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Calibrating

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Ray12 Plus
6 150 1 United Kingdom
27 Oct 2017 2:30PM
Hi all.
What i would like to know, is it poss to Calabrate 3rd party Lenses ie Sigma, Tamron to a branded body, ie Sony, Canon, ect.
The reason i am asking is that we have a members practicle evening next Tues at our Camera Club, We have a member who is going to show us how to calabrate Lens and camera.
If this is not possable it is not worth me going, as i have two Sony body's A77, a77mk2 but tamron & sigma lenses..
Many thanks Ray Grin

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Euan65 Plus
1 316 United Kingdom
27 Oct 2017 2:58PM
Calibrate what, exactly?
ChrisV Plus
12 2.3k 26 United Kingdom
27 Oct 2017 3:33PM
sfaik [I assume you're talking about focus calibration?] with most brands it's a manual process of micro adjustment, so it should work with any AF lens your camera works with. It isn't required by mirrorless cameras as there's no separate PDAF sensor which may cause slight misalignment and therefore front or back focus.
Ray12 Plus
6 150 1 United Kingdom
27 Oct 2017 5:03PM
Hi ChrisV.
Thanks for your information Smile.
We have had a E-mail from the guy who is going to do this saying " it is up to each member to sort out our camera settings b4 the said night" would you know what this would entail?
Thanks.
ChrisV Plus
12 2.3k 26 United Kingdom
27 Oct 2017 5:12PM
Sorry Ray, I'm not sure - I use mirrorless cameras mainly. I would have thought it may just be something like making sure your camera is in aperture priority and opening up as large as it will go as that will demand the most precise focusing, but I'm guessing tbh.
Dave_Canon 12 1.5k United Kingdom
27 Oct 2017 5:27PM
There is also creating bespoke lens profiles but that is not trivial or necessary for most people. You can also create a bespoke colour profile for your camera for rendering Raw files but again this is not for the faint hearted. My guess would be that ChrisV is right and it is focus calibration. You could google this and find out a lot more than we could include in a post. I am not sure why you would be reluctant to attend as surely you will learn a lot more about this topic even if you did not actually calibrate your combination on the night.

Dave
ChrisV Plus
12 2.3k 26 United Kingdom
27 Oct 2017 5:28PM
Just had a quick look at a tutorial. I expect they guy at the club is going to be supplying the measure and that there'll be a tripod?

You do need to be shooting with the shallowist DoF your lens is capable of. This process is a lot more critical if you either have ultra fast primes or quite long lenses and particularly on larger sensors. If what you're talking about is fairly slow standard zooms, particularly on crop sensor cameras, you are very unlikely to see much difference.

But your set up needs to be so you'll get the finest level of detail possible. So - set to your camera's base ISO, maximum [smallest number] aperture [longest focal length if a zoom], mirror lock up [you don't want any vibration] and cable, or timed shutter release. You will also need to hunt through your camera's menu system and find either 'micro adjust'/ 'AF fine tune' or whatever your brand calls it.

As I say, unless you are shooting with very limited DoF [any macro, for example], it really isn't going to be all that crtitical.
Ray12 Plus
6 150 1 United Kingdom
27 Oct 2017 6:24PM
As far as I can tell he would like us to take the equipment we would normally use.. camera, lenses and tripod, he is going to supply a type of cardboard pyramid with lines on, not sure how they work.
Thinking bout it now Dave_canon it would be well worth going.
The lenses I have are:- sigma 10-20, sigma 24-70, tamron 18-270, sigma 150-500, and a sigma 105 macro.
Philh04 Plus
13 2.0k United Kingdom
27 Oct 2017 6:50PM
Basically he is supplying a ruler that is normally set up at 45 degrees, which in theory should tell you if your combination is front or back focusing and you can then enter a correction... there is lots of conflicting information out there on the interweb and lots of different methods.

In practice it is quite hard to get right and each camera manufacturer has slightly differing settings (they all do the same thing though)

Also zoom lenses will only be calibrated and matched at one focal length (some of the latest bodies allow for different adjustments at differing FL's).

Tried many ways of doing this and finally invested in Reiken Focal software which works a dream for me.
DerekL 14 204 24 England
27 Oct 2017 10:11PM
Try this useful focus check gauge. I've set up all my lenses using this.
http://www.squit.co.uk/photo/focuschart.html

sausage Plus
14 576 United Kingdom
28 Oct 2017 8:13AM
I use a program called Focal, it tells you what to set the camera to in the fine tune menu, the range is betweem -20 to +20. It takes a series of pictures of a special target then tells you what to set your camera at. On Canon dslrs it does this automatically but on Nikon it's a manual process.
This only works if your dslr has a fine tune menu option. Works with any lens attached to the camera, the camera remembers the settings when the lens is attached. On my Nikon it will remember up to 20 lenses.
LenShepherd 11 3.9k United Kingdom
28 Oct 2017 11:34AM

Quote:Basically he is supplying a ruler that is normally set up at 45 degrees, which in theory should tell you if your combination is front or back focusing and you can then enter a correction..w for different adjustments at differing FL's).


With respect your conclusion is at least 200% misleading Sad
AF detection zones usually extend beyond the size of viewfinder rectangles and AF can often lock on detail quite a bit smaller than the size of an AF retangle.
When focussing on a ruler you have no instant way of knowing if the AF focussed on where you intended on the ruler, further away (likely when starting AF from infinity) or closer than intended (likely if starting from minimum focus) Sad Sad
The first requirement for fine tuning of a subject the AF should focus on accurate is often overlooked Sad Sad Sad
ChrisV Plus
12 2.3k 26 United Kingdom
28 Oct 2017 11:40AM
He didnít say two intersecting rulers, but thatís the way these things work. You focus on the intersection and the angled ruler gives an indication of how far youíre out, front or back.
LenShepherd 11 3.9k United Kingdom
28 Oct 2017 11:46AM

Quote:Try this useful focus check gauge. I've set up all my lenses using this.
http://www.squit.co.uk/photo/focuschart.html


This suggested target can be unsatisfactory - unless you know to focus off centre!
Cross type sensor detect line detail parallel to either the horizontal or vertical side of the frame. Ideally you need to focus off centre to meet this important requirement.
Liveview can usually only focus on detail parallel to the long dimension of the frame (eg Canon) or parallel to the short dimension of the frame (eg Nikon).
A bar code type target with variable spacing between the lines can be more reliable.
The target should be an appropriate size under the AF mark - requiring changing focus distance each time there is a marked change in focal length.
Digressing, my own testing has confirmed for some years none of my lenses need fine tune.
Interestingly with the inbuilt fine tune option on my Nikon D500 and D850 also shows nil fine tune with my lens with a bar code type target parallel to the short dimension of the frame Grin
An average of 8 with is indicatedthe lines parallel to the long dimension of the frame which Nikon Liveview is unlikely to read accurate Sad
A target where AF should work good is usually an essential requirement for an accurate result.
LenShepherd 11 3.9k United Kingdom
28 Oct 2017 1:06PM

Quote:He didnít say two intersecting rulers, but thatís the way these things work. You focus on the intersection and the angled ruler gives an indication of how far youíre out, front or back.

This seems very unclear.
The implication is there are parts of the target which are different distances from the sensor.
As I said earlier AF can focus on quite small areas, sometimes at the edge or even outside a focus rectangle.
Unless the target is exactly parallel to the sensor there is the obvious chance AF might focus where not intended.
When AF focuses where you did not intend this has nothing to do with a fine tune issue.