10D focus test

[jim_joh]

I decided to test my 10D which is a month old I printed the ruler from Bob Atkins site ( http://www.photo.net/learn/focustest/ ) on a 8 x 10 white paper. I used the 50mm at f1.8 and placed the white chart at 45 degrees leaning toward the camera and had the camera 6 ft. and level with the chart and made 6 shots using AF single spot exactly like Atkins showed. I was so pleased that in every shot both of the rulers on the chart was razor sharp from left to right. MY problem is on Atkins site the results show the center only as being in fucos & the left & right sides was not but in my case the entire chart was real sharp. I did a futher test from 2 ft with the same results so I am wondering is mine OK or not. Thanking all Jim Johnston

[daveh]

It sounds to me like you're not shooting wide open.

[jim_joh]

I neglected to say that I shot at f1.8 & 1/125 using a tripod Jim Johnston

[topeju]

If your image is razor sharp at both edges and you are shooting at 45 degrees to the image, you really can't be shooting at f/1.8. From 6 ft, your depth of field at f/2 would be approximately 10 cm, which would be a range of 14 cm on the paper (since it is at an angle of 45 degrees), or roughly half the width of the paper. At f/4 the depth of field will be approximately equal to the width of the paper.

In any case, you will need to move your camera closer to the paper. With a 50mm lens, you would want to be approximately 1.5 to 2 ft from the paper. The paper should fill the whole frame of your image. From 1.5 ft, your DoF will be much more narrow, less than a centimeter on the paper at f/1.8.

Could you re-verify that you really were using f/1.8 (from the EXIF data in your images). Or, could you post your test shot somewhere so we could also check it out?

[RichardtheSane]

I think we need to confirm exactly what is being said before we suggest jim_joh had made an error.

jim_joh, are thedges that are furthest away/nearest the camera in sharp focus? Or is it the edges parallel with the focus point?

[jim_joh]

I ran the tests again and this time I shot about 2ft. from the chart & the top set of lines were real sharp & the bottm was much softer but again on both lines from right to left there was no change. The shot from 6 ft showed the entire chart & the 2nd shot from 2 ft' reduced it to the number 3 on both side.
exif from 2nd shot 2 ft from target.
ile Name
IMG_0414.JPG
Camera Model Name
Canon EOS 10D
Shooting Date/Time
7/13/2003 8:36:42 AM
Shooting Mode
Aperture-Priority AE
Tv( Shutter Speed )
1/60
Av( Aperture Value )
1.8
Metering Mode
Center-weighted averaging
Exposure Compensation
0
ISO Speed
200
Lens
50.0 mm
Focal Length
50.0 mm
Image Size
3072x2048
Image Quality
Fine
Flash
Off
White Balance
Auto
AF Mode
One-Shot AF
Parameters
Contrast Normal
Sharpness Normal
Color saturation Normal
Color tone Normal
Color Space
sRGB
File Size
1726KB
Custom Function
C.Fn:01-0
C.Fn:02-0
C.Fn:03-0
C.Fn:04-0
C.Fn:05-0
C.Fn:06-0
C.Fn:07-0
C.Fn:08-0
C.Fn:09-0
C.Fn:10-0
C.Fn:11-0
C.Fn:12-0
C.Fn:13-0
C.Fn:14-0
C.Fn:15-0
C.Fn:16-0
C.Fn:17-0
Drive Mode
Single-frame shooting


I can send this by email if I had your address



Jim Johnston

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[jim_joh]

RichardtheSane wrote:
I think we need to confirm exactly what is being said before we suggest jim_joh had made an error.

jim_joh, are thedges that are furthest away/nearest the camera in sharp focus? Or is it the edges parallel with the focus point?

I am sorry Richard that I did not answer your questiosn. The left & right edges were all in parellel and from one side to the other was in sharp focus. There are 2 sets of lines with a vertical line in the center & in between the 2 lines which I used a the focus point. In the test 6 ft. away the botton row of lines was almost the sharpness of the top line. A little amt. of differenve. In the test of 2 ft. there clearly was a difference between the top row & the bottom with the top being clearer. To me this shows the DOF is the reason. The pics will not show any more than I am saying. Thanking you Jim Johnston

[PacAce]

Seems to me that you're not doing the test exactly right. It might be that the orientation of your chart is not correct. To explain it simply, the one side of the chart that has the number "3" has to be CLOSE to the camera and the other side with the other "3" needs to be AWAY from the camera so that the face of the chart is 45 degrees from the camera. It sounds like what you did was make the side with the one set of rulers close to the camera and the other side away from the camera. That's the reason the lines in your shots from left to right are all in focus. :)

[jim_joh]

Thank you Pac for your help. You was right. Looking at Atkins site it seems like the 45 degree was top to bottom so that was the way I did the first tests. In accordance with your advice I repeated the test with the 45 degrees left to right. Results of the tests was great. In most of the shots ( 8 ) the center 10 lines were razer sharp and on both sides equally and started to drop off the same. On 3 shots to a very small degree it slightly favored one side or the other. From this test I am of the opinion that my 10D is doing the job. Thanks to all. Jim Johnston