Astismatism: need some help understanding astismatism and how much it effects my image focus quality. Shooting with Canon 7d MK ll & Canon 100-400 MK ll. Just ran the Focal Pro...

Tom70 Loc: NY

need some help understanding astismatism and how much it effects my image focus quality.
Shooting with Canon 7d MK ll & Canon 100-400 MK ll. Just ran the Focal Pro Calibration test with & without Canon 1.4 ll extender, results showed
normal Factor 1.3-3.8 my test measured 19.0
range Factor 1.2-3.3 my test measured 17.7

Is this really bad?
Not being a pixel peeper but I strive and love the sharpest image possible,
will I really notice any distortion with these test results?

If really bad can this be corrected? if so should Canon be the people to fix?

Thanks all in advance - Tom

Longshadow Loc: Audubon, PA, United States

Curious, how do the pictures look?

TriX Loc: Raleigh, NC

Tom70 wrote:

need some help understanding astismatism and how m... (show quote)

Have you run the acutance vs aperture test? What are the results (what is the highest acutance at the optimum aperture?)

DWU2 Loc: Phoenix Arizona area

I assume you mean astigmatism?

a6k Loc: Detroit & Sanibel

I have astigmatism in both eyes. Although my vision with my cataract replacements is significantly better than 20/20, each eye has a ghost image from the astigmatism. So, yes, you did the math and I am seeing 4 images. To make matters worse, I need special prisms in my glasses to put the two eyes at the same level or angle else I see one pair of images displace both horizontally and vertically from the other pair. But I usually only use one eye and the EVF.

My point in sharing this much personal detail is to also say that my AF on my 3 cameras works pretty darn well and so I have to let it help me. I usually use spot focus so as to ensure that the thing which I want to be sharp will be sharp. It usually works out well. Since the camera is "mirrorless" that means it takes the focus from the sensor. Two of the three are actually not true "mirrorless" because they don't have interchangeable lenses. Same thing in this case. On my a6500 using a Minolta lens, I did have to calibrate the focus for the lens. For Sony lenses on my Sony a6500, that is not necessary. Sadly, the Minolta lens has its own mirror which can actually be slightly displaced and require the calibration which the camera allows for.

My recommendation, then, is to take advantage of the technology.

Tom70 Loc: NY

DWU2 wrote:

I assume you mean astigmatism?

yep, my spelling looks like its almost as good as my photgraphy skills

Tom70 Loc: NY

TriX wrote:

Have you run the acutance vs aperture test? What are the results (what is the highest acutance at the optimum aperture?)

no, ran out of time, had to cut session short, will do that inn the next day or 2,

birdman12 Loc: Pinopolis, SC

Tom70 wrote:

need some help understanding astismatism and how m... (show quote)

If you use AF, astigmatism in your eyes should have no effect on your pictures. There is no astigmatism in your camera.

Canisdirus

I also have astigmatism, though nowhere near your level (sorry about that btw).

I also see three or four moons...overlapping a bit...sans glasses.
But my vision is still pretty much top notch...I missed driving without glasses by one letter ( I pulled out a 20...she just smiled and said...no...lol).

But... it doesn't affect my photography, since I can still easily see if I am in focus when shooting manually.
I suspect you can as well...no?

burkphoto Loc: High Point, NC

birdman12 wrote:

If you use AF, astigmatism in your eyes should have no effect on your pictures. There is no astigmatism in your camera.

Camera LENSES often do have some astigmatism. They can also have coma, pincushion or barrel distortion, chromatic aberrations, vignetting, alignment issues, coating issues, and transmission losses. A great lens minimizes all of these. A cheap lens might have some visible effects from some of them. Sometimes that can be put to special effect.

TriX Loc: Raleigh, NC

burkphoto wrote:

Camera LENSES often do have some astigmatism. They can also have coma, pincushion or barrel distortion, chromatic aberrations, vignetting, alignment issues, coating issues, and transmission losses. A great lens minimizes all of these. A cheap lens might have some visible effects from some of them. Sometimes that can be put to special effect.

👍👍 Exactly. Here’s a good read that details astigmatism and other aberrations in lenses: https://www.lensrentals.com/blog/2010/10/the-seven-deadly-aberrations/

birdman12 Loc: Pinopolis, SC

burkphoto wrote:

Camera LENSES often do have some astigmatism. They can also have coma, pincushion or barrel distortion, chromatic aberrations, vignetting, alignment issues, coating issues, and transmission losses. A great lens minimizes all of these. A cheap lens might have some visible effects from some of them. Sometimes that can be put to special effect.

Yes, but surely not in the Canon 7D mk ii that the OP and I have. LOL

Tom70 Loc: NY

a6k wrote:

I have astigmatism in both eyes. Although my visio... (show quote)

thanks, will do, the technology is better then my talent

Tom70 Loc: NY

burkphoto wrote:

Camera LENSES often do have some astigmatism. They can also have coma, pincushion or barrel distortion, chromatic aberrations, vignetting, alignment issues, coating issues, and transmission losses. A great lens minimizes all of these. A cheap lens might have some visible effects from some of them. Sometimes that can be put to special effect.

From all my reading of the lens reviews of the Canon 100-400 mk ll, it has some, but very slight defects, which are less then most lens. Not being much in the tech world was just wondering if these things really matter to a everyday hobby photographer - Thanks for the feedback

Longshadow Loc: Audubon, PA, United States

Tom70 wrote:

From all my reading of the lens reviews of the Canon 100-400 mk ll, it has some, but very slight defects, which are less then most lens. Not being much in the tech world was just wondering if these things really matter to a everyday hobby photographer - Thanks for the feedback

Wouldn't matter to me....
Not a pro, simply an aficionado.

I don't (won't) characterize/analyze any of my lenses.
I don't worry about to what extent they may be good or bad, I just use them.

Can you notice anything in the images or prints?