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 06/04/2005 09:43:28 AM · #1
Hi Everone,

Can anyone tell me if the autofocus on a Rebel XT is controlled by the lens or the body? I am thinking of exchanging the kit for a body and separate lens if that will help the focus. I bought the kit last week but they gave me an incompatible flash card so I am going back anyway and thought I might do this exchange.

thanks,

Bj
 06/04/2005 09:58:59 AM · #2
a body is a body is a body. the lenses are totally seperte items. all the kit does is put a lens with the body so you have a complete camera ready to take pictures.

what do you mean an incompatible flash card? If it is a compact flash card, it will work. they all do. some better than others, etc, but it is a standard.

If this is your first SLR, and it sounds like it is, be VERy patient as there is a steep learning curve. 90% of the issues folks have with focus or exposure etc are the fault of the USER, not the equipment.

Raed the manual. start by shooting in full auto mode, then try P mode. The camera has many modes, and each one is there for a reason, and each one does different methods of focusing and exposure metering. in some modes, you can choose how that is done.

'bad focus' can be caused by bad focus, by the camera's focus point not being what you think it is, too shallo a DOF, camera shake, the subject moved...and it can sometimes take someone else to identify what it is.
For example:
The face is soft...bad focus? NO! One of two things..the kids moved OR the camera picked a point other than her to focus on. How do i know? Look at the upper right, there is a door pull and it is sharp. I tested this lens on a bottle on the counter. it was sharp when focused on the label...so the pic in question is user error in some form.
 06/04/2005 10:16:30 AM · #3
The camera body does the focusing, as long as you have "EF" type lenses (no other type will work in autofocus...and Tamron/sigma also make EF compatible lenses)

I don't know that there is such a thing as imcompatible CF card (unless you meant to say, they gave you a SD, SM or memory stick instead of the CF that fits in your camera)
 06/04/2005 10:26:20 AM · #4
Thanks for the reply!

Yes - my very first slr:)

I have kept it in auto mode for now and the focus problem is exactly what you said - I think it is focused on one thing, yet when I upload the photo the focus was somewhere entirely different - for example a dog photo where I think it is focusing on the dog but it is actually focused on something way behind the dog and the dog is slight out of focus. I will keep trying!

The card is an issue with some lexar cards not being compatible with some canon cameras - see //www.lexar.com and canons website. They are issuing some kind of firmware (which I don't understand yet), but based on the error messages I got while trying to upload and missing images, I am returning it for a different card. Maybe I am overreacting, but I don't have a lot of money and want something I feel will not hurt the camera or be a problem. I will see if they will take it back at the store (which based on the date of the first press release they should have known about this and not sold me that card anyway).

Thanks so much for your input it is very helpful.

Yes, first time slr user - not too obvious is it:)
06/04/2005 10:28:34 AM · #5
Thanks Gil - It is that type of lens:)
06/04/2005 10:31:48 AM · #6
If you're using it in fully-automatic mode, perhaps it is set so that all the focus points are being used. If that is the case, you will have to keep an eye on which one illuminates, as that is the point at which the camera has focussed upon. You may decide to use only one of the focus points, which may well make it all a little more predictable.
 06/04/2005 10:33:51 AM · #7
I think you have a good case that the store really should have known about the Lexar card issues, and recommended a different card. They should, IMO, exchange it. Get a Sandisk Ultra II, IMO best combination of price/speed.
Regarding AF control, the camera does tthe "processing, sends a signal to the lens, and the lens moves inresponse. The process is repeated until focus lock is achieved.
Some lenses will focus better than others, namely "faster" lenses thta allow more light to the focussing system, and those that have USM focus motors that can respond more quickly.
In auto mode, you are using all of the AF "points" in the viewfinder, and the camera is selecting what it thinks is the area of interest, which is not always where you want it to be. One recommendation would be to ditch full auto mode, and set the center focus point as the active one. Then you know where it is picking up focus from. You may have to focus/recompose if you want your subject off-center though.
 06/04/2005 10:34:07 AM · #8
Originally posted by BJ:
...I think it is focused on one thing, yet when I upload the photo the focus was somewhere entirely different - for example a dog photo where I think it is focusing on the dog but it is actually focused on something way behind the dog and the dog is slight out of focus....


One way to be absolutely sure where your focus point is is to use only the centre focus point and make sure it's on the subject...if your subject is off centre then choose an off centre focus point.
 06/04/2005 10:41:02 AM · #9
Not to complicate things for a noob, but if you shoot in RAW then look at it in canon's software, it will tell you where the focus point was, as in which AF point was the one that was focused on.

Proper focusing is my biggest issue. Yesterday i was taking bird pics arounfd my hard with a 300mmlens. It seems the center AF point is actually about 2 inches below what i see in the viewfinder. Tests to follow..
 06/04/2005 10:56:54 AM · #10
Originally posted by doctornick:
Originally posted by BJ:
...I think it is focused on one thing, yet when I upload the photo the focus was somewhere entirely different - for example a dog photo where I think it is focusing on the dog but it is actually focused on something way behind the dog and the dog is slight out of focus....


One way to be absolutely sure where your focus point is is to use only the centre focus point and make sure it's on the subject...if your subject is off centre then choose an off centre focus point.


This is one of the first things to get used to on a first dSLR along with which AF Mode (Single Shot, AF AI and AI Servo) mode...For example: If you use center focal point and AF Servo Mode and move the focal point just a hair off the subject one could easily end up back focusing.

Likewise If using AF Single Shot and Center Focal Point and you Lock on a subject but recompose the shot while half shutter squeeze by moving closer or furter from the subject (or the subject moves closer/further) the Focal Point will change and front or back focusing might occur.

I would get used to the Focusing System of the camera before doing any major lens purchases/swapping... I myself fell into the "It has to be lens is soft/bad" syndrome in the first weeks of use of my first dSLR.
06/04/2005 11:04:32 AM · #11
Originally posted by kirbic:
... set the center focus point as the active one. Then you know where it is picking up focus from. You may have to focus/recompose if you want your subject off-center though.

I find that on both my Olympus and Canon cameras, the "focus-lock" function doesn't really lock -- I focus, hold the shutter halfway, recompose, and the camera still changes the focus/exposure before I can take the picture. It's very annoying.
 06/04/2005 03:24:43 PM · #12
The issue with the LEXAR card is only with the --80X 1G card-- and as of yet ONLY with the 1DsMkII.
 06/04/2005 07:50:43 PM · #13
Originally posted by Gil P:
The issue with the LEXAR card is only with the --80X 1G card-- and as of yet ONLY with the 1DsMkII.


My cousin with Rebel XT is having the same problem.
 06/04/2005 07:57:27 PM · #14
Originally posted by Gil P:
The issue with the LEXAR card is only with the --80X 1G card-- and as of yet ONLY with the 1DsMkII.


I have that lexar card in question and have yet to have a problem with either the card or camera.

edit: But yes the kit lense sucks ass. something you may want to keep incase you ever decide to re-sell the camera and need a lense to go with it.

Message edited by author 2005-06-04 19:58:25.
 06/04/2005 08:04:21 PM · #15
I forget the name, but some microdrives are incompatible with certain cameras. Stay away from cheap green microdrives.
 06/04/2005 11:37:14 PM · #16
I have the Lexar card in question as well, and the Rebel XT, and after 125 shots nothing has happened yet....we'll see about the future though.
 06/05/2005 01:46:36 AM · #17
Hi again everyone,

Sorry I should have been more specific about the card problem. Please go to the following link (hope it works!) for more info. Hope I did not cause anyone inconvenience, but also if you have an affected camera and card you can find out more info on it from LEXAR and Canon.

//www.dpreview.com/news/0505/05052001canonlexaralert.asp

bj
 06/06/2005 09:12:02 PM · #18
If I may, can I ask another quick question? Is the autofocus issue I was having the same on all dslrs or just the rebel xt?

By the way, the store (Ritz Camera) took the card back no problem. I printed out something from the internet for the salesperson as an FYI and he thanked me. Not a plug for Ritz, but just thought it was kinda cool they did not give me a hassel.

Actually, I returned the whole thing as I only had a day before I couldn't return it, now I miss my rebel xt and will probably buy another one - from the same company. My hobby is stressing me out:) how's that for irony? lol!

bj
 06/06/2005 09:18:06 PM · #19
Originally posted by GeneralE:
Originally posted by kirbic:
... set the center focus point as the active one. Then you know where it is picking up focus from. You may have to focus/recompose if you want your subject off-center though.

I find that on both my Olympus and Canon cameras, the "focus-lock" function doesn't really lock -- I focus, hold the shutter halfway, recompose, and the camera still changes the focus/exposure before I can take the picture. It's very annoying.


I've seen this as well, but I believe it happens only/mostly if you don't actually get a focus lock (the beep). It's hard with USM because its so quiet--I use the center point, it looks like its in focus, I recompose, and it shifts. But then I noticed I wasn't waiting for the beep!
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