FoCal 2.0 Pro -- lens calibration...anyone used it?

[IzzieK]

I do not know if I am in the right forum here but I "accidentally" came to a website (unfortunately a U.K. one) about lens calibration and the guy in the video uses FoCal. I don't know what version or which he uses because there are three of them. Anyway, I finally found the Pro version at B&H after researching if that is what I need...So in this time when lens calibration terminology is nearly sinking in to my brain, I would like to take advantage of a software than can do it.

My question is -- has anyone used this lens calibration or you have a better way to teach me some more terminologies and technique so the information doesn't go way above my head like before...???
thanks for any response....

[Shadowman]

I haven't used it but I think in order for it to be immediately effective you need to be able to make micro adjustment to your camera's focusing system. I believe your camera has the functionality, but for others if they notice a focusing issue they'd have to send their camera in for adjustment.

Upon further reading, supposedly the software makes adjustments to your camera.

http://s449182328.websitehome.co.uk/...%20Use_1.0.pdf

[Manfred M]

I would suggest that this might be of use to a super-techie that wants their lens super calibrated (even if you won't notice anything in real life shooting). It seems to me that this is something to leave to the "experts" as you could just as easily screw up the calibration and end up having to send your gear in for repair.

I've looked at this in the past, but the cynical side of me suggests that this is a solution in search of a problem 95% of the time. The other 5% might be real. On the other hand, I'd rather be shooting than messing around with micro adjustments that likely won't effect my shooting. I haven't noticed any back focus or front focus issues with any of my lenses.

[IzzieK]

Thanks for the responses...I do appreciate them very much.

[James G]

Hi Izzie, I love techie measurement/calibration/optimisation thingies.... but in the context of lens calibration I agree totally with Manfred and John.

I push my macro lens to the extreme continuously, trying to capture very small insects. At one point I considered checking my lens performance to check if it was slightly 'off'.

The point though was that even if it was slightly off, most of the capture problems are down to me. i.e. I'm not superman! (despite what Janet tells me ), and all the slightly blurry or front as opposed rear focus faults are directly attributable to either me and my shaky hands, or the wind, or the little crittur moving at the critical moment.

Better management of the above will be much more important for improved images than complicated minor adjustments to the lens.

Now ... if you were considering setting up a microscopy rig in a laboratory...... but you wouldn't use Fo-Cal.

Actually I found for my particular problem, calming my breathing and breathing steadily while clicking was much more effective!

[PhotomanJohn]

I have used FoCal on and off for several years. The earlier versions had issues especially on Apple computers and would hang up forcing one to start the process over. I used the latest version on my D750 when it came back from the shutter replacement recall and was very impressed with the improvements over previous versions. If worked flawlessly and provides more information than before. The program is useful if one wants to really understand the differences in focus accuracy with changes in distance, aperture and zoom setting. It performs multiple measurements to determine variation and plots the performance. This level of detail would be very time consuming to do with manual methods.

Now, as for whether one needs to perform micro-focus adjustments can be debated and is more important with cameras with higher resolution sensors than it was before if one is a pixel peeper. As has been said above, it is generally not a necessity. In the past, I have found that most of my lens and camera combinations required little, if any, focus adjustment. That was the case with my D750 until I got it back from Nikon Service for the shutter recall. The work order paper work said they readjusted the auto focus and they certainly did. Now the required adjustment for all my lenses has shifted at least -15 micro-focus points putting one of my lenses off scale and others right at the limit. So I would say that focus calibration is important in situations like this one.

So my recommendation is to check the focus accuracy of you camera and lenses using a ruler with a line marked on it for a focus point. If the focus is close than forget about going farther. If not, go ahead and make adjustments based on your tests with the ruler and let it go at that. FoCal works very well but is really not necessary.

[NorthernFocus]

Hey, Izzie. I haven't used FoCal but have used Focus Tune. The main difference is that FoCal actually makes the adjustments to the camera during the tuning process. Focus Tune produces graphical output and you do the adjustment manually. I would NOT use Focus Tune again. Mainly because of the manual nature of it. It takes to long to do it. And unless you are shooting in a studio environment with controlled lighting, even tiny ambient lighting changes during the test effect the results. I still use it but analyze the data manually.

I used to have an opinion similar to Manfred regarding focus accuracy. But having had a problem with one long lens and having now done some tuning and seen the results I've changed my mind. A lot depends on what/how you shoot. Focus tuning is more applicable when shooting long lenses at wide apertures (i.e. narrow DOF). Shooting short lenses at narrow apertures you're not likely to notice the difference. I now tune all of my bodies to my long lenses for wildlife shooting. I don't worry about precise tuning. Just make sure my DOF is more or less centered.

Without spending any money you can do some easy testing by shooting a brick wall at an angle and checking to see if DOF is more or less centered on your focal point. Or as was already mentioned if you don't have a brick wall handy you can lay a yardstick down at an angle and shoot with focus point on the center of the scale.

[IzzieK]

Thank you for the positive input, John...I appreciate this thought very much. I have already bought the product from B&H before I asked. It should have been the other way around...I was just hoping I haven't wasted my money. Too late for that now...

I have used FoCal on and off for several years. The earlier versions had issues especially on Apple computers and would hang up forcing one to start the process over. I used the latest version on my D750 when it came back from the shutter replacement recall and was very impressed with the improvements over previous versions. If worked flawlessly and provides more information than before. The program is useful if one wants to really understand the differences in focus accuracy with changes in distance, aperture and zoom setting. It performs multiple measurements to determine variation and plots the performance. This level of detail would be very time consuming to do with manual methods.

Now, as for whether one needs to perform micro-focus adjustments can be debated and is more important with cameras with higher resolution sensors than it was before if one is a pixel peeper. As has been said above, it is generally not a necessity. In the past, I have found that most of my lens and camera combinations required little, if any, focus adjustment. That was the case with my D750 until I got it back from Nikon Service for the shutter recall. The work order paper work said they readjusted the auto focus and they certainly did. Now the required adjustment for all my lenses has shifted at least -15 micro-focus points putting one of my lenses off scale and others right at the limit. So I would say that focus calibration is important in situations like this one.

So my recommendation is to check the focus accuracy of you camera and lenses using a ruler with a line marked on it for a focus point. If the focus is close than forget about going farther. If not, go ahead and make adjustments based on your tests with the ruler and let it go at that. FoCal works very well but is really not necessary.

[IzzieK]

Thank you, Dan...your input is the way I thought when I bought the product -- for my long lens. And from what I gather, that made my decision to buy the software, it say it can now automatically calibrate lenses longer than 400mm compared to the the last version. I have calibrated my 70-300mm with just a word document target on the wall of my den and I was quite impressed with it lately. It wasn't micro-adjusted as I have to fully understand the video instructions I watched but it mentioned FoCal so I ended up looking for it. I also looked at Lens Align and other products and had settled on FoCal so I bought the product.

Thank you again for your input. I always get something positive from your opinion EVERY TIME!

Hey, Izzie. I haven't used FoCal but have used Focus Tune. The main difference is that FoCal actually makes the adjustments to the camera during the tuning process. Focus Tune produces graphical output and you do the adjustment manually. I would NOT use Focus Tune again. Mainly because of the manual nature of it. It takes to long to do it. And unless you are shooting in a studio environment with controlled lighting, even tiny ambient lighting changes during the test effect the results. I still use it but analyze the data manually.

I used to have an opinion similar to Manfred regarding focus accuracy. But having had a problem with one long lens and having now done some tuning and seen the results I've changed my mind. A lot depends on what/how you shoot. Focus tuning is more applicable when shooting long lenses at wide apertures (i.e. narrow DOF). Shooting short lenses at narrow apertures you're not likely to notice the difference. I now tune all of my bodies to my long lenses for wildlife shooting. I don't worry about precise tuning. Just make sure my DOF is more or less centered.

Without spending any money you can do some easy testing by shooting a brick wall at an angle and checking to see if DOF is more or less centered on your focal point. Or as was already mentioned if you don't have a brick wall handy you can lay a yardstick down at an angle and shoot with focus point on the center of the scale.

[george013]

From what I learned is that one shouldn't use lens calibration unless you think you need it. So don't calibrate just for calibration.

Correct me when I'm wrong, but I think the basic idea of calibration is to gain the same result using auto focus in phase detection as what you got in live view. If there is a visible difference one corrects the behaviour of the auto focus. All the tools are in your camera. And if not you can't correct it..

Further I think a calibration only counts for the conditions under which the lens was calibrated. The variables are the focal length in case of a zoom lens and the distance.

George

[NorthernFocus]

From what I learned is that one shouldn't use lens calibration unless you think you need it. So don't calibrate just for calibration...

The literal meaning of calibration implies that adjustments are made. In that context, I agree completely with your statement. However, if one is doing critical shooting it is wise to do a calibration check/test prior to doing so. If testing shows that the lens/camera combination focal point is near center of DOF, then it is not wise to make adjustments purely for purposes of seeking perfection.

Correct me when I'm wrong, but I think the basic idea of calibration is to gain the same result using auto focus in phase detection as what you got in live view. If there is a visible difference one corrects the behaviour of the auto focus.

This is not correct. I think perhaps you are confusing some methods of manual calibration which use the live view function in order to do the calibration itself. The purpose of calibration is to ensure that the focus correction signal generated by the camera achieves the intended resulting lens movement (i.e.focus).

All the tools are in your camera. And if not you can't correct it..

Of course.

Further I think a calibration only counts for the conditions under which the lens was calibrated. The variables are the focal length in case of a zoom lens and the distance.

This is theoretically true. However point calibration is a method that is universally applied to both analog and digital instruments of all types the world over. In many cases very precise instruments in very critical applications. Best practice is to calibrate as near to service conditions as possible. This is typically achieved by calibrating the two end points of a service range and/or at/near a mid-point. So in the case of photography, for example if one's normal target distance is between 50 to 100 meters, calibration should be done at 75 meters then preferably checked at the two extremes.

Zoom lenses are more difficult because both focal length and intended shooting distance may change. But typically the need for accurate calibration is more critical at long focal lengths which have narrower depth of field under shooting conditions. So common practice with zoom lenses is to calibrate at the long end and check at short end and mid-range of zoom.

[george013]

This is not correct. I think perhaps you are confusing some methods of manual calibration which use the live view function in order to do the calibration itself. The purpose of calibration is to ensure that the focus correction signal generated by the camera achieves the intended resulting lens movement (i.e.focus).

That was what I thought. The view we want to capture, and its focus, is what the sensors captures: live view.
AF works with the interpretation of the light rays with the AF sensors. That light is travelling another way as the light hitting the sensor. If the mirror, prism, AF-sensors are a little out off position, you have a wrong focus.
I'm not sure, but I believe one can't get focus problems with live view.
From what I read FoCal works like that: comparing live view with the results of AF.

George

[NorthernFocus]

Now I see your point, George. At least I think so.

The way that focusing software works is simple in concept. It relies on three things. First, a flat target oriented in a plane that is perpendicular to the axis of the lens. Second, a constant distance to the target. And finally, a constant level of illumination of the target. Then the software simply analyzes multiple images captured while varying the tuning parameter of the camera. The tuning parameter that corresponds to the image with maximum contrast is considered the proper calibration point. Automatic software accomplishes this by analyzing the imaging sensor in real time without the need to actually capture the images for comparison. So in essence, yes, it is comparing different focus points with the "live view" image.

[Manfred M]

In some ways, things were so much easier in the old days prior to all the automation. Lenses were assembled and tested on an optical bench. The infinity setting would be a hard stop set by the technician doing the final assembly / testing on the lens.

Today we rely on electronics to do this for us, and while there are great advantages to that, having a properly calibrated lens / camera setup is critical to getting focus.

[NorthernFocus]

In some ways, things were so much easier in the old days prior to all the automation. Lenses were assembled and tested on an optical bench. The infinity setting would be a hard stop set by the technician doing the final assembly / testing on the lens.

Today we rely on electronics to do this for us, and while there are great advantages to that, having a properly calibrated lens / camera setup is critical to getting focus.

Well stated, Manfred. Honestly without the modern tech I'd be incapable of shooting wildlife. Particularly BIF. I'm in awe when I see photos that were shot back in the days of film, typically with 100 speed film or even as low as 25. With the complexity of modern camera systems and the number of potential failure points, it is really a testament to the design that they function and survive as well as they do. I guess I used to be in awe of the photographers. Now I'm in awe of the engineers

[george013]

@Dan,
Yes, that was my point.
My example of the way the light travels in the camera doesn't give me an explanation why there're different corrections for different lenses on the same camera. The only thing I can think of is the elektronical system in the lens.

@Manfred,
I don't think there where no issues with focusing prior to all that automation. In our digital and computerised environment a fault is easier to see, even when you don't see it.

George

[Manfred M]

@Manfred,
I don't think there where no issues with focusing prior to all that automation. In our digital and computerised environment a fault is easier to see, even when you don't see it.

I totally agree, George. With automation, I have a lot less shots that are not good enough because of focusing errors.

I was merely pointing out that calibration was not an issue in the days before autofocus. Your lens was effectively calibrated by a technician working on an optical bench in the lens factory. I knew that if I turned the lens against the hard stop at ∞, I would be in focus at infinity.

If I look at my modern lenses, and I autofocus at infinity, I have to trust the camera / lens electronics to get it right. Merely lining up to the middle ∞ mark is not going to be precisely correct and each of my lenses will be at a slightly different position relative the the ∞ mark.

[Manfred M]

Now I'm in awe of the engineers

Only us engineers will totally appreciate the humour in that statement.

[rpcrowe]

My Canon lenses always appear to be pretty well spot-on regarding focus... I think that a lot of folks who think that teir lenses are off are guilty of poor focusing techniques. Of course, there is the occasional lens that may be off!

[IzzieK]

Thanks all for the info. Since I am going to get my software today, I will not be dissuaded from using it. I will only return it if it cause any problem in my computer. In the meantime, at least I have it when I need it.