Luminous Landscape Forum

Equipment & Techniques => Cameras, Lenses and Shooting gear => Topic started by: hjulenissen on January 10, 2012, 05:11:40 pm

Title: Reikan FoCal focus micro-adjustement automation software
Post by: hjulenissen on January 10, 2012, 05:11:40 pm
http://www.reikan.co.uk/focal/

I just purchased this utility - I think that MA is a great concept, but I just hate tedious repetitive tasks. And to trust something like this, I would like to repeat it at different distances, different focal lengths and perhaps for a few different (large) apertures. Life is too short for doing that manually...

Only working for the Canon 5Dmk2 and 7D for now. I purchased the "pro" version.

So far I have only done an initial test of my 17-55 f/2.8 IS USM EF-S at a fixed distance of approximately 3.5 meters and at 17mm, 30mm and 55mm. Seems that you need lots of light and very stable light conditions to get good results.

So far the application have been quite helpful in informing me why a certain operation cannot be carried out (e.g. that the lense is set to manual focus, that the camera must be in single-shot, centre focus point Av mode ect). It has crashed once, and a couple of times I have had to quit or close more windows than seemed necessary in order to do what I set out to.

By choosing "fully automatic" and "Analysis information", you can track the progress as it goes along (see attachements). I found that interesting and a nice early feedback if something was dubious. So I seem to need [-2 +4 -2] at [17mm 30mm 55mm]. 0 Might not be so bad then...

I have repeated this test several times, and the tendency seems to be there every time.

In every case there was a visible improvement from the "before" to the "after" shots (final attachement).

-h
Title: Re: Reikan FoCal focus micro-adjustement automation software
Post by: hjulenissen on January 10, 2012, 05:46:28 pm
I just tested a 100mm f/2.8 Macro USM lense and it seems to be quite erratic. Response is all over the place. I did not try the af range limiter. FoCal properly informed me that the fit was "Not Acceptable" and no correction was loaded into my camera.
Title: Re: Reikan FoCal focus micro-adjustement automation software
Post by: Alan Smallbone on January 11, 2012, 01:49:39 pm
Thanks for posting, have you tried any other lenses?

Alan
Title: Re: Reikan FoCal focus micro-adjustement automation software
Post by: Bart_van_der_Wolf on January 12, 2012, 08:15:34 am
I just tested a 100mm f/2.8 Macro USM lense and it seems to be quite erratic. Response is all over the place. I did not try the af range limiter. FoCal properly informed me that the fit was "Not Acceptable" and no correction was loaded into my camera.

Hi,

I know that my copy of that lens showed quite a bit of hysteresis, so it matterd whether the AF comes from the minimum focus distance direction of from the infinity position direction. Reversing the direction by 1 smallest focus step could throw focus off significantly.

I'm not sure if that plays a role here, as it seems from the description that focus is approached from -20 to +20 AFMA settings, which should move from closer to farther AF positions, but if focus overshoots the optimal position then such a reversal of direction on the next AF could play a role.

Cheers,
Bart
Title: Re: Reikan FoCal focus micro-adjustement automation software
Post by: hjulenissen on January 13, 2012, 03:54:39 pm
Now doing my 85mm f/1.8 and 50mm f/1.8 II.

LenseFocal LengthSuggested MAFit QualityAge/condition
17-55 f/2.8 EF-S IS USM17-2Excellent2y/Excellent
17-55 f/2.8 EF-S IS USM304Good2y/Excellent
17-55 f/2.8 EF-S IS USM55-2Excellent2y/Excellent
100mm f/2.8 EF USM Macro100-1Not Acceptable??/Good
85 f/1.8 EF USM85-12Excellent??/Good
50mm f/1.8 II EF50-12Good5y/Good
70-200 f/4.0L EF IS USM700ExcellentNew/Excellent
70-200 f/4.0L EF IS USM1200ExcellentNew/Excellent
70-200 f/4.0L EF IS USM2001/2GoodNew/Excellent

Did the 85mm and 50mm now with very different results. My batteries are flat, so that might have affected results (should not, but who knows). Will redo those and also my telezoom when battery is charged.

Enclosing screenshots of new calibrations.

The 85mm seems to be very consistent (large aperture, hits same focus every time, seems to have a significant predictable offset -> perfect candidate for MFA).

The 50mm is less consistent, but I am surprised at how consistent it was (a lot more bell-shaped than the considerably more expensive, although more specialized 100mm macro). When using this lense tethered, I have been shocked by how large the minimum step of the AF motor was, thinking that indicated coarse AF performance.


I was hoping to repeat the same test at large distances. FoCal supposedly can do this thing against any target that is flat and contains sufficient high-frequency contrast. 3.5 meter and 50 meter measurements should do for general purpose photography, right? If results are similar@3.5m and 50m, then I suppose that they are global. If they are very different, then I'll either ignore them, average them, or do more detailed testing.

I am very confident that I would never do this much testing if I had to do it manually (30-50 shots at 1/3 focal lengths for primes/zoom lenses, hopefully 2 distances, repeated at least 2 times), and judging from the progress of the analysis, errors/noise are sufficiently large that I could have ended up doing things worse had I settled for smaller sample sets.

-h
Title: Re: Reikan FoCal focus micro-adjustement automation software
Post by: futura on January 14, 2012, 05:06:00 am
Thanks for the post hjulenissen, I am interested in purchasing a license and its good to find a good writeup. I do have one question though, how accurate have the micro adjustments been in post real-world shooting?
Title: Re: Reikan FoCal focus micro-adjustement automation software
Post by: hjulenissen on January 14, 2012, 03:05:37 pm
...I do have one question though, how accurate have the micro adjustments been in post real-world shooting?
A good question. How can one be certain?

I am doing some rounds with testing, and will double-check against liveview for stationary targets afterwards.

Edit:
Updated the table with 70-200 results.

Edit:
This application is fiddly. I have restarted my camera and unplugged the USB cable quite a few times, seen a hand-full of application crashes, and often see that the application unable to connect to the camera (or able to connect ut not to run liveview/AF) for no apparent reason, only to work again after some time and possibly a restart. Be warned.

-h
Title: Re: Reikan FoCal focus micro-adjustement automation software
Post by: hjulenissen on January 14, 2012, 05:17:07 pm
Redoing the 85mm f/1.8 test, I get consistent results.

Have also been using the "semi automated" test on this lense, and observed some peculiar effects. Seems like some "hysteresis" or mechanical hang-up that cause a complex relationship between MFA, sharpness and history.

-h
Title: Re: Reikan FoCal focus micro-adjustement automation software
Post by: MarkL on January 15, 2012, 07:53:45 am
Interesting. SLR manufactures should really could implement this into camera, all it would have to do is compare a live view focused image with a normal af image.
Title: Re: Reikan FoCal focus micro-adjustement automation software
Post by: hjulenissen on January 15, 2012, 04:14:35 pm
Yes, I think that this feature could easily be built into live-view equpped DSLRs. Even more useful now that the 1DX is reported to have separate MFA for the wide and narrow end of zooms. The next will be close focused and infinity?

Anyone know what is causing this error? Ideally, a PDAF sensor should return a "peak" when in focus, what would cause it to consistently miss? A miss-alignement of the contrast sensors vs the alignement of the image sensor? Is there reason to believe that the different AF sensors could have different biases?

-h
Title: Re: Reikan FoCal focus micro-adjustement automation software
Post by: futura on January 18, 2012, 12:22:55 pm
A good question. How can one be certain?

A good question. How can one be certain?

I think one the reasons I want to test ma is because I've identified which of my lenses are poor performing and would like to know if a ma update with fix the issue. So I guess the best way to see if FoCal is doing a good job is to pick a lens that you know is not focussing correctly (taking technique and other variables out of the equation).

One thing that held me back from picking up a copy is the recent disclaimer about mirror lockup not working when used with the 1dsmk3 (something about the SDK used by FoCal not working too well with older cameras). In your opinion is this as much of a deal breaker as I think it is?

Thanks!
Title: Re: Reikan FoCal focus micro-adjustement automation software
Post by: hjulenissen on January 18, 2012, 01:34:07 pm
One thing that held me back from picking up a copy is the recent disclaimer about mirror lockup not working when used with the 1dsmk3 (something about the SDK used by FoCal not working too well with older cameras). In your opinion is this as much of a deal breaker as I think it is?
I don't know anything about the support for 1dsmk3.

I do believe that the "fully automatic" mode was important for me. Given the "noisy" estimates and the time-consuming process, I need to base my conclusions on a bell-shaped curve that I can believe in, otherwise I might succumb to making erroneous conclusions based on what seemed like patterns but was really only coincidence.

-h
Title: Re: Reikan FoCal focus micro-adjustement automation software
Post by: Alan Smallbone on March 01, 2012, 12:47:23 pm
Hi all,

I have been running the software now and I have done most of my autofocus lenses, I still have the 500mm f4L to do as well as the 100-400mm at 400mm when I get some time to setup for a long distance. I used approx 50x the focal length for all the testing and this was done using the Pro version of the software. One thing that is critical to getting good calibration, or at least for me, is to have a well lit target. I ended up setting up with led video lights to illuminate the target, this helped a lot, and also it really needs a place that is out of the wind, etc. running was pretty straightforward and I am overall happy with the results. Here are some of the numbers I got, all lenses are Canon EF lenses unless noted, the quality is the quality of the curve fit.

                                                      1DMarkIV                              5DMarkII
Lens                                                 AFMA    quality                AFMA    quality
50mm f1.4                                         6              ex                    5               ex
100mm f2.8L macro                            2               ex                   2                ex
180mm f3.5L macro                            3               ex                   1               ex
85mm f1.8                                         -8               acc                13               gd
100-400mmf4.5-5.6L @100mm            0               ex                   0               gd
70-200mmf4L  @70mm                       5               ex                  -4               ex
70-200mm f4L @200mm                     4               ex                  -5               ex
17-40mm f4L  @17mm                       -4               ex                 -7               gd
17-40mm f4L @28mm                        -4               ex                 -7               gd
17-40mm f4L @35mm                         0               gd                 -1               gd
17-40mm f4L @40mm                        -3               ex                  3               gd
24-105mm f4L @24mm                      -7               gd                  6               ex
24-105mm f4L @105mm                     3               gd                   5               ex
Tokina 16-28mm f2.8 @16mm             3               ex                   1               ex
Tokina 16-28mm f2.8 @28mm            11              ex                   7               ex
300mm f2.8 L IS                                3               ex                    7               ex
35mm f2                                          -4                pr                    0               pr
50mm f1.8 II                                      7               gd                   11               ex

At least I am getting repeatable results, I have a lensalign that I never got real repeatable results with so I never trusted it, but overall I am very happy with this software solution. I am sure that my problems with the LensAlign was strictly operator error but I was never happy with my results from it.

I am also surprised that how much the MA was off on some of the lenses and it kind of makes sense from what I have seen in the past. It was not surprising that I got poor results with my Canon EF35mm f2, that is a very cheap lens with a similar build to the EF50mm f1.8. My EF 50mm f1.8 was the one that I dropped and exploded into little pieces and Canon rebuilt it and I have hardly used it since but it is essentially a new lens and it worked quite well.

Be happy to answer any questions and I do recommend this software if you want to calibrate your lens and autofocus.

Alan
Title: Re: Reikan FoCal focus micro-adjustement automation software
Post by: hjulenissen on March 02, 2012, 06:17:59 am
It seems that the 5Dmk3 will have separate MA for near and close focus (as well as small and large focal lengths?).

That could make utilities like FoCal a lot more useful.

-h
Title: Re: Reikan FoCal focus micro-adjustement automation software
Post by: albedo13 on April 30, 2012, 12:37:52 pm
I have been running the software now and I have done most of my autofocus lenses, I still have the 500mm f4L to do as well as the 100-400mm at 400mm when I get some time to setup for a long distance.

Hi Alan-

Did you ever get results for your 500mm and 100-400mm?  I have both these lenses and have been thinking about getting this software, and would be curious to hear how it worked on these, and what results you found.  Thanks!

Jim
Title: Re: Reikan FoCal focus micro-adjustement automation software
Post by: Alan Smallbone on April 30, 2012, 10:10:51 pm
Hi Alan-

Did you ever get results for your 500mm and 100-400mm?  I have both these lenses and have been thinking about getting this software, and would be curious to hear how it worked on these, and what results you found.  Thanks!

Jim

Jim,

I finished the 100-400mm and at 400mm it was very close to what it was at 100mm, since the camera can only have one MA value, I left it as it had been previous set. I think it was within 2 steps. I have not done the 500mm yet, mostly because of the length needed and every time I get around to setting up outside to do it, it is windy and the target will move slightly. I need to find a better place or try to do it indoors in a building. I have been very pleased with the software. For me it was a lot easier and more repeatable than the Lensalign and similar products. He has made some improvements to the software since I last posted about it, the features are quite nice. Overall I think it has improved my focus accuracy enough to justify the cost quite easily. Also it is pretty easy to setup and run a bunch of lenses in a afternoon, as long as the target is well lit. I end up using some led lights for video to illuminate the target and they work well to give enough light for good accuracy. Remember to use the larger target for the longer focal length lenses. I ended up printing the targets on some Epson cold press paper and mounting the targets to some black gatorboard, works well.

Alan

edit: typos
Title: Aperture sharpness test
Post by: hjulenissen on July 07, 2012, 07:31:07 am
I have just tested the new "aperture sharpness test" found in recent versions of the Reikan software (1.4.4 Pro). A nice extra to have some crude, quantitative idea about lense performance vs aperture. Using an aluminium stand, target at 5.5 meters, Canon 85mm f/1.8 and Canon 7D.

Too bad that the y-axis "Quality of focus" is not described anywhere. If could be a linear or non-linear function of any "sharpness" criterion. But I think it is safe to hope that it is monotonically increasing for "better focus". Not sure why the curve seems to flatten between f/3.2 and f/10. The exposure time creeps from 1s (f/22) to 1/8 s (f/6.3), might be that minor focus misalignement along with camera shake make for an upper limit to achieved sharpenss?



Title: AF consistency test
Post by: hjulenissen on July 07, 2012, 07:44:01 am
Another new test option is the "consistency test". You choose how to defocus the lense in-between trials (Maximum defocus - far, Maxiumum defocus - near and some other options, a range of AFMA values to sweep across). I found this reassuring to find if there is a offset difference when the focus motor goes one way vs the other.

Title: Estimating AFMA at f/1.8, f/2.2 and f/5.6
Post by: hjulenissen on July 07, 2012, 08:14:46 am
Yet another option is to run the test at an aperture different from the max aperture of the lense. I assume that this option still use max aperture (f/1.8 in my case) when doing actual PDAF, but that the image is taken at another aperture (for sharpness analysis). I believe that many lenses tend to change the focus slightly when changing aperture, and that Canon are not able to compensate for this in their AF. This undesired behaviour should be more pronounced at moderate to large aperture (where DOF is still small) - when DOF gets large, minor focus errors should tend to be irrelevant (as long as they are absolute distance errors, and do not scale with DOF). If there is a consistent bias, and you are mostly using your f/1.8 lense at f/5.6, you might want to do the test most suitable for your real-life needs.

Summary:
aperture | suggested AFMA
f/1.8:    |  0
f/2.2:    |  2
f/3.2:    | -3
f/5.6:    | -8
f/7.1:    | -6

I have to admit that I am confused by the results. Seems that for every new dimension I add to the testing matrix, a new and totally different MA value appears to be "best". If Canon wants to deliver "pixel-peeping" sharp AF at large apertures in the real world, it would seem that they would either:
1. Compensate for various errors in-camera/lense
2. Offer the customer a larger set of correction values

Option 3 is, of course, to ship the camera + lenses to Canon for adjustement (hoping that it is returned in a better state than when it was shipped). Since my camera is >1 year, the cost of doing that for my 4 lenses is about 50% of the value of the camera itself. It might be more economical to live with what it does today, and swap the camera for a new one (free adjustement of camera + lenses)....

-h
Title: Re: Reikan FoCal focus micro-adjustement automation software
Post by: Ellis Vener on July 07, 2012, 10:09:00 am
It seems that the 5Dmk3 will have separate MA for near and close focus (as well as small and large focal lengths?).

That could make utilities like FoCal a lot more useful.

-h

The Canon 5D mark III and 1D X bodies share the same AF systems (phase based in reflex mode and contrast based in Live view mode) . I've sent the Niko D4 and D800 bodies  I was loaned for reviews back to Nikon but I'm pretty sure they also share AF systems as well. In both cases the RGB inputs in the metering circuits interact with the auto-focus systems. That may (or may not) effect the ability to use the contrast based AF to "tune" the phase based AF system.
Title: Re: Estimating AFMA at f/1.8, f/2.2 and f/5.6
Post by: Bart_van_der_Wolf on July 07, 2012, 10:19:21 am
I believe that many lenses tend to change the focus slightly when changing aperture, and that Canon are not able to compensate for this in their AF.

Hi,

Most modern lenses do not suffer from this enough to be noticeable, if at all. The fact that the Reikan software suggests so, may have something to do with the software rather than the lens, although it doesn't rule out the lens.

I'm also a bit surprised that the module for finding the best aperture apparently in this case isn't accurate enough to detect the peak, but instead a rather broad range. The example (3rd attachment (http://www.luminous-landscape.com/forum/index.php?topic=68089.msg539018#msg539018)) from my software tool shows that it is possible to be quite exact (in my chart lower blur is better resolution).

Cheers,
Bart
Title: Re: Reikan FoCal focus micro-adjustement automation software
Post by: Wayne Fox on July 07, 2012, 03:50:02 pm
Even more useful now that the 1DX is reported to have separate MFA for the wide and narrow end of zooms.
This is confirmed, this feature is also in the 5D Mark III.

I hope to test how well it works and how it tracks through various focal lengths.
Title: Re: Aperture sharpness test
Post by: Wayne Fox on July 07, 2012, 04:01:56 pm
Not sure why the curve seems to flatten between f/3.2 and f/10. The exposure time creeps from 1s (f/22) to 1/8 s (f/6.3), might be that minor focus misalignement along with camera shake make for an upper limit to achieved sharpenss?

I've done this test using enough light to not need that slow of shutter speeds and seen the same results with every lens.  I've also clicked on the resulting points to see the various images, and to me the image quality is pretty consistent for many lenses once you stop down enough to get it sharp all the way to f/10 or so.  I guess the point would be diffraction, while perhaps having some slight impact, doesn't really seriously degrade image quality until you reach certain point, after which the sharpness falls off dramatically. So far it appears most lenses on the d800e are very similar from about f/4 to about f/8 and show only slightly more softness even at f/10.  At f/11 things are visually degraded and by f/22 every lens I've tested so far is complete mush ... very unusable.  f/16 would only be useful for scenes where no micro detail has any value. 
Title: Re: Reikan FoCal focus micro-adjustement automation software
Post by: Rand47 on July 09, 2012, 09:18:29 am
Have any of you seen real world improvement in your images?  This is an honest question.  I purchased a lens align device. The more I read about how to use it and the more I read the Q&A on their web forum, the more I began to think that the variables are too numerous for me to think I was going to achieve a practical improvement in AF performance for my lenses that did not have an obvious and "visible in prints" AF problem. The variables were too numerous to allow a single MFA to provide an optimal outcome for all focus distances and apertures (not to mention focal length ranges for zooms,).   For obviously troubled lens/body combos it could certainly improve matters, but other than that it wasn't of value.

I ended up seeing the device as merely a diagnostic tool for identifying the degree and "direction" of visibly mis-focusing body/lens combinations.  I returned the device.  I can do that kind of diagnosis as easily with printed targets taped to the wall & carefully tripod mounted camera & tape measure.

So, I'm honestly interested to know if this new software based system actually produces real world improvements at working apertures with lenses whose performance was not "obviously troubled" prior to testing and adjustment with the software?
Title: Re: Reikan FoCal focus micro-adjustement automation software
Post by: stever on July 09, 2012, 09:51:46 am
the answer, Rand is yes and no.  i just spent yesterday afternoon using LensAlign to microadjust my lenses for new 5D3 (i've used it for the 5D2 and 7D as well).  the Wide/Narrow adjustments intrigued me, but of the 24-105, 70-200 f4 IS, and 100-400, only the 24-105 required the most adjustment (from 40 to 90 as i don't have a long ruler for wider and try not to use the lens at 105) to be noticeable wide open -- -3 at 40, 0 at 90. the 70-200 was +2 at 85 and +3 at 190.  the 100-400 was -2 at 100 and 0 at 400.  these are all adjustments that would noticeable wide open on close inspection and i think useful to me as these lenses often get shot wide open.  since i'm generally unhappy with the 24-105 wide open i'm looking for any help i can get.

in the past i've used LensAlign to identify problems and check results from Canon repair (generally satisfactory).  One exception being my 50 1.4 which has pretty well known focus shift issues and has been to Canon a couple time with minor improvement in performance at f2.8 (it's always been great above f4 and terrible wide open).  it requires -9 at f1.8, -12 at f2.8, and -16 at f4 presenting a dilema.  i'll do some resolution tesing with Imatest soon out of curiosity and for guidance (don't expect another trip to Canon to help and don't think it's worth testing more lenses as i believe this focus shift is a design issue).

i think that Canon could correct for aperture focus shift in the future if they are willing to do it.
Title: Re: Reikan FoCal focus micro-adjustement automation software
Post by: Scott O. on August 17, 2012, 12:16:32 am
Hi, my name is Scott and I have been a micro-adjustor for several years.   ;D ;D ;D

Actually, there are so many variables that a guess is the best you will do...the variables are:
- focal length of zoom lens
- aperture used
- distance from target
- maybe amount of light on target or paper it is printed on

All this effort for something that may or may not be significant in the final quality of the image...gads I am anal!
Title: Re: Reikan FoCal focus micro-adjustement automation software
Post by: Ellis Vener on August 17, 2012, 04:25:56 pm
Have any of you seen real world improvement in your images?  This is an honest question.  I purchased a lens align device. The more I read about how to use it and the more I read the Q&A on their web forum, the more I began to think that the variables are too numerous for me to think I was going to achieve a practical improvement in AF performance for my lenses that did not have an obvious and "visible in prints" AF problem. The variables were too numerous to allow a single MFA to provide an optimal outcome for all focus distances and apertures (not to mention focal length ranges for zooms,).   For obviously troubled lens/body combos it could certainly improve matters, but other than that it wasn't of value.

I ended up seeing the device as merely a diagnostic tool for identifying the degree and "direction" of visibly mis-focusing body/lens combinations.  I returned the device.  I can do that kind of diagnosis as easily with printed targets taped to the wall & carefully tripod mounted camera & tape measure.

So, I'm honestly interested to know if this new software based system actually produces real world improvements at working apertures with lenses whose performance was not "obviously troubled" prior to testing and adjustment with the software?

Yes I have used the LensAlign, both the Pro and now the Mk II model. I do see a real noticeable difference between an untuned body/lens combination and a tuned one. I have seen this with various Canon and Nikon bodies and lenses.

Your point about the number of real world variables is a sound one however getting a baseline for "best" AF  performance  beats not having a measured baseline at all.  This will hold true whether you use the LensAlign or the Reikan FoCal or any other system to check AF performance.

In situations where your subjects are not moving and neither is your camera (because it is mounted on a tripod or camera stand) focusing using Live View either manually with an external magnifier like the Hoodman Loupe and also increasing the live view magnification or using the contrast detection of AF (as opposed to the phase detection based AF system used when you are shooting and viewing through the viewfinder) will yield best results.


Focus is focus and sharpening is sharpening and it is a wonderful thing when they meet.
Title: Re: Reikan FoCal focus micro-adjustement automation software
Post by: Scott O. on August 17, 2012, 10:43:43 pm
Software version 1.6 was released today...according to FoCal the algorithm has been changed to give more repeatable and accurate results, among other things.
Title: Re: Reikan FoCal focus micro-adjustement automation software
Post by: Rhossydd on November 09, 2012, 06:07:27 am
Following on from the release and discussion of Michael Tapes new MFA tool here on Lula (http://www.luminous-landscape.com/forum/index.php?topic=71660.0), plus having recently had a few less than optimally focused shots myself, I decided to have a fresh look at FoCal and see if things have progressed since this thread was started.

The first observation is that FoCal is now a very well documented, easy to use and reliable program. It also works well on hardware below their recommendations, so I've been able to work outdoors with a little 1.4ghz netbook to calibrate longer lenses without being tied to a desktop system.
The target validation routines seem to work well and are simple to use which should ensure good reliable results.

FoCal Pro automatically shoots and evaluates dozens of shots without any intervention. I would expect the greater number of samples should lead to more accurate results.
The analysis information being presented in real time as testing progresses instils a good degree of confidence in the procedures used. The reports generated and saved at the end of analysis add to that confidence by including the sample images for user review.

As the process is so simple once the target has been set up, it's easy to carry out extensive testing of how MFA changes with f stop and how consistent the AF system is. Trying to do this sort of testing manually would take a very long time and might be prone to errors unless it was carried out with meticulous attention to detail recording results.

As previously noted in this thread, one curiosity of the whole MFA testing procedure is that it reveals the differences in AF performance on lenses depending on the selected f stop and shooting distance and, in the case of zoom lenses, focal length too. This is information that people may be unaware of if they just do very basic testing with only a few variables.
Once you do have a full picture of how AF performance is varying with different settings it's possible to consider the optimum value for one's own shooting style and preferences. For some this might be easy, e.g. always using a 85mm f1.2 wide open for portraits at 15ft. For others it might need more consideration e.g. when FoCal shows a wide ranges of values for a zoom that will be used at many different settings.
I'm tending towards using the setting recommended for the most critical conditions, wide open at the longer focal length, so far that's working well for me.

My own initial testing is suggesting that previous chart based manual evaluations had given poorer results than I realised, or that values have shifted over the last two years, possibly a bit of both. It will be interesting to see if these values actually change over time or with different environmental conditions.

The next question is "Does AFMA make a difference in real world shooting ?"
There's no easy answer to that. Although unlikely, you may have a set of lenses that are so close to perfect AFMA isn't necessary or your technique may be so poor that you wouldn't see any difference anyway.
More probable, is that one or more of your lenses will benefit from applying an AFMA correction that will deliver sharper results. Anyone doubting this can try the simple test of doing some shots with large changes in AFMA settings and studying the results. It does make a difference.
With the back garden tests I've done so far, I can see significant improvements after getting the correct AFMA and now AF performs better than I can achieve manually through the OVF.
I've also done some compassions using different ISO values. FoCal recommend using the base ISO for best performance, but I doubt there's much difference in the resolution of JPGs out of my 5Dii up to 400iso. So in the UK winter gloom with long lenses I can see improvements in consistency of results by using a higher ISO to use faster shutter speeds.

Given that getting AFMA correct is worthwhile, FoCal is a worthwhile investment as it seems to deliver the results you need to make an informed decision about settings without needing the large amounts of effort needed to check settings manually.

Paul


Title: Re: Reikan FoCal focus micro-adjustement automation software
Post by: hjulenissen on November 09, 2012, 06:36:23 am
Thanks for your update. Did you experiment with the different "reset" methods? ("move the focus to infinity between measurements" vs "move the focus to 0 between measurements")

-h
Title: Re: Reikan FoCal focus micro-adjustement automation software
Post by: Bart_van_der_Wolf on November 09, 2012, 06:55:59 am
Thanks for your update. Did you experiment with the different "reset" methods? ("move the focus to infinity between measurements" vs "move the focus to 0 between measurements")

Hi,

That is indeed, in my experience with tethered manual focusing, the main variable. Phase controlled AF cannot really be user adjusted for that, other than averaging the hysteresis bias that will exist. As Michael Tapes suggests with his more manually driven software solution, be consistent when calibrating and always defocus in the same direction between shots. I'm not sure what the automated Reikan software does.

Cheers,
Bart
Title: Re: Reikan FoCal focus micro-adjustement automation software
Post by: hjulenissen on November 09, 2012, 07:43:44 am
...be consistent when calibrating and always defocus in the same direction between shots. I'm not sure what the automated Reikan software does.
There is a user setting, somewhat well-hidden with 4-5 choices. "reset towards infinity" and "reset to 0" are two. I dont remember the default.

I wonder if AFMA settings could be accessed by magic lantern software? If so, For those willing to spend time and money to get a large number of camera/lense focus error data might wish for more extensive correction (i.e. a function of focus distance, focus movement direction, focal length, aperture, etc).

http://www.magiclantern.fm/
-h
Title: Re: Reikan FoCal focus micro-adjustement automation software
Post by: Rhossydd on November 09, 2012, 08:09:37 am
Did you experiment with the different "reset" methods?
Not yet. It would be interesting to see if AFMA changed with which direction you approach focus from, but I'm not sure knowing the result would actually be much help in real world shooting.
Title: Re: Reikan FoCal focus micro-adjustement automation software
Post by: Bart_van_der_Wolf on November 09, 2012, 11:19:56 am
Not yet. It would be interesting to see if AFMA changed with which direction you approach focus from, but I'm not sure knowing the result would actually be much help in real world shooting.

If approaching from one direction repeatedly gives an adjustment of +5, and approaching from the other direction +7, then on average a +6 setting will give the overall lowest front/back focus bias.

Cheers,
Bart
Title: Re: Reikan FoCal focus micro-adjustement automation software
Post by: Rhossydd on November 09, 2012, 11:42:39 am
If approaching from one direction ......
... average a +6 setting will give the overall lowest front/back focus bias.
Sure, I understand that, but once you start looking at the full range of possibilities direction to focus is one of the variables we're least able to control in normal AF shooting.
Title: Re: Reikan FoCal focus micro-adjustement automation software
Post by: hjulenissen on January 16, 2013, 09:46:19 am
They are now publishing (anonymous) info about focus/sharpness from their users. I think this adds valuable information about real-world mean/variance performance of a particular lense/cam combo in addition to what lense reviews/measurements of a single lense, manually focused optimally can tell us:
http://www.reikan.co.uk/focalweb/index.php/online-tools/lenscamera-information/
(http://www.reikan.co.uk/focalweb/focaldb1/Canon%20EOS%205D%20Mark%20III~EF70-200mm%20f_4L%20IS%20USM.png)

Sadly, the y-axis is not a well-defined function of e.g. mtf50, but it seems safe to assume that it is a more or less monotonous function of sharpness/focus.

Unsurprisingly, 50mm f/1.8 II tends to degrade its performance more than the 70-200 f/4 IS as aperture is moved towards their respective maximums:
(http://www.reikan.co.uk/focalweb/focaldb1/Canon%20EOS%205D%20Mark%20III~EF50mm%20f_1.8%20II.png)