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Old Jun 21, 2007, 3:27 AM   #1
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Howzit everybody....

I was cruising around this forum - kinda revisiting old posts that had info on my trusty 3600hs-d.

I had hoped I could learn more on "ADI".... how it works, and what lenses are compatible. It's my understanding that any "D" type lens would support this - so am I safe in assuming my Sigma 24-135 f2.8-4.5 D would work okay?

Addmitedly, I've had both for a while, but just never tried them together.

Looking forward to hearing back from you!

~aloha~
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Old Jun 21, 2007, 3:33 PM   #2
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It should.

Sigma has done there best to reverse engineer the dataa lense needs to send to the body.
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Old Jun 21, 2007, 3:58 PM   #3
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The easy way to tell is to count the lens mount contacts.

If there are only 5 contacts, it's not ADI compatible. If there are 8 contacts, it should be ADI compatible if Sigma implemented it correctly.

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Old Jun 21, 2007, 4:20 PM   #4
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P.S.

Basically, the lens is sending back more accurate focus distance information to the camera with an ADI compatible lens. The idea behind it is so that the flash system can better determine the flash burst length needed to properly illuminate your subject.

Note that KM and Sony DSLR models always use a preflash anyway, regardless of whether or not you have an ADI compatible lens, and regardless of whether you're using ADI or pre-flash TTL settings for flash.

I've seen no conclusive evidence that ADI really helps improve flash exposure accuracy with these models. I can remember a thread on another forum a while back where users were trying both ADI and pre-flash TTL modes and couldn't tell the difference. That could just be the current algorithms (and I don't think the users were testing in controlled conditions anyway).

There is also evidence to suggest that focus distance information is available to the camera, even without ADI lenses.

I can remember some comments from Dalibor Jelinek stating something to the effect that this information is "surprisingly accurate" when he was doing some testing with non-ADI lenses with .mrw files from a 7D. Speculation is that the camera is probably counting the turns of the focus screw to determine it, as long as it "knows' the characteristics of the lens, even without the extra information being passed via the new ADI specific contacts.

Dalibor Jelinek figured out where Minolta puts the focus information a long time ago and has publically commented on the focus distance being recorded from non-ADI lenses in forums before.

He has some good documentation on the maker notes tags here:

http://www.dalibor.cz/minolta/makernote.htm

He's got some documentation on .mrw format here:

http://www.dalibor.cz/minolta/raw_file_format.htm

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Old Jun 21, 2007, 5:42 PM   #5
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Mahalo Jim.

So in a nutshell, I pretty much won't be able to tell the difference between ADI and TTL modes?

A while back, a forum member posted that he found most success when shooting his 5d and 3600hs(d) in AWB, auto ISO, A mode with ap. set to f8.Can't remember who it was, but he did quite a lengthy write up and posted up comparison shots in different modes in different lighting situations. I found this works the best (and easiest) for me - I guess my ADI question is moot as I've heard once the flash goes into bounce mode, it defaults back to TTL anyways.

~aloha~
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Old Jun 21, 2007, 5:47 PM   #6
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Do some tests both ways in controlled conditions and let us know what you find out. lol

It would be pretty difficult to really tell for sure how much (if any) it may help, as the camera settings for ADI or Pre-flash TTL may not alter everything about the algorithms when you use an ADI lens. To do a more thorough test, you'd probably need the same lens model in both ADI and non-ADI versions, and run a lot of tests of different subject types in controlled conditions.

But, with a Sony or KM DSLR, you get a metering preflash either way (even using an ADI lens with the camera flash mode set to ADI).

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