Good vs. Bad UV Haze filters?
in [Digital Cameras]
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From: jean-daniel dodin on 8 Jan 2010 03:11 Le 08/01/2010 00:10, Chris Malcolm a �crit : > field. At f/2.8 at 50mm on a APS-C sized sensor I can photograph > camera, but the quality has nothing to do with the swallowing of > obstructions close to the lens in depth of field. That's just the > basic optics, and would work with a really cheap crappy film camera of > the same dimensions. > quality is not only for big aperture. It's for any use jdd -- http://www.dodin.net Le wiki des forums son-image fran�ais: http://new.dodin.org/frsv/ http://valerie.dodin.org
From: whisky-dave on 8 Jan 2010 08:31 "jean-daniel dodin" <jdd(a)dodin.org> wrote in message news:4b4621d7$0$29883$426a74cc(a)news.free.fr... > Le 07/01/2010 18:45, Neil Harrington a �crit : > >> Not in my personal experience, but I have read that even a fairly deep >> scratch is unlikely to make any visible difference in imaging. > > urban legend... may be related to the focal length. Or rather DOF. So suppose you have a 3mm human hair (pubic or not). Would it be more noticable if it were on the filter or on the front element of the lens, and would that depend on the focal length of the lens. Then consider the focusing point I assume if it were infinity it'd be less noticeable than if the lens was focused at 1/2 metre. So if you have the same fault on a filter or the lens which is worse for image quality. i.e is it better to have the same size scratch on a filter or the lens from the POV of image quality rather than replacement costs. > > put a hair on the lens of a smartphone, you can see it (or it's > shadow). Some of the 'optics' I've seen on smart phones a human hair is almost a lens cap ;-) >Try the same on a better lens with different aperture. after > all, experimenting is easy with digital cameras. My other point is at which point do you decide to throw the protective filter in the bin because it's too damaged and is degrading your images.
From: Outing Trolls is FUN! on 9 Jan 2010 00:04 On Thu, 7 Jan 2010 12:04:53 -0500, "David Ruether" <d_ruether(a)thotmail.com> wrote: > >"whisky-dave" <whisky-dave(a)final.front.ear> wrote in message news:hi4rvf$99e$1(a)qmul... >> "rwalker" <rwalker(a)despammed.com> wrote in message news:etfak5lvh3gsfcp6v253e5manpencsir12(a)4ax.com... >>> On Wed, 6 Jan 2010 09:37:08 -0500, "David Ruether" >>> <d_ruether(a)thotmail.com> wrote: > >>> snip >>> >>>> But, on the >>>>other side, I do use good (Hoya and Nikkor) filters to keep lenses clean >>>>(cleaning multicoated surfaces completely is very difficult, and I would >>>>rather scrub a filter, which I can also wash, than a lens surface...) >>> >>> snip > >>> That is the primary reason I have UV filters on most of my lenses. >>> I've shot without and with the filters, and the difference is not >>> noticeable to me. And since I only shoot for me, that's all that >>> matters. And, as you say, I'd rather clean the filter than the >>> actual lens. I don't have any illusions that the filter is magically >>> going to protect the lens from breaking in a high impact accident. > >> I've always concidered the filter to be protection from dust and grime >> but what I found strange was that some people/photographers didn;t consider the fact that cleaning a filter quickly i.e without >> care because it's cheap and replaceable will degrade the quality of the image. This was in the days of film. So my thoughts were >> that if a filter gets scratched/damaged then it should be changed but I've rarely heard of people actully doing this and prefer to >> just keep using the >> 'protective' and somewhat scoured filter. > >8^) And, remember the days when "pros" used to "clean" their lenses >with quick swirls of their neckties on them? Those lenses were soon >good for little more than taking "moody portraits"... :-( I agree that >anyone concerned about optimizing the performance of their gear >should examine it and replace it as needed - but it is surprising how >many *barely visible* scratches an optical surface can have without >impairing its optical qualities. >--DR > All bullshit. A common idiot's tale told and passed down on the net by pretend-photographers. A lens can even have some bubbles in the glass and still perform admirably. Any large scratches in any filter can be blacked-out with a sharpie with no perceivable performance lost. One of my favorites for Fall photography is an antique filter I found in a junk-box one time. I cannot find a filter today with the same band-pass profile. A large conchoidal fracture on one edge and several large scratches in it. All defects blacked out with a sharpie and it performs admirably. A large research-telescope mirror was shot at with a high-powered rifle by someone with an unstable agenda and left huge divots in the mirror. They were patched over and blacked out, with hardly any performance lost. (Perhaps someone can find that link to show these idiots they are idiots.) Stop parroting net-nonsense invented by armchair-photographer trolls.
From: Outing Trolls is FUN! on 9 Jan 2010 00:09 On Thu, 7 Jan 2010 14:17:06 -0500, "David Ruether" <d_ruether(a)thotmail.com> wrote: > >"jean-daniel dodin" <jdd(a)dodin.org> wrote in message >news:4b4621d7$0$29883$426a74cc(a)news.free.fr... >> Le 07/01/2010 18:45, Neil Harrington a �crit : > >>> Not in my personal experience, but I have read that even a fairly deep >>> scratch is unlikely to make any visible difference in imaging. > >> urban legend... may be related to the focal length. > >Yes. A relatively long focal length lens with a relatively large >sensor area would probably show little or no ill effect from >a fairly deep scratch even at a smallish stop with textured >subject material - but with a good WA converter on a good >1/3rd" CCD video camera set at WA, even the tiniest, barely >visible pin-prick sized "tick" in the front element glass can >show in side and back lighting conditions. That's because at wide-angle everything from the front lens surface to infinity is in focus you idiots. I have a fish-eye lens where I have to keep the front of it in pristine condition or it will put any dust on that lens in focus. This is NOT true for the average focal-lengths that all others use, nor any filters placed in front of those lenses.
From: Outing Trolls is FUN! on 9 Jan 2010 00:13
On 7 Jan 2010 23:10:15 GMT, Chris Malcolm <cam(a)holyrood.ed.ac.uk> wrote: >jean-daniel dodin <jdd(a)dodin.org> wrote: >> Le 07/01/2010 18:45, Neil Harrington a ?crit : > >>> Not in my personal experience, but I have read that even a fairly deep >>> scratch is unlikely to make any visible difference in imaging. > >> urban legend... may be related to the focal length. > >> put a hair on the lens of a smartphone, you can see it (or it's >> shadow). Try the same on a better lens with different aperture. after >> all, experimenting is easy with digital cameras > > >It's not urban legend, and it's got nothing to do with "better". It's >the simple basic optics of aperture physical size and depth of >field. At f/2.8 at 50mm on a APS-C sized sensor I can photograph >through thick wire netting which becomes completely invisible if it's >less than about two inches from the lens. It so happens that to get a >lens and image sensor of that size you probably have to buy a better >camera, but the quality has nothing to do with the swallowing of >obstructions close to the lens in depth of field. That's just the >basic optics, and would work with a really cheap crappy film camera of >the same dimensions. Keep a good black magic-marker in your camera kit. When shooting through a chain-link fence or other mesh-like obstruction (provided I have not found a way to get around it temporarily) I just black-out the small portion I am shooting through and can use almost any aperture. |