Canon EOS 40D vs. EOS 50D
I am often consulted when people I know are looking at purchasing a new camera, particularly if they are going to buy a single lens reflex (SLR) camera. Today I got one of these questions in my inbox from a relative and I thought as long as I was writing it up, I’d go ahead and blog it. So here you are: which camera do you buy - the Canon EOS 40D or the EOS 50D – if you are taking wide-angle photographs of home theaters?
First of all, I should review the basics of these two models. Both are built from a very similar body. The major differences in my opinion are as follows:
Resolution: the 50D is a 15 megapixel camera, the 40D is 10.1 megapixels
Sensitivity: the 50D has an extra stop of sensitivity at ISO 3200 versus 1600 for the 40D. The 50D also has two ISO extension levels that can take it to ISO 12,800
LCD: the 50D has four times the number of pixels in the LCD preview screen on the back – 920,000 dots versus 230,000 for the 40D
Price: street price for a 50D looks to be about $300 more than the 40D, which is selling for around $1,000
The other differences between the two are probably not material to the choice at hand here. Although there may be some folks who just can’t live without sRAW2 or something and thus won’t purchase a 40D, these are both excellent cameras.
In the case of the analysis I’m doing here, the subject matter (and discriminating criteria for the camera) is shooting interior photographs of home movie theatres. And I’m not talking about a plasma screen and HiDef cable either. I’m talking serious, high-end home theatres that cost between tens and hundreds of thousands of dollars. With that in mind, let’s go back over the top three criteria and get some commentary.
Resolution
The rule of thumb for resolution is that you don’t tend to get a strikingly noticeable improvement from increased megapixels unless you are jumping at least 2x the number you have (100% increase). In this case, the jump is 50% (10 mp to 15 mp). That’s a very attractive value for a few hundred dollars of price difference, but it doesn’t swing the decision either way, in my opinion.
The camera companies want you to think that more megapixels are better. Of course it is in a theoretical way. But now that we’re into double-digit megapixels, it is much more important that the image be properly exposed, focused correctly and shot through a good lens than the number of megapixels.
Sensitivity
In this particular application, home theaters, the shooting will likely be done on a tripod. It is extremely complicated to use a flash in this setting since there is most often going to be a very large video display in some part of the picture. It obviously gets worse when you consider home theaters with projection displays – in that scenario you can’t take a picture of the projected image if you are using a flash. Well, OK, not without a huge amount of light control equipment for the flash. An interesting exception to this: there are screw in flashes with a very low guide number (like 40 to 60) that you can stick inside a lampshade. When they detect another flash going off, they fire, leaving you with a nicely illuminated lampshade. But you have to trigger them with a flash, so I don’t think they’ll come into play here.
In this case, you might assume the extra sensitivity is a big win, but actually, it is not. As you increase the ISO speed (100 to 200 to 400 and on up) you tend to lose image quality and see noise introduced. That loss is very minor the first couple of jumps, like 100 to 200. But it gets more significant as you ramp up the ISO. If you want maximum image quality and you are shooting on a tripod and nothing in the camera’s field of view is moving, you will want to shoot at a low ISO and you have very little reason not to.
Some situations that need the higher sensitivity modes like ISO 3200 include:
- Shooting performances where you need a decent shutter speed to avoid blur and you cannot use a flash
- Shooting handheld under low light conditions where a flash is ineffective, like a street scene at night
LCD
The LCD discussion is quite interesting. I have to disclaim my comments as I have not actually viewed a 900,000+ pixel LCD, but I don’t know that it will change my point of view. In my opinion, there are three things you get from the LCD (liveview-type stuff aside):
- A histogram indicating the overall quality of the exposure
- A check on the composition, including, importantly, the full view of the image. Most SLR’s do not have 100% viewfinder coverage and so there are often things at the edges of the image that you didn’t see when taking the picture. Both of the camera here have 95% viewfinder coverage.
- A check on the subject matter. This is probably more relevant with people than with move theaters. For example, the LCD is the easiest way to tell if a person’s eyes were closed when you took the picture.
Here’s what you don’t get from an LCD:
- A complete understanding of whether the focus is accurate, unless it is not. If anything you see in the LCD is blurry, it’s going to look far worse when you get it on the computer. On the other hand, if it looks sharp, you often can’t distinguish whether or not it is sharp in the right places. A good example of this is a 3/4 portrait where you can see both of the subject’s eyes. If you focused on the far eye, the picture will not look good. (That’s another shutterbug trick – always focus on the closest eye.) Can you tell this from the LCD, though, is the question.
- Overall image color and saturation. You will note that when you move the LCD around, the image color and saturation changes depending on the angle you are viewing it from. This provides only scant guidance as to how the actual photo will look.
You have to remember that a straight print from one of these cameras is pretty large. My EOS 10D is only 6 mp and if I open up a RAW file at 6 mp and 300 dpi, the actual print is 10 inches wide by 6 and change. The LCD is only three inches wide. Don’t let those numbers mislead you – we are dealing in two dimensions. The area of the straight print is over 20 times larger than the area of the LCD for an 11 or so megapixel camera, for example.
In the question I received was a great example of camera manufacturer spin:
The increased detail available is said to make it much easier to review your pictures and make better decisions as to quality of the shot.
Dave’s rule of LCD’s is that the only thing you can decide with the LCD is whether or not the shot is flawed. You generally cannot tell from the LCD if the shot is a true keeper. That’s a very significant distinction.
Lenses
The questioner is looking at a number of wide angle lenses and trying to decide what is right. Choices include:
- Canon EF-S 10 – 22 mm ƒ/3.5 – 4.5 USM
- Sigma 10 – 20 mm ƒ/4 – 5.6 EX DC HSM
- Sigma 12 – 24 mm ƒ/4.5 – 5.6 EX DG IF HSM
We are at a distinct disadvantage in this case, because both cameras use a sensor that is ’sub-full-frame‘ (The APS-C sensor is roughly 22 x 15 mm versus film which is 36 x 24 mm) and thus the focal length has a multiplication factor. If getting a really wide shot was the primary consideration, purchasing a camera with a full-frame sensor would be the best choice. But they are still very expensive.
I should also take a moment to explain some of the salad bar of acronyms in these lens models.
- HSM and USM are simply the types of motors that drive the auto-focus (Hypersonic versus Ultrasonic)
- The Sigma DC lenses are designed specifically for use with sub-full-frame sensors like the APS-C size
- The Sigma DG lenses are designed to work with full-frame-sensors on digital cameras, although they work fine on film too. They mainly try to focus light more directly onto the sensor, the sensor being more sensitive to the incident angle of the light than film is.
- The Sigma EX designation is for lenses that have a bit more robustness in the exterior.
- The Sigma IF designation simply means that the outside of the lens doesn’t move as it focuses (Internal Focus).
- The Canon EF-S designation is for lenses that will only work on Canon sub-full-frame cameras. You can’t use them on any Canon film camera or full-frame digital cameras.
So you don’t need to purchase a DG lens if you don’t have a full-frame camera. Alternatively, if you purchase a Canon EF-S lens or a Sigma DC lens, you won’t be able to use them on a full-frame digital camera or a Canon film camera. (A 35mm film camera is, by definition, full-frame).
What does all this mean? Not anywhere near as much as Canon and Sigma would have you believe. There’s a few things that are important to know when selecting a wide-angle lens:
- The image quality at both ends of the aperture scale is worse than in the middle. That means that you’re not going to want to shoot at, say, ƒ3.5 with the Canon – you’ll probably want to be at ƒ8 or ƒ16.
- Gross generalization – wide-angle lenses are sharper than telephoto lenses when the size of the subject matter is the same in the photograph. The main reason for this is that when all other things are equal (except for the focal length), there is more depth of field the wider you go. Since we are talking about a subject matter where everything needs to be sharp, whether that’s side-to-side or close-to-far, a wide-angle lens is going to perform very well.
- Again, generally, wide-angle lens quality is very high when shot in the middle of the aperture range, regardless of the manufacturer. You could check the bench tests at a site like Popular Photography to see examples of this, but basically most good quality lenses perform really well in the middle of the aperture range.
Recommendation
Buy the EOS 40D with the Sigma 10 – 22 mm lens. You’ll save yourself almost $500 over a Canon EOS 50D with the Canon 10 – 22 mm EF-S lens. There will be plenty of other things to spend that money on that you will soon find you need, like:
- A good, solid tripod with easy to adjust legs and a pistol-grip or ball head.
- A spirit level made for photographers (more on that below)
- An external shutter release
- A circular polarizer
There’s another $500 right there.
Final Thoughts:
Taking interior photographs with a wide-angle lens is trickier than it looks. A wide-angle lens has to be plumb in the context of the subject matter in order to minimize distortion in perspective. The classic example of this is when you lean back to take a wide-angle picture of a tall building and it looks like it’s falling over. In order to have the movie screen appear plumb, you will want the plane of the camera’s sensor to be parallel to the plane of the screen and the center of the screen to be close to the lens axis (that’s an imaginary line that runs down through very center of all that glass in the lens. The further you move away from those two requirements, the more distortion will appear in the perspective of the subject of the photo. that’s where the spirit level comes in. With a level in the flash hot-shoe(or mounted in the tripod), you can at least ensure that the lens axis is parallel to the ground. Aligning the film plane in parallel with the subject plane is harder, but you can use the gridlines in the viewfinder to compare right angles (you can even use the viewfinder border itself – it’s a rectangle after all).
You are going to be shooting exposures that are long enough that camera shake (and mirror flapping) become significant. This is most notable from 1/30s to maybe 2 seconds. After that, the vibration from the shutter release is really immaterial compared to the length of the exposure. That’s why you need a good, solid tripod and a remote release. The poor man’s equivalent of the remote release is to set the camera’s shutter timer, but I can tell you that gets very old after about five minutes. You are going to want to shoot a lot of photos and having to wait 10 seconds for each is really problematic, especially if you are under time pressure.
When a professional does this type of work, they often use a view camera (or the modern digital equivalent). This type of camera allows for both the back and front of the camera to be swung, raised and lowered or shifted from side to side. These controls allow for excruciatingly precise perspective control and control over the direction of the depth of field (more specifically, the plane of sharpness – an imaginary plane that represents the exact sharpest focus in the image). With a Canon, you could look at the 24mm ƒ3.5L TS-E lens that has some of these controls. But it probably won’t be wide enough without a full-frame sensor camera.
And finally, the polarizer. A circular polarizer can really help in these situations. It polarizes light. I won’t get into the physics, but basically there are two significant benefits to using one in this situation.
- The polarizer removes glare and can help reduce reflections, depending on a whole bunch of factors.
- When you are shooting something that already is polarized (like an LCD display), rotating the polarizer allows you to change the intensity of that light from complete darkness to the straight image. That means that if you have to shoot a picture of an LCD and it is too bright for the shot, you can simply rotate the polarizer to dim the screen. This will change the appearance of other parts of the image, notably glare and reflections, but it’s usually a pretty good trade-off.
Comments
Comment from DaveO
Time September 30, 2008 at 12:42 am
Those are excellent questions. The technical issue at hand here is called the image circle. The lens is designed to provide the best image quality within the image circle. Because the sensor is rectangular and the lens is circular, there is a also minimum size of image circle that can correctly illuminate the sensor. In an EF-S lens, for example, the design specification for the image circle is smaller because the sensor is smaller. In a full-frame lens, the image circle is correspondingly larger. If you could mount an EF-S lens on a full frame camera, the corners of the sensor will fall outside of the image circle. That’s very bad. In the other direction, it’s not generally a problem because the image circle is that much larger than the sensor. Yes, there is stray peripheral light that does not hit the sensor. Angle of incidence aside, the quality of the image tends to be excellent at the center and falls off towards the perimeter of the image circle, although it’s certainly not a linear function.
Many of the lenses with a ‘DG’ or ‘designed for digital’ designation are also built to allow the incident light to strike the sensor at a steeper angle, i.e., closer to the lens axis. The idea there is that film is unaffected by the incident angle, but a digital sensor actually has millions of photon wells with microscopic filters over them. So you’d get better sensitivity and color gamut from a digital lens. Personally, I think this is all a bit too much hype. I believe that using a full-frame lens on an APS-C camera just gives you more of the sweet spot of the image circle. But you can’t go the other way and a Canon EF-S lens, for example, will not physically mount on a full-frame camera.
Circular polarizers are made to be rotated. If you buy one, you’ll either get one that rotates in its’ housing, or attaches to a rotating filter holder from Lee, Cokin, etc. With a polarizer, you generally focus and compose the shot and then rotate the polarizer for impact. If the lens racks in and out autofocusing after this point, and you are focusing on the same point, the polarizer should wind up in the same place. If you change the focus point (specifically, the distance between the film plane and the focus point) that won’t hold true and you’ll have to adjust the polarizer. The other issue with the autofocus turning the focus ring on the barrel of the lens during auto-focus is that your hand is going to be on the lens :^). There’s a simple solution for this: turn off the auto-focus. Sometimes I’ll put the camera on a tripod, autofocus, and then turn off the autofocus (although I don’t know if those lenses allow it) for the rest of the shooting.
We’re talking about very deliberate, tripod mounted shots for this application. The polarizer issue is much more acute when you are outside on a sunny day with a bunch of kids in a pool or something, and you keep moving the camera from portrait to landscape orientation.
What may be a bigger issue is that it can be very hard to rotate a polarizer when you have a lens hood on, although this is less of an issue with a wide angle lens because the hood has a much broader angle. Having spent a day eating my own dog food, i.e., shooting an LCD monitor with a polarizer, I’m a bit less sold on using it for contrast control, but I was doing a close-up of the screen only and needed to see a good rendering of fine detail on the screen.
As a photographer, I always purchase polarized sunglasses, which is a great way to get a simple preview of what’s going to happen. That’s why people will sometimes see me looking up at the sky moving my head from side to side. I’m checking out how the sky looks through different rotations of the sunglasses. On a super-clear day when you are looking at a right angle to the sun, the sky can turn almost black from the polarizer.
Comment from JohnD
Time October 2, 2008 at 12:52 am
Cool, Thanks again. Looks like it is time to go shopping! It has been a good 10 or more years since I have messed around with my Canon A1. I am really looking forward to getting back into this, but I can see that I have a steep hill to climb. I always felt that I was at a real disadvantage when I was shooting with film because I never took the step into developing and enlarging my own shoots. Their certainly seems to be a greater opportunity to get more involved on the ‘creative’ side of this hobby in the digital realm. I just hope I have the time to invest to make it as rewarding as I feel it could be.
Comment from Winston
Time October 23, 2008 at 3:08 pm
Thanks for the comparison of the 40D and the 50D. I am thinking of upgrading from the 20D to the 50D, which would just about satisfy your rule of thumb on resolution, but I note that the pixel size of the 50D is smaller than that of the 20D (and also the 40D). What, if any, will be the impact of the smaller pixel size of the 50D on image quality?
Comment from DaveO
Time October 23, 2008 at 8:39 pm
Hi Winston, thanks for the question. Here’s a quick answer that’s more of an opinion based on what I’ve read. I think we’re dealing with the intersection of geometry and fabrication here. Overall, the sensor is the same size, so you have to shrink the size of the photon well sites on the chip to get more pixels and therefore higher resolution. It’s probably harder to shrink the materials between the photon well sites and clearly there’s a limit to how much you can shrink the ‘in-between’ parts as well. Once again, in a purist world, the larger the photon well, the better the data coming out of it – that means better color fidelity, higher ISO shooting without loss of quality, etc. But in practice, there are lots of other improvements that are being introduced into the newer cameras. They do have much better high-ISO/low light performance, etc. Some from advances in chip fabrication and some from advances in the software used to extract the data (noise reduction algorithms and so forth). You have the best chance of seeing the difference if you compare an APS-C sensor at a certain megapixel rating with a sub-APS-C sensor at the same rating. For example, a typical Nikon or Canon 8MP digital SLR with a compact 8MP point and shoot that might have a 2/3″ sensor in it. If you took the same photo with those two cameras, I think you’d have a shot at seeing the difference. But it would have to be a very controlled experiment because the lens would be the most significant variable between the two.
When you have more pixels overall, there are some interesting things that happen that can compensate for the reduction in size. For one, you have more samples in a given area to extract color information. The individual photon sites do not see in color. There are tiny red, green and blue filters mounted over them in a known pattern. Software embedded in the camera’s electronics constructs color by analyzing the relationship of the colors it measures in each site relative to the neighboring sites. This is known as a Bayer pattern, or Bayer interpolation. I would assert that generally when you have more pixels in a given area, you’ll get a better color fidelity overall. Wikipedia has a good page on this – search on ‘Bayer filter’.
Comment from myord
Time January 18, 2009 at 2:00 am
Canon 40D VS 50D, or Why did I return my 15 MP 50D and kept its 10MP bro…
The following is what I posted on Epinions.com
I’ll leave all camera body details and the list of features for the magazines and get right to the question: Which camera should I get?
(Note: I have already owned the following DSLRs: Canon XTI, Canon 5D and as of three weeks ago – a Canon 40D.)
Around Christmas, Aden Camera Toronto started selling Canon’s excellent 40D body for $809.99 CAD. As of last week, they reduced the price of the brand new Canon 50D camera body by $250 and are selling it for $1119.99 CAD. Not bad.
The latest price cut triggered the question: Is the new 50D worth the extra $400 and should I exchange/upgrade to it? Some of the new features that attracted me to 50D were: 15MP which is 50% greater megapixels, micro adjustments – referring to the feature borrowed from the Pro camera, better LCD screen, Digic4 chip, etc. Well, I made my move and purchased the 50D, however, for comparison purposes I kept my less than a month old Canon 40D as well. The reason was that I wanted to make an educated purchase e.g. did not get caught in the camera release hype…
Round 1: Tripod mounted shots
Reading the Canon 50D specs I was pretty amazed. Therefore my initial intention was to prove to myself that the new 15MP camera body offers much better picture quality, better focusing and greater details. To minimize any personal bias in my intended testing I created a “semipro shooting set”: I arranged a small table and placed some suitable items on it including the free Resolution Card from Digital Camera magazine (actual card size is a half letter size).
See pic.1:
http://img58.imageshack.us/img58/9607/unprocessed40auislq2.jpg
I placed two tripods 4’ across from the table and started shooting. At first I began attaching various fixed and zoom lenses to the two tripod mounted bodies. Such lenses were the Canon 50mm f1.8 II, Canon EFS 17-85mm f4-5.6 IS, Sigma 24-60mm f2.8 EX DG and the Canon 75-300mm f3.5-5.6 II. Well, as you can see all is (joking) “semipro” e.g. not overly expensive optics. Soon I realized that due to the variables added by each lens it would be really hard to compare the data. Therefore, all pics shown will be from the Canon EFS 17-85mm IS USM lens.
Some very important notes:
- Images are straight from the camera and no manipulation whatsoever was done to the pics
- All focusing is right at the middle of the setup picture shown above, where the magazine cover shows a tripod. I always focused on the square logo on the tripod head shown. Mind you, due to the depth of field, some 3D objects I displayed may be a bit off focus.
- Some more info is given in the title bar of the pictures shown: 40 or 50 refers to Canon 40D or 50D, AU means autofocus, IS means the 17-85mm IS was used and all at Av (Aperture priority the lowest number for the lens).
- When reviewing the images I made sure I select a picture representable for a whole group of images and it is a quality shot. That’s why the results I show represent not a lucky or bad shot but predominantly consistent performance.
After the first 20 or so shots were done, I reviewed them and then something started to change: Both cameras produced outstanding pictures (see Pic.2: 40D is on the left and 50D on the right side),
http://img294.imageshack.us/img294/6899/unprocessed40dleftand50hh4.jpg
but they were exactly the same. Except the slightly bigger size of the 50D images, I was not able to see the benefit of the added 50% more megapixels.
The only difference in resolution I was ever able to see was from the black and white bar code tests I did, where two parallel lines are just a microscopic part away. Although it depends on the distance the picture is taken from, the 50D showed a more pronounced white gap in between. In all other shooting situations when we have colours, shapes and shades it would be impossible to observe that. Here is the proof, where virtually, no detectable resolution differences can be found on the 1:1 crop from the right end of the set table where the Resolution Card is. See Pic.3: 50D in on top and 40D on the bottom.
http://img172.imageshack.us/img172/8474/focusingcanon40dbottom5ti0.jpg
The picture shows that from this shooting distance both cameras start to blur below the number 7 line on the left side of the card.
Round 2: Handheld shots
Most people in the “semipro market segment” including myself would be shooting from hand. Although I sometimes carry a travel tripod, typically I’m caught without one. That’s why I did bunch hand held shots using the IS lens I have. Once again The picture review showed that both cameras produce very good images. However in my tests 40D provides better quality images including colour saturation and dynapics, contrast and resolution. See Pic.4 showing four wide angle images: two 40D pictures are on the left side and two 50D on the right.
http://img107.imageshack.us/img107/4858/brickhouses40dleft50drizs6.jpg
Pic.5: four zoom images at 85mm and again two 40D on the left and two 50D on the right. Check the focus achieved on the glass… Unless the case is that 50D needs a focus adjustments the pics show 40D doing a better job.
http://img107.imageshack.us/img107/1139/brickhouseszoom40dleft5or8.jpg
Pic. 6. One more time, I wanted 50D to shine and did another brick focusing test. Although the focusing was not as easy as I thought the wall test showed 40D focuses better.
http://img103.imageshack.us/img103/3590/walltest40dleftand50drich5.jpg
Pic.7: My favorite test that I always do: The INDY test. For all 4 pictures shown the focus is between both NNs. 40D is on the left side, 50D on the right. One can see the DOF changing but altogether-amazing quality from about 3 feet.
http://img292.imageshack.us/img292/4659/indydetailcanon40dleft5vz1.jpg
Results, based on my expectations
Focusing:
From the nearly 800 shots taken, just couple of times the focusing of the 50D was a little better than the 40D. Possibly due to required adjustment issues. However for the vast majority of pics both focused really well and consistently.
Sharpness:
Rather than shots of barcodes no increased sharpness was noticed on the pics. Actually lost of detail was consistent on the pictures from the 50D (discussed further down).
Colour saturation:
The colour saturation of 40D is (not by much) better than that 50D. I tried some post processing and saturated the slightly “bleached” colours of 50D, but it got me into dealing with each colour individually and I abandoned the approach. Most of the time 40D provided much better shading range resulting in more details on the pictures. Again, 50D showed lesser dynamic range.
LCD display:
The new screen is obviously cleaner. However, soon after I started using it, I personally got used to it. Switching back to the 40D’s screen did not cause even the slightest discomfort.
Micro adjustments:
One of the selling points of the camera was the in camera micro adjustments. When I used it I found that my lenses did not really benefit from it and never tried it again.
Megapixels:
That is probably the marketing tool Canon uses the most. Well for me it produced nearly twice as big JPEG file size, but did not get me anywhere near the expected picture improvement. The 50 percent increase in megapixels did not show even 1 percent increase in quality.
Review conclusion:
I can say that feature wise Canon 50D is the better “feature packed” camera. Offers more refined use and flexibility. However image wise both cameras performed exactly the same. Since I love Canon cameras I do not want to go to extremes and say that 40D is the better camera. Many settings like sharpness, colour saturation and contrast can be adjusted by the user but definitely in my test pics I noticed that 40D provides cleaner, colour rich surfaces and detail just everywhere you look.
Therefore personally I cannot justify using bigger file size images but still get same focus, resolution, saturation and detail. If both cameras were priced the same, I would’ve thought which one to keep, but not at 50 percent ($400) higher price. Based on my tests I decided to stay with the 40D and use the money and go on a photo trip, thanks for the idea Rob 
…
Recommended:
Yes
Amount Paid (US$): 663
This Camera is a Good Choice if You Want Something… Solid Enough for a Professional
Comment from Carmine
Time March 30, 2009 at 1:55 pm
Rob, where did you find the 40D for $663?
Comment from John
Time September 30, 2008 at 12:11 am
Dave,
Great input! It does bring up a few additional questions (a newbie, with ‘real’ digital photography).
When I followed your link to a discussion on APS-C sensors, the author said he had both APS-C lens and full frame lenses. He did not indicate that he used the full frame lens on the APS-C camera, but it seemed to be implied. Can you do this? What would happen if you use a lens designed for a full sized sensor on an APS-C camera. I would think that a portion of the image would be lost as it would miss, or fall outside the edges of the smaller APS-C sensor, but I am am having trouble visualizing the full effect of doing this. The image that is received on the APS-C sensor would be cominng more from the center of the lens, which I think would be a good thing. You would not be getting the full benefit of all the incoming light that would be available, so effectively resulting in a smaller apeture openning than where the lens is set. And finally, would there be issues with some of the ‘excess’ light buncing around and causing image problems?
Also, if I go with the Sigma 10 – 22, it does not show IF in its model name, so I believe this means that the outer barrel of the lens would rotate as the camera focuses. Do the circular polarizing filters have an independently rotating portion that allows for rotation of the filter once it has been mounted to the lens? I have seen comments in the lens descriptions for those with internal focusing touting that filter users will appreciate that the outside barrel does not rotate during focussing.
Thank you,
John