Cornerfix - lens profile assistance please

[mmradman]

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I have taken ZM 21mm f4.5 profile picture on M9 with following parameters;

 

Illumination setup - grey card on the table next to the window with daylight hitting card

sideways, no noticeable shadows.

Grey card - SECOL freestanding negative storage cardboard box about 30x30cm square.

Exposure - Auto

Aperture - maximum f stop

White Balance - Manual set against white paper.

Compensation +2EV

Focus - minimum distance, camera is placed level on mini tripod approx. 30cm away from grey card.

Lens detection (a) OFF and ( 21mm pre ASPH - looks better when set as 21mm pre ASPH.

 

Images corrected via CF are improvement on the original but I have a question; did i do everything right, for instance is my focus distance correct, i.e. minimum distance or infinity.

 

Suggestions welcome.

 

p.s. I have read manual, googled and searched LUF beforehand.

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[tobey bilek]

You are supposed to use a large white board on the north side of your house in the shade. Do not let it pick up a color cast from green grass. I actually used a blacktop drive and my car. Grey may work if you overexpose it to white, around 235 in PS.

 

I got a 2x3 footer SMOOTH one from the local art store.

 

Use infinity focus and move close enough to fill the frame. Out of focus does not matter.

 

It better be smooth or CF will try to cancel the texture if it sees any.

 

This works better than in camera corrections, but I still allow my camera to do its thing, then perfect it with CF. Make a profile for each lens and every stop wide open to 8. You will need two sets, one with lens detection on and one off. I only use the profiles generated from DNG with camera detection enabled now so the camera does the heavy lifting and I use my profiles for critical scenes where perfect color is required like snow scenes. Otherwise camera correction is sufficient alone.

[mmradman]

Thanks Tobey,

 

Some good application notes, need to get hold of big sheet of smooth either matt white or matt light grey card to repeat reference image(s).

[Guest JMF]

I used Cornerfix with the 21 Elmarit pre asph and M8.

In order not to over correct, you might test various degrees of correction with different reference shots done at different f stops . Same for the focus, see which works best for each situation. It's quite a subjective process.

Then keep a bank of references handy !