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Archive 2016 · Micro Focus - Daylight or Tungsten
  
 
leethecam
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p.1 #1 · p.1 #1 · Micro Focus - Daylight or Tungsten


Interested to know which colour temp of light people are using to set their micro focus accuracy.

I've a 5D3 and traditionally I use daylight. But reading up on the subject it seems there can be differences between 3200K and daylight.

Much of my shooting is at events, so tungsten and down to 2200K at times, but then commercial stuff and weddings might take me outdoors...

Any experiences with either type? (I'm about to use Reikan FoCal Pro as I'm fed up trying to guess on chart type systems and Dot Tune didn't seem to get it for me).



Nov 19, 2016 at 12:34 PM
schlotz
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p.1 #2 · p.1 #2 · Micro Focus - Daylight or Tungsten


AFMA requires bright light to ensure the AF system can operate effectively. IMO nothing better than a bright sunny day and no wind to perform it. I've used both FoCal & Dot Tune for afma. While FoCal is certainly more detailed, at the end of its process I got the same setting result as DT, so not having to lug a laptop and cables outdoors is an advantage for me. YMMV.


Nov 28, 2016 at 01:41 AM
Peter Figen
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p.1 #3 · p.1 #3 · Micro Focus - Daylight or Tungsten


I do it in my studio using a Lens Align and an Arri 650 fresnel lighting the target. Works great.


Nov 28, 2016 at 05:04 AM
leethecam
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p.1 #4 · p.1 #4 · Micro Focus - Daylight or Tungsten


Initial tests with FoCal seem promising. The ability to test at 50x distance with a decent size target is a real bonus and I like the history tab in the program to check repeated tests.

I've printed the target at 210mm on smooth matt art paper with an accurate profile for max black / contrast print.

I've set it for high number of tests, requiring a strict level of focus accuracy and target optimisation.

I nuke the target with an open face 800W tungsten light so @ ISO100 I'm getting 1/320, (academic I guess with the mirror up function).

I'm getting consistent results and quick tests are showing sharp images. I'll be doing some more detailed real-world shooting to be sure before using with a paying client.

I must admit, it is nice not to be peering at a small ruler and trying to guess which lines are most in focus - ha.



Nov 28, 2016 at 09:21 AM
Michael White
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p.1 #5 · p.1 #5 · Micro Focus - Daylight or Tungsten


Daylight


Nov 30, 2016 at 06:04 AM
 

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Abbott Schindl
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p.1 #6 · p.1 #6 · Micro Focus - Daylight or Tungsten


Daylight


Dec 11, 2016 at 05:50 PM
JimboCin
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p.1 #7 · p.1 #7 · Micro Focus - Daylight or Tungsten


The FoCal Quick Start Guide has this interesting comment:

"Whilst the target is black-and-white, the analysis does take into account the way different colours travel through the lens, so itís a good idea to try and light the target with a light that is relatively close to white."

and a note as to things that impact AF "Even the colour of the lighting youíre shooting under!"

This sounds interesting. I believe I recall emailing FoCal about the impact of lighting color on AFMA, and I recall them telling me the impact was minor with the color balance between tungsten at 2800K and daylight (nominally 5500K) but that you should not use colored lighting.

Of course one could do a test AFMA with each type lighting to see if there is any difference.

---

The FoCal Quick Start Guide has a lot of interesting technical information in it that I have not seen elsewhere.

For example, they have information on the impact of target distance versus lens focal length that I have not seen anywhere else. This includes a graph and a table with some pretty interesting data. (Pages 19 through 21 of the document linked to below.)

Here is the link to that document:
http://s449182328.websitehome.co.uk/focal/dl//Docs/Manuals/Reikan%20FoCal%202.4.0%20Quick%20Start%20Guide.pdf



Feb 10, 2017 at 03:18 PM
gschlact
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p.1 #8 · p.1 #8 · Micro Focus - Daylight or Tungsten


Many Photographers for their set of camera and lenses carry a cheat sheet with different MFA settings for different lighting. Tungston at most 2700K typically will cause a shift if AF opposite to say cool Florescent at 5000K+. It really stinks when as a photog you are stuck needing different MFA values for a single lens such that you get oof results when the lighting changes. If MFA using Tungston, and then shoot at cool white, you will if I remember correctly, g t consistent back focus, and visa versa. My original 24-70 mk1 on my 7d (orig) had this issue. The worst part about it was Canon not acknowledging it during the three trips despite me showing a single MFA number could not be used. The amount of time spent chasing them was unbelievable. If they hadn't told me that a single MFA is supposed to work then I wouldn't have pushed so hard. It was not due short long as a single FL displays this phenomenon. Only afterward did I find corroboration online by other photogs who simply acknowledge it and don't try to fix it. So, literally if you only shoot in one type of light, MFA using that type, otherwise pick a Kelvin Temp in the middle of the type of lighting you'll use. Indoor bright halogen works quite well for MFA. Halog n also has then benefit of high CRI (color rendering index) to appease any color sensitivity of the AF sensor. Good luck, but most lenses do afford sing set of MFA across lighting types.


Mar 06, 2017 at 02:57 AM
Zenon Char
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p.1 #9 · p.1 #9 · Micro Focus - Daylight or Tungsten


For using Focal I purchased 2 daylight balanced studio CFL's and my MFA target is located in a bright porch. I have had accurate results with using incandescent light but I prefer the clean look of daylight which is which I shoot in most of the time.


Mar 14, 2017 at 03:28 PM
leethecam
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p.1 #10 · p.1 #10 · Micro Focus - Daylight or Tungsten


As a follow up...

I calibrated my lenses under tungsten and have been shooting in a variety of lighting conditions, (daylight / tungsten / mixed) - often wide open between f2.8 and f1.4

I calibrated using FoCal.

So far results have been spot on. Sharp, accurate every time. If there is a difference, I've not seen it in the end results.



Mar 14, 2017 at 06:47 PM







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