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Canon Rebel XT - Is the problem me, lens or camera... ?
Hi.

I recently purchased a new Canon Rebel XT and am very disappointed with the quality of the photos being produced - I am particularly disappointed with the pictures I am getting from the new Tamron 18-250mm f/3.5-6.3 AF Di-II that I am using..

I seem to be having a problem getting a sharp focus (in fact in many of my photos, I am not getting ANYTHING in SHARP focus). In addition to this, where are the nice bright, intense colors that I seem to find on other folks Rebel XT galleries ... ? .

I have posted a few photos on flickr - they were all taken with the Tamron 18-250 on the Rebel XT - I took about 100 photos of the pandas & not one of them seemed to be in sharp focus - yes "some" of the shutter speeds were a little slow, but the camera was on a monopod at all times..

Http://www.flickr.com/photos/hypercane/.

All photos were taken AF & I have posted EXIF data with each photo..

Is it me, the lens or the camera... ? I seem to get much clearer, sharper pictures on my little canon sd400..

Many ThxMike..

Comments (15)

Two things.

Often / usually little point and shoot cameras are set up o take sharper pictures than are REbel XT cameras. I don't know why, but I have to sharpen many of my pictures, too. I use Photoshop Elements..

And two.

Regardless of the monopod, your shutter speeds are much too slow. Try to use a shutter speed twice as high as your focal length i.e. oif the lens is zoomed to 250mm, use 1/500 and if the lens is at 50mm, use 1/100..

Trust the monopod to gain you one full shutter speed, so you can numerically match shutter speed and focal length..

BAK..

Comment #1

Aslo, it appears the AF point is off in the shot of the panda in the tree, as the tree bark appears sharp. Subject movement also seems to be an issue in one picture..

Check your AF points and for wildlife, set the focus point on the eye, lock the focus and exposure then recompose and shoot the image. For wildlife, I find it best to set the camera to use only the center point AF..

JohnPentax *ist-D, K100D, Fuji F20/31fd, Oly Stylushttp://www.pbase.com/jglover..

Comment #2

I think most of the problem is shutter speed. Although you said a monopod was used, the rule is:.

Shutter Speed Rule: Don't take hand-held pictures at shutter speeds slower than 1 over the focal length of the lens..

Especially for a moving object. I didn't see any problem with the street scene. It was a much faster shutter speed than the 1/60 and 1/80 I saw of the pandas. I'm thinking bump up the ISO or raise aperture (smaller number) until you get a workable shutter speed.From one beginner to another...Jon.

Give me something to shoot..

Comment #3

Well as the other respondent mentioned, your shutter speeds are too slow for the long focal lengths, you would need a tripod or IS to make that combination succesfull. The exif indicates that your aperture is stopped down a fair bit, what mode are you using? Try using Av and opening up the aperture a bit more, or Tv and keeping shutter speeds up..

The other thing I notice is that you are set to continuous AF and drive. CAF will usually give more unpredictable focusing than SAF. Instead of going the 'machine gun' approach, take more time on getting a single shot right, instead of the 'spray and pray' method...

Comment #4

Hey Michael,.

I think this is the 2nd post regarding a complaint about the XT. I purchased the XT a few months ago and it is my first SLR. So take any of my observations with a grain of salt as I am a beginner. I am not familiar with that particular lens you are using. Are you shooting RAW or JPG? If RAW, are you doing any post processing?.

IMG_5133 - the bear does look fuzzy. Not sure if he was moving or not. I notice your shutter speed is is 1/125 and focal length is 155. I believe the general rule for handheld shots w/o IS is at least 1/focal length, preferable 1/2*focal len so maybe the shutter speed was too slow? Does this lens ahve IS? Also, maybe it was mis-focused? The leaves on the left side look fairly sharp..

IMG_5226 - shutter speed is 1/60 and focal len is 200mm. May be same as above? Too slow to freeze bear anyway?.

Those are just my intial thoughts. Sorry if you are experienced and what I said you already considered. Again, I'm not familar with that lens and if it has IS or not, but the shutter speeds may be your problem..

I will say this that as a beginner, I found that my biggest "techical" problem has been focusing. I finally am overcoming it and getting better results. Some of it may have to do with the lens. Also, I noticed on at least one of your pics, the aperture was f/13. Maybe this is too small? I know lenses have sweet spots. The kit lens has a sweet spot of around f/7 or f/8 I think.

But I can tell you that the XT is very capable of producing vibrant, excellent pictures. I get my best results with the Canon 50mm f/1.8. Muy only other lens is the kit and I feel the 50mm blows the kit out of the water in terms of vibrancy, quality, and sharpness. It almost looks like it could be a different cam. I'm not slamming the kit lens either, I like that lens too and for the price it's good, but I do know the lens can make a big difference..

How does the wide end of the lens look? Is it any better? From what I've read, a lot of telephoto zooms get soft on the long end, maybe that's what's happening? How do other lenses look? See if you can borrow another lens, or pick up the Canon 50mm as I love that lens and you may too depending on what you shoot. The rebel is an excellent cam but I guess it's possible you may have a prob with the camera, i've seen people who've had to get them serviced or calibrated..

But from experience and me being a beginner and unsure of your skill level, don't be discouraged that the pics are not as good as your P&S. Mine weren't in the beginning and honestly I'm not good enough yet to get to the point where most of my pics are better than my P&S. but I have seen the capabilities of hte cam and have taken nice shots (in my mind at least) that beat out any P&S hands down. For me, I've just continued to shoot and get better each time. But I still misfocus a good amount of time and it's annoying. The one that made me the most sad was this excellent pic (or at least could have been) of my wife and daughter sitting by a huge bed of bright purple flowers.

I'm still trying to salvage that picture b/c I think besides the focus issue, it is one of the most vibrant and colorful shots I've taken.Just trying to learn.

Blog: http://novicephotog.blogspot.com/Flickr: http://www.flickr.com/photos/9778447@N07/..

Comment #5

Hahaha, wow in the 15 minutes or so I took to type my posting, it went from no replies to 5 or 6! sorry if I duplicated what others said.Just trying to learn.

Blog: http://novicephotog.blogspot.com/Flickr: http://www.flickr.com/photos/9778447@N07/..

Comment #6

Looks like you (camera's focus) missed the 'correct' place to focus on in all the shots..

Also, shutter speed is way too slow.. as others have mentioned, 1/FL is a good place to start.. but with moving subjects, you often need significantly faster shutter speeds to freeze the motion - eg: the panda by the boulder - (focus was on the near side of the boulder, with not enough depth of field to cover the bear), I would like to see at least 1/250, 1/350 would be better..

Use either one-shot or AI-servo for focus unless you are tracking a bird or moving car..

S.**My XT IS Full Frame APS-C/FF of course!*****So is my 5D 35mm/FF**..

Comment #7

Michael Cummings wrote:.

I recently purchased a new Canon Rebel XT and am very disappointedwith the quality of the photos being produced - I am particularlydisappointed with the pictures I am getting from the new Tamron18-250mm f/3.5-6.3 AF Di-II that I am using..

Looking briefly at the photos and their EXIF, every shot with a problem can be explained from the settings used - I don't believe there is anything wrong with the hardware - just poor choices for the shots in question..

In most cases, the shutter speed is the main culprit - too slow for the focal length and a living subject. As others have stated you need around 1/focal length x 1.6 (crop factor) - so for the shot I have open at present, which was taken at 250mm.

1/80 sec, f/7.1 and ISO: 200 - you'd really need 250 (FL) x 1.6 = 1/400 shutter speed - you can knock a little off for the monopod - but that only really offers a significant benefit if you know how to use it properly - I've yet to see anyone in the field who did - so the best you could expect a properly sharp shot for that focal length would be something like 1/300. For that you'd need to up the ISO - you were only at 200, so if you'd gone to 800 and opened the lens a stop, you'd have a much more reliable result..

I'd also knock off the continuous focus, again, unless you know how to use it properly, concentrate on focusing where you want to and getting that right. So I would have taken the shot in Av mode, 800ISO, centre focus point focused on the panda's eyes (that might require you to focus and recompose) and as all seem to be a little over-exposed and you were using evaluative metering - I'd add a little negative exposure compensation - maybe only 1/3 or 2/3 stop and that would have gained you some shutter speed..

I seem to be having a problem getting a sharp focus (in fact in manyof my photos, I am not getting ANYTHING in SHARP focus). In additionto this, where are the nice bright, intense colors that I seem tofind on other folks Rebel XT galleries ... ? .

I think that is down to the over-exposure in the panda shots, there isn't much colour in the scene anyway, but over-exposing a little has bleached the tones out of them too. In most of them, the light panda's head is blown or close to it in most shots - you want to retain detail there..

Is it me, the lens or the camera... ? I seem to get much clearer,sharper pictures on my little canon sd400..

This is a very oft quoted mantra by new DSLR users. Point and shoot and compact cameras are aimed at a different market and are set up to give instantly gratifying results for people who aren't experienced photographers who will take some holiday images, take the memory card to the local supermarket or photo shop and get a 4x6 off each frame and be happy with that limit of use - many won't even own a computer. The saturation and sharpness algorithms are set high for that sort of out of the camera good results. Manufacturers assume that if you buy a DSLR you want more control over your image quality and ease back the camera processing..

You'll find, when you get the shots right, there is much more detail in the XT shots and much more potential for adding vibrancy and sharpness later - you start off with less initially, but have much higher quality shots and detail to work with..

I believe your hardware is performing entirely as might be predicted and expected and results will be significantly better when you get more experienced and learn how to tame your beast. Practice, learn from mistakes as well as successes and ask questions when you encounter problems like this..

So many photos, so little time.http://www.peekaboo.me.uk - general portfolio & tutorialshttp://www.boo-photos.co.uk - live music portfoliohttp://imageevent.com/boophotos/ - most recent images.

Please do not amend and re-post my images unless specifically requested or given permission to do so...

Comment #8

I'll add one point to what's already been said. As they said, your main culprit appears to be shutter speed. But to check your focus points after the fact (and learn from successes and mistakes), you can use Canon's ZoomBrowser software that comes with the Digital XT. It has an option to show the focus point. It's a cool way to verify if the AF occurred on the spot where you intended. I'm not sure how it handles one thing that many of us do: focus on one spot, then hold the shutter halfway down and recompose..

Also, remember there is Auto Focus, and Auto Select of the focus point. Two separate things. You can manually select the focus point while still letting the camera auto focus on that point. If you're not familiar with manually selecting the auto focus point (sounds like a play on words, I know!), study your owner's manual and practice, practice, practice. There are times when I switch to manual selection and then have to designate the correct AF point very quickly. You can use the 4 arrow keys on the camera back, or even use the wheel by the shutter..

Thanks for using this forum. It's a great place to learn and enjoy this wonderful hobby.Mike D.http://www.mikedphoto.smugmug.com..

Comment #9

Mike_In_UC - that's an excellent tip on ZoomBrowser and seeing the focus point. I guess I'll find out how it handles the recomposed shot since almost all of mine are..

Just trying to learn.

Blog: http://novicephotog.blogspot.com/Flickr: http://www.flickr.com/photos/9778447@N07/..

Comment #10

You shot it at 1/125 sec at 155mm. That is part of the problem. Rule of thumb is to never shoot a shutter speed slower than the focal length of the lens. Unless you use a tripod, mirror lock up and a cable release. A faster shutter speed would help. 1/200 or 1/250 sec.



Bill.

Shoot liberally!..

Comment #11

So, it sounds like the biggest culprit is the shutter speed - guess I was assuming that using a 'monopod' would allow me to use pretty slow shutter speed, but obviously my speeds were still too slow..

When I was taking the photos it was about 10am on a bright sunny day & I really did not think I would have any problems with shutter speed, especially using the monopod..

Also, I did not realize the impact that the zoom lens would have - I probably should have opened the aperture up, though due to my inexperience, I remember thinking at the time "better close down the aperture, otherwise depth-of-field will be too shallow and I might not get ALL of the bear in focus...".

Auto-focussing is definitely proving much more difficult than I expected - particularly when using the zoom, I often find it hard to tell "which" of the AF focus points lights up, yet alone try to focus exactly on the bears eyes....

I like the idea of using Zoom Browser to see where the lens auto focused - will try this tomorrow.

ThanksMike..

Comment #12

Michael Cummings wrote:.

So, it sounds like the biggest culprit is the shutter speed - guess Iwas assuming that using a 'monopod' would allow me to use pretty slowshutter speed, but obviously my speeds were still too slow..

It will improve things and helps largely with up/down movement and you can still effect movement side to side if it's not held properly. It also doesn't have any impact on subject movement, one of the shots was blurred on the panda as it moved within the exposure and in that frame, most of the scene was reasonably sharp otherwise..

I can't find the site I was looking for, but this has similar information on using a monopod correctly. Don't just stand it straight upright on the ground in front of you, it can still move considerably. Make a triangle with it wedged in the instep hollow of the back-most foot and against the thigh of your other leg - make a triangle of support with it, much more effective than a straight upright line..

Http://www.outdooreyes.com/photo5.php3.

Also, I did not realize the impact that the zoom lens would have.

The more you zoom - longer focal length - the faster your shutter speed should be. Also on the less expensive zoom lenses, you lose aperture (had you started off wide open) as you zoom too - which would also lower your shutter speed. For example, had you started off at 50mm and wide open at f3.5, then zoomed to 250mm, your aperture would automatically gone to f6.3 - losing you around 2 stops and dividing your shutter speed to a quarter-ish of what it was - so had it been 1/100, it would now be something like 1/25. And conversely, now with the increased focal length, you'd actually need it to be much faster to eliminate camera shake. Your only option is to increase ISO - I think you were at 200, so you had plenty of capacity to do that..

- Iprobably should have opened the aperture up, though due to myinexperience, I remember thinking at the time "better close down theaperture, otherwise depth-of-field will be too shallow and I mightnot get ALL of the bear in focus...".

This is also true, the more you zoom, you reduce DOF too. See this DOF calculator and put in some numbers and see what it does to DOF: http://www.dofmaster.com/dofjs.html.

Using the hypothetical example above, at 50mm and f3.5, at the fictitious distance of 10m away, your DOF would be about 5.4m. Zoom in to 250mm and the camera would close the aperture to f6.3 and your DOF from the same spot would now be 0.38m! The zoom - even with a stopped down aperture - has seriously impacted on DOF. Even if you'd been stopped down more at say f8, you'd start with over 19m of DOF at 50mm, but at 250mm, it would drop to less than half a meter!.

Just to illustrate that, this is at *300mm* and f8, from about 6 feet away - you can see that even a tiny little birds like this isn't fully in focus and the background has blurred to nothing:.

Image control:Zoom outZoom 100%Zoom inExpand AllOpen in new window.

Yet, this shot, also from about 6 feet away and f8, at *12mm* has infinite DOF:.

Image control:Zoom outZoom 100%Zoom inExpand AllOpen in new window.

I've written a tutorial on DOF, see: http://www.zenadsl5251.zen.co.uk/photos/doftut.html.

Auto-focussing is definitely proving much more difficult than Iexpected - particularly when using the zoom, I often find it hard totell "which" of the AF focus points lights up, yet alone try to focusexactly on the bears eyes....

It's proving difficult *because* you were using multi-point AF - I'm a very experienced photographer and I wouldn't dream of using it. There are good arguments when it is the right tool for the job and that is also helps the camera meter better, but I've never felt any desire to put it into practice. Put the camera in single AF point and start off with the centre one only. You may need to half touch the shutter to establish focus where you want it, then re-frame to compose your scene, but I'd argue that this is much more reliable than hoping the camera chooses to use the AF points over your subject..

You can of course, on a shot to shot basis, change which AF point the camera uses, which can remove the focus/re-compose part of the process, but I'd highly recommend only using one AF point, not multi..

I like the idea of using Zoom Browser to see where the lens autofocused - will try this tomorrow.

This only has value where you used multi AF points and you didn't re-compose. All it does it tell you which AF points locked focus. As I use one only and almost always the centre point, it has no value to me as it always just lights the centre one red - no matter where I actually focused. If you used multi on a scene and didn't re-compose, then it is useful as it will show which of the points had focus lock and this would illustrate where it might have latched onto the background or foreground rather than your subject..

I'd really recommend that you go to single AF point - the AF system will use areas of high contrast, often with vertical lines and if the camera happens to decide that your background makes for a better focus source than your subject, your shot is spoiled. With a single AF point, you're in control and can see and decide where it's in focus, rather than the camera, which doesn't know what you want from the scene..

So many photos, so little time.http://www.peekaboo.me.uk - general portfolio & tutorialshttp://www.boo-photos.co.uk - live music portfoliohttp://imageevent.com/boophotos/ - most recent images.

Please do not amend and re-post my images unless specifically requested or given permission to do so...

Comment #13

Thanks for taking the time to post this info Boo - I've learnt so much from everybody's feedback..

I had no idea that DOF was impacted to such a massive extent by the focal length used, plus I will definitely switch over and start using just ONE AF point..

One question on DOF: Given that the camera has all the info, I wonder why the viewfinder could not give an indication of DOF, based on the aperture, focal length etc. ? .

I know the Rebel XT has a DOF-Preview button, but I seem to remember that you have to switch to a specific DOF_Preview mode to use that - must read the manual again sometime soon.

ThxMike..

Comment #14

Michael Cummings wrote:.

I had no idea that DOF was impacted to such a massive extent by thefocal length used, plus I will definitely switch over and start usingjust ONE AF point..

It's really the field of view/composition that determines DOF - i.e. the combination of focal length with distance from the subject. A 100mm focal length at a given distance from the subject, would give approximately the same DOF as a 50mm lens from half the distance. In both those cases, your image in the viewfinder would be the same field of view/composition/framing, so the DOF for the same aperture would be almost the same..

In the panda examples in question - because you were in the same place, zooming alone compressed the DOF. Had you stepped further away, but then zoomed to keep the same view, the DOF would have remained the same. But if you stand still and then zoom in to go in tighter, you do lose DOF, without changing anything else. Very often, that's used deliberately to lose background clutter. Sports photographers very often aim for a shallow DOF using long focal lengths and wide apertures, deliberately to isolate the action from backgrounds and crowds etc..

One question on DOF: Given that the camera has all the info, I wonderwhy the viewfinder could not give an indication of DOF, based on theaperture, focal length etc. ? .

I don't know the answer to that - it seems that some cameras certainly can - I answered a topic a few days ago about this same subject in respect of a Canon G7 with a firmware upgrade to allow this, which does give a display of the variables, see:http://forums.dpreview.com/...forums/read.asp?forum=1002&message=24967947.

I suspect it's because the lens can be focused manually and separate from the camera - although you'd think with AF it could potentially be done..

I know the Rebel XT has a DOF-Preview button, but I seem to rememberthat you have to switch to a specific DOF_Preview mode to use that -must read the manual again sometime soon.

Nope, don't need to switch anything - just wiggle your left thumb. When you look through a lens to compose, the lens aperture is wide open to it's own maximum - so an f3.5 max aperture lens will open to f3.5 to give you the brightest image possible on the viewfinder - so you're actually seeing the DOF in the scene that f3.5 would give you. If your camera is set to a smaller aperture than that, you can hit the DOF preview button with your thumb and all it does is stop down the lens blades to the set aperture to mimic the perspective you'd get taking the shot..

The scene will darken as you're looking through the lens, as you're seeing it through a smaller hole, so less light is hitting the mirror, but you can now see the DOF you're likely to get in the final shot..

My own personal preference to check DOF is to use AF where I think would be best - then switch the lens to MF to preserve that focus and run the lens over the elements of the scene I want to be in focus and I touch the shutter button lightly over those items - if they'll be within focus, the focus confirmation spot in the VF will show and the AF point selected will flash red over the scene. If you don't get the DOF you want, one of the elements of either focus point, focal length, distance or aperture needs adjusting..

So many photos, so little time.http://www.peekaboo.me.uk - general portfolio & tutorialshttp://www.boo-photos.co.uk - live music portfoliohttp://imageevent.com/boophotos/ - most recent images.

Please do not amend and re-post my images unless specifically requested or given permission to do so...

Comment #15

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This question was taken from a support group/message board and re-posted here so others can learn from it.

 

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