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11-08-2015, 09:22 AM   #1
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Would a wider 'glass' give less vignetting at the same focal length?

Lets say I use a 18-250mm zoom with a filter or 2 attached. The filter thread on this lens is 62mm. Sometimes when you have too many filters, to avoid vingnetting, you would loose some of the wide mm angle, so the 18mm is lost and you may be at 24mm. Now if you had a lens, 18 - 300mm with the same 1 or 2 filters, thread size of 72mm, would you get less vingnetting at 18mm? Meaning does the wider lens glass(at 72mm) have a less chance of vignetting? thanks. Many times I like to use 2 filters, CPL & enhancer, and I loose corner edging(vingnetting), it's a killer for me but I like the wide angle.

11-08-2015, 09:35 AM   #2
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QuoteOriginally posted by fstop18 Quote
Lets say I use a 18-250mm zoom with a filter or 2 attached. The filter thread on this lens is 62mm. Sometimes when you have too many filters, to avoid vingnetting, you would loose some of the wide mm angle, so the 18mm is lost and you may be at 24mm. Now if you had a lens, 18 - 300mm with the same 1 or 2 filters, thread size of 72mm, would you get less vingnetting at 18mm? Meaning does the wider lens glass(at 72mm) have a less chance of vignetting? thanks. Many times I like to use 2 filters, CPL & enhancer, and I loose corner edging(vingnetting), it's a killer for me but I like the wide angle.

Why not use a step ring and a wider filter to avoid the issue? So then you could mount 77mm files on the 72mm lens and hopefully avoid vignette issues.
11-08-2015, 09:43 AM   #3
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Hey uncle, good Idea, a thought to consider.
11-08-2015, 10:56 AM   #4
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QuoteOriginally posted by fstop18 Quote
would you get less vingnetting at 18mm? Meaning does the wider lens glass(at 72mm) have a less chance of vignetting?
UncleVanya has the best solution. But to answer your question: maybe. I do not think you can make a general statement that this would be true, it would depend on the lens design and how much 'extra' image circel the lens designer built into it. In some cases, yes but in others no.

11-08-2015, 12:25 PM   #5
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Wider glass? Do you mean larger diameter front element? Assuming so, here are a few points:
  • The width of the front element does not affect angle of view. Example: I have several 28mm f/2.8 lenses on my shelf with filter size ranging from 49mm to 67mm. All have the same angle of view.
  • Angle of view may affect the tendency of a filter stack of hood to vignette. Whether that happens depends on the depth of the front element, the thickness of the filter ring(s), and the filter diameter.
  • As noted above, stepping up to a wider diameter filter may help avoid the "tunnel" effect and resulting vignette


Steve
11-08-2015, 01:46 PM   #6
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QuoteOriginally posted by fstop18 Quote
when you have too many filters...
Use fewer filters.
11-08-2015, 03:10 PM   #7
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QuoteOriginally posted by stevebrot Quote
The width of the front element does not affect angle of view.
But the diameter of the entrance pupil does effect vignetting. However, having said that I doubt using a larger diameter filter than is suggested for the lens will have any significant effect on mitigating it.
11-08-2015, 03:13 PM   #8
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QuoteOriginally posted by Digitalis Quote
But the diameter of the entrance pupil does effect vignetting. However, having said that I doubt using a larger diameter filter than is suggested for the lens will have any significant effect on mitigating it.
Even Stacked? That was the original question.

11-08-2015, 03:16 PM   #9
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QuoteOriginally posted by UncleVanya Quote
Even Stacked? That was the original question.
The answer is still no, the optical geometry of a filter is flat, to have any measurable effect you need a lens to bend light.

Stacking two filters will cause more problems than it will solve, vignetting might be reduced, but flare will be much worse.

Last edited by Digitalis; 11-08-2015 at 07:29 PM.
11-08-2015, 04:50 PM   #10
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QuoteOriginally posted by Digitalis Quote
The answer is still no, the optical geometry of a filter is flat, to have any measurable effect you need a lens to bend light.

Stacking two filters will cause more problems than it will solve, flare will be much worse.
I think I'm confused now. The question (right or wrong) was about observed vignette with stacked filters. I know some lenses need thinner than normal filters to avoid vignette so I assume that stacking filters is a variation of the same problem. Just as too narrow of a hood can be corrected by either using a shorter or wider hood. The idea of stacking filters is one I'd not be likely to do since only a cpl ever gets used on mine.
11-08-2015, 07:07 PM   #11
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QuoteOriginally posted by fstop18 Quote
Lets say I use a 18-250mm zoom with a filter or 2 attached. The filter thread on this lens is 62mm. Sometimes when you have too many filters, to avoid vingnetting, you would loose some of the wide mm angle, so the 18mm is lost and you may be at 24mm. Now if you had a lens, 18 - 300mm with the same 1 or 2 filters, thread size of 72mm, would you get less vingnetting at 18mm? Meaning does the wider lens glass(at 72mm) have a less chance of vignetting? thanks. Many times I like to use 2 filters, CPL & enhancer, and I loose corner edging(vingnetting), it's a killer for me but I like the wide angle.


After reading your questions, I conducted a little test. Here are the details:


I shot two different 28mm M42 lenses on full frame (Canon 5D). All shots were at f/8 with no hood.
Lens #1 is a Sears 28 f2.8 "macro" with a 52mm filter thread. Lens #2 is a Vivitar 28mm f2.5 with a 67mm filter thread.
The first shot in each sequence is the lens only - nothing attached.
The second shot is with a polarizing filter and a UV (or skylight or somesuch) filter stacked.
The third shot uses a step up ring with larger diameter polarizing and UV filters stacked.

(The different diameter filter stacks were approximately the same depth / length.
Click on the images for larger versions.)


Sears 28




Vivitar 28




So, with my lenses anyway, the larger filter thread (Vivitar 67mm vs Sears 52mm) does show less vignetting with two filters stacked. And the large step of the 67-77mm ring on the Vivitar really helped - much more than the smaller 52-58mm step ring on the Sears.
YVMV.
11-08-2015, 07:47 PM   #12
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good test. I'm with whoever said use less filters though unless you are stacking macro filters for increased close focus. i feel like their nature would negate this effect though unless you added a bunch of +1's maybe. what other filters are you stacking?youre asking for more than just vignetting.
11-08-2015, 08:40 PM   #13
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QuoteOriginally posted by .a.t. Quote
the larger filter thread (Vivitar 67mm vs Sears 52mm) does show less vignetting with two filters stacked.
But the adapter itself still causes vignetting. The effect of this is also dependent on the lens itself too, so testing will be needed.
11-09-2015, 11:25 AM   #14
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I recently used a medium format film camera with a wide angle lens and the wrong hood.
fstop18's thread here prompted me to query whether the image inside the wrong hood is as good as when the lens is used with the proper hood.

To check, I used a hood which is much too small for the Pentax 18~55mm mm kit lens
Using the tripod, I took a photo with the lens at 24mm f/4, the camera focussed the lens almost at infinity.
https://app.box.com/s/p3q4215jzx9rex0cvdh33bqv4shodosy
then immediately placed the small hood in front of the lens and took another
https://app.box.com/s/fojioo70xtccujrs97r78p9ka99r24n6

From this rather extreme test it is fairly obvious that the image quality with the wrong hood is degraded, even on the axis.
As to how much the image quality is reduced, I suppose it depends on how wide the lens aperture is compared to the shadow of the hood.

The pictures below are of a model of a double-gauss 80mm medium format lens with the aperture ( at centre of lens) at f/4.
The beam is from infinity,
at 1 degree off axis:
https://app.box.com/s/aimop5kscsu3tdwwql3qoiwyy50rgvch
at 27 degrees:
https://app.box.com/s/l4wa40q8ea6raprb8rfj74p1adc6usam

To allow that lens to be limited by its aperture out to its maximum angle of view, it looks like the ring or hood needs to be at least 1.5 times the diameter of the front element.
11-09-2015, 08:33 PM   #15
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QuoteOriginally posted by .a.t. Quote
So, with my lenses anyway, the larger filter thread (Vivitar 67mm vs Sears 52mm) does show less vignetting with two filters stacked.
And how deep was the front element set on the Sears? Both lens may have the same angle of view, but if your Viv is anything like mine with 67mm filter* the front element is only a few millimeters shy of the filter thread. I wonder how my Tamron 28/2.5 would fair in your test. It has 49mm filter threads. The front element is fairly small and deeply set. The dedicated hood is about 15mm deep and a full 70mm in diameter.



I can get way with a single filter with a normal thickness filter ring with no vignette and the same with hood attached.


Steve

* Kiron made fall of 1974

Last edited by stevebrot; 11-09-2015 at 08:46 PM.
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