topic What distance should I use? in EF & RF Lenses

What distance should I use?

inkjunkie — Wed, 28 Mar 2018 01:08:50 GMT

At what distance should I set up my 5D Mark IV from the Spyderlenscal? I have read all sorts of varying info. My 70-200L is a bit soft, especially at 200mm. One site says the distance you shoot at, another says 50x the focal length..should I change the distance when I have the lens set at 70 vs 200? While I have both tripods out I am going to also check my Sigma 24-70 ART lens...suppose the same questions apply to it...Thanks in advance for your help....

Re: What distance should I use?

Waddizzle — Wed, 28 Mar 2018 01:57:58 GMT

@inkjunkiewrote:
At what distance should I set up my 5D Mark IV from the Spyderlenscal? I have read all sorts of varying info. My 70-200L is a bit soft, especially at 200mm. One site says the distance you shoot at, another says 50x the focal length..should I change the distance when I have the lens set at 70 vs 200? While I have both tripods out I am going to also check my Sigma 24-70 ART lens...suppose the same questions apply to it...Thanks in advance for your help....

I use the "Dot Tune" method, which recommends 50x the FL, and it seems to work fairly well. I have only one camera body that needed AFMA adjustments with "L" lenses, that is until I sent it to Canon for a check and calibraiton.

As far changing the distance as you change focal length goes, yes, you should change the distance. You should also take a series of shots, and average the results. Doing an AFMA adjustment is a good test of one's skills as a photographer. It is not quite as simple and straightforward as it might seem.

BTW, your results should be fairly consistent. I would also advise conducting the tests in sunlight, or under the lighting conditions that you expect to use the lens. Sunlight has a broad spectrum, while most indoor lighting does not.

Re: What distance should I use?

ebiggs1 — Wed, 28 Mar 2018 06:27:27 GMT

"My 70-200L is a bit soft, especially at 200mm."

You know that AFMA does not make a lens any sharper. All lenses are as sharp as they will ever be when they are manufactured. Unless some physical component is changed this can not be altered. A 'soft' lens will always be a soft lens.

Lenses that are f2.8 and faster are the ones that can benefit from AFMA the most. Slower lenses probably never need it.

There is a lot of hype out there about AFMA. Some guys claim every lens they ever owned needed it and some guys, like me, claim very few lenses ever need it. The guys that claim every lens needs are probably feeding their ego and I may not be as critical as some are. Truth in the middle I suspect.

Re: What distance should I use?

RobertTheFat — Wed, 28 Mar 2018 12:53:53 GMT

@ebiggs1wrote:
"My 70-200L is a bit soft, especially at 200mm."

You know that AFMA does not make a lens any sharper. All lenses are as sharp as they will ever be when they are manufactured. Unless some physical component is changed this can not be altered. A 'soft' lens will always be a soft lens.
Lenses that are f2.8 and faster are the ones that can benefit from AFMA the most. Slower lenses probably never need it.

There is a lot of hype out there about AFMA. Some guys claim every lens they ever owned needed it and some guys, like me, claim very few lenses ever need it. The guys that claim every lens needs are probably feeding their ego and I may not be as critical as some are. Truth in the middle I suspect.

Only Canon's higher-end DSLRs have AFMA; the lower ranking ones ("Rebels" in USA-speak) do not. Which leads to the following paradox: "L" lenses rarely need AFMA and are used almost exclusively on camera bodies that have it; non-L lenses are much more likely to need AFMA and are widely used on camera bodies that lack it.

Re: What distance should I use?

ebiggs1 — Wed, 28 Mar 2018 14:03:59 GMT

"...leads to the following paradox: "L" lenses rarely need AFMA and are used almost exclusively on camera bodies that have it..."

The stars must be aligned Robert since we have been in agreement on most things lately. I think a person that really gets into this thinks it makes their lens sharper and therefore it does. I have seen it. The mind is a powerful thing and will tell you just about what you want it to.

All AFMA does is move the pin point focus point.

Re: What distance should I use?

inkjunkie — Wed, 28 Mar 2018 14:48:34 GMT

I will be lugging my camera bag to town today. Will have an hour or so between appointments so I will be sitting on the side of a road somewhere, pushing the shutter button. I very well may be the problem with my soft looking images. I have been messing around with various settings on the camera, just trying to see how things work. I very may have had something set a bit off. I was messing around with the 5D and the 24-70mm ART lens taking pictures of our EXTREMELY rowdy puppies, they were all tack sharp.

Appreciate your input.

Re: What distance should I use?

Waddizzle — Fri, 30 Mar 2018 00:50:51 GMT

@ebiggs1wrote:
"My 70-200L is a bit soft, especially at 200mm."

You know that AFMA does not make a lens any sharper. All lenses are as sharp as they will ever be when they are manufactured. Unless some physical component is changed this can not be altered. A 'soft' lens will always be a soft lens.
Lenses that are f2.8 and faster are the ones that can benefit from AFMA the most. Slower lenses probably never need it.

There is a lot of hype out there about AFMA. Some guys claim every lens they ever owned needed it and some guys, like me, claim very few lenses ever need it. The guys that claim every lens needs are probably feeding their ego and I may not be as critical as some are. Truth in the middle I suspect.

Some people fail to understand that an autofocusing lens is a s different beast from a manual focusing lens. Automatic focusing is an electromechanical system. If the lens miss its’ focus, either back or front focusing, your images may look soft.`

A mechanical lens will focus only as well as the hand that controls it. The same is true for an autofocusing lens. It is only as sharp as the electro-mechanical system controlling it. Some lenses do not focus on a subject accurately.

An AFMA can tune the focusing SYSTEM, which corrects for back or front focusing. Your images may look sharper. AFMA corrects the electronics. It has absolutely nothing to do with the accuracy of the actual glass.