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FORUMS Canon Cameras, Lenses & Accessories Canon EF and EF-S Lenses 
Thread started 17 Dec 2014 (Wednesday) 10:12
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EF 100-400mm f/4.5-5.6L IS II USM Review WOW!

 
clipper_from_oz
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Post edited 4 months ago by clipper_from_oz. (8 edits in all)
     
Apr 28, 2018 08:10 |  #8161

sploo wrote in post #18615141 (external link)
On a phone, so sorry for terse reply:

You need about 50x the focal length for test distance. So 20m for a 400mm lens (though calibrating at your most commonly used shooting distance is also probably fine too).

Focus on a target using live view or manually (MFA has no effect here; it should always be "perfect"). Set the lens to MF, IS off. Set MFA to -20 and check for the dot by half pressing the shutter button. Try -15, -10... up to +20. Narrow down on the range where it illuminates constantly (no flicker).

If you get -10 to +5 the MFA to dial in will be -2.5.

For +1 to +8 it'd be +4.5.

Obviously you can only choose whole numbers so just go for the nearest.

I tend to go up and down the MFA values a few times just to be fairly certain where the edges are of the good range.


I did what you have indicated above .....However as I said in my above post there was no dot appearing in Live view...unless I was missing it amongst the other screen icons. I will try again tomorrow with this method for 100-400 . Maybe that will work ok

BTW.... I think its important to point out that many canon users are thinking to put the camera in LV to do these tests. But if the user focuses using live view the camera is using contrast detect to focus, which to my understanding of the way my camera works entirely bypasses the phase detect autofocus system that the DSLR uses when you’re looking through the viewfinder. It is the phase detect system for which microadjustments are necessary, not the contrast detect system (which should always be accurate with a high contrast target, decent light, and camera locked down on a good tripod).

So all my tests have previously been done through the lens align method through the viewfinder using phase detect and then adjusting via MA. What I need to know is how to do this via the green dot method not using LV with camera locked in Manual Focus in Viewfinder mode. And tahst where the issue is because once the lens is in manual focus and viewfinder mode half pressing the shutter to get the AF dot happening after a MA change results in no AF light/dot flashing in viewfinder.


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Canon EF 16-35mm f4 L, 17mm TSE f4 L,50mm f1.4, 24-70 f2.8 L, 70-200mm F4 L, 85mm f1.8, 100-400mm II L,
EF 400mm f2.8 IS II L, Fujinon XF18mmf2, XF35mmf1.4, XF60mm f2, XF18-55f2.8-4.5, XF55-200f4
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Pondrader
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Post edited 4 months ago by Pondrader.
     
Apr 28, 2018 08:59 |  #8162

sploo wrote in post #18615142 (external link)
The problem is that shot-to-shot variation with AF (plus subject movement) can throw you off (one backfocused shot doesn't mean the camera is backfocusing).

Dialing in a good MFA value under controlled conditions means, on average, most shots should be centered around an accurate focusing distance.

Otherwise, your sharpest focal plane will, on average, always be a bit off - leading to fewer in focus images.

sploo when I head out to shoot for the day I expect 100% in focus images 100% of the time. for me thats about 2 to 3 thousand images for that day or about a 4 Terabyte hard drive a year roughly... and the subject is varied from birds to Moose to Pine Marten and could be fox in the 30 minutes kind of thing. I get the problem of accurate focus and have found a way that works.

So I do understand the focus challenges very well and the one thing I can say with certainty is there is no rules of thumb to get perfect focus.

For me its about perfect "Image"... Its the only thing that matters. So if your shooting birds and your front focusing the smart shooter will fix it. it only takes seconds...

you can come out of it with some sharp images. Sometimes its as thin as a sheet of paper.


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digital ­ paradise
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Apr 28, 2018 09:34 |  #8163

sploo wrote in post #18615202 (external link)
It really should only take a matter of minutes for any single focal length. A difference of one or two MFA units is probably not going to make a big difference, so I just go up and down the MFA values a few times and when I appear to find the edge I will spend a little bit of time to see which value does or doesn't cause the dot to flicker, then I dial in the middle value between the two extremes.

As a geeky programmer I also start out with a binary chop type method of finding the edge; i.e. start at 20, then 10, then 5 or 15 and so on (based on whether the dot does or doesn't light up). It means you can usually find one end of the range with just four or five different MFA values.

More time consuming, but arguably ultimately more accurate, is Sigma's system of having multiple MFA values for different focus distances. I have a 35 Art that took some work, but now seems to hit focus pretty much every time even when shooting at f/1.4.

Your point about the light source though is very important. Although I try to do calibration indoors I will always try to do it with natural daylight.

It should but I just still don't trust myself. My eyes are getting older and judging in the field is not as easy. You are dealing with a bit of variation as well with PDAF that FoCal compensates for. Yes a few ticks don't matter. Before FoCal I never even adjusted it if was a few out. If I get a prime I'll revisit this both using FoCal and my eyeball. We''l see.

Page 1, last paragraph, last sentence however I know some don't agree with this.

http://www.learn.usa.c​anon.com …oadjustment_art​icle.shtml (external link)

Also in the field you are dealing with this.

http://arihazeghiphoto​graphy.com …ment-is-it-always-needed/ (external link)

My background was print media. If we didn't set a gap in the folding machine at 0.0030 it would prevent a 10 million dollar printing press from starting. A human hair is 0.00338. I'm more comfortable with numbers and something telling me what the adjustments should be.


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sploo
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Apr 28, 2018 10:12 |  #8164

clipper_from_oz wrote in post #18615214 (external link)
I did what you have indicated above .....However as I said in my above post there was no dot appearing in Live view...unless I was missing it amongst the other screen icons. I will try again tomorrow with this method for 100-400 . Maybe that will work ok

BTW.... I think its important to point out that many canon users are thinking to put the camera in LV to do these tests. But if the user focuses using live view the camera is using contrast detect to focus, which to my understanding of the way my camera works entirely bypasses the phase detect autofocus system that the DSLR uses when you’re looking through the viewfinder. It is the phase detect system for which microadjustments are necessary, not the contrast detect system (which should always be accurate with a high contrast target, decent light, and camera locked down on a good tripod).

So all my tests have previously been done through the lens align method through the viewfinder using phase detect and then adjusting via MA. What I need to know is how to do this via the green dot method not using LV with camera locked in Manual Focus in Viewfinder mode. And tahst where the issue is because once the lens is in manual focus and viewfinder mode half pressing the shutter to get the AF dot happening after a MA change results in no AF light/dot flashing in viewfinder.

By "no dot in live view" I'm wondering if there's a mistake in your procedure? You're only using live view or manual focus with the LCD in order to get what should be a perfect focus example. You then switch to using the viewfinder and check the dot there.

What's going on is that the dot tells you when the camera thinks it has achieved a lock (even if the lens is currently set to MF). As you know that the lens is currently in perfect focus (due to focusing it with live view or manually) you're then trying to find the range of MFA values where the camera's phase detect autofocus system also believes the image to be in focus.

In essence you're finding the difference (the error) between the phase detect sensor on your camera (plus the current lens) and what is really in focus.


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sploo
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Apr 28, 2018 10:16 |  #8165

digital paradise wrote in post #18615246 (external link)
It should but I just still don't trust myself. My eyes are getting older and judging in the field is not as easy. You are dealing with a bit of variation as well with PDAF that FoCal compensates for. Yes a few ticks don't matter. Before FoCal I never even adjusted it if was a few out. If I get a prime I'll revisit this both using FoCal and my eyeball. We''l see.

Page 1, last paragraph, last sentence however I know some don't agree with this.

http://www.learn.usa.c​anon.com …oadjustment_art​icle.shtml (external link)

Also in the field you are dealing with this.

http://arihazeghiphoto​graphy.com …ment-is-it-always-needed/ (external link)

My background was print media. If we didn't set a gap in the folding machine at 0.0030 it would prevent a 10 million dollar printing press from starting. A human hair is 0.00338. I'm more comfortable with numbers and something telling me what the adjustments should be.

My eyes aren't that great these days either, but remember that the beauty of DotTune is that you're not having to judge any images by eye. In fact if your camera produced a beep when the dot illuminated it would in theory be possible to do the dot tune method with your eyes closed (ok, so actually going into the menu and changing the MFA settings might be a bit difficult ;)).


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clipper_from_oz
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Post edited 4 months ago by clipper_from_oz.
     
Apr 28, 2018 10:21 |  #8166

sploo wrote in post #18615265 (external link)
By "no dot in live view" I'm wondering if there's a mistake in your procedure? You're only using live view or manual focus with the LCD in order to get what should be a perfect focus example. You then switch to using the viewfinder and check the dot there.

What's going on is that the dot tells you when the camera thinks it has achieved a lock (even if the lens is currently set to MF). As you know that the lens is currently in perfect focus (due to focusing it with live view or manually) you're then trying to find the range of MFA values where the camera's phase detect autofocus system also believes the image to be in focus.

In essence you're finding the difference (the error) between the phase detect sensor on your camera (plus the current lens) and what is really in focus.

Yes I switch to viewfinder and then in Viewfinder no dot. Are you saying after getting optimal focus in LV with lens AF set to manual that when you go to viewfinder the lens is then set back to AF?.....Because if lens is still set to manual there is no af dots in my viewfinder when I press the shutter halfway like there is when lens is set to AF


Also below link I found a very interesting discussion on shifting focus from front to back when calibrating lens with MA This is exactly what I was getting with my 100-400 when I was doing MA on it with a 1.4 extender

https://www.dpreview.c​om/forums/thread/40498​01 (external link)


Clipper
5DSR,5DMkII,Fuji XPRO1,X-T1&X-T20,Fotoman 6x17cm Large Format Panorama Camera,Mamiya Universal 6x9
Canon EF 16-35mm f4 L, 17mm TSE f4 L,50mm f1.4, 24-70 f2.8 L, 70-200mm F4 L, 85mm f1.8, 100-400mm II L,
EF 400mm f2.8 IS II L, Fujinon XF18mmf2, XF35mmf1.4, XF60mm f2, XF18-55f2.8-4.5, XF55-200f4
Rodenstock, Sinar& Nikkor LF lens for Pano (75,95,150+210mm)
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sploo
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Apr 28, 2018 10:21 |  #8167

Pondrader wrote in post #18615235 (external link)
sploo when I head out to shoot for the day I expect 100% in focus images 100% of the time. for me thats about 2 to 3 thousand images for that day or about a 4 Terabyte hard drive a year roughly... and the subject is varied from birds to Moose to Pine Marten and could be fox in the 30 minutes kind of thing. I get the problem of accurate focus and have found a way that works.

So I do understand the focus challenges very well and the one thing I can say with certainty is there is no rules of thumb to get perfect focus.

For me its about perfect "Image"... Its the only thing that matters. So if your shooting birds and your front focusing the smart shooter will fix it. it only takes seconds...

you can come out of it with some sharp images. Sometimes its as thin as a sheet of paper.
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forum: Canon EF and EF-S Lenses

If in a particular shooting scenario (i.e. a particular focus distance) you're finding the camera is consistently front or back focusing then I'd agree it would make sense to trim the calibration in the field. In an ideal world however once you've got the MFA correctly calibrated for your lens it should be pretty accurate at all focus distances. In theory, granted.


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Post edited 4 months ago by sploo.
     
Apr 28, 2018 10:26 |  #8168

clipper_from_oz wrote in post #18615270 (external link)
Yes I switch to viewfinder and then in Viewfinder no dot. Are you saying after getting optimal focus in LV with lens AF set to manual that when you go to viewfinder the lens is then set back to AF?.....Because if lens is still set to manual there is no af dots in my viewfinder when I press the shutter halfway like there is when lens is set to AF

Also below link I found a very interesting discussion on shifting focus from front to back when calibrating lens with MA This is exactly what I was getting with my 100-400 when I was doing MA on it with a 1.4 extender

https://www.dpreview.c​om/forums/thread/40498​01 (external link)

You can get your perfect focus through the LCD manually or with the lens set to AF. Then switch to MF and use the viewfinder. If there's no MFA value that would then cause the focus indicator dot on the viewfinder to illuminate then that would be somewhat odd.

Oh, do focus on the centre of the LCD, and then use a single AF point in the centre through the viewfinder.


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Apr 28, 2018 10:34 |  #8169

All of this MFA anxiety will vanish once Canon releases their mirrorless :) Sadly though, I bet they change the lens mount too, so it’s either adapters or M-lenses after that.


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Apr 28, 2018 10:53 |  #8170

sploo wrote in post #18615266 (external link)
My eyes aren't that great these days either, but remember that the beauty of DotTune is that you're not having to judge any images by eye. In fact if your camera produced a beep when the dot illuminated it would in theory be possible to do the dot tune method with your eyes closed (ok, so actually going into the menu and changing the MFA settings might be a bit difficult ;)).

I found Dot Tune inconsistent.I live in windy area and even a bit of movement will alter your results.


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Apr 28, 2018 11:11 |  #8171

digital paradise wrote in post #18615282 (external link)
I found Dot Tune inconsistent.I live in windy area and even a bit of movement will alter your results.

Don't do it in the wind ;)

Being serious though; it is best to set something up in controlled conditions. You should only need to do a body + lens combo once.


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Apr 28, 2018 11:13 |  #8172

MatthewK wrote in post #18615277 (external link)
All of this MFA anxiety will vanish once Canon releases their mirrorless :) Sadly though, I bet they change the lens mount too, so it’s either adapters or M-lenses after that.

True; though I understand even the best phase AF on mirrorless bodies doesn't match the DSLRs... yet.


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Apr 28, 2018 11:18 |  #8173

MatthewK wrote in post #18615277 (external link)
All of this MFA anxiety will vanish once Canon releases their mirrorless :) Sadly though, I bet they change the lens mount too, so it’s either adapters or M-lenses after that.

Or comes up with a closed loop MFA system like the Nikon D500.


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Apr 28, 2018 11:19 |  #8174

sploo wrote in post #18615290 (external link)
Don't do it in the wind ;)

Being serious though; it is best to set something up in controlled conditions. You should only need to do a body + lens combo once.

Unfortunately, I'd don't have access to an indoor space large enough to dot tune a 560mm lens. I wound up just doing multiple test shots with mirror lockup at a long stake with numbers printed on it, leaned against a wall.




  
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Apr 28, 2018 11:37 |  #8175

sploo wrote in post #18615290 (external link)
Don't do it in the wind ;)

Being serious though; it is best to set something up in controlled conditions. You should only need to do a body + lens combo once.

Well I'm not unhappy with FoCal's results which matched mine. The lens just seems twitchy with a TC from time to time. Besides I paid for it so I'm going to use it.


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