August 23, 2014, 03:29:47 AM

Author Topic: FoCal Target Image  (Read 1322 times)

gbchriste

  • EOS M2
  • ****
  • Posts: 172
    • View Profile
FoCal Target Image
« on: June 25, 2013, 02:14:10 PM »
I bought the FoCal software package but haven't tried it out yet.  The user guides say to set up the target at 50X the focal length you are trying to calculate.

I'm having real problems with me 70-200 2.8L when shooting at 200mm and longer distance.  I shoot mainly people/portraits and when I try to do a full body standing shot at 200mm I have to be backed up quite a ways.  Lately every shot I've taken in that set up comes out a muddled, mushy mess.  I have this lens for 3 years and now on my 3rd body (a 5D III) and this behavior has only recently started.

But to my question...when I print out the target and set up at 50X focal length at the working distance I'm trying to calibrate for, the target is pretty small in the view finder.  Hardly even extends out of the spot meter circle.

I haven't tried running through the software yet because I can't find a good day of light outdoors and the light inside my house sucks.  But I did a trial set up to see what it would look like at 32 feet distance - which is 50X 200mm and that target is awfully small.

Can I still calibrate with that target at that distance or do I need to get the target enlarged?

Drizzt321

  • 1D X
  • *******
  • Posts: 1668
    • View Profile
    • Aaron Baff Photography
Re: FoCal Target Image
« Reply #1 on: June 25, 2013, 03:08:41 PM »
Yes, you should. If you zoom in 10x on LV, you'll see it actually is still pretty clear. Remember, the AF point is actually fairly small, and that FoCal (in normal, default mode) is only checking the center AF point (I think) and using that to determine the AFMA. Also you'll have to change the AFMA settings yourself in between each test. Not FoCal's fault, Canon decided to remove the settings in the SDK for the 5d3 and 1DX. Bug Canon to get them to fix that. I have, hasn't done any good. I keep getting back generic, politely worded "thank you for your input, go suck an egg" responses.
5D mark 2, 5D mark 3, EF 17-40mm f/4L,  EF 24-105mm f/4L IS USM, EF 135mm f/2L, EF 85mm f/1.8
Film Cameras: Mamiya RB67, RB-50, RB-180-C, RB-90-C, RB-50, Perkeo I folder, Mamiya Six Folder (Pre-WWII model)
http://www.aaronbaff.com

neuroanatomist

  • CR GEEK
  • ********
  • Posts: 13862
    • View Profile
Re: FoCal Target Image
« Reply #2 on: June 25, 2013, 03:50:57 PM »
The standard target works fine at 50x focal length (I test at 25x and 50x).  I use a set of three 150 W-equivalent gooseneck lamps for a target taped to a wall in my basement, where I can test up to a 300mm lens. 
EOS 1D X, EOS M, and lots of lenses
______________________________
Flickr | TDP Profile/Gear List

Drizzt321

  • 1D X
  • *******
  • Posts: 1668
    • View Profile
    • Aaron Baff Photography
Re: FoCal Target Image
« Reply #3 on: June 25, 2013, 04:56:13 PM »
The standard target works fine at 50x focal length (I test at 25x and 50x).  I use a set of three 150 W-equivalent gooseneck lamps for a target taped to a wall in my basement, where I can test up to a 300mm lens.

So you can test a 300mm in your basement, use a 600mm for indoor (tight) portraits...how freaking big is your house?!
5D mark 2, 5D mark 3, EF 17-40mm f/4L,  EF 24-105mm f/4L IS USM, EF 135mm f/2L, EF 85mm f/1.8
Film Cameras: Mamiya RB67, RB-50, RB-180-C, RB-90-C, RB-50, Perkeo I folder, Mamiya Six Folder (Pre-WWII model)
http://www.aaronbaff.com

agierke

  • 7D
  • *****
  • Posts: 346
    • View Profile
Re: FoCal Target Image
« Reply #4 on: June 25, 2013, 04:56:41 PM »
just downloaded the manual today. it helps to read it. you may want to print a larger target.

http://www.reikan.co.uk/focalweb/index.php/why/documents-to-download/
5D3, 5D2, 5DC, s15mm Fish, 24mm TSE, 35mm F1.4L, 50mm F1.2L, 85mm F1.8, 100mm F2.8L, 24-70mm F2.8L, 70-200mm F2.8L, 580EX, 580EX2, 600EXRT

Canon1

  • EOS M2
  • ****
  • Posts: 181
    • View Profile
Re: FoCal Target Image
« Reply #5 on: June 25, 2013, 06:00:26 PM »
I have had great luck calibrating my lenses with FoCal and I use a much shorter focusing distance.  For 500mm I shoot from 13m instead of 50xfocal length which is 25m.  Basically I calibrated all my lenses using 25xfocal length which I found to produce much more accurate and repeatable results.  Then I did real world testing in the field and shot the target at longer distances and it was still spot on.  By getting closer you will reduce your DOF dramatically and give the program more pixels on the target for software evaluation. 

This is how I have done it for a couple of years now, and with the last version of FoCal they released this info:
http://s449182328.websitehome.co.uk/focal/dl//Docs/FoCal%20Test%20Distance_1.1.pdf

This PDF describes minimum focusing distances recommended by the software.  This tends to agree with my personal findings of using this software.  Just keep in mind that as your subject moves away from the camera the AFMA point for that shooting distance will change slightly. 

The way that I look at it: As subjects are farther away from you, DOF increases and absorbs some of that AFMA variance.  If subjects are close then it is absolutely critical that your AFMA is dead on as DOF is very small.  Therefore I calibrate at much closer distances then 50x focal length and achieved excellent results.  I don't change my AFMA at all while in the field... don't have to.

serendipidy

  • 1D X
  • *******
  • Posts: 1306
    • View Profile
Re: FoCal Target Image
« Reply #6 on: June 25, 2013, 06:12:53 PM »
The standard target works fine at 50x focal length (I test at 25x and 50x).  I use a set of three 150 W-equivalent gooseneck lamps for a target taped to a wall in my basement, where I can test up to a 300mm lens.

So you can test a 300mm in your basement, use a 600mm for indoor (tight) portraits...how freaking big is your house?!

Maybe it's not the size but the shape?

600mm X 50= about 100 feet
so a rectangular house that is average 2000 sq ft might be 100' X 20' and be perfect for FoCal and 600mm lens calibrations ;D
EOS 5D miii, EOS 7D, 70-200mm f/2.8L IS ii, 100-400mmL IS

Mt Spokane Photography

  • Canon EF 600mm f/4L IS II
  • ********
  • Posts: 8419
    • View Profile
Re: FoCal Target Image
« Reply #7 on: June 26, 2013, 12:48:59 PM »
I bought the FoCal software package but haven't tried it out yet.  The user guides say to set up the target at 50X the focal length you are trying to calculate.

I'm having real problems with me 70-200 2.8L when shooting at 200mm and longer distance.  I shoot mainly people/portraits and when I try to do a full body standing shot at 200mm I have to be backed up quite a ways.  Lately every shot I've taken in that set up comes out a muddled, mushy mess.  I have this lens for 3 years and now on my 3rd body (a 5D III) and this behavior has only recently started.

But to my question...when I print out the target and set up at 50X focal length at the working distance I'm trying to calibrate for, the target is pretty small in the view finder.  Hardly even extends out of the spot meter circle.

I haven't tried running through the software yet because I can't find a good day of light outdoors and the light inside my house sucks.  But I did a trial set up to see what it would look like at 32 feet distance - which is 50X 200mm and that target is awfully small.

Can I still calibrate with that target at that distance or do I need to get the target enlarged?

If you are having problems with target size, print a large one, 20 X 30 or something like that.  Just measure the distance of the bar on the chart in mm, and put that number into FoCal, and it will then recognize the distance to target correctly.