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Tech Camera Focus Fine Tuning

rga

Member
Victor,

That's true, that infinity is not a measurable distance, and that's why Alpa gives a infinity distance = 20 x Focal Length in Meters. That's the minimum which should be taken for infinity, when calibrating the back.
I have seen photographers using simply the focal length in meters.

Thierry
I love this. I think I'll call it Thierry's Theory: "Infinity has no end, but we know where it starts."
:thumbup:
Made my day!! Thank you Thierry!
 

Thierry

New member
Calling it "Alpa's Theory" would suffice for my happiness.

;)

But yes, it's a good definition.

Thierry

I love this. I think I'll call it Thierry's Theory: "Infinity has no end, but we know where it starts."
:thumbup:
Made my day!! Thank you Thierry!
 

vjbelle

Well-known member
Of course one can do this at any distance. Alpa does the shimming for instance at 2-3 meters, allowing therefore to do it inside and not be dependent of the weather. But then it needs special tools like a laser-pointer and a special target telling how much to shim. Also, a special lens is used, calibrated for a distance of 2 m and a maximum opening of f 2.2.
Thierry,

This sounds a lot to me like the OP!! How about that....I just ballparked infinity (which is all you can do) and then fine tuned for close distance and I didn't have to have a special lens or spend a couple thousand CHF. All I needed was a Disto and a LensAlign:). Thank you for substantiating my hypothesis:salute:

Victor
 

Thierry

New member
Victor,

That sounds fine, no problem with that. I was speaking how we do it, in a way that can be repeated, with the same lens, the same distance, the same target, thus excluding as much variables as possible, and how we recommend to do it without any additional cost.

:thumbup:

Best regards
Thierry

Thierry,

This sounds a lot to me like the OP!! How about that....I just ballparked infinity (which is all you can do) and then fine tuned for close distance and I didn't have to have a special lens or spend a couple thousand CHF. All I needed was a Disto and a LensAlign:). Thank you for substantiating my hypothesis:salute:

Victor
 

delled

New member
Longer Arca R lenses -- at least my 70mm and 120mm -- are marked on the back of the lens board with a sticker: "~ = 2Km". I take this to mean that they have been calibrated for infinity (extension = 0) at 2km. No marking appears on my 43mm lens.

Dave.
 

Thierry

New member
I loved this, so am tempted to make a connection between infinity and eternity and equate distance and time:

"Eternity is really long, especially near the end" - Woody Allen

Thierry

"Infinity has no end, but we know where it starts."
 

rga

Member
I loved this, so am tempted to make a connection between infinity and eternity and equate distance and time:

"Eternity is really long, especially near the end" - Woody Allen

Thierry
Have to go see his new movie; his "photography" is always stunning in his later films.

Great quote: thanks!
 
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