Does a filter degrade the image? You decide!

StewartR

StewartR

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Stewart
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We seem to have had quite a few "what filter" or "should I or shouldn't I filter" threads here recently. Of course a protective filter will degrade an image to some extent, but the key issue is whether it's noticeable. Some people claim that they can tell the difference; some claim that the difference is obvious. But I don't think we've seen any with-and-without comparisons.

So here's one.

I took a shot of part of my garden, using:
* my trusty old Canon 350D
* a brand new Canon EF-S 10-22mm f/3.5-4.5 USM
* a brand new Hoya Pro 1 Digital protector filter
and then I took the same shot without the filter. Or maybe it was the other way round?

Both were shot in RAW and processed identically - the same RAW conversion parameters, then the same levels adjustments, USM sharpening, etc. As well as the whole frame, I've prepared a coupe of 100% crops - again processed identically.

In the pictures below, numbers 1B and 1C are crops from 1A. Similarly, 2B and 2C are crops from 2A. So your challenge is to decide:

Were 1A/1B/1C taken with the filter, and 2A/2B/2C without the filter?
Or perhaps 2A/2B/2C were taken with the filter, and 1A/1B/1C without?

Can you tell the difference?

1A. Full frame. With filter, or without?
339645649_sDoLQ-L.jpg


1B. Full frame. Without filter, or with?
339645951_3Vf3J-L.jpg


2A. 100% crop. With filter, or without?
339645832_ET6D8-L.jpg


2B. 100% crop. Without filter, or with?
339646121_kAZBb-L.jpg


3A. 100% crop. With filter, or without?
339645740_bo9Fg-L.jpg


3B. 100% crop. Without filter, or with?
339646025_pXz3j-L.jpg


So tell me what you think. Which is which, and why? Or can you not see any difference?
 
Well I cant see any difference... and if there IS any difference I think Id rather have my lens protected than worry about that tiny amount. (y)
 
I agree with Janice, (y) buggered if I know :shrug:
 
Going by physics it Must degrade the image but in real life you probably wont notice unless it's a pants filter :)
 
My puter is pulling the web through my mobile at the mo, compressing all the images to state near death but I'll plump for set one without and two being with the filter.

Not a fan of them myself, although in that shot I'd not really expect to lose or gain an awful lot either way. Bring the sun round to fall across the lens and then perhaps my risk might pay off. :)
 
Difficult to judge because of your subjects. Do it on a large brick wall please.
My guess:
1B, 2B, 3B are with filter
StewartR said:
In the pictures below, numbers 1B and 1C are crops from 1A. Similarly, 2B and 2C are crops from 2A. So your challenge is to decide:

Were 1A/1B/1C taken with the filter, and 2A/2B/2C without the filter?
Or perhaps 2A/2B/2C were taken with the filter, and 1A/1B/1C without?

Can you tell the difference?

Which is which, and why? Or can you not see any difference?
Click to expand...

I don't get your file numbering....
 
strobemonkey said:
Difficult to judge because of your subjects. Do it on a large brick wall please.
Click to expand...
I would respectfully suggest that it you need photos of large brick walls to be able to tell the difference, then the difference is too small to worry about.

But if you think there's a different type of everyday subject which would accentuate the difference, just name it. I'd be happy to consider taking another couple of shots.
 
StewartR said:
I would respectfully suggest that it you need photos of large brick walls to be able to tell the difference, then the difference is too small to worry about.
Click to expand...

I think that's true.

StewartR said:
But if you think there's a different type of everyday subject which would accentuate the difference, just name it. I'd be happy to consider taking another couple of shots.
Click to expand...

How about macro shots with a macro lens???
 
Try shooting into the sun or with the sun in the periphery, or take a night shot with point sources of light (such as street lights or car headlights) or a landscape shot with glistening water, or fireworks & bonfires, I'm sure we'll all be able to see a difference then :)
 
So let's have a look at the scores on the doors so far.

Janice ... can't tell
Cobra ... can't tell
mrgrubby ... can't tell
dazzajl ... A=without, B=with (but probably guessing)
strobemonkey ... A=without, B=with, but would prefer shots of a brick wall
Veracocha ... A=without, B=with
sprog ... probably can't tell
Kerioak ... A's look better than B's

Any more takers? I'm inclined to let it run a little longer before revealing the answer. And I'd really like to see some of the "difference is obvious" brigade have a go at it...
 
1B. 2B, 3B with filter i think, they are ever so slighty softer at 100% crop.

Bugger all in it ***
 
dazzajl ... A=without, B=with (but probably guessing)
Click to expand...

Nope, right or wrong I'm happy to stand by that as a firm decision.... but it's not on resolution that's for sure. :D
 
For the life of me I can't tell which are with and which are without.

However, there is a very slight difference between the two (2A & 2B). If you look at the large leaves on the bottom of each picture you'll notice that those in 2A are darker than those in 2B! :shrug:

Still, both are of the same standard. So, whichever is with a filter - from these two - I wouldn't care!
 
Would be intersting to also know what type / brand of filter you've used; and if possible a comparison in a dark setting (say in doors, or at night) with a lot of side light(s) (like in a street) which can be problematic :shrug:
 
A looks darker than B, in the first image anyway.
I couldn't say which is running a filter :shrug:, but I'm gonna go with the A's since adding glass never made anything lighter.
The difference isn't worth a fart for this exercise.
Maybe with fullsize images, and double hard pixel peeping at atomic level, you might see a difference.
 
Firstly, thank you Stewart for running this test as I was one of those who posted asking what was the best filter to use to protect my lenses.

As for the difference, I've looked at them, gone way, looked again, and I still can't tell the difference.
 
A bit off topic for Stewart:

Could you please kindly do a test between EF 50 1.8 and an "L" zoom lens that cover 50mm.

Both at 50mm and same apperture, say f4 and f11. Remove exif data and we'll guess which image is from what lens...
 
StewartR said:
I would respectfully suggest that it you need photos of large brick walls to be able to tell the difference
Click to expand...

Dumb newbie question; why a brick wall? :thinking:
 
I'm going for A is with and B is without.... Mainly to do with colour saturation - A is marginally more saturated... B less so. Can't notice difference in sharpness though as most parts of the image may or may not be moving due to the wind
 
sprog said:
Try shooting into the sun or with the sun in the periphery, or take a night shot with point sources of light (such as street lights or car headlights) or a landscape shot with glistening water, or fireworks & bonfires, I'm sure we'll all be able to see a difference then :)
Click to expand...

Yep, this is what I was thinking as the filter obviously won't have the same coating(s) that the actual lens will have.
 
StewartR said:
So let's have a look at the scores on the doors so far.

Janice ... can't tell
Cobra ... can't tell
mrgrubby ... can't tell
dazzajl ... A=without, B=with (but probably guessing)
strobemonkey ... A=without, B=with, but would prefer shots of a brick wall
Veracocha ... A=without, B=with
sprog ... probably can't tell
Kerioak ... A's look better than B's

Any more takers? I'm inclined to let it run a little longer before revealing the answer. And I'd really like to see some of the "difference is obvious" brigade have a go at it...
Click to expand...

I'm with Kerioak, the A's have slightly deeper colours, have a look at the sky in 1 & 2.....

Steve
 
There's a minor difference in the colours and I think I can only see it because I'm deliberately looking for the difference in the two shots side by side (or one on top of the other). I have no idea which is with or without the filter though.
 
For what it's worth, I would say A=with, but the difference in this situation is obviously too small to say for sure either way. :shrug:
 
Im in the 'the colours seem better in the A's camp' especially on the the 1st and 3rd image.

I'm running a calibrated monitor if that makes any difference but for all that does my eyes are knackered :)
 
No idea, and there is such a minor difference in the colours that if others had not posted about it I would not have noticed them either!!
 
I think it quite often boils down to the quality of the filter, I've used (in the distant past) cheapo UV filters and experienced degradation, particularly flare in my images.

A good quality filter (as you have used), you would be hard pushed to tell any difference. (IMO)
 
If I was to guess I would say A had the filter.

However.... hardly any noticeable difference. So much so, that I can't really tell which has it or not, but a gut feeling goes with A. They just seem slightly darker
 
I don't think we need to worry about which is which. What this just demonstrates is that there is hardly any noticeable difference to the images yet alone anything that indicates a drop in image quality. I imagine there are short falls in certain lighting etc but on the whole I'm impressed with the results.
 
:bang:After scratching the front element on a £300 lens last year I put a quality UV one on every one of my lenses now :bang:
 
Ill too go with A`s filtered and B without, the colour is slightly richer on the A`s and would suggest a UV filter to my untrained eye............:shrug:

When are we gonna find out the suspense is painful.
 
OK, time to let the cat out of the bag.

1A/2A/3A are with the filter. 1B/2B/3B are without.

Some people got it right, some people got it wrong, and some couldn't see any differences. But I think we can all agree that any differences which do exist are entirely marginal.

The only difference that I can detect is that the colours are slightly more saturated in the A's, ie with the filter. But that could be an artefact of the processing. I processed the two images identically. If I had processed each one on its merits (assuming of course that I had the skill for that, which I don't!) then I expect this difference would disappear.

So where does this leave us? I think it's reasonable to conclude that, in decent light, if you use a good quality filter (this was a Hoya Pro 1 Digital), then your image quality will not suffer.

Is anyone up for doing another test with more challenging lighting?
 
Woohoo I was correct...

I think testing for flare would be a good idea. Maybe induce some and then remove the filter to see how it alters the effect.

Could be worth testing for vignetting on something wide like a 10-22 lens? (you previous pics may have answered this if they were at 10mm)
 
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