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Sigma 1.6X MD/MAF adapter

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vsldk View Drop Down
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Posts: 276 		Post Options Post Options   Quote vsldk Quote  Post ReplyReply Direct Link To This Post Topic: Sigma 1.6X MD/MAF adapter
    Posted: 20 January 2008 at 21:54
When I use this adapter/converter WITH a 1.4x AF converter AND a MD/MC lens AF on a Dynax 5D and a Sony a 100 works.
Can anyone explain why ??
Whitout the 1.4x converter it works not and AF is not possible.

Best regards,
vsldk

Edited by vsldk - 20 January 2008 at 21:55
 



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pegelli View Drop Down
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Posts: 39007 		Post Options Post Options   Quote pegelli Quote  Post ReplyReply Direct Link To This Post Posted: 20 January 2008 at 22:00
Does your 1.4x converter have a chip ?
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vsldk View Drop Down
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Posts: 276 		Post Options Post Options   Quote vsldk Quote  Post ReplyReply Direct Link To This Post Posted: 20 January 2008 at 22:21
Originally posted by pegelli pegelli wrote:

Does your 1.4x converter have a chip ?


I think so Sir, because whitout that converter it will not work on DSLR,
only on my old Monolta 5000 body.

Best regards,
vsldk
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eccl View Drop Down
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Posts: 757 		Post Options Post Options   Quote eccl Quote  Post ReplyReply Direct Link To This Post Posted: 21 January 2008 at 05:32
The Sigma 1.6X MD/MAF is designed for the earliest Maxxum AF camera.
Just like some other early Sigma lens, it will work if use together with a 1.4X or 2X TC.

I have this Sigma 1.6X TC and found out long ago it will work with a 1.4X or 2X TC. But the issue here is if you add a 1.4X or 2X TC on top of the 1.6X, you will need lens faster than F2.5 or (F1.4 for 2X) in order to AF which limit your choice to just a few lenses.
16/2.8 24/2.8 28/2 28/2.8 35/2 50/1.4 50/1.7 50/2.8 85/1.4 100/2 100/2.8 180/3.5 200/2.8 300/4 400/5.6 500/7.2 500/8

Zoom, TC and other lenses too numerous to list!
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vsldk View Drop Down
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Posts: 276 		Post Options Post Options   Quote vsldk Quote  Post ReplyReply Direct Link To This Post Posted: 21 January 2008 at 19:34
I try again :
"Can anyone explain why ??"

Best regards
vsldk
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pegelli View Drop Down
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Posts: 39007 		Post Options Post Options   Quote pegelli Quote  Post ReplyReply Direct Link To This Post Posted: 21 January 2008 at 20:32
eccl says it all, but I've chosen different words, so maybe (and hopefully) this is clearer to you:
+ doesn't work w/o another converter because it has an old chip which is not compatible with the A-mount DSLR's
+ doesn't AF with a 1.4 or 2x converter because the remaining aperture gets too small (too high number). Normally AF doesn't work above f-stops of 5.6 (in some rare cases f8 works, but no guarantee). so only if you have a MF lens faster than ~f2.5 largest aperture you won't get AF (or focus confirmation) to work.
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eccl View Drop Down
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Posts: 757 		Post Options Post Options   Quote eccl Quote  Post ReplyReply Direct Link To This Post Posted: 22 January 2008 at 17:23
Originally posted by vsldk vsldk wrote:

I try again :
"Can anyone explain why ??"

Best regards
vsldk


I'm not an expert in the Minotla AF lens protocol but I'll try one more time:

In the beginning Sigma reverse engineered the Minolta AF protocol and that is fine with the Minolta (5000/7000/9000 etc) cameras.

When Minolta introduced a new series of AF camera (i, xi, si, 7 etc.) it changed/updated the lens protocol in the body to improve function but still maintain backward compatibility with any Minolta AF lenses.

OTOH, Sigma earliest lens does not work on the newer camera body since something in the lens protocol is different or missing. Even newer Sigma lenses have problem with newer Minolta/Sony bodies and requires rechipped.   

Almost all chipped 1.4X/2X TC will work with any Minotla AF cameras and provide the correct information to the camera. When you put an early Sigma AF lens and a chipped 1.4X/2X together, the TC's chip read the lens information from the original lens and output the resulting FL/F stop combination to the camera. The resulting output is compatible with all Minolta cameras and this is why the cobmination works.

The 1.6X MD/MAF contains the same/similar chip as the earliest Sigma AF lenses and falls under the above category.

Hope this help.
eccl


Edited by eccl - 22 January 2008 at 17:27
16/2.8 24/2.8 28/2 28/2.8 35/2 50/1.4 50/1.7 50/2.8 85/1.4 100/2 100/2.8 180/3.5 200/2.8 300/4 400/5.6 500/7.2 500/8

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vsldk View Drop Down
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Posts: 276 		Post Options Post Options   Quote vsldk Quote  Post ReplyReply Direct Link To This Post Posted: 23 January 2008 at 21:50
To eccl and pegelli :
Thank you very much for your answers.
I think it is more clear for me now.

Best regards,
vsldk
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TCav View Drop Down
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Posts: 29 		Post Options Post Options   Quote TCav Quote  Post ReplyReply Direct Link To This Post Posted: 06 February 2008 at 00:31
I'm looking for a 1.4X TC that supports AF. Most don't.

Can you tell me what brand yours is?
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Posts: 757 		Post Options Post Options   Quote eccl Quote  Post ReplyReply Direct Link To This Post Posted: 07 February 2008 at 17:27
Originally posted by TCav TCav wrote:

I'm looking for a 1.4X TC that supports AF. Most don't.

Can you tell me what brand yours is?


Can you tell me what lens does not AF with a 1.4X TC?
Almost all 1.4X TC will AF with lenses with F5.6 or faster.
16/2.8 24/2.8 28/2 28/2.8 35/2 50/1.4 50/1.7 50/2.8 85/1.4 100/2 100/2.8 180/3.5 200/2.8 300/4 400/5.6 500/7.2 500/8

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Posts: 29 		Post Options Post Options   Quote TCav Quote  Post ReplyReply Direct Link To This Post Posted: 07 February 2008 at 18:03
Originally posted by eccl eccl wrote:

Originally posted by TCav TCav wrote:

I'm looking for a 1.4X TC that supports AF. Most don't.

Can you tell me what brand yours is?


Can you tell me what lens does not AF with a 1.4X TC?
Almost all 1.4X TC will AF with lenses with F5.6 or faster.


See my Chipped 1.4X TC post.

It seems that vsldk's 1.4X TC is doing exactly what I need a 1.4X TC to do. If I could find out what brand his is, then I will try to find one for myself.
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Posts: 276 		Post Options Post Options   Quote vsldk Quote  Post ReplyReply Direct Link To This Post Posted: 08 February 2008 at 09:27
Hi Sir !
I use a generic brand from Ebay for around 20,- L, the brand is :
"Photoco 1.4x M/AF Tele-Converter Japan"
I have also tryed a "Teleplus" it works too.
Bouth has 5 pins
I think all generic brand will works.
Good luck
Kind regards

Originally posted by TCav TCav wrote:

I'm looking for a 1.4X TC that supports AF. Most don't.

Can you tell me what brand yours is?
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eccl View Drop Down
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Posts: 757 		Post Options Post Options   Quote eccl Quote  Post ReplyReply Direct Link To This Post Posted: 08 February 2008 at 21:28
Any 1.4X TC with 5 Pin (Kalima, Rokuar, Quantaray, Vivitar etc.) will most likely have a chip inside.

Edited by brettania - 16 February 2008 at 06:48
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Posts: 29 		Post Options Post Options   Quote TCav Quote  Post ReplyReply Direct Link To This Post Posted: 09 February 2008 at 18:57
Originally posted by eccl eccl wrote:

Any 1.4X TC with 5 Pin (Kalima, Rokuar, Quantaray, Vivitar etc.) will most likely have a chip inside.


What I'm looking for is a 1.4X TC that supports autofocus for a lens (or lens assembly) that doesn't.

Originally posted by vsldk vsldk wrote:

When I use this adapter/converter WITH a 1.4x AF converter AND a MD/MC lens AF on a Dynax 5D and a Sony a 100 works.
Can anyone explain why ??
Whitout the 1.4x converter it works not and AF is not possible.


It seems to me that the 1.4X TC that vsldk is using is exactly the kind of TC I need.

Originally posted by eccl eccl wrote:

Correct F Stop and Focal Length Information With A Teleconverter

If a teleconverter has an IC chip (ROM) inside, it should display the correct F stop and focal length information to the camera body and EXIF data.
Example:
50mm F1.4 + 1.4X TC = 75mm F2
50mm F1.4 + 2X TC = 100mm F2.8
50mm F1.4 + 3X TC = 150mm F4

Based on my observation, almost all 2X teleconveter report the correct F stop and focal length information.

For 1.4X and 1.7X teleconverter, it depends on the particular make and model. Minolta APO 1.4X and Vivitar 1.4X TC both report the correct information while some other TC does not. Apparently some manufacturer has decided to design their TC without any IC Chip. This has resulted in incorrect information being displayed in the viewfinder and EXIF data. Other than the incorrect information, there is no issue of using the teleconverter.

The following 1.4X or 1.7X teleconverters (partial list) do not have chip inside therefore it will not report the correct F stop or focal length information to the camera.
Kenko Pro 300 1.4X (dedicated)
Kenko Pro 300 DG 1.4X (dedicated)
Promaster Spectrum 7 1.7X (generic)
Soligor 1.4X Pro (Probably a rebadged Kenko Pro 300)
Soligor 1.7X C/D4 AF (generic)
Sakar MC4 1.7X (generic)
Tamron SP 1.4X (dedicated)
Tamron MC4 1.4X (generic)

The camera just ignores the presence of the teleconverter although you still have correct exposure since exposure is based on actual amount of light passing through the lens. You'll also notice the viewfinder is dimmer and the focusing is slower because of the reduction of light to the camera.

One side benefit of using non-chip passthrough TC is the camera will attempt to AF with a slower lens previously not possible.

Example:
75-300mm or 100-300mm F4.5-5.6 with a 1.4X TC will normally not AF, but with a non-chip 1.4X or even 1.7X TC, it will try to AF but whether it can lock focus is another story :)


Edited by brettania - 16 February 2008 at 06:49
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