Rebel XTi: Why are my pictures so blurry?

<p>Hi all,<br>

I was wondering if I could get some input as to why my pictures are so blurry?<br /> <br /> It seems like every photo I take, the pictures come out very blurry.... no matter the lens. You don't really notice it until you apply a maxed out sharpener filter and then the picture really pops.<br /> <br /> I understand that it could be related to the lens quality but, no matter which lens I choose, even on my EF-S60mm f/2.8 Macro USM, the same effect can be seen as my stock EF-S18-55MM f/3.5-5.6.<br>

This image is a good example:<br /> Shutter Speed: 1/200<br /> Aperture: f/11<br /> ISO: 400<br /> Lens: EF-S18-55MM f/3.5-5.6<br /> <br /> As shot:<br /> <img src="http://img142.imageshack.us/img142/4227/blurry.png" alt="" /></p>

<p>With Apple Apperture sharpen mask all the way up:<br /> <img src="http://img142.imageshack.us/img142/3179/sharpened.png" alt="" /></p>

<p>Sure it jacks up the contrast a very little but check out the detail in the grating in the window above the bike and on the door gate and compare the two.<br>

Any ideas? Could this be camera related or is this REALLY the difference between a good lens and a professional line lens?<br /> <br /> Thanks,<br /> Josh</p>

<p>I would avoid apertures smaller than f/8 on a cropped sensor camera as a general rule - though there could be exceptions in unusual situations. The issue is diffraction blur that sets in as you stop down - and it sets in about two stops sooner on a cropped sensor camera than on a full frame camera.</p>

<p>I'd generally shoot this camera at a lower ISO unless I had no choice but to go as high as 400. 100 or 200 are optimum. The lens will project the same sharp image in any of these cases, but noise can diffuse lines and so forth that say "sharp image" to us when we look at it.</p>

<p>Do you use a tripod, mirror lockup, and remote release? If not, give these a try - if for no other reason than to narrow the possible causes of what you perceive as a lack of ideal sharpness.</p>

<p>Are you shooting jpg or RAW? If the former I can't say much since I have little experience with in-camera sharpening. If the latter, RAW files _must_ be sharpened in post-processing if you want to achieve the image quality they are capable of. I'll save the details until we see the cropped version of the image and until we know what software you use.</p>

<p>A major aspect of images that appear sharp is not sharpness per se, but due to other elements including post processing application of curves, saturation, color balancing and other adjustments. You'll occasionally hear people claim that these techniques are somehow "not authentic," but the truth is that virtually all photographers (film or digital) apply a number of post-processing techniques to produce final prints that reflect their vision for the photograph. I won't go into all of the philosophical or physiological aspects of this here.</p>

<p>It is hard to analyze the photo for sharpness when we only see the small jpg of the full image. In this format it actually looks pretty decent and not all that different from what a very sharp photograph would look like at this size. If you can post a small section of the image at 100% magnification it will be easier to give you meaningful feedback on the sharpness.</p>

<p>Are you using the in-camera sharpening settings at all? Are you shooting JPG files or RAW?</p>

<p> </p>

<p>This looks normal to me for the XTi kit lens (I use it all the time). It is not the best lens and has always been known to be soft. However you say it doesn't matter which lens. What other lenses are you using? Other entry level lenses like the 75-300 (Which I also use regularly) are also known to be soft. Are you shooting JPEG or RAW? Raw will require sharpening in post, JPEG may also depending on your camera settings. Hand held or tripod? Hand held should be acceptable at this shutter speed for that lens if you have a reasonably steady hand, but if you don't it just adds to the problems with the kit lens.</p>

<p> </p>

<p>I'm going to respectfully disagree with Mr. Mitchell here. This is not an aperture issue and you should have no problems shooting at f/11 or even f/16. The difference in the amount of diffraction at f/11 vs f/8 is nearly non-existent.</p>

<p>See the first figure under "Practical Examples" on this page:<br>

http://www.bobatkins.com/photography/technical/diffraction.html</p>

<p>If you're shooting JPG's, your camera has settings for sharpening that you can control. If you're shooting RAW then the in-camera settings are a reference point, but you will be required to make your own determination in post as to what is or is not the right amount of sharpening. </p>

 

<p>I agree with Dan. Using ISO 100 would make a big difference. About the only thing I can add at this point is do you have a filter on your lenses? Have you tried it without those filters? I thought my kit lens was getting worse than when I first bought the camera, then I reallized that my wife had put a diffuser filter on the lens and left it there.</p>

<p>Have you tried shooting with a tripod - I think we need to rule out some things before we can come to any conclusions. At a minimum try shooting the same scene with similar settings on a tripod - use different lenses. Post those results here and we can look at them and figure out what's wrong. It could very well be that it is your camera, but we need more information.</p>

<p>1st shot looks fine to me. How about a 100% crop?</p>

<p>First shot looks not so much blurry as less saturated. Also, in the doorway, it is obvious that the curves have been altered (mid tones) so that the inside is visible. There is a lot more than sharpening going on here.<br>

Post processing always helps.</p>

<p>Sorry buddy but the shot looks fine to me - if you are worried about 100% views you have to think 'What are other people going to see my shots at?' if they look good in a 'fit to frame' format like the size shown here then that is how they will be seen. You'll go mad if you turn down every shot because all or part of it is slightly soft at 100 % or viewing actual pixels.</p>

<p>i actually think the sharpened one is worse, its quite harsh, it looks like its been HDR'd and as you say it bumps up the contrast.</p>

<p>I dont think the lens helps you out as far as pixel peeping will be concerned, its not a pro lens but its not priced as such and performs well for what it is. If, like Sheldon suggests, you can post some crops at 100% perhaps it will be easier to see if there are any obvious problems.</p>

<p>why dont you try focusing on one area for your next shot, get in close to the bike or the bucket by the door, set a low aperture, focus on a nice clear feature and get a shot - the subject should be a lot easier to isolate like this and im pretty sure what you focused in on will be sharp</p>

<p>It's a bit hard to tell much from the photo posted, as it's small. A 100% crop would help.</p>

<p>I assume you 18-55 is the non-IS version. That's one of Canon's least sharp lenses. (The IS version is actually quite good, BTW.)</p>

<p>With all due respect to Dan, who knows a whole lot more about lenses than I do, diffraction limits are a relative thing. For your particular lens, which is somewhat soft, diffraction doesn't "worsen" the optical quality of the lens until maybe f/16. You'll probably get your best sharpness at f/8 and f/11. If you had the IS version, you'd start noticing the degrading effects of diffraction starting at f/11 or so, with f/5.6 and f/8 being your best apertures (in general). The same is true with your 60/2.8, which is a pretty sharp lens.</p>

<p>It's hard to debug your problem with the info given. You're going to need to do some well-controlled testing. Try this: Disable in-camera sharpening. Mount up your 60/2.8, with no filters on it. Put the camera on a good tripod. Enable the mirror lockup, and set the camera to the self timer mode. Set aperture to f/8 and exposure mode to Av. Put a ball or other object in your back yard, perhaps 20 ft from the camera, and focus on it. Take a test shot, and post a 100% crop here. This test will rule out camera shake and filters and will test focus accuracy. Also a 100% crop will allow people here to see if the sharpness is all that it can be. That's a start.</p>

<p>Wow. Thanks for the great responses, all around.<br /> <br /> Here is the actual RAW file:<br /> http://tinyurl.com/cxlqgb<br /> <br /> <br /> @ G Dan Mitchell:<br /> Yes, I am shooting in RAW. I did not know that post-process sharpening was so important to be labelled as a 'must'. Why is that? Shouldn't it be naturally capable of sharp images? Post-process sharpning adds a bit of noise and messes with various characteristics of the photograph such as contrast, no?<br /> <br /> I am using Apple Aperture as the RAW processor. The images in the original post were exported as PNGs from Aperture.<br /> <br /> @Rob Bernhard:<br /> I haven't changed any in-camera sharpening settings from the factory default but I'll look into those. Thanks.<br /> <br /> @Michael Lawson:<br /> My camera bag stocks the following lenses:<br /> EF-S18-55mm f/3.5-5.6<br /> EF-S60mm f/2.8 Macro USM<br /> EF28-90mm f/4-5.6<br /> EF75-300mm f/4-5.6<br /> <br /> Yes, this happens to me on my 75-300mm, too. I assume you notice the same on yours, then?<br /> <br /> I usually always hand hold unless shooting below 1/30ish or so.<br /> <br /> @Dan Ferrel:<br /> Just a UV filter. My 60mm macro doesn't have anything on it and I still notice the blur.</p>

<p>Regarding diffraction, I'm not necessarily saying that the primary "issue" that the OP sees in these photographs is due to diffraction blur. As I wrote, I did not have all of the information about the images (including access to a 100% magnification crop that would be a bit more definitive) - and that is why I provided a list of potential issues that <em>might</em> be related to the question.</p>

<p>Regarding diffraction blur and 1.6x cropped sensor cameras, there is no question that image sharpness decreases due to diffraction blur at apertures such as f/11 or f/16 on these cameras. It doesn't matter what lens you use - the most expensive L prime or the kit lens - whatever the resolution qualities of the lens for other reasons, diffraction blur has a negative effect on resolution at these apertures on cropped sensor cameras.</p>

<p>It is reasonable to ask "how much of an effect" and "is the negative effect balanced by other positive effects of the small aperture" when it comes to a specific photograph. For example if you are shooting a subject with the intention of creating a soft image and you need a longer exposure or larger depth of field, giving up some sharpness to get those things is a reasonable choice. I've made this choice when shooting, for example, long exposures of seascapes in which I <em>wanted</em> a diffuse effect from motion blur by means of a long exposure... and where maximum resolution wasn't important.</p>

<p>However, in this case, we have a shot of a flat subject that is more or less parallel to the sensor, made at f/11 and ISO 400 and 1/200 second. In just about every way it would make a ton more sense to shoot this at, for example, ISO 200, 1/100 second, and f/5.6. 1/100 should be enough to control camera motion blur with good technique, ISO 200 would provide better noise performance on this camera, and f/5.6 would give sufficient depth of field for the subject and would not negatively affect sharpness through diffraction blur.</p>

<p>I won't argue with the idea that many people might not notice the difference in a 4 x 6 inch print or in a web image. (I thought this one looked fine on the screen.) But the OP asked specifically about sharpness, and in that light recommending a larger aperture than f/11 on crop is a good recommendation, especially in light of the details of the specific photograph and how it was made.</p>

<p>Dan</p>

<p>BTW, if the OP is using the non-IS version of the 18-55 kit lens, it will be limited as to sharpness. IQ is only "OK" with that lens. If the OP is using the newer IS version of the kit lens, it can produce quite decent results if everything is done correctly.</p>

<p>Josh, I do notice it on both the kit lenses (18-55mm and the 75-300 both non-IS), but it can be controlled with good technique and a good post processing work flow. I used to shoot mostly hand held, but purchased a monopod last year and it has made a noticeable difference in the quality of my shots and the number of keepers I get. I would certainly consider getting a nice monopod to use for walk around shooting when possible, and a tripod for the macro lens. Here is an article about the sharpening work flow you should consider reading: http://www.pixelgenius.com/tips/schewe-sharpening.pdf . It will explain better than I can why sharpening is a must.</p>

<p>Here are a few more that I found:<br>

http://www.luminous-landscape.com/tutorials/sharpness.shtml<br>

http://www.luminous-landscape.com/tutorials/sharp.shtml<br>

http://www.geofflawrence.com/photoshop_tutorial_sharpening.php</p>

<p>Yes, if you are shooting RAW you MUST sharpen your images in post. If you do not do this, they will always look blurry and will never be as sharp as in-camera jpgs - which ARE sharpened in-camera.</p>

<p>If you are using Photoshop, try the following as a starting point: Without sharpening in ACR (Adobe Camera RAW) during conversion, apply one layer of smart sharpening and one USM (unsharp mask), best as smart layers.</p>

<p>Smart Sharpen at 150, 1.0 (but think about lowering the second number to taste)<br>

USM at 12, 50, 1</p>

<p>Dan</p>

<p>[[Regarding diffraction blur and 1.6x cropped sensor cameras, there is no question that image sharpness decreases due to diffraction blur at apertures such as f/11 or f/16 on these cameras]]</p>

<p>[[and that is why I provided a list of potential issues that]]</p>

<p>You stated, immediately, that you "would avoid apertures smaller than f/8 on a cropped sensor camera as a general rule." This is a strong statement and one that does many new photographers an extreme disservice, IMHO. </p>

<p>Discussion of diffraction issues in this context are about as useful as talking about adding the right amount of air to the tires of a car that is missing its engine. Great information, but not helpful in actually getting the car up and running. In fact, I'd go so far as to say it is distracting to the point of being a disservice.</p>

<p> </p>

<p>Rob, you are welcome to your opinion, but I disagree that pointing out that diffraction blur at small apertures is be among a set of issues that could affect sharpness is "an extreme disservice" to new photographers. I did not suggest that it is the only issue, and I went on to discuss several others that could also be important.<br>

In the context of the OP's broad question and in the context of my overall response, I think my reply was appropriate and relevant.</p>

<p>"I would avoid apertures smaller than f/8 on a cropped sensor camera as a general rule - though there could be exceptions in unusual situations. The issue is diffraction blur that sets in as you stop down - and it sets in about two stops sooner on a cropped sensor camera than on a full frame camera."</p>

<p> this is misleading at the very least, when I shot a 40D I never had problems with diffraction at f11.</p>

<p>Ross</p>

<p>Folks, please do a bit more reading about diffraction blur before you dismiss what I write out of hand - and not just one post that agrees with your current notion.</p>

<p>I'll leave it at that.</p>

<p>Dan</p>

<p>There is nothing wrong with what Dan said. All he said was that HE would avoid...as a GENERAL rule. And he's right too. What's the big deal?<br>

The real issue here, is that the OP has no idea that when you shoot raw, the camera doesn't sharpen the image for you. You must do it yourself in post.</p>

<p>"I did not know that post-process sharpening was so important to be labelled as a 'must'. Why is that? Shouldn't it be naturally capable of sharp images?"</p>

<p>There's a thing called an AA filter in front of the sensor which softens the image, requiring you to sharpen in PP it to compensate. If you had something like a medium format back with no AA filter you would get (apparently) a fair bit sharper image right out of the camera</p>

<p>There's also the issue of what output you're sharpening for - are you sharpening for screen or print? I have found that I have to sharpen more for prints than screen</p>

<p>As a relative newbie who only started shooting raw relatively recently, I'll add something to Brandon's comment. Yes, the main issue for the OP is that all digital images need sharpening. Josh, a few extra points may be useful. If you do shoot jpeg, the camera's software does some sharpening (although not a great deal). Josh, the "picture styles" on your XTi tell the camera's software how to process the raw image to get the jpeg, and one difference between them is the amount of sharpening. The second thing you should know is that when you process your raw file in something like DPP or Lightroom, the camera profile you apply, if you do, will also apply some sharpening. It won't be enough. The third thing you need to know is that the amount of sharpening and contrast you will want will depend on your use. You will often want more for a print than on screen, and the greater the distance from the print, the more you want. For example, I was fussing with this one tonight:</p>

<p>http://dkoretz.smugmug.com/photos/498982942_2Hqfj-X2.jpg</p>

<p>This is pretty high contrast in the original because of the lighting. When I printed an 8x10 from the image at the URL, it looked pretty drab from 8 feet away. So, I increased the contrast, primarily in the bottom half of the range, and the print looks better, but when I put that version on the web (I have taken it down), it looked like plastic--way overdone.</p>

<p>Re lenses: I agree with one of the posters that the non-IS kit lens is pretty soft. I rarely use mine anymore. My walk-arounds I use instead are a Tamron 28-70 f2.8 (much heavier, but faster and much sharper), and an EF-S 60mm f 2.8 macro, which is sharp as a tack and does OK as a slightly long prime. The shot at the link above was with the macro lens. If you buy a moderately priced lens and pick carefully based on reviews, you will see a difference.</p>

<p>Finally, re diffraction: you will never get everyone to agree. It's true that if you open up or close down past a lens's sweet spot, you lose resolution, for different reasons. My experience is that the softness from shooting wide open is really obvious with some lenses (including the kit lens), even without much magnification, but with my lenses, the impact of diffraction from closing the lens down too far is much less. The image at the link above was shot at f 20, and I have others that don't look greatly different that I shot at f 32 (trading off a little less sharpness for a much more noticable increase in depth of field). You be the judge.</p>

<p>Hi Josh,<br>

I'm having the same problem on my xti, I purchased little less than two years ago. It started off with a bang and now no matter what the light, setting, speed etc. I'm getting soft or lousy focus. I use the kit lens and 75-300 f 4-5.6 III. not the best lenses but its what i could afford to start with and i'm not sure if I HAVE to upgrade the camera or the lenses (eventually I will) but for now this is what I got. You actually answered my question because it seems that the lenses may not be the problem maybe its a rebel xti problem. my pop up flash no longer pops up either. its been cleaned and cared for but no flash. so unfortunatley I don't have an answer but can relate and I hope it helps you to know that your not the only one. looks like a trip to the repair shop for me... </p>

<p>Ambur, no, using kit lens and 75-300 on a better body (or just higher megapixel one like 500D) is going to make things worse. More magnification, more clearly you see all the defects.<br>

Put your camera on a tripod and see what you get. Also, if you can borrow a 50/1.8 or similar optically good lens, stop it down to f4 or f5.6 and take the same shots on a tripod and see the difference.<br>

Josh's problem is not the XTi, he just didn't know you *have to* sharpen RAW files.</p>