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
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.
but they won't vigniette, which is the point of this thread. I'll let the OP decide if that's a solution.
Hi.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.
When not using a filter I have many other shots showing no vignetting at all, even wide open I believe. I think I have always only used red filter with this lens. I am under the impression the vignetting is indeed related specifically to the red filter.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.
I always use the lens hood.I suppose lens hood is not involved in this experiment ?
I just did. It's impossible to see the rim of the filter.Hi.
You could do this test:
First set the camera speed to B, open the rear back (without film), open the shutter and hold it open.
Then look from the edges of the film gate through the lens plus filter.
If you see the rim of the filter, it will vignette at the aperture you used.
Jens
I'll soon do a test roll with and without the red, at f4 as well as stepped down 2 stops.Here's what AI has to say. Seems on the ball, but doesn't consider CND filters.
The Pentax 67 45mm f/4 lens has some light fall-off (vignetting), particularly when shot wide open at f/4
. The effect is mild and typically disappears when stopping down the lens to f/5.6 or f/8.
Light fall-off characteristics
- Aperture: The vignetting is most noticeable at the maximum aperture of f/4 and improves significantly as you stop down. Some users consider the lens an "effective f/5.6 lens," because of this improvement in corner performance when stopped down.
- Filters: Using a filter, especially a thick one or an unsuitable step-down ring, can cause or worsen mechanical vignetting. This happens when the edge of the filter itself blocks light from reaching the film plane. However, some photographers report using slim step-down rings without issue.
- Overall impression: For a wide-angle medium format lens, the 45mm f/4 is generally a solid performer, and many photographers find the light fall-off to be minimal and acceptable. The performance is often compared favorably to other lenses in the system, though the 55mm f/4 is sometimes cited for its slightly better corner sharpness.
How to manage light fall-off
- Stop down the aperture: The most reliable way to reduce light fall-off is to shoot at f/5.6, f/8, or a smaller aperture.
- Use a slim filter: If you use filters, choose a slim-profile version to minimize the risk of mechanical vignetting.
- Embrace it: Some photographers intentionally use the vignetting effect to draw focus to the center of the image, embracing the characteristic rather than correcting it.
And .. it is the dedicated one ? Obvious follow up question. Original hood in no way will obstruct anythingI always use the lens hood.
And .. it is the dedicated one ? Obvious follow up question. Original hood in no way will obstruct anything
Secondly, I seriously doubt photos show light fall-off, as it is to me way too abrupt.
All I can say, to me it does not look light fall off, nor lens hood issue. I have the lens and the hood, have not used it much, but had not noticed any of it. No filters though. If you see it on negative then scan is not the problem. So it's all leading to filters you have. Probably best to see frames with slim type on. You can get some "cheap" ones of Amazon or ebay. All you need is skylight for the test, just slim version.Yes, the original P67 lens hood for the 45mm. You mean to say the light fall-off would come from the scan? If that would be so, all my photos would have that and it's not the case. I just double-checked the negative and on inspection I can see the vignetting. Although I will admit it looks more subtle there. I could do a proof print of the whole film sometime soon.
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