8thcross Photography

Since a few years ago, I had been using an excel­lent process to fine tune my lenses. It is a painstak­ing exer­cise, but nev­er­the­less a very very use­ful and crit­i­cal thing to do on a peri­odic basis.

Recently — I felt the need for a faster way to do this. This past christ­mas, when Michael Tapes announced the new Lens Align Mark II at a new price, I couldn’t resist it.

Just to show how use­ful this lit­tle gad­get is, I decided to go back and tune my lenses again. I found myself in sur­prise when all my lenses needed a slight tweak again. Here is a shot of my lens align shot with 50mm f1.4 lens:

The prod­uct itself comes shipped in a manila enve­lope. It is fairly easy and straight­for­ward to set it up. It is very well made . Once you assem­ble it, you can either mount it on a tri­pod (It has a tri­pod mount socket) or in my case, since I do have a draft­ing table — was able to set it up on it. For added ben­e­fit, I did add a level to check the accu­racy as well (See above image with arrow point­ing down). The next thing to do is set up your cam­era on a tri­pod, level it accu­rately (For­tu­nately on a D700 — you have a built in ver­ti­cal hori­zon tool).  I set the cam­era up to the same height as the cen­ter of lens align.

With the aper­ture opened up all the way (f1.4 on my 50mm f1.4 lens) I took a test shot. Oh, BTW — I did use a cable release and had set the cam­era to shoot in Live View mode (for fine focus­ing — with magnification).

Here is an exam­ple of the image after AF Fine tune (it took sev­eral iter­a­tions to final­ize the exact num­ber. In my case, it was –4. This of course varies between cam­era to cam­era and lens to lens. So, this above num­ber for AF Fine tune is just for my cam­era and lens com­bi­na­tion. Once you set this num­ber up, the cam­era remem­bers it and every time I use this lens, my fine tuned adjust­ment is auto­mat­i­cally used.

A note about using Live view for adjust­ment: On my D700 (most likely on other cam­eras as well) , the Live view mode uses a dif­fer­ent tech­nol­ogy (con­trast based auto focus) as com­pared to the nor­mal auto focus (phase detec­tion auto focus). While the phase detec­tion AF is faster and gen­er­ally accu­rate, the con­trast based AF (although slower) can deliver more accu­rate focus. The above process is noth­ing but to cal­i­brate your phase detec­tion AF with your more accu­rate con­trast detec­tion AF. You can read up more about the AF detec­tion sys­tems here. BTW — Most of the point & shoots have con­trast based AF, since it is more eco­nom­i­cal to mass pro­duce this.

Here is an exam­ple of the results after AF fine tun­ing. Warn­ing: Once you tune your lenses — there is no going back! You will invari­ably do this every time and for all your lenses! Here is a shot of my son after alignment:

This was a hand held shot, shot with the just tweaked Nikon 50mm f1.4 lens at f2. Sharp­ened with R-L Decon­vo­lu­tion tech­nique (no out­put sharp­en­ing, just cap­ture sharp­en­ing). I think I can count the num­ber of eye­lashes if I spend a bit of time…which I am not going to do. If you wish to see the full image — click here.