MicroAdjustment if you need it?

https://learn.usa.cano​n.com …roAdjustGuide_d​esktop.pdf

Russ

russellsnr2 wrote in post #18459100
https://learn.usa.cano​n.com …roAdjustGuide_d​esktop.pdf

Russ

Good Reading, thank you.

^^ ditto, thank you.

Thanks OP!

I have this one as well. This procedure says to do it at 50X of the focal length. Our manuals say for best results to do it at the shooting location.

This procedure says

• Shoot test pictures using the lens(es) you normally use, and at the distances you typically use them. In other words, if you're seeing a consistent focus shift when you shoot group pictures at weddings, don't take test shots of a ruler on your desk with a macro lens.

http://www.learn.usa.c​anon.com …oadjustment_art​icle.shtml

Just thought I'd throw this in because often 50X is impractical for longer lenses.

This is also helpful and it does make a difference.

http://arihazeghiphoto​graphy.com …ment-is-it-always-needed/

Yes, I must admit I check focus as I shoot and have enough experience to adjust depending on the circumstances and sometimes subject. For initially testing a lens I can tell very quickly and dial something in without a test setup. If you can't get something consistent shooting, then you've probably got other issues.

Second article very good. I should have read that after getting my first long lens. I never realized how bad atmospheric distortions can be.

ejenner wrote in post #18462552
Yes, I must admit I check focus as I shoot and have enough experience to adjust depending on the circumstances and sometimes subject. For initially testing a lens I can tell very quickly and dial something in without a test setup. If you can't get something consistent shooting, then you've probably got other issues.

Second article very good. I should have read that after getting my first long lens. I never realized how bad atmospheric distortions can be.

Having been a competitive rifle shooter, usually shooting at longer ranges, I have been fighting with those atmospheric distortions for over 30 years. One really unfortunate problem is that as you improve the quality of the lens the specific distortions caused by the atmosphere actually become more noticeable. So where a cheap lens will just seem to be a little low in contrast etc, the really good quality, expensive, lens will show you what type of distortion you are looking at, in temperatures where you would doubt they could even exist. These effects are also much more pronounced over water, or even wet grasslands. The added water vapour makes the change in refractive index with temperature much larger.

On the bright side, for bird photographers at least, they will be much more evident closer to the ground, and usually once the wind speed gets to about 12 mph they simply can't form. The biggest problem with these effects for a rifle shooter is that they move the location of the image of the target in the same direction as the wind. Often when shooting a smallbore match it will move the image of the target downwind by about as much as the wind will physically move the bullet. This means that you actually have to use twice the correction in order to hit the center of the target. At least as a photographer you don't need to worry about the image not being where you think it is.

Alan

digital paradise wrote in post #18461512
...

• Shoot test pictures using the lens(es) you normally use, and at the distances you typically use them. ......

Just thought I'd throw this in because often 50X is impractical for longer lenses.
...

But then again, longer lenses are typically used at more than 50x fl.

gjl711 wrote in post #18462728
But then again, longer lenses are typically used at more than 50x fl.

This is true however it is still inconvenient. At 560mm I would need 92 feet. I have no facility where I could do this and outdoors is not practical - for me anyway. I'd need roller skates to go back and forth. I'm not 59 anymore

I had a hard time with this for many years. 35 years in print media. If we did not set a gap in the folding component properly it shut a 10 million machine down. The gap had to be 0.0035 = 35 thousands of an inch. I'd question all these different procedures and methods out there. This is precision stuff and even Canon has two different explanations.

Since I adopted FoCal I decided to follow their suggestion. Page 2 describes when a lens settles down. Me thinks 50X is possibly suggested by Canon cover themselves as if not done properly can make it worse. The manual even says not normally needed and can cause AF issues.

http://s449182328.webs​itehome.co.uk …20Test%20Distan​ce_1.1.pdf

The Distance tool.

http://support.fo-cal.co.uk …tion-target-distance-tool

Forgot to say. Romy Ocon who is member here and at FM who's site name is Liquidstone is a well known and respected birder. He was my BIF mentor except he did not know it

He does MFA at MFD. You can't argue with success. At one time someone here mentioned a company in Europe that did MFA with the long primes at around 21 ft. I never did get a follow when I asked more about it.

digital paradise wrote in post #18462748
The gap had to be 0.0035 = 35 thousands of an inch.

Did you use one to many zeros after the decimal point or did you mean 35 Ten Thousandths? No offense. Just curious mind you.

coopernut wrote in post #18463740
Did you use one to many zeros after the decimal point or did you mean 35 Ten Thousandths? No offense. Just curious mind you.

It might be 0.035

I looked it up but I may have misread it. Actually now that I look at it typed that is what it said on the gauge. It has been 10 years. Thanks for pointing it out. No offence taken.