GH2 vs GH3 video quality comparison

When Panasonic released the GH3, it was expected to raise the bar even further in terms of video quality. To compare it against the GH2, I connected both cameras to a piece of wood, using Manfrotto Superclamps, so that they would record the same scenery for comparison.



On both cameras, I used the Lumix G 14mm f/2.5 pancake lens, a favourite of mine. I focused on "infinity", and then set both cameras to manual focus. The lenses were set to f/5.6 for the best sharpness, and I used the base ISO on both cameras. With the ambient lighting, the shutter speed was usually around 1/120s. Both cameras had the same settings in terms of sharpening and saturation. It was all recorded in 1080p, 25fps.

Even if the cameras have identical lenses mounted, they still have different field of view during video recording. This is due to only the GH2 having the an over-sized, multi aspect sensor, giving a wider field of view in video mode.

Here are the videos combined, for easy comparison:



Some may doubt that the quality of the YouTube rendering of the video is sufficient to really tell the difference between the cameras. I agree with that, and to assist in comparison, I uploaded parts of the video at 200% size, which probably makes the video image quality easier to assess. And I made some 100% crops from the original out of camera video files, uncompressed in PNG format below:





This last image comparison is from the ISO 1600 footage:

Conclusion

Just like I have concluded previously, the GH3 features somewhat less rolling shutter artefacts in video mode. Further, I think it looks like the GH3 handles high contrast better, and the overall sharpness of the video stream is better. Not unexpected, since the GH3 can record at up to 72Mbps bitrate, as compared with 24Mbps for the GH2. I used 50Mbps with the GH3 here, though. Of course, the bitrate is not everything, the sensor, AA filter, downsampling algorihm and compression algorithm are also important.

I also like the colours of the GH3 better. At high ISO, the GH3 does provide more details.

As far as I can see, the GH3 does deliver on the promise of delivering even better video quality than the predecessor GH2.

Lumix X 12-35mm f/2.8 sharpness evaluation

The Lumix X 12-35mm f/2.8 is the new premium standard zoom lens from Panasonic. It was launched before the Panasonic GH3 camera, but obviously intended as the kit lens for their highest quality cameras. With a steep price tag to boot, there is much anticipation to the image quality from this lens.

A viewpoint commonly found in online discussions is that a prime lens is always better than a zoom lens. With this in mind, it is sensible to compare this zoom lens with some prime lenses. I chose to compare it with the Lumix G 14mm f/2.5 pancake lens and the Sigma 30mm f/2.8 EX DN, which are both covered by the zoom range of the Lumix X 12-35mm lens.

At 14mm

Using a tripod, and with the GH3 camera at the base ISO 200, I took the same picture with both lenses. The focus distance was very short, about 30cm/one foot. The pictures are out of camera (OOC) JPEGs. I made sure to focus on the same item in both images, the lone branch in the upper left corner.

Lumix G 12-35mm @ 14mm f/2.8	Lumix G 14mm @ f/2.5

Now, let me be the first to admit that there are many problems with this test setup. For example, the lenses have different lengths, so that the field of view turns out to be different in the two cases, even though the camera is at exactly the same place in both examples.

Also, since I am focusing on an item close to the border of the frame, what is in focus could be quite different in the centre of the frame, due to different focal plane curvature. However, despite these shortcomings, I think we will be able to see examples of items that are in focus in both pictures, and, hence, be able to do some comparison of their relative sharpness.

Here are some enlargements (100% crops) from the top left corner, where I set the focus point.

And from the top middle:

Finally, from the centre:

Based on these images, keeping in mind that the focal plane may be slightly different in the two last crops, I think we can conclude that they are pretty much equally sharp.

The Lumix X 12-35mm zoom lens appears to give a bit nicer bokeh, but on the other hand, the Lumix G 14mm f/2.5 handles the flare better. These observations are perhaps not surprising: We already know that the pancake lenses are not optimal in terms of bokeh. And when it comes to flare, we would normally expect that the simpler lens, with fewer lens elements, handles flare the best. The Lumix G 14mm pancake lens has only six lens elements, while the zoom lens has a whopping 14 lens elements. Flare is usually caused by unwanted stray reflection and refraction between the lens elements.

I think we can conclude that both lenses perform very well here.

At 30mm

This time, I focused in the single leaf in the centre of the frame. The focus distance was about one meter (three feet), suitable for a portrait photo.

Lumix G 12-35mm @ 30mm f/2.8	Sigma 30mm @ f/2.8

While I thought that I focused on a single leaf in the centre, it turns out that they were two different leaves, at some distance, and the Sigma lens focused on the left leaf, while the Lumix lens focused on the right leaf.This just shows that extreme caution must be taken when doing these studies. Still, I think the 100% crops from the centre are interesting:

We see that both lenses are very sharp in the centre. We also see that the Sigma 30mm lens is more resistant to flare, again probably because of the simpler construction using only seven lens elements.

Here are some crops from the lower left side, to look at the bokeh:

Based on these examples, the bokeh looks just fine for both lenses.

Conclusion

My experience so far indicates that the Lumix X 12-35mm f/2.8 zoom lens has very good optical properties. I plan to make more comparisons later.

Despite using "nano surface coatings", the lens is prone to flare, though, but it is not unexpected for a lens of this class.

Geometric distortion correction

Most of the Micro Four Thirds lenses need geometric distortion correction applied for the output images to become rectilinear. This is done totally seamlessly by the camera and software, both for JPEG and RAW images. So the user never notices that the image, as seen by the camera through the lens, is not rectilinear in the first place.

This is in contrast to older DSLR systems. In these systems, there is an optical viewfinder, in which the users sees exactly what the sensor sees, through the lens. With a DSLR system, the lens must be rectilinear, otherwise, the user will be appalled by the geometric distortion when using the camera.

Here is an illustration of two basic kinds of distortion: Pincushion distortion (left) and barrel distortion (right):

In reality, the geometric distortion might very well be more complicated than what is illustrated by these simple models.

I have previously tested the geometric distortion properties of some Micro Four Thirds lenses, and I found that virtually all lenses featured some distortion correction. Especially wide angle lenses, or the wide end of zoom lenses. Since this time, I have acquired some new lenses, and I wanted to test them in the same way.

Again, I have done the tests by taking a pictures of a tiled wall. The images look like this:

Since I am only interested in the geometric distortion, I have increased the contrast so that the images become monochrome. I also superimposed the corrected out of camera JPEG images (black) onto the original RAW uncorrected images (red).

I included the appropriate adjustment needed. The adjustment numbers in percent refer to the "Lens Distortion" filter in The Gimp, an image processing software. Of course, to become rectilinear, some lenses might require more complicated adjustment than the simple model given by the "Lens Distortion" filter. So these figures are just intended to be approximate relative indicators of the degree of distortion. A positive figure indicated barrel distortion, while a negative figure indicates pincushion distortion.

Here is a comparison of the uncorrected and corrected images for some lenses.

Panasonic Lumix 14mm f/2.5 pancake: -16%

There is a significant barrel distortion, which is corrected in the in-camera JPEG image. However, there is some residual barrel distortion even in the corrected image. I have noticed this previously. In fact, the lens is rectilinear (after correction) at long focus distances, but has some barrel distortion at close focus distances. In this example, we see the barrel distortion at close focus distance. This is not an uncommon behavior for lenses that feature internal focus.

Olympus M.ZD 45mm f/1.8: 0%

No distortion correction at all. It looks like there is a small amount of pincushion distortion, though, so perhaps there should have been some in-camera correction done by the camera.

Panasonic X PZ 45-175mm f/4-5.6 @ 45mm: 0%

No distortion correction at 45mm.

Panasonic X PZ 45-175mm f/4-5.6 @ 100mm: +5%

There is some pincushion distortion correction at 100mm, but not a lot.

Panasonic G 100-300mm f/4-5.6 @ 100mm: 0%

No geometric distortion correction at 100mm.

Summary

Including the results from my previous study, I can present a table with the relative distortion corrections of various lenses:

Lens	Focal length	Relative distortion correction
Lumix G 20mm f/1.7 Pancake	20mm	-11%
Lumix G 14mm f/2.5 Pancake	14mm	-16%
Lumix G 14-42mm f/3.5-5.6	14mm	-18%
Lumix G 14-42mm f/3.5-5.6	30mm	0%
Lumix G 7-14mm f/4	7mm	-17%
Lumix G HD 14-140mm f/4-5.8	14mm	-17%
Lumix G HD 14-140mm f/4-5.8	30mm	-4%
Lumix G 45-200mm f/4-5.6	45mm	+1%
Lumix X PZ 45-175mm f/4-5.6	45mm	0%
Lumix X PZ 45-175mm f/4-5.6	100mm	+5%
Lumix G 100-300mm f/4-5.6	100mm	0%
Olympus M.ZD 45mm f/1.8	45mm	0%
Panasonic Leica Lumix DG Macro-Elmarit 45mm f/2.8 1:1 Macro	45mm	0%
Lumix 8mm f/3.5 fisheye	8mm	0%
Sigma 30mm f/2.8	8mm	0%

Conclusion

We see that wide angle lenses and zooms typically feature barrel distortion (negative figure) in the wide end. On the other hand, longer lenses are often not corrected, or are corrected for a small amount of pincushion distortion (positive figure). The in-camera distortion correction is some times insufficient, for example we've seen that the Olympus M.ZD 45mm f/1.8 and Lumix G 14mm f/2.5 pancake lenses feature some geometric distortion in the short focus range, while behaving better at infinity focus.

There are some who have speculated that Leica-branded lenses are not subject to any software corrections. I have looked at the Panasonic Leica 45mm f/2.8 1:1 macro lens, and found no indications of software adjustments to the images. However, I still don't believe that statement. One of the first cameras for which the software corrections were widely discussed online, was the Panasonic Lumix LX3 high end pocked camera from 2008. And it does feature a Leica-branded lens, and quite clearly, there is a significant barrel distortion in the wide end of the zoom, which is corrected by software.

"Dances with fire", example Lumix 14mm video

This video was recorded using the Panasonic GH2 and the Lumix G 14mm f/2.5 pancake lens.



I left everything on auto, and just pushed the red video button. This gives me a 720p AVCHD video stream. Since I dislike the highest resolution 1080i mode, due to the interlace, I tend to use 720p progressive mode. I have the European version of the camera, so the frame rate is 50fps.

Sadly, the camera does not seem to record the image parameters when making video captures. So I don't know for sure what aperture, shutter speed and ISO was used. But I would guess the camera selected the largest aperture, f/2.5. And the shutter speed was probably as slow as possible for a 50 fps video, so around 1/60 second. The ISO was probably pushed up quite a lot, I would guess around 1600-3200.

Focus

I had autofocus selected (AFS). It would probably have been a good idea here to prefocus, and then select manual focus (MF) during the video capture. That is to avoid having the focus hunt during the video capture. You can see that the camera jogs the focus back and forth now and then, to verify that the image is in focus. But since the Lumix G 14mm lens focuses very fast, this is barely noticeable, even in this low light situation.

With the Lumix G 20mm f/1.7 pancake, the focus is slower, and it can wander off for some seconds when recording a video. For the 20mm lens, it is best to have some control over the focus during videos.

White Balance

The white balance was also left on auto (AWB). This gives a slightly yellow tint to the images. Perhaps I could have tweaked the white balance better. But this is hard to do when you don't have time to plan the video capture in advance. On the other hand, the yellow colours are actually true to the actual lightning conditions.

Flare

Notice that there is some flare in the video. You can see that the flames generate greenish ghosting symmetrically opposite along the optical axis. This is quite common when you have strong light sources inside the image frame.

This illustration shows the relationship between the actual light source and the flare:

A lens hood would not have helped, since the hood is only designed to keep out light which comes from outside the image frame.

Generally, flare is more of a problem the more lens elements the lens is composed out of. So generally, you would find flare to be a bigger problem for a zoom lens, which can easily have more than ten individual lens elements, than for a prime lens. The Lumix G 14mm f/2.5 pancake lens only has six lens elements. However, the optical formula and the quality of the lens elements is also important for the flare characteristics.

Using a protective lens filter on the front of the lens can give you more lens problems, especially for low quality lens filters.

Audio

I used the onboard microphone, and left the levels on auto. It sounds like the sound is clipped some times. But I would guess this is actually due to the sound system being run to loud, and not due to the microphone.

Using an external microphone probably has the potential to give better sound in the video recording. But it makes the setup look much more professional, which might scare some people, and hence negatively affect the video. Using the GH2 with the 14mm pancake lens gives a very compact and non-obtrusive package, which is handy for recording everyday life.

Lumix 14mm as a video lens.

The very fast autofocus and the inaudible focus action make the Lumix G 14mm f/2.5 an ideal video lens.

It has a generously wide field of view, which is useful when video recording a group of people. The wide field of view also makes it easy to handhold the camera without the hand shake affecting the video stream too much.

The small size and unobtrusive looks also makes it easy to get close to people without scaring them, which is a big plus if you intend to video record people.

On the other hand, a zoom also comes handy for video use. For some more flexibility, I would recommend the Lumix G 14-42mm f/3.5-5.6 basic kit zoom. It is light, very fast focusing, and pretty good quality.

Focus noise compared

Focus noise can be distracting. If you are in a silent environment, noise from the autofocus will distract the people you try to photograph, and will potentially make you look stupid.

Most Micro Four Thirds lenses have internal focusing, meaning that some smaller lens elements inside the lens move to achieve focus. This is generally fast and silent.

To illustrate the difference in focus noise, I made some measurements using an Iphone. Now, I don't believe the Iphone is very well calibrated. So the absolute noise measurements are probably not too accurate. But the relative noise levels can be studied this way.

To measure the noise, I put various lenses on the Panasonic GH2, and put the camera in continuous autofocus mode, AFC. In this mode, half pressing the shutter will make the focus job back and forth continually. I pressed the shutter 3-5 times for about one second each time, to capture the noise level.

Here is a video showing the study:



The results:

Lens	Measurements	Average
Lumix G 8mm fisheye	50 46 52 51	50 dB
Lumix G 14mm	49 51 47 48	49 dB
Lumix G 20mm	61 60 58 59	60 dB
Leica Lumix DG 45mm macro	51 52 50 52	52 dB
Lumix G HD 14-140	55 62 65 62 61 60	61 dB
Lumix G 45-200	50 53 56 54	54 dB
Olympus ZD 4/3 50mm f/2	76 79 81	79 dB

Conclusions

The outcomes are mostly as expected. The Lumix G 20mm f/1.7 pancake lens is the odd man out in this test. Since it is the only Micro Four Thirds lens that features a traditional focus mechanism, and not internal focus, it is also the most slowly focusing and noisy. The lack of internal focus means that the whole focus assembly moves during focus. You can see this in the video.

Perhaps the only surprise in the test is the relatively loud focusing noise from the Lumix G HD 14-140 superzoom lens. This lens is marketed as a video optimized lens, and features fast and silent operation. I would speculate that the noise picked up is not only from the focusing, but also from the OIS unit, which is powered when half pressing the shutter. Also, since this is the largest lens, the sound comes from a source closer to the mobile phone picking up the noise. Hence, the sound reading should be expected to be more audible. So I would take the measurements from the 14-140mm lens with a grain of salt.

The Olympus ZD Four Thirds 50mm f/2 macro lens is not a contrast detection autofocus (CDAF) optimized lens, and therefore it is rather slow to focus. It also generates a lot of noise, since it moves large lens groups back and forth. This lens is mostly useful for studio work on Micro Four Thirds, I'd say, due to the very slow autofocus.

The final word is that most Micro Four Thirds lenses, except the 20mm pancake, focus very fast and virtually noiseless.

Another aspect is the noise from the aperture change. I have not measured this, but my experience is that this is rather noisy with all lenses, except the Lumix G HD 14-140 superzoom lens. The 14-140mm lens has an almost inaudible change of aperture.

I would have liked to test the Lumix G 14-42mm f/3.5-5.6 kit lens. However, I took my lens back to the store due to a bad aperture diaphragm. After more than two months, they have still not fixed it.

Bokeh comparison @ 14mm and 20mm

Many people are looking for camera systems that can give a thin depth of focus (DOF). With a thin depth of focus, objects that are beyond the focus distance, or closer, are out of focus.

The Micro Four Thirds system is not ideal for getting thin DOF. To get a thin DOF, you are better off buying a camera with a large sensor, for example full frame DSLR cameras.

However, it is still possible to get a thin DOF with Micro Four Thirds if you use a close focusing distance. I have evaluated the out of focus rendering (bokeh) at close focus using three lenses: The Lumix G 14mm f/2.5 pancake, the Lumix G 20mm f/1.7 pancake and the Lumix G 14-42mm f/3.5-5.6 kit zoom lens.

I took the same picture using the three lenses at various apertures. Here are the full images at maximum aperture:

Lumix G 14mm @ f/2.5	Lumix G 20mm @ f/1.7
Lumix G 14-42mm @ 14mm f/3.5	Lumix G 14-42mm @ 20mm f/4.1

The focus was set on the emblem on the bell in the middle left part of the image. I used the Panasonic GH2 at base ISO, and the shutter speed was around 1-6 seconds. I used a tripod, and also two second shutter delay, to avoid camera shake.

The images above are taken using the maximum aperture available with the given lens. Hence, the DOF is as thin as possible, given the focal length and focus distance.

To better evaluate the bokeh, I have made 100% crops from two parts of the image (click to enlarge):

The first crops are from the focus area. From these images, it could look like the 14mm pancake lens is unsharp. However, these images were taken primarily to evaluate the bokeh, not the sharpness, and the focus point might be slightly different between the lenses. In my experience, the sharpness of the 14mm pancake lens is rather good.

In the seconds image, we see the out of focus highlights. I suppose one could say that neither of the lenses give a very nice bokeh. They have various problems. They all exhibit some ringing, but it seems to be worst at 14mm. Also, the bokeh is uneven, and "dirty", "swirly".

The 20mm pancake lens shows the most non-circular highlights, both wide open and closed down.

The 14-42mm lens shows some strange irregularity at f/5.6, at both 14mm and 20mm. This could look like a construction error of the aperture diaphragm. However, it is not likely to pose much of a problem, since only at very close focus distance would you see much out of focus rendering at f/5.6

In terms of roundness, the 14mm pancake has the most consistent appearance.

Geometric distortion correction

Many Micro Four Thirds lenses feature in-camera geometric distortion correction. Two examples are the Panasonic pancakes, Lumix G 14mm f/2.5 and Lumix G 20mm f/1.7. Both have pretty similar distortion correction needs. When converting the sensor output to the out of camera JPEG image, around 10% of the pixels in the border area are lost.

This is somewhat controversial. Some feel that a quality lens should not require further software correction. In fact, the lack of geometric distortion is a traditional sign of a high quality lens.

I think that this is mostly a non-issue. By allowing some aspects of the image to be adjusted in software, the lens designers can focus on issues which cannot be corrected in post processing. This has the potential of making the lenses better, at a smaller size, and potentially a smaller cost. Panasonic Micro Four Thirds lenses are adjusted for geometric distortion and some chromatic aberrations. The geometric distortion is also corrected in Olympus Micro Four Thirds cameras. At this time, though, Olympus does not correct chromatic aberrations.

To illustrate the geometric distortion done with various lenses, I have photographed a tiled wall with them, and shown the sensor output compared with the corrected JPEG output.

Here is an example pair from the Lumix G 20mm f/1.7 pancake lens:

uncorrected RAW output	JPEG image

Note that this is in no way a criticism of using RAW images. There are many RAW image converters which will do the distortion correction automatically and seamlessly, and you will never notice that there was any geometric adjustment done at all. I am using the RAW images to visualize the initial image captured by the sensor, as it is the only way to access it.

Here is a comparison of the uncorrected and corrected images for some lenses.  Since I am only interested in the geometric distortion, I have increased the contrast so that the images become monochrome.  I also superimposed the corrected out of camera images (black) onto the original uncorrected images (red).

I have also included the appropriate adjustment needed. The adjustment numbers in percent refers to the "Lens Distortion" filter in The Gimp.

Lumix G 20mm f/1.7: -11%

Lumix G 14mm f/2.5: -16%

Lumix G 14-42mm f/3.5-5.6 @ 14mm: -18%

Lumix G 14-42mm f/3.5-5.6 @ 30mm: 0%

Lumix G 14-140mm f/4-5.8 @ 14mm: -17%

Lumix G 14-140mm f/4-5.8 @ 30mm: -4%

Lumix G 45-200mm f/4-5.6 @ 45mm: +1%

Conclusion

Normal zoom lenses pretty consistently feature barrel distortion in the wide end. The tele zoom Lumix G 45-200mm appears to have some very small pincushion distortion, but very minor.

Some lenses that do not feature any geometric distortion correction are the Lumix 8mm f/3.5 fisheye and Panasonic Leica Lumix DG Macro-Elmarit 45mm f/2.8 1:1 Macro lens.

Bokeh comparison @ 14mm, take two

I have previously looked at the bokeh of the Lumix G 14mm f/2.5 pancake and Lumix G 14-42mm f/3.5-5.6 lenses.

That comparison featured an image without any highlights in the out of focus background. This time around, I figured I would try a high contrast night exposure, with bright highlights out of focus. Again, I set ISO 160 on the Panasonic GH2. The camera was on a tripod, and the exposures lasted around 1-8 seconds.

Here are the full images from both lenses:

Lumix G 14mm @ f/2.5	Lumix G 14-42mm @ 14mm f/3.5

The focus was set on the post to the left, which is around 30cm from the camera, close to the minimum focus distance for these lenses. I used the A (aperture) exposure mode.

To evaluate the bokeh, let's enlarge some of the areas from the image.

From the centre of the image:

And from the top of the image:

(Click for larger images.)

I think the bokeh from both lenses is a bit "dirty" and "swirly". The 14mm pancake lens has the most ringing in the out of focus rendering.

Conclusion

My conclusion, which is a bit unexpected, is that the zoom lens has the best bokeh. Or perhaps it is better to say it has the least displeasing bokeh, since neither are very good. But the difference is small.

The 14mm pancake lens has non-circular bokeh even at the largest aperture, which is not so usual. The Lumix 20mm f/1.7 pancake lens also exhibits non-round bokeh. So perhaps it is related to the pancake design?

Keep in mind that these enlarged images are 100% views from the 16 megapixel GH2 sensor. most people will probably downscale the image some, in which case the dirtiness and ringing of the bokeh becomes a smaller issue.

Also, bokeh and wide angle is not that much of an issue anyway. To get some out of focus rendering at 14mm focal length, I had to focus close to the minimum distance, and look at objects in the far background. It is not so likely that you'll find the same situation in real life.

For example, if you're photographing people, you'll want to keep then at a distance of around 1 meter or more, to avoid perspective distortion. At this focus distance, you're unlikely to see much bokeh with a 14mm lens, even at f/2.5.

So even if the bokeh for these lenses at 14mm could have been better, you should not see it as a fatal problem.  It is, at worst, a minor annoyance for some types of images.

Using protective filters on lenses

A topic of much debate is whether or not to use clear glass filters on the front of lenses, for protection. Some would argue that putting on a clear filter protects the lens against objects touching it, and against water, dust, and so on. If something hits the front of the lens, they would say, it breaks the filter and not the lens itself.

Others argue that the front lens element typically is strong, and does not need extra protection. Some would even say that adding a filter may be negative, that it breaks more easily, and that the glass shards could add more to the damage of the front lens element.

Another argument is that an extra glass filter deteriorates the optical properties of the lens.

Now, I wouldn't want to drop my lens on the pavement to examine if using a filter helps protect it or not. Besides, as all lens accidents are different, one drop would not prove much anyway.

But to look at the resulting images when using a filter, as opposed to not using a filter, is possible. To examine the effect of using a clear glass protective filter, I took the same picture with and without a filter.

Example @ 200mm

Here is an example picture taken using the Panasonic GH2 with the Lumix G 45-200mm f/4-5.6 lens at 200mm f/5.6.

without filter	with filter

This is an image with fairly low contrast, and on first glance, the two images are pretty similar. Let's look at an enlargement:



So is there any difference? Not really, I would say. Perhaps one could say that there is a tad bit more contrast in the left image, without the filter.

Example @ 14mm

Another example taken using the Panasonic GH2 with the Lumix G 14mm f/2.5 lens at f/5.6.

without filter	with filter

In this case, we barely need to look at an enlargement to see the differences. Clearly, there is more flare when using a filter. The right image also has some odd "phantom lights" in the frame, from light reflections between the filter and the lens. Here is one example in the centre of the frame:



Beyond the flare, it's hard to argue that the right image is worse in terms of sharpness, for example.

Example @ 45mm

Finally an example picture taken using the Panasonic GH2 with the Lumix G 45-200mm f/4-5.6 lens at 45mm f/4.

without filter	with filter

In this case, it is very clear that the presence of the filter deteriorates the image. Not only is there much more flare, there is also a severe reduction in the contrast and sharpness across the whole frame.

Here is an enlargement which demonstrates this:



Conclusion

In low contrast situations, it is hard to find much evidence of negative impact from using a filter. However, when there is more contrast, e.g., a strong light source in front of the camera, the presence of a filter generates significantly more flare, and potentially also less contrast.

People who are proponents of using clear protective filters may still not agree with me. They could argue that if I had used higher quality multi coated filters, I would not have gotten these negative impacts. And perhaps they are right.

Since I don't believe in using filters for protection myself, I haven't invested in the most expensive filters. So it could be that higher quality filters would have reduced the deterioration.

Still, I believe it is fair to say that adding a filter will generate some deterioration of the image quality. But if using a protective filter gives you more peace of mind when using your expensive lens, perhaps that is an acceptable cost to you.

Personally, I prefer using hoods for basic protection of the front lens element.

Appendix

The filters used were: "Kenko Digital Filter UV" (52mm) for the Lumix G 45-200mm f/4-5.6 lens, and "Green Digital Filter UV" (46mm) for the Lumix G 14mm f/2.5 lens. Both filters are littered with terms like "High Quality" and "Premium Quality", but I would take that with a grain of salt.