my 400mm 5.6 wont focus sharp

[colin333]

Hi Guys

Appreciate any help here

I have my camera  (5d mkiv) set up on tripod and trigger with my 400mm lens. It is set up as one shot with the center focusing point. I take a picture in live view at 25m and it is pin sharp, however when i use normal position it is not as sharp, I have gone thru the micro settings from -10 to +10 but still cannot get it as sharp as live view. Any suggestions would be most welcome

[ebiggs1 · Accepted solution]

"If focus is all over the place (there is no trend) ..."

It sounds like it is simple mis-focus.  If it is we don't want to make a simple problem into a difficult one. One fact I see often is the better or more expensive cameras that have focus adjustment need it the least. Lower end cameras that could benefit form it don't have it. I think a more controlled test is warranted here. A lot of people jump into AFMA when it isn't the problem only to make things worse.

[colin333]

Hi

Thanks for all the help here guys, the problem 1st come to light when photographing birds my pics were not of the same clarity as others.

anyway I have just spent the last 3 hours meticulously going through various focusing methods and have sorted the problem (I hope) by adding a plus 10 AMFA.

one interesting point though was when I was shooting in Live View with auto ISO selected it was a lower setting (1 stop) from when I was using the view finder.

I think my lens needs a service

Once again thank you for all your input

[ebiggs1]

If you had auto ISO selected, you can not be sure of anything.  You need to fix the ISO and try again. It sounds like it might be wise to do a reset on your camera. Menu under tools, clear all settings and also in the custom setting, too.  You may have inadvertently set or mis-set something.

The lens does nothing. It is the camera that sets or tells the lens what to do.

[colin333]

yes I did fix the ISO, it was just an observation whilst I was experimenting. With the adjustment I have done the viewfinder focus is now the same as the Live view.

I tested my other lenses and they did not need anything doing , it was just my 400mm that was the problem

[Waddizzle]

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@colin333 wrote:

yes I did fix the ISO, it was just an observation whilst I was experimenting. With the adjustment I have done the viewfinder focus is now the same as the Live view.

I tested my other lenses and they did not need anything doing , it was just my 400mm that was the problem

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You know, of course, that ISO has absolutely nothing to do with a camera’s ability to focus a lens.  Nothing.

[colin333]

I know that but as I said I just thought it was interesting that it came up different. The changes i made was to the microadjustment

[jrhoffman75]

The exposure metering pattern for Live View and focusing screen may be different. 

You can get different readings between evaluative, partial and center weighted, depending on scene content. 

[Waddizzle · Accepted solution]

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@colin333 wrote:

I know that but as I said I just thought it was interesting that it came up different. The changes i made was to the microadjustment

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Of course, you should get the same ISO value whether you use Live View or the viewfinder.  But, if the viewfinder were left uncovered when you measured the exposure, then that could explain the difference in ISO values.  

The metering sensor is at the top of the viewfinder.  Under normal shooting conditions, your face covers the viewfinder, which cuts off stray light from entering the viewfinder and reaching the sensor.  

When the camera is on a tripod, the viewfinder is frequently left uncovered.  The 1D series of bodies have a little curtain that you can flip into place, which blocks the viewfinder for just this reason.  You do not have to rely on the top LCD to read the exposure, though.

You can see the metering info when the camera is on a tripod by pressing [INFO] until you see the Quick Menu display.  If the shutter is not set to blank the. LCD, half pressing the shutter will allow you to see a dynamic of exposure prior to taking a shot.

[jrhoffman75]

Do you have another lens? Then you could at least rule out the camera.

Can you describe what you are trying to photograph?