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VIP
Posts: 11,096
Registered: ‎12-07-2012

Re: my 400mm 5.6 wont focus sharp

"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.

EOS 1DX and 1D Mk IV, even less and less other stuff.
Occasional Contributor
Posts: 10
Registered: ‎01-08-2019

Re: my 400mm 5.6 wont focus sharp

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

VIP
Posts: 11,096
Registered: ‎12-07-2012

Re: my 400mm 5.6 wont focus sharp

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.

EOS 1DX and 1D Mk IV, even less and less other stuff.
Occasional Contributor
Posts: 10
Registered: ‎01-08-2019

Re: my 400mm 5.6 wont focus sharp

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

VIP
Posts: 8,041
Registered: ‎08-13-2015

Re: my 400mm 5.6 wont focus sharp


@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


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

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"I don't rent software. I use Photoshop CS6, ACR 9.8 and Lightroom 6.8 ."
Occasional Contributor
Posts: 10
Registered: ‎01-08-2019

Re: my 400mm 5.6 wont focus sharp

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

Honored Contributor
Posts: 5,709
Registered: ‎11-13-2012

Re: my 400mm 5.6 wont focus sharp

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. 

John Hoffman
Conway, NH

1D X, Rebel T5i, Many lenses, Pixma PRO-100, MX472, LRCC Classic
VIP
Posts: 8,041
Registered: ‎08-13-2015

Re: my 400mm 5.6 wont focus sharp


@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


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.

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"I don't rent software. I use Photoshop CS6, ACR 9.8 and Lightroom 6.8 ."
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