Lens align: Opinions and alternatives?

[D.P.]

I've been borrowing my wife's D7000 fr a few events recently and have been noticing potential focus errors but when ever I have tried to do microadjustment with test charts the combo has always appeared well aligned.
I also started using my 70-200mm on my D800 which I hardly ever touch (I use a 300mm + 1.4X for wildlife) and that definitely needed a little MA.

I've always coped OK with home printed test charts such as this http://www.dphotojournal.com/focus-test-chart.pdf
or home made copies of Len Align made form a cardboard box.

The latter I tend to throw out afterwards because it looks unsightly and takes space.


I'm just wondering if I should shell out for an official Len Align http://www.amazon.com/LensAlign-MkII-Focus-Calibration-System/dp/B004G3PANY
With the hopes that it is easier, more accurate, collapsible and slightly less ungainly than a modified amazon box. However, they always just seemed like a rip off for what is essentially a high contrast pattern and an inclined ruler.

Any opinions out there?
Waste of money, or do you find you get more consistent results, test more often because you always have it?

 

[D.P.]

For a 70 - 200 rulers and the lens align are mostly redundant as it's too long a lens imo. For longer lengths lens i tend use an my average shooting distance say 3 -4m in the case of a 70 - 200, line up a row of three coke bottles, aim at the centre one while tethered and MA accordingly. After i've done that i note down the adjustment and run a Magiclantern dottune and compare the final results for the best one.

The problem using bottles is they are rounded and so it makes analyzing focus errors extremely difficult. You need a linear scale like a ruler. My Homemade lens align solutions form a cardbox work OK with the 70-200mm, I can make a bigger box and shoot from further away.

 

[D.P.]

I use the Reikan Focal software which works well for me.

My understanding of Reikan Focal is it is purely a software solution that merely measures sharpness. In the basic version you have to still make the manual adjustment, in the pro version it does that automatically. I don't see it being that helpful TBH, I can check sharpness with my eyes. I can see with the sigma lenses that can use the dock it could save some decent time when adjusting multiple focal lengths and focal distances.

I will research it in more detail, it might be a nice addition on top of a Lens Align tool.

 

[D.P.]

Not at all, being rounded if anything helps as you can see the focus fall away.

Worked perfectly fine for me.

I don't see how it can be at all accurate, I'm observing focus errors of down to 1cm, I need a ruler that can give me DoF measurements with an accuracy closer to to 1-2mm. Solutions like lens Align do that. With a row of 3 bottles 2 will be completely out of focus and the middle one will mostly be out of focus.

The last thing you want to be doing is focusing on a curved surface anyway. The Focus points are not accurately depicted in the viewfinder so you would really have no idea at which exact depth the camera will be focusing at. If the camera focuses a few mm to the left then the focus distance might be a few mm closer or further away due tot eh curve of the bottle. You need a flat plane to focus on with a single prominent high contrast feature to focus on.

 

[D.P.]

Yes it's still the same process as doing it manually, it just automates it to some degree. Some bodies are more automated than others, eg. with my 7D it would do it all for me but it can't actually change the MA settings on my 5D3 so it tells me what it wants and I set it. It just takes test shots and "homes in" on the best setting.

The other benefit over doing it manually is I find it a bit more objective. Whenever I've done adjustments manually, at some point I end up comparing two shots and having a tough time deciding which is sharper, if either, which is a little subjective. The software uses a set algorithm to determine the sharpness of each shop which seems a bit more consistent.

It is true, when things get close it is hard to see the difference. One technique that helps is to compare 2 MAs that are purposely wrong either side of the suspected true value. E.g. if you think -10 is the correct value then compare -14 and -6. They should be equally wrong but in the opposite direction. If -6 appears closer then the true value might be more like -9 than -10.

 

[D.P.]

Stop theorising and try it.

3 - 4m away dof at 200mm is 4 to 6cm, plenty of scope to check accuracy. At 70mm at the same distance the dof is greater.

My 70 - 200 and 400 are tack sharp given the above MA method. Shorter focal lengths i use the propped up ruler method next to a target where mm's matter.

The 70-200mm is not the only lens I want to test. I also have and 85mm f/1.8, DoF is around 3cm at my subject distance.

I'm not theorizing it, I have plenty of experience focus testing. Curved surfaces would be a nightmare to deal with. You really have no idea where the camera focuses, the viewfinder points are largely meaningless. My intention from going form a home made cardboard box solution to a COTS is to improve accuracy, not degrade it.

Thank you for your time and effort, but that just isn't the kind of solution I am looking for. I can do similar with a tape measure on the floor, I just want a more professional solution. Such bottles tests are useful quick and dirty solution to double check a combo but I want something more consistent and dependable.

EDIT: i really don't want to sound condescending and I am thankful for your effort, as I said, I just want something which is as accurate as possible and something I can put away n a cupboard and quickly pull out again whenever I need.