Lens calibration

Rgollar · May 28, 2015

Hello I am calibrating a Tamrom 150-600 lens to my Canon 7d Mark II. Does this look like its dialed in close? I cant decide when I zoom in if the lower number 1 is clearer or the 0. To me with out zooming in the lower 1 looks clearer but when I do zoom in the 0 looks clearer. Any helpful eyes would be appreciated. Thanks

_61A1244 by rgollar, on Flickr

dennybeall · May 28, 2015

Not familiar with this process but blowing up the photo it looks to me like the area from the lower 1 to the upper 1 is all sharp but blown up the upper 1 looks to be slightly sharper.

Rgollar · May 29, 2015

I think I need to try this again when there is good lighting I think I did it when it was to dark had to crank up the iso to much

fjrabon · May 29, 2015

If it's properly calibrated the upper 1 **should** look sharper than the lower 1. DoF diminishes faster in front of the subject than behind the subject.

To answer the OP, I'd re-shoot it, on a tripod, with base ISO. It looks right to me, but it's missing sharpness to tell for sure if it's DEAD ON ACCURATE. If you're gonna calibrate, might as well completely nail it.

Rgollar · May 29, 2015

Here is another attempt. I used and ISO of 100 and it was on a tripod with a shutter speed of 1/250 of a second and had mirror lock up with a 2 second delay for the shutter. Does this look better. And the sharpness on this lens to me seems horrible. I tried this on my canon 6d to see if it was just the canon 7d mark II that was just not sharp. But nope same thing just not sharp. I know this lens is capable of sharp images as I have seen it all over this site from other users. Does this picture look soft and does the calibration look acceptable? I have it leaning more towards the upper 1 as suggested by fjrabon.

_61A1249 by rgollar, on Flickr

JacaRanda · May 29, 2015

What angle is the ruler? Zero looks good to me on this one.

Rgollar · May 29, 2015

The ruler is set at I think 45 degrees. The back is straight and the ruler is I think 45 degrees. The rulers sits on some tabs to position it where it needs to be set at.

DarkShadow · May 29, 2015

The second one looks about spot on to me and even if its off a tad,with those aperture values of the lens, you probably will never notice it in field use.

Derrel · May 29, 2015

fjrabon said:
If it's properly calibrated the upper 1 **should** look sharper than the lower 1. DoF diminishes faster in front of the subject than behind the subject.

To answer the OP, I'd re-shoot it, on a tripod, with base ISO. It looks right to me, but it's missing sharpness to tell for sure if it's DEAD ON ACCURATE. If you're gonna calibrate, might as well completely nail it.

I've always felt that as well...there will be a little bit of DOF behind the focus point with "most" lenses....so...

fjrabon · May 29, 2015

Derrel said:
fjrabon said:

If it's properly calibrated the upper 1 **should** look sharper than the lower 1. DoF diminishes faster in front of the subject than behind the subject.

To answer the OP, I'd re-shoot it, on a tripod, with base ISO. It looks right to me, but it's missing sharpness to tell for sure if it's DEAD ON ACCURATE. If you're gonna calibrate, might as well completely nail it.

Click to expand...

I've always felt that as well...there will be a little bit of DOF behind the focus point with "most" lenses....so...

There's physics reasons why, but yeah, it's definitely true. And it's immediately understandable if you think about focusing at infinity. At infinity literally thousands of miles can be in focus behind the actual focus plane in comparison to just a few thousand feet in front.

It's one of the reasons I really adore the Nikon 105 DC, because you can actually adjust this.

fjrabon · May 29, 2015

To the OP, looks in calibration to me, and it looks acceptably sharp. I wouldn't freak out about the sharpness here, as in most real world shooting scenarios it won't be noticeable.

Rgollar · May 29, 2015

I think I am just comparing it to my Canon EF 70-200mm f/2.8 L IS II USM lens picture when I calibrated that lens. When I calibrated that lens the picture when zoomed in was sharp as heck. Thank you all for helping me with this.

TCampbell · May 30, 2015

JacaRanda said:
What angle is the ruler? Zero looks good to me on this one.

The ruler is on a 45º angle. When assembled, the 0 mark is precisely located at the surface of the flat focusing target. The scale measure centimeters, but the scale is stretched in real life so that when viewed from a level position to the target, the 45º angle ruler will technically be accurate.

When using a focus-test chart, I run the focus all the way "in" and shoot at least a half-dozen shots (moving the focus all the way in after each shot.) This forces the camera to re-focus the lens on every frame. I then run the focus all the way "out" and repeat another half-dozen checks. This allows you to be sure that focus is accurate regardless of which direction the lens needed to move to focus a subject.

I agree that from these photos, your lens appears to be focusing accurately and needs no adjustment.

Rgollar · May 30, 2015

Thank you TCampbell for your suggestions. Never thought about doing it multiple times in each direction great suggestion. I had to adjust it 3 points in the camera to get it there thats why I was wondering if I was close. I am going to try it like you suggested and make sure it repeats thanks again.