45mm. I am under the impression it only happens when using a filter. I always use a single filter (red most of the time), normal flat design. Other users have that experience ?

 

[Tom Taylor]

I believe that you need to use "thin" type filters with that lens.

 

[DREW WILEY]

With very wide angle lenses at larger apertures, one can also use a step-up ring with oversized filters.
But what shows up in the posted examples is probably not filter vignetting, but just the natural illumination falloff characteristic of this lens and most other especially wide ones.

 

[Taylor Nankervis]

That is not natural light falloff, but quite pronounced vignetting, akin to a Zero Image pinhole camera, where such vignetting is a natural characteristic. I do have this P67 lens – a go-to rav-fav in my open landscape arsenal of optics.

I use low profile B+W C-POL filter on this lens, not a full thickness filter. I suggest switching ovr to a slim profile filter and see if that improves the result. Also check there is nothing unscrewed on the front of the lens. I doubt the gelatin filter clasp at the rear element can be implicated, but check down there too.

My gut feeling though is that something more involved is at play with vignetting like that – not a characteristic at all of this excellent lens.

 

[DREW WILEY]

There's a pretty dramatic difference in the amount of falloff between the medium wide 75's and the much wider 55's; and it's even more pronounced with the 45. It's hard to judge the degree in web images. Actual cutoff vignetting would probably look a little more triangular rather than round toward the corners, with a much more dramatic transition into blackness. I'm assuming he's giving us a "before" (left image) and "after" the filter attachment (right image) comparison. The left clearly exhibits some falloff; the right is much harsher.

But the fact that a red filter is involved means the rate of darkening of a blue sky increases more dramatically, disproportionately, even towards the corners, once one approaches the bottom of the film curve - entirely possible in this kind of scenario. I can only go from my own experience with a 55, where I deliberately gamed that characteristic. I can't remember if I ever borrowed my 82mm Super Angulon center filter to experimentally even out the field of illumination; it would have done the job, but only at annoyingly small f-stops.

 

[Taylor Nankervis]

To be sure, it is now many years since I owned and used (in the landscape context) the SMC Pentax 67 55mm lens. I have written about this lens here and there; a particularly annoying problem being the internal rattling with the 55mm (latest generation) — so annoying in fact that I could not tolerate it rattling as I rolled along the plains! The archive would have several pics made with that lens, but off the top of my head, if there was any vignetting from it, I would never have bothered printing, and many prints were made with that lens, but many, many more with the 45mm.

@DREW WILEY, the sample images from the OP are certainly very, very high in contrast — shooting in bright light illustrated in those pics is not something I do, so your explanation certainly is plausible, but the vignetting is still very pronounced — a quite jarring effect.

____________________________________________________________________
SMC Pentax 67 45mm f4 with CPOL, Velvia 50 (@EI40)
Diffuse, shadowed light.
Ancient redgums in the dry bed of Umberumberka Creek,
Silverton, New South Wales, Australia.

 

[abruzzi]

its also worth pointing out the the P67 45mm ƒ4 lens is designed to allow the use of a gelatin filter in the rear:

 

[Taylor Nankervis]

its also worth pointing out the the P67 45mm ƒ4 lens is designed to allow the use of a gelatin filter in the rear:

View attachment 410770

Yes, and few owners actually know about this! While undoubtedly handy...even novel, it is at the risk of ghosting and flare; and they are a PITA to use. No good at all in the wet, cool to cold environments I work in.

 

[DREW WILEY]

I have a number of specialized Wratten gels in the lab. But out in the field, with sweaty hands and dust and grit flying around, they're an awfully fragile option, expensive too. Damp conditions, even worse.