filters messing with IQ?

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elainethepain

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Hi all, i finaly got my Sigma 70-200f/2.8.
Thing is when i got it i also went for the Sigma UV filter for protection. I was talking to a friend and telling them i had bought the lens and the UV filter when they said (wow bad idea putting a filter on that lens).

When i asked why they told me that the lens performs poorly with a filter fitted. I am now looking for you's fine people to give me any thought's on this and have you had this problem?

Is there any way i can do a sure fire test on this i.e i have seen people testing there lens on a scaled paper can i print/buy this test paper?

Thanks.
 
I've never used a UV or anything like that to protect any lens because every extra piece of glass between the sensor and the subject does lower the IQ, regardless of the lens. Mind I am a bit anal with my equipment and have never scratched a lens.
 
Mark.A said:
I've never used a UV or anything like that to protect any lens because every extra piece of glass between the sensor and the subject does lower the IQ, regardless of the lens. Mind I am a bit anal with my equipment and have never scratched a lens.
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well me neither i do look after my kit, the onlt reason i got the filter is i aint the most well off person in the UK and this was a big purchase for me that i don't want to break.
 
I've experimented a bit with this idea. I used to use UV filters on all my lenses but noticed that I did get a softened image on lenses over 70-100mm. The effect was very slight though and almost not worth worrying about. I now don't use a filter in my Canon 70-300 IS but I do use them on all my other lenses and I cannot see any image deterioration. Maybe it is related to telephotos?
 
nb62 said:
I've experimented a bit with this idea. I used to use UV filters on all my lenses but noticed that I did get a softened image on lenses over 70-100mm. The effect was very slight though and almost not worth worrying about. I now don't use a filter in my Canon 70-300 IS but I do use them on all my other lenses and I cannot see any image deterioration. Maybe it is related to telephotos?
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well thats what i was thinking.
 
I have been a photographer for over thirty years - probably owned fifty lens in that time - never used a filter on the lens full time and have never scratched a front element.
They do affect image quality and should only be used when needed,if i was working on a boat for instance i would put on a clear filter to stop salt spray,maybe a polariser now and again ? but no more.
 
I agree Tom. About 30 years for me with no lens fatalities. I have used UV filters a lot in the past and I have been wondering how much loss of IQ I've blamed on the lens.
 
Filter or no filter is a question that crops up time and time again. And it's never really resolved because both sides have a valid argument.
I'm very much in the pro filter camp, because I think you can always take the filter off if you think it's causing flare, but it's a bit too late to put one on when you've managed to scratch the front element. I wouldn't argue that another layer of glass doesn't degrade the image, of course it does... the question is can you actually see the degradation in real life? Most times I can't. If I can, I remove the filter, end of story.

But I do feel much more relaxed about cleaning a filter than the front element of the lens. Maybe (probably) it's just psychological. Personal choice I guess.

cheers
 
Im one for not using UV filters, the lens hood is alot better protection.

The only time i would actually use one if i was by the sea on a windy day.

Which I also use a cut black bin liner loosely wrap round the lens, taped at both ends fully giving it enough room to focus and zoom with let me tell you it's the best way to keep that sand grains from getting inside your lens.
 
I think fabs has got a point. I'm sure filter quality plays its part. You get what you pay for.
 
nb62 said:
I agree Tom. About 30 years for me with no lens fatalities. I have used UV filters a lot in the past and I have been wondering how much loss of IQ I've blamed on the lens.
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My experience is different, 2 lens saved by the filter, in one case the filter was very badly scratched, the second actually broken, in both case the lens were undamaged, worth every pennyin my opinion. Your probably looking around £100-£200+ for a front element (depending on the lens) and theres the inconvenience of being without it.
One of the camera magizines did a test a few years back, only the really cheap filters caused any noticable issues.
 
well i went for the sigma filter thinking they would not do a cheap one, and i would not say £57 was cheap or am i wrong?
 
swanseamale47 said:
My experience is different, 2 lens saved by the filter, in one case the filter was very badly scratched, the second actually broken, in both case the lens were undamaged, worth every pennyin my opinion. Your probably looking around £100-£200+ for a front element (depending on the lens) and theres the inconvenience of being without it.
One of the camera magizines did a test a few years back, only the really cheap filters caused any noticable issues.
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Good point, it's all down to what you have experienced yourself and you have to make your own decision on whether you use them or not. I'm pretty sure that most of the UV filters I've used have been on the cheap side so it probably explains my experiences.
 
elainethepain said:
well i went for the sigma filter thinking they would not do a cheap one, and i would not say £57 was cheap or am i wrong?
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I paid £60 for a 77mm Hoya Pro-1 so no, I would say that wasn't cheap and it should do you fine. You can get UV filters for as cheap as £5 but you'd probably just end up with an expensive coaster! ;)
 
Are we saying here then that the run of the mill non pro shooter would never notice the effect anyway?

It's just mt friend was saying they read about a guy shooting birds and was for sending his lens back till they where told to remove the uv and re-shoot and it made the lens what he hoped and paid for.
 
Arguments pro and anti aside, filters can very much affect the quality of the bokeh even if sharpness isn't compromised.

Bob
 
I have always used a protection filter for 35 years as a pro plus about 20 as an amateur.
If you get high quality thin ones you will have no problems.

After 5 years use if you look at the front glass of most lenses you will see fine abrasions mostly in circles on the surface this is caused by cleaning.

In the last year I have dusted or cleaned the filter my 17-55 f2,8 most days, as I mostly shoot on construction sites. in that time I have cleaned the lens surface once.

This lens also sucks dust into itself if you do not use a filter. I have had no dust in the lens.

Make your own choice, but for me it is a no brainer.
 
Canon Bob said:
Arguments pro and anti aside, filters can very much affect the quality of the bokeh even if sharpness isn't compromised.

Bob
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A filter does not effect Bokeh, that is mostly down to the shape of the diaphragm and lens design.
 
interesting one - and i have blamed the IQ on my siggy 70-300 due to the lens. I guess the sensible way to check would be to go take half a dozen pics with lens and half a dozen without.......... in fact i will do that tomorrow, and post in this thread (ok - maybe 3 with and 3 without) and we'll have a blind test......

Pics will be 3 subjects - 2 pics of each, one with UV filter (Hoya 57mm) and one without.....

Maybe for completeness will repeat with the 120-400....... (new toy)........

Only one way to see if it makes a difference!!!
 
Terrywoodenpic said:
I have always used a protection filter for 35 years as a pro plus about 20 as an amateur.
If you get high quality thin ones you will have no problems.

After 5 years use if you look at the front glass of most lenses you will see fine abrasions mostly in circles on the surface this is caused by cleaning.

In the last year I have dusted or cleaned the filter my 17-55 f2,8 most days, as I mostly shoot on construction sites. in that time I have cleaned the lens surface once.

This lens also sucks dust into itself if you do not use a filter. I have had no dust in the lens.

Make your own choice, but for me it is a no brainer.
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Is this true about the dust?
I always wondered how it got in there.
 
Lynton said:
interesting one - and i have blamed the IQ on my siggy 70-300 due to the lens. I guess the sensible way to check would be to go take half a dozen pics with lens and half a dozen without.......... in fact i will do that tomorrow, and post in this thread (ok - maybe 3 with and 3 without) and we'll have a blind test......

Pics will be 3 subjects - 2 pics of each, one with UV filter (Hoya 57mm) and one without.....

Maybe for completeness will repeat with the 120-400....... (new toy)........

Only one way to see if it makes a difference!!!
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Was thinking the same, I will maybe try the same but not sure what a good subject would be.

This is why i was asking about the scale test i have seen where people focus the lens on BUT this might not be the ideal way.
 
Terrywoodenpic said:
A filter does not effect Bokeh, that is mostly down to the shape of the diaphragm and lens design.
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Canon Bob said:
We'll have to disagree on that one Terry.

Bob
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I'm with Bob on this one as I've had first hand experience of it on two different lenses - the 300mm F4 L IS & the 400mm f5.6 L.

On both these lenses I had a cheap Hoya attached when I first bought them & experienced very odd diagonal patterning in the bokeh. Removing the filters (and replacing with Pro 1 Digitals) removed the issue completely.

If you really doubt this I'll dig out before & after examples.

Also, I've heard that some lenses are more susceptible to poor filters than others - the 100-400 has that reputation amongst others - perhaps it is more obvious the longer the FL.

Phil
 
elainethepain said:
Can anybody give me a good subject to test on, one that will show half decent results, Thanks.
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Something static with plenty of detail and an out of focus area in the background.

Phil
 
as a motocross photographer mainly(not professional ***) i always have a UV filter on my lens, never had one smashed or damaged yet(but been close a few times). using the Pro1 Digital UV, and not found much of a difference:D

on my 50mm f1.4 i dont use any filters ***, as dont think its needed.
 
I tend to keep either a Uv or CPL filter on whichever lens I'm using at teh time and only take off for shooting if necessary. Still a bit of of a newbie but I like the peace of mind that the extra protection gives me even if it's not needed. I did buy good quality filters though and never noticed any sort of image degradation from them. :shrug:

Tommy.
 
The main problem with filters is flare, and the primary cause of that (but not the only one) is the image reflected off the mirror-like surface of the sensor, back off the rear surface of the filter, and back and forth and so on. Recent threads on here have shown some alarming examples, like this one http://www.talkphotography.co.uk/forums/showthread.php?t=130960&highlight=filters+flare

It is easy enough to see for yourself, if you provoke an extreme reaction with a bright light source against a dark background, like street lights, or a security light. For guaranteed drama, shoot car headlights straight on. You perhaps won't see much in the viewfinder, since it's a sensor creation, but in the recorded image you will see multiple images of the lights, and the black background will also be slightly lighter when comparing with/without filter shots as the flare gets progressively diffused and reduces contrast all over the image.

Cheaper single-coated filters are worse than premium multicoated ones, and it's up to you if you think it's a problem, bearing in mind that the same effect is happening to a greater or lesser extent with every photograph.

The issue with with slight sharpness degradation and bokeh problems seems to be much more pronounced with long lenses. I am not certain of this as I've not tested it and no longer own any UV filters to try it with, but the experience of respected users suggests this is the case and I know one way of immediately seeing if a filter is optically clear (ie plano-parallel surfaces) is to hold it up against the end of a binocular and move it slightly.

I suspect that acrylic filters, eg most grads, will show this effect worse than high quality glass ones. If anyone fancies doing a test and has a both a cheaper UV filter and a premium one, and a long lens of 300-plus, I'd really like to see with/without pictures, and to know if the same sort of effect is as obvious with shorter lenses. Anyone ;) ?
 
philthejuggler said:
I'm with Bob on this one as I've had first hand experience of it on two different lenses - the 300mm F4 L IS & the 400mm f5.6 L.

On both these lenses I had a cheap Hoya attached when I first bought them & experienced very odd diagonal patterning in the bokeh. Removing the filters (and replacing with Pro 1 Digitals) removed the issue completely.

If you really doubt this I'll dig out before & after examples.

Also, I've heard that some lenses are more susceptible to poor filters than others - the 100-400 has that reputation amongst others - perhaps it is more obvious the longer the FL.

Phil
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I have never used poor quality filters... but that description itself suggests every sort of horror.

You are warned when using some very long lenses not to use filters except those that fit in the rear of the lens. with these, a filter is part of the lens computation, and is in fact problematic if you use them without.
 
Just a thought, and it won't protect the glass, but when I'm not using a polariser, I usually leave the step-up ring on the end of the lens.

It can (and does) protect the outer metal rim of the lens from damage caused by impact with fence posts, the ground etc, when accidents happen.

j
 
Terrywoodenpic said:
I have never used poor quality filters... but that description itself suggests every sort of horror.

You are warned when using some very long lenses not to use filters except those that fit in the rear of the lens. with these, a filter is part of the lens computation, and is in fact problematic if you use them without.
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There is a section on long lenses and filters in the book Canon Lens Work III. Here, page 13 http://software.canon-europe.com/files/documents/EF_Lens_Work_Book_7_EN.pdf Basically, to eliminate the mirror reflection problem off the sensor, Canon produces custom protection elements with a curved surface.

I don't think there is any suggestion that rear mount filters are part of the lens computation and references to always needing to shoot with them fitted is simply to do with not leaving out the filter mount, for obvious reasons.
 
jerry12953 said:
Just a thought, and it won't protect the glass, but when I'm not using a polariser, I usually leave the step-up ring on the end of the lens.

It can (and does) protect the outer metal rim of the lens from damage caused by impact with fence posts, the ground etc, when accidents happen.

j
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Personally I feel a lens hood would be far better suited to the protection task that the step up ring... with that added bonus of flare reduction
 
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