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FORUMS Canon Cameras, Lenses & Accessories Canon EOS Digital Cameras
Thread started 01 Aug 2012 (Wednesday) 00:11
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"Adjust by Lens" Microadjustment?

 
BTBeilke
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Aug 01, 2012 00:11 |  #1

According to both the Canon manual and the FoCal software, the recommended distance to the target when testing for microadjustment is 50X the focal length of the lens. My longest focal length currently would be 400mm (70-200 with 2x extender) which would mean a target distance of 65.6' according to the 50X rule.

I'm curious as to how you all have set up for these tests. I can't get that long of line-of-sight in my house. If you go outside, you have to worry about changing light, the wind blowing you target around (moving the target even very, very little between shots can mess up the analysis), not getting the target parallel to the plane of the sensor can cause problems, etc. Perhaps I'm being overly cautious about all of this. But I'm wondering how the rest of you have handled these longer focal length adjustments.

BTW, it doesn't apply to my situation, but when dealing with a crop camera do you take focal length x 50 x 1.6?


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apersson850
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Aug 01, 2012 02:01 |  #2

400 mm * 50 = 20000 mm = 20 m. Metric is easy.

Anyway, it's the characteristic of the lens, not the sensor you are working with, so the sensor size has no influence here.

As a general rule, you should do micro adjustment in the environment where you are shooting. With a 400 mm lens, indoors isn't very likely. So just make sure you have a good subject outdoors and do your tests there.


Anders

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kawi_200
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Aug 01, 2012 02:13 |  #3

If I was doing something long like 200mm or longer, then I'd shoot out my garage at the neighbor's house, or if my yard was long enough I would shoot at my own house.

I recently had to do a MA to my 24L. I just set a cereal box on the kitchen table and the camera with a hotshoe bubble level on a tripod and had at it. I actually like having the target at an angle because then you can actually tell how far off you are. Choose a feature on the target as the center and aim at it. As you shoot (at an angled target) you can see how close or far you are from the aim point.


5D4 or 6D2..... Waiting to find out which I buy | 8-15L |24-70mm f/4L IS | 24L II | 40mm pancake | 100L IS | 70-200mm f/2.8L IS mk2 | 400mm f/4 DO IS

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walmartmartyr
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Aug 01, 2012 07:54 |  #4
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For a Zoom, if you micro adjust at the long end, shouldn't that correct for the whole zoom range. I mean, if you sharpen a 70-200mm at 200mm, will that mean it's sharpened 70mm also, or do you need to pick a focal length your expecting to use most and sharpen it there?


Currently Have [Canon 7D] [17-55mm f2.8 IS USM] [70-200 f4L IS USM] [430exII] [50mm f1.8] [Canon s100]
No Longer Have [Canon T2i][Canon Xti][17-85mm IS USM][50mm f1.4 USM][28mm f1.8 USM][15-85mm IS USM]

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jwp721
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Aug 01, 2012 08:04 |  #5

walmartmartyr wrote in post #14799287external link
For a Zoom, if you micro adjust at the long end, shouldn't that correct for the whole zoom range. I mean, if you sharpen a 70-200mm at 200mm, will that mean it's sharpened 70mm also, or do you need to pick a focal length your expecting to use most and sharpen it there?

Not always... sometimes you will find that a zoom will behave differently from one end to the other. If you have a favorite focal length that you shoot at the majority of the time then that would most likely be the best setting to use. Otherwise I would test at both ends and then the middle and maybe compromise if neccessary.

Of course if the differences are too extreme then a trip to Canon may be the best decision (it was for my 24-70mm which now only needs +5 for all ranges).

BTW: The 5DMKIII (I think) and the new 1dx now have the feature where you can set different MFA settings for a zoom lens for the long and short ends. So Canon is aware that a zoom can require different settings at different focal lengths....




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BTBeilke
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Aug 01, 2012 08:58 |  #6

jwp721 wrote in post #14799322external link
BTW: The 5DMKIII (I think) and the new 1dx now have the feature where you can set different MFA settings for a zoom lens for the long and short ends. So Canon is aware that a zoom can require different settings at different focal lengths....

That is correct.


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BTBeilke
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Aug 01, 2012 09:13 |  #7

kawi_200 wrote in post #14798751external link
If I was doing something long like 200mm or longer, then I'd shoot out my garage at the neighbor's house, or if my yard was long enough I would shoot at my own house.

I recently had to do a MA to my 24L. I just set a cereal box on the kitchen table and the camera with a hotshoe bubble level on a tripod and had at it. I actually like having the target at an angle because then you can actually tell how far off you are. Choose a feature on the target as the center and aim at it. As you shoot (at an angled target) you can see how close or far you are from the aim point.

That would be true, IMO, if you are doing these adjustments manually. However, the FoCal software has specific targets (2D) that they recommend that you use. Their software compares/analyzes differences between photos taken of these targets at different MA values. I can't see how that system would be very effective if you have the target off angle enough to cause some areas of the target to be in focus while other are not and then have those areas shift around from shot to shot. After all, the software would have no idea which direction you had angled the target or by how much. And that is also why having small movements of the target between shots can invalidate the whole process.

I do think using an angled target would be a good way to check "final" FoCal recommended MA settings however.


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apersson850
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Aug 01, 2012 09:18 as a reply to BTBeilke's post |  #8

Angled targets are a complete no-no when it comes to focus adjustment. Due to the physical size of the AF sensors, they cover a certain block in the viewfinder. That block is usually quite a bit larger than the rectangle depicting the AF point in the viewfinder. Thus if you use an angled target, you can't know if the camera tried to focus to the left, in the center or to the right of the AF point. It will pick some part where it locates a reasonable contrast. Due to AF sensor noise (yes, they are affected by that too), which is random in nature, this side offset may shift from one picture to another.

You may have something angled in the picture, for reference, but you must focus on something perpendicular to the optical axis.


Anders

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BTBeilke
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Aug 01, 2012 09:48 |  #9

apersson850 wrote in post #14798722external link
400 mm * 50 = 20000 mm = 20 m. Metric is easy.

Anyway, it's the characteristic of the lens, not the sensor you are working with, so the sensor size has no influence here.

As a general rule, you should do micro adjustment in the environment where you are shooting. With a 400 mm lens, indoors isn't very likely. So just make sure you have a good subject outdoors and do your tests there.

Hey, I'm an engineer and I love working in metric units! Unfortunately, that whole movement fizzled out long ago here in the US. (As an aside, I have a company vehicle and have to report my mileage occasionally. The lady in our office who generates those reports was giving me a bit of a good-natured ribbing. So in response, I reported my mileage to her in millimeters.)

I've read the recommendation to do the MA process in the environment where you'll be shooting. While I think that would definitely be ideal, it seems pretty impractical (for me anyway). For example, I often use my 70-200 with extenders outdoors but I also use them indoors from the back of a theater for close-ups of stage and musical performances.

In truth, these adjustments will never be perfect under any circumstances. Even within the same environment changes in lighting, temperature, etc. will have some impact on these settings. I'm just wanting to do the best I can and then forget about it for a good while and focus on photography.


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Snydremark
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Aug 01, 2012 09:59 |  #10

I set my 100-400 up at around 30ft (longest section I could get in the house) and did the MFA from there; it's been just fine for any shooting that I've done since then.


- Eric S.: My Birds/Wildlife (external link) (7D MkII, Canon 10-22 f/3.5-4.5, Canon 24-105L f/4 IS, Canon 70-200L f/2.8 IS MkII, Canon 100-400L f/4.5-5.6 IS)
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TeamSpeed
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Aug 01, 2012 11:54 |  #11

apersson850 wrote in post #14799602 (external link)
Angled targets are a complete no-no when it comes to focus adjustment. Due to the physical size of the AF sensors, they cover a certain block in the viewfinder. That block is usually quite a bit larger than the rectangle depicting the AF point in the viewfinder. Thus if you use an angled target, you can't know if the camera tried to focus to the left, in the center or to the right of the AF point. It will pick some part where it locates a reasonable contrast. Due to AF sensor noise (yes, they are affected by that too), which is random in nature, this side offset may shift from one picture to another.

You may have something angled in the picture, for reference, but you must focus on something perpendicular to the optical axis.

Agreed :D

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BTBeilke
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Aug 01, 2012 13:19 |  #12

TeamSpeed wrote in post #14800241external link
Agreed :D

I saw your Focus Genie and it looks like a simple and inexpensive way to check front/back focusing. However, according to what I've read, laminating focus targets would be a big no-no. In fact, the FoCal instructions recommend that you print their targets on heavyweight matte paper using an inkjet printer rather than a laser printer. Supposedly, just the reflectiveness/shinine​ss of the toner used in laser printers can adversely affect the reliability of the results.

Have you noticed any problems focusing on a laminated target?


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TeamSpeed
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Aug 01, 2012 14:17 |  #13

BTBeilke wrote in post #14800576external link
I saw your Focus Genie and it looks like a simple and inexpensive way to check front/back focusing. However, according to what I've read, laminating focus targets would be a big no-no. In fact, the FoCal instructions recommend that you print their targets on heavyweight matte paper using an inkjet printer rather than a laser printer. Supposedly, just the reflectiveness/shinine​ss of the toner used in laser printers can adversely affect the reliability of the results.

Have you noticed any problems focusing on a laminated target?

Nope, no issues at all, and I have used this to MA all my lenses over the past couple of years. I actually think having high contrast (which you get with sheen) helps the AF latch on more positively then something printed flat and with low contrast personally. Also, you are pointing directly perpendicular to the target so unless you have a light directly on the camera pointed at the chart or directly behind you (that would then bounce back at you at the same incident angle), you should not even notice the lamination.

There is a free version you can print if you want, there is a link on the sale post.


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BTBeilke
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Aug 01, 2012 15:15 |  #14

TeamSpeed wrote in post #14800774external link
Nope, no issues at all, and I have used this to MA all my lenses over the past couple of years. I actually think having high contrast (which you get with sheen) helps the AF latch on more positively then something printed flat and with low contrast personally. Also, you are pointing directly perpendicular to the target so unless you have a light directly on the camera pointed at the chart or directly behind you (that would then bounce back at you at the same incident angle), you should not even notice the lamination.

There is a free version you can print if you want, there is a link on the sale post.

Thanks, TeamSpeed.

Although I'm a little confused by the statement I've highlighted above. My understanding of contrast in relation to photography has always been similar to this dictionary definition:

Contrast (Photography) . the relative difference between light and dark areas of a print or negative.

Does contrast really have anything to do with glossy versus flat surfaces? It seems to me that highly reflective surfaces could have the effect of reducing contrast by making a very dark surface look much lighter (i.e. bright highlights on a gloss black car). (For the record, I'm talking in generalities here and not specifically about your Focus Genie.)


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TeamSpeed
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Aug 01, 2012 15:18 |  #15

BTBeilke wrote in post #14801070external link
Thanks, TeamSpeed.

Although I'm a little confused by the statement I've highlighted above. My understanding of contrast in relation to photography has always been similar to this dictionary definition:

Contrast (Photography) . the relative difference between light and dark areas of a print or negative.

Does contrast really have anything to do with glossy versus flat surfaces? It seems to me that highly reflective surfaces could have the effect of reducing contrast by making a very dark surface look much lighter (i.e. bright highlights on a gloss black car).

That comment was in regards to a "sheen" that a laser printer might put on a sheet of paper for the printed material. It is also in regard to any light reflections you might get off the lamination depending on light placement and your position to the focus chart. In any case, I have only received compliments from a majority of customers that liked how simple and well it worked for their needs.


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"Adjust by Lens" Microadjustment?
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