focussing questions on rebel xti

Hi my name is mike and I am just a serious shooter for fun. I am new to this

forum and hope to find good honest answers to my questions. I own a rebel xti

and recently made a major investment in the 300mm f2.8L lens. My problems are

concerning the focussing. I have done alot of looking into this but want some

input from any of you. I seem to be able to only get a few of my sporting

action shots in perfect focus. My still shots of wildlife are about 80% perfect

focus. By this I mean absolutely perfect and the ones that are not perfect are

just off a little. I think with this lens I should be able to get all of my

still shots in perfect focus. Am I asking too much? I believe that the lens is

too much quality for the camera. I do get some very awesome shots but I am

disapointed in my ability to get more of the action shots. I am considering

upgrading to the new markIII mainly for this reason. I want to find out for

sure if this will indeed solve my issues. thank you for any help

Mike, I'm usually not compelled to throw out my opinion but shooting sports is one of my passions and I've been working on it for several years now. I want to reiterate that this is strictly my opinion and you know what they say about opinions so take them for whatever they are worth.

First, you've got a top notch lens and a fairly good body but the quality is in the glass mostly anyway. Moving to a Mark III may not be a good move right now until Canon gets the bugs out of the AF. Do your homework carefully before you make that jump. A 1D Mark II would be a better choice (my opinion) and a more reasonable jump. The 8 frames/second is a extreme advantage over the XTi's 3/second and the AF sensitivity of the 1D is a huge improvement. However, the XTi is still a very capable of getting it done. Also, I assume you are setting the AF in Al Servo mode--right?

Second, I personally think your expectations are too high if you expect perfect focus on every shot when shooting anything that is fast moving. I'll fill up several 8 GIG CF cards shooting one football or baseball game(RAW) and consider it successful if I come out with a couple of dozen sharp images--before PS.

You just need to practice.

 

Keith

Hi Mike! I have to agree with Gary that your equiptment should be more than fine to provide you with a shaper picture. I also have to agree with gary that I also will take several pictures during an action event and may only come away with what might be called "perfect".

 

Now as for you equiptment and personal technique...... the XTi is capable of razor sharp focus assuming the right lens. The 300mm F2.8 you have should be able to yield some great pictures. So unless there is a problem with your equiptment I would then question your technique. What F stop and shutter speed are you using? Are you shooting with a monopod or hand held? Assuming the lens is not an IS model, at 300mm anything much slower then 1/200 of a second you will likly find it hard to get that "perfect" focus. Now as for the F stop, are you shooting wide open @ F2.8? If so you my want to stop down to mabey F4 and see what the results are. Most lenes will not produce thier sharpest image wide open but usually around the F4 to F8 will usually make a notable difference although in action photo this may not be an option unless you are in bright sunlight.

 

In conclusion I would try this....

-Try a monopod

-If shooting at F2.8 try stopping down a bit and see if it helps

-If you are sold on hand held shooting only then bring the shutter speed to at least 1/200 of a second.

 

Good luck!

Jack...You suggest a shutter speed of '200 for sports hand held with a 480mm equivalent focal length lens? Have you been smoking that crack-cocaine again? That will make EVERY picture unsharp, regardless of whether or not the subject is in focus...not to mention camera shake. To freeze your average-speed sports action reliably with a 480mm lens, you should try to use a shutter speed of about '1000 if at all possible. You can probably get away with a bit slower if your subjects are moving along the lens axis instead of across it.

 

Keith

Keith...your right I wasn't even thinking of the 1.6x crop factor. As well as with your comment on a faster sutter speed with sport photos. I was think more in line of "over all" photography that is hand held and keeping in mind of the focal lenght of the lens. Give the 1.6x crop the correct focal lenght of 480mm as you correclty stated then the slowest shutter speeds to at least a chance of a sharply focused picture would be at least 1/400 - 1/500 of a second, action of not. Athough I did mention these "slower" shutter speeds are not likly an option with action photos or anything faster than the wheel chair race at the senior center anyway. You point is taken and I agree, i over looked that key issue of the crop factor when stating the shutter speed but he also mentioned wildlife photography which more often than not wildlife photos are of the animal stating still not running like a weekend foot ball player. Anyway,the point of my post to Mike was get him thinking more on technique and less about equiptment. Even the best of equipment can't over come improper technique.

Keith had it. You need practice. A 1D would improve af speed a bit, but in the end your technique is what will make the biggest difference.

I generally concur with the above answers, however, I shoot trains, at speeds varing between 0 and 100 MPH and at focal lengths of 50mm to 400mm on a 400D and 7e. If you are using a "heavy" lense forget about the 1/focal length rule. That might work where you can take some time to compose yourself and steady your camera, for fast shooting it doesn't work for me. I find I need to go to at least half that speed eg 1/1000 instead of 1/500th. If you are restricted in how fast a shutter speed you can use then you need to have something else going for you, a bean bag, monopod, IS lense etc. As for action, well I don't always get the focus perfect, but stopping down helps and prefocussing also helps. I only use the centre focussing point. I find the 400D to be a big improvement on the 7e.

 

Neill Farmer

Hi Mike,

 

Just to add a few more things to confuse you ...

 

I've recently upgraded from a 20D to the 1D Mk3 - it's one hell of a camera. There has been a lot of press recently regarding it's autofocus performance - to be honest, I really don't know what to make of it ...

 

The thing that seems to trip it up the most is the subject to camera distance is changing in a non-linear fashion - and yet the book says that it's algorithims are for LINEAR changes in distance - so perhaps people are expecting too much?

 

When you think about it the camera doesn't have distance information to calculate focus information from - it works the other way around in that it knows the distance info from where the focusing is - if it focuses one shot at 100 feet - a 2nd at 90 feet - it's not too hard to work out where to focus for one at 80 feet - if however the 3rd shot is at 110 feet I can't see how 100 mS is enough to move to the new point - find it's out of focus - hunt the focus (which direction?) - and get the new focus sorted before it's time to take the next shot) - some point out that the 1D MK2 did a better job - perhaps this is because at only 8 fps the lens elements had 20% more time to move?

 

By the way, you can set the 1D3 to burst fire "X" number of shots, and at a fps of between 1 and 10 - whatever you need. The other nice thing about it is the time it takes to acquire initial focus - about as fast as you can blink - far out it's quick!

 

Who can say if the 1D3 is for everyone - only you can decide. Having got mine though I can say I wouldn't part with it for love nor money (well not for money anyway!) - comparing it to the 20D is like comparing a Formula 1 car with your average 6 cylinder family saloon.

 

With regards to blur caused by handshake - you've got the equivalent of a 500mm lens - so the often cited recipocity law says you should have a shutter speed of at least 1/500th - however - I've also read that if you want to eliminate ALL shake then you need to be aiming around 5 times even that speed. If you can, use a tripod - and if you're having trouble using it to track animals etc, point your browser at www.tripodhead.com and have a look at the Winberley Head.

 

Cheers,

 

Colin

I want to thank everyone for the much useful advice. WOW! this was my first time to ask a question and was amazed at how many people were there to help me. To explain a few things farther. I have not had my new lens very long and have not had the chance to work on all the different techniques you suggest. I have a 7 year old son that plays ice hockey. This was one of my reasons for buying this lens. I have only used it one time shooting him at hockey. It was not as bright inside as I had hoped for and was not able to shoot as high a shutter speed as i wanted. I was using a monopod and the camera was set on al servo. One reason for focussing concerns is my comparison to pictures we bought from a man using a 1D. We bought a disc from him and withing hours of shooting and I believe that every picture he shot was on that disc. This leads me to believe that his camera did the job of focussing faster and locking onto the moving skaters. But after reading all your suggestions I will keep working on my techniques. last night I was out by my treestand and was able to shoot a doe(with my camera). I had the 1.4x extender on. Again the pictures were not razor sharp. The deer was 50 yards away and I use the single focus point in the middle with the monopod. I was only able to get to 1/500 and 1/640. They are some very good pictures but I must need just a little more shutter speed. I will still be saving my coins for a 1D someday just in case. Thanks for the advice on the markIII. I certainly do want a proven camera if I spend that kind of money. thanks again...you people are great!

Hi Mike,

 

I just had a quick look at your deer shot - to me it looks undersharpened.

 

I don't know if you're shooting RAW or JPG, but I typically sharpen all of my RAW images twice - initially at 300%, 0.3 Radius, Threshold 0 and then (to improve the overall look) 20%, 20 Radius, Threshold 0. If it's a high res JPEG then I usually have to have a much higher radius on the first pass (sometimes up to 1.0).

 

If you get the change, have a play with the 1D Mk3 - it's like taking a sports car for a spin when all you've been driving is a family saloon for years!

 

Cheers,

 

Colin

This was a sample of what i call out of focuss issues I am having. Maybe this is caused by something else. I am sorry but I must not have the type of photo software that you have because most of what you suggest went right over me. I shoot in RAW and normally do some touching up. I do not know what threshold and radius are. Please fill me in.

Mike,

The software Colin is likly referring to is Photoshop using the unsharp mask tool. As for the hocky shot when the condition and light just simply will not allow a faster shutter speeds I find at times it helps to shoot in 3-5 shot busrt. When you press the shutter naturaly you will move the camera just enough to create some blur or the appearance of being out of focus although when shooting in burst, in the usually low lite area like a hockey game,"may" help. The first shot will be "bad" as usually but the second or third shot usually will be better as you will not be pressing the shutter a second or third time but rather holding the shitter release down and in turn moving the camera less. This may also help some while shooting wildlife as well. Additionaly the teleconverter is only going to need even faster shutter speeds. You may want to try/consider a tripod with a remote release for the wildlife.

 

Jack

The sharpening in Photoshop is not a tool that will make an out-of-focus picture in focus, so I am not sure why that is coming up here. Digital sharpening is to counteract the blur introduced by filters in front of the sensor.

 

Also, sharpening is different for each picture, and different depending on the details of your final output, so nobody can give you a formula that will work. Just keep your pixel radius at 0.5 or below, threshold at zero, and inch up the amount until it looks natural to you.

 

But, as I said before, sharpening has nothing to do with your problem. The doe looks oversharpened if anything, as things can tend to do when they are out of focus or blurry as a result of camera shake.

 

Keith

Keith Lubow wrote:

 

"The sharpening in Photoshop is not a tool that will make an out-of-focus picture in focus, so I am not sure why that is coming up here."

 

It's more accurate to say that sharpening isn't a substitute for good focusing - but (depending on the display size of the image) it can compensate to a very effective degree - after all, enhancing edge contrast be it by sharpening or better focus will both provide the perception of improved focus.

 

In the case of the deer, I opened it in photoshop - gave it a sharpen - and got a considerable improvement, leading me to think that possibly the image simply hadn't been sharpened correctly in the first place - unfortunately it wasn't possible to do a lot with the sample, being JPEG and low res - I could certainly get a much better result on a higher-res original (especially if in RAW) with a little sharpening.

 

Keith Lubow wrote:

 

"Just keep your pixel radius at 0.5 or below, threshold at zero, and inch up the amount until it looks natural to you."

 

This works for countering the effects of the AA filter (Personally I refer to this as pre-sharpening - there's usually very little variation in images shot from the same camera) - however I've found it easier to preset the amount to 300%, then vary the radius - usually 0.2 to 0.4 is about right (for a RAW shot) (needs to be viewed at 100%) - however to improve global sharpening you'll probably be looking at something like 20% @ Radius of 20 or so (which is typically what I use for 22 x 33" prints) (whilst looking at the whole image, preferably at a similar size to what it will be printed at.

Thanks for all the help, my main point here was to figure out why I should even need to "sharpen" the pictures at all when using the sharpest lens canon makes. I did go back and adjust the deer picture which made a nice improvement. As Keith stated using the sharpening tool is not a substitute for good focussing. One thing I think may be happening is that the deer may have been too far away for the rebel xti to get a good reading on. as far as my sports shots go I will try shooting bursts of pictures as suggested. I was unsure if professionals need to do that or not? I believe my techniques here are my biggest problems so I need to get out there and keep practicing. Thanks again you guys are great!

<<my main point here was to figure out why I should even need to "sharpen" the pictures at all when using the sharpest lens canon makes.>>

 

Because, due to sensor design, there in an Anti-Aliasing filter in front of the sensor which softens the details a bit. It does this to avoid moire in images. You can search here for more details if you're curious. The upshot is that you should learn to apply some sharpening to your digital RAW images in a post-production environment. How much sharpening depends on subject matter and personal taste.

Mike Houfek wrote:

 

"As Keith stated using the sharpening tool is not a substitute for good focussing."

 

Um, actually I'll claim the fame for that pearl of wisdom ;)

 

Seriously Mike, sharpening isn't something that simply compensates for lack of sharpness in any particular lens (although this is indeed an added benefit) - it's actually quite an involved process with all sorts of compromises (the frequency of the image - the resolution of the image - the resolution of the print/display - amount of noise etc) - so much so that the late Bruce Fraser wrote a 288 page book on it (Real World Image Sharpening with Adobe Photoshop CS2) - and some portions of it require several re-reads to get the hang of it! It usually takes at least 3 "sharpens" at various stages to get an image to the point where it's ready to be printed (more if noisy areas have to be masked off first).

 

People have different "tolerances" for image sharpness - it sounds as though you're a lot like me in that you like things as clear and in focus as possible - if that's the case, and from what you've said so far, I'd suggest you consider starting to shoot in RAW mode, and learn how to process your images in Photoshop. It IS a bit of a learning curve, but having said that it gives the best results - is very rewarding - and of course, we're always here to help you on that journey.

 

(I'd you'd like to take a RAW shot and send it to me I'd be happy to process it for you and send it back to give you an idea as to what you're missing).

 

All the best,

 

Colin