GET RID OF THE UV FILTER TO GET SHARPER IMAGES

You know i have been wondering all this while why the images that i got from my Canon 400mm f5.6 non-IS lens not as sharp as the photos shot through the same lens by other photographers on the internet.

I have tried to eliminate one by one the variables that may affect the final image quality like using a fast speed of at least 1/500 second for stationary birds, 1/1000 second upwards for bird in flight, using AI servo, spot focus and sometimes spot with assist points. When the light is low i used flash with high speed synch mode so i can shoot faster than the standard 1/250 second on tripod. But still, i got slightly soft images when zoomed all the way on the computer screen.

I started to think that i got my self a lemon lens here, i bought it new from Canon. I did not use the 1.4X tele-converter with this lens because i will lose the auto-focus at f8.0 on my 5DMK3.

So yesterday i came across a debate of using the UV filter vs do not use UV filters, and how it may or may not degrade the image quality on the internet. Some say the UV filter usage is the remanance of the film days because the film is sensitive to the UV light, the modern image sensors in the digital cameras are not so sensitive and some has built-in low pass filter which cut out any UV light that go through the lens. Some use it for extra protection for the lens front element against dirt, moisture, fingerprint smudge and damages when they happen to drop the lens, and also for easy cleaning.

Now, i also use UV clear filters on all my lenses for protection at least because i was advised to do so by the seller when i first bought my DSLR. My most expensive one is Hoya HRT CIR-PL UV circular polariser filter which cost me RM280(USD77.00 at today's rate) which is quite expensive to me.

What i am interested in is does the 77mm UV filter i put in front of my Canon 400mm f5.6 non-IS L lens affect to a certain extent the final image quality of my shots for so long? This filter is a cheap one by i-lens and not the high quality B+W MRC filters that a lot of people recommend. Some discussion on various forums said that if you use a cheap filter it may affect the final image quality, it is better not to use them at all. 

So, i decided to do a simple test myself by shooting a few shots with the UV filter and some without the UV filter on to see if there is any difference in the final image quality. I used a very sturdy Manfrotto 055X PRO B tripod and used a 10second timer mode to eliminate any vibration during shutter release. I used the fine spot focus and f5.6 aperture for all the shots.

The results were amazing and can be observed in the example shots below that the usage of UV filter(at least the cheap ones) does affect to a certain extent the final image quality of my shots. Without the UV filter my images are sharper and more contrasty than with the UV filter on. I guess if i were to use a higher-end filter like the B+W ones, the result might be more positive as claimed by some on the internet.

Example 1:

This panel was about 200 feet away and was shot with a UV filter on

Without a UV filter on

Both of the images above were not altered at all and had only been cropped to get a more close-up look. The one without the UV filter is sharper and has better contrast overall. The screws on the right and left of the board, and the red and yellow round knob are sharper. The image with the filter on appears soft.

Example 2:

A tree trunk about 200 feet away shot with a UV filter on

Without a UV filter on

In this example the difference is so obvious. The texture of the tree trunk and the timber posts is clearer.

Example 3:

Palm leaf at 20 feet away with a UV filter on

Without a UV filter on

In this example the image without the filter is brighter and the lines are more well defined.

Example 4:

This wall light fitting was 30 feet away shot with a UV filter on

Without a UV filter on

In this example the one without a UV filter on is brighter, the fine lines on the side of the light and the light casing itself is sharper.However, in this example the difference might not be so significant.

Example 5:

This hole in the wall at about 200 feet away shot with a UV filter on

Without a UV filter on

In this example the image without the UV filter on is brighter, better white balance and sharper details and wire mesh.

In conclusion, not using the UV filter on your lens does improve the final quality of your images and may make a difference in showing the fine details of the bird feathers in your photos. Of course you might get a better difference in quality if you can invest a big sum of money and get yourself a 600mm f4 IS ll L lens which costs your arm and leg, but not everybody can afford that. Sometimes all you need is a little tweaking with your existing gears at your disposal to get the images that you can live with. For me, from now on i will be shooting without using a UV filter on unless it is really necessary, like shooting in a really dusty and wet environment which when using the UV filter can save me a lot of headache cleaning my lens later on.

One thing though if you decided to not using the UV filter and you are worried about damaging your lens, you should use a lens hood because it can absorb the impact in case the front of your lens bumped into a wall or something, and use a lens cap when you are not using your camera to prevent dust and moisture from messing up the front element of your lens.

Give it a try, until then happy birding. Thanks for reading.