Lens calibration for micro 4/3s lenses.

[Phill D]

I was having a discussion about lens calibration with a friend and I told him that I didn't think m4/3s lenses needed calibration as it was done automatically. Having said that I began to doubt what I thought I knew. So having just looked up Tordan's excellent posts on calibration I see he only did 4/3s lenses and no micro ones. Is this because I'm right for once and they don't need it?

[blackfox]

If you check online ,you should find that normally you don’t but the one that does get mentioned a lot is the PL100-400 . I have done mine to the cluster of central focus points set for long/full range To -3 there is a definite improvement on long range shots with this .. you have to be very thorough when doing it i.e first establish it needs doing via test card ,then each individual point has to be set individually unlike canon or Nikon which is a block setting .

I’m not sure whether this has to do with slightly different tolerances between olympus and Panasonic or if it’s to do with the long reach of the lens ,but I’m not alone in finding this and it does work as can be seen in my images .

If you do contemplate this first ensure it’s needed ? then make sure that your set at long length (in a little box At bottom of screen) just do centre point initially then check Again before proceeding with surrounding points . It should take if your thorough around 1 to 2 hours to get right

[Graham_of_Rainham]

The DXO Optics Pro Elite has profiles for all lenses.

But they are minimal corrections based on the lens design. I have never made any “calibrations” of individual lenses.

[Mark_R2]

Are we talking about calibration of auto focus or a lens profile for correction of aberrations, e.g. distortion, chromatic aberration. The former needs to be done yourself if there is a problem with af accuracy. The latter are applied by the camera for jpeg and by external software for raw.

[Phill D]

I was refering specifically to lens af calibration and if it was effective for micro 4/3s lenses.

[blackfox]

It’s called micro adjust ..see my post above .. if it wasn’t needed with certain lenses then it would not be included in your menu .. you can be thankful that 95%+ of olympus lenses dont need it .. but some will always slip through the net ,just as Rolls-Royces never break down (allegedly)
The best anology is your simply fine tuning you equipment... the longer the focal length / reach the more chance for errors to creep in

[c12402]

I’ve done micro4/3 calibration with some lenses just to see if there was possible to get any improvement in the automatic focus.

in some lenses I found some slight improvement, but at the end I left all of them untouched.

My conclusion was that it was not really needed, but the possibility is there anyway.

[Phill D]

Just found this. Not completely definitive but not bad.
https://unlockingolympus.com/2017/12...-zuiko-lenses/
and this one, very detailed for 4/3s, m4/3s comments are a long way down near the end of the first page. That was as far as I got as well!
https://www.mu-43.com/threads/em1-mi...perform.95155/

[Bengeo]

I have had to make the adjustments for using the two converters with my 40-150mm and 300mm lenses. Without the converters the two lenses are fine. I have used the 'all points' option and haven't bothered with the separate points. I had wondered why my 300 + 1.4x wasn't as sharp as my 100-400mm and then I realised from the photos that it was front focusing slightly. Testing confirmed that. I'd bet that a lot of users don't have it set optimally but the results are 'good enough'.

[Phill D]

Andy I have a suspicion that my 40-150 is slightly out with the x2 converter. Bit difficult to tell if it's the combo or me hand holding really as some shots are great and a few are a bit off. I tend to shoot short bursts and pick the best focus position. So might just have to get a calibration set up and give it a test. Haven't tried the 300 enough yet to get a view.

[Wreckdiver]

How do you go about checking lenses?

Thanks,

Steve

[Bengeo]

How do you go about checking lenses?

There are several devices on the market - Lens Align is one.

You can do a rough check by using 3 bottles (with detailed labels) spaced closely in a diagonal line and then focus on the centre one. That should give you an indication if there is any front or back focus. For telephoto lenses do at a reasonable distance - 10 metres plus. Beer bottles work well - try and make sure they have the same labels as that makes them easier to compare.

[IainMacD]

"Beer bottles work well"
Do I empty them first? It might influence the results!

[blackfox]

You can also use AA batteries ,don’t space them to far apart or d.o.f will override things , the only way to do it is to use single shot ,lens wide open , on a sturdy tripod and locked town tightly on target ,turn off I.s to
Or you could use the rear screen with magnify enabled
the best way is a proper sliding scale test kit though ..as I stated earlier it only seems to effect certain lenses or lenses with t.cs attached .. and if you don’t think you have the Know how it’s best left well alone ,my experience comes from 20 + years of playing with various brands of cameras and lenses And I still Get it wrong At times

[Bruce Clarke]

You certainly need to calibrate 4/3 lenses, as the PDAF focus path was via the sub mirrors on DSLRs, and there can be variances in the lens AF mechanism. I calibrated mine on my E-5 and maybe E-3, and on EM1.1 and EM1.2 using this DIY version of expensive bought ones. Probably a bit more accurate than milk bottles I did mine on all points as the centre, as I usually focus / recompose. I think once you've done a lens on an M4/3 body, you can probably copy the results to a new body, as there's no sub-mirror path to calibrate, only the mechanism with the lens. My old 50-200mm Mk I needed a fair bit of correction. I have heard of people calibrating M4/3 lenses, but I haven't felt the need.

https://petapixel.com/2013/03/12/ghettoca-a-diy-lens-calibration-tool-for-micro-adjustment-enabled-dslrs/