What is the difference between 8 pin and 5 pin lenses?

Just wondering why some lenses have 8 pin connections and some have 5 pin connections?

All my current lenses have 5 pin connections but a new lens that I am looking to get has 8 pins and I was wondering why the difference and is there any advantaages to the 8 pin over the 5 pin?

ADI

http://forums.dpreview.com/forums/read.asp?forum=1035&message=17337741

The manual should also have more info

These identical examples may help if these are uploaded in a useful size. The first image is my Minolta 75-300 at 300mm. The second image is my Tamron 5 pin also at 300mm, the subject is about 5 metres away and a speedflash was used on a Sony A290. The Minolta has much better clarity which can be seen mainly in the stitching on the black jacket near the velcro patch which was the point of focus. The Tamron has never given me the clarity I've wanted, always just a little out of focus and the colours are always washed out and dull. I'm assuming with my limited knowledge of the electronics that it's to do with the pins. I definitely won't risk a 5 pin lens again.

8 pin

5 pin

Mark Shepherd wrote:

... The Minolta has much better clarity which can be seen mainly in the stitching on the black jacket near the velcro patch which was the point of focus. The Tamron has never given me the clarity I've wanted, always just a little out of focus and the colours are always washed out and dull.

Those are optical characteristics unrelated to the electrical contacts.

I'm assuming with my limited knowledge of the electronics that it's to do with the pins.

Absolutely not.

I definitely won't risk a 5 pin lens again.

That's kind of sad because some of the finest A-mount lenses are 5-pin designs.

bobotech wrote:

Just wondering why some lenses have 8 pin connections and some have 5 pin connections?

The answer is here.

Why do some lenses have 5 contacts, and some have 8?

The original Minolta A mount had 5 lens contacts. Later, with the xi generation of cameras and lenses, 3 contacts were added. These were used as an additional power source and an additional communication path. They were required for the auto-zoom feature of xi lenses. Also see “What's a “xi” lens?”.

Later, the three additional contacts were also used for the (D) and SSM function. Also see “What's a “D” lens?” and “What's a “SSM” lens?”. So xi, D and SSM lenses necessarily have 8 contacts, while non-xi, non-D and non-SSM lenses need only 5 contacts. Basic information about focal length, aperture, etc. is communicated via the 5 original contacts. This means that even on older 5-contact bodies you can use 8-contact lenses. Of course, ADI, SSM and auto-zoom won't work, then, but basic metering and program mode operation will work just fine.

Mark Shepherd wrote:

These identical examples may help if these are uploaded in a useful size. The first image is my Minolta 75-300 at 300mm. The second image is my Tamron 5 pin also at 300mm, the subject is about 5 metres away and a speedflash was used on a Sony A290. The Minolta has much better clarity which can be seen mainly in the stitching on the black jacket near the velcro patch which was the point of focus. The Tamron has never given me the clarity I've wanted, always just a little out of focus and the colours are always washed out and dull. I'm assuming with my limited knowledge of the electronics that it's to do with the pins. I definitely won't risk a 5 pin lens again.

8 pin

5 pin

if you disabled those contacts on both lenses (and used them fully on manual ) you would still have the same difference.

BTW, I had to micro focus adjust one of my Sony lenses (probably made by Tamron) but did not have to adjust my two Tamron lenses.