Back Focus Help Please.

I have done the tests etc and am pretty sure my 70-200 (2nd Hand BTW) is suffering from this issue.

My question is simple something i have not tried as i have just really finished the tests.

Can i just step down i.e 5.6/7.1/8 etc etc or is this pretty much a repair date? I only ask as i am going on holiday in a week and have not got the repair window time.

It will be sent in but can i take it and just hope it is ok not so wide open?

Stop Down Take trip Have it Repaired and
Be very wary of used equipment from Jack Squat in future.

it sounds like you have not tested the focus rigorously...I would test this by single center focus shooting at a particular key on keyboard (like "G" so you review the image whether the keys in front or back are more focused than your intended target) at different focal length (in this case at 70, 100 150, 200mm) on a tripod using using timer/ext shutter release. You also have to test against aperture (ex. using 2.8, 4, 5.6, 8, 9, 11, 14, and F22 at 70, 100,150, and 200mm lengths). review the images at 100% and crop the center image of each sample condition to compare them side by side. Youll notice that images will be soft at the widest aperture 2.8 or 4 (depending what 70-200mm you have) and at extreme focal lengths (70 and at 200mm). After reviewing the images, you can micro-adjust the images if its really front or back focusing (use small increments to see improvements ex. -15, -10, -5, 0, +5, +10, +15, and +20). this is a lot to test and will take time. But youll be able to tell whether it really needs to be sent in or not

dude cam wrote in post #14624602
=dude+cam;14624602]it sounds like you have not tested the focus rigorously...I would test this by single center focus shooting at a particular key on keyboard (like "G" so you review the image whether the keys in front or back are more focused than your intended target) at different focal length (in this case at 70, 100 150, 200mm) on a tripod using using timer/ext shutter release. You also have to test against aperture (ex. using 2.8, 4, 5.6, 8, 9, 11, 14, and F22 at 70, 100,150, and 200mm lengths). review the images at 100% and crop the center image of each sample condition to compare them side by side. Youll notice that images will be soft at the widest aperture 2.8 or 4 (depending what 70-200mm you have) and at extreme focal lengths (70 and at 200mm). After reviewing the images, you can micro-adjust the images if its really front or back focusing (use small increments to see improvements ex. -15, -10, -5, 0, +5, +10, +15, and +20). this is a lot to test and will take time. But youll be able to tell whether it really needs to be sent in or not

60D doesn't have MFA.

A battery test- with say 5 to 7 AA batteries, forming a line- diagonal to the camera- where none of the batteries are overlapping- forms a better test for testing front-focusing/back focusing. You want DISTINCT targets, and not one continuous target. Shoot, focusing on the center battery. Shoot from a tripod, using either the 2 or 10 second timer, or remote. Shoot in WELL LIT conditions. Shoot with the center point. Shoot wide open initially to tell how much it is front/back focusing.
You can shift your camera left and right to change the diagonal and to help narrow down how much it is off. The problem with shooting a continuous target- is you DON'T know where the camera is focusing on- just where you are putting your dot. They are not necessarily the same spot. That's why you want distinct targets and not continuous ones. Save your pics for when you send the lens into Canon.

It is not uncommon to have to stop down any particular lens to achieve sharpness- especially closer subjects. Use the test to figure out how much you need to stop it down to... I generally find that it is on closer objects that you might need to stop it down on- while objects further away - don't need as much stopping down- if any. It's because the DOF is thinner closer than when the subject is farther away.