Technical references

This page is a collection of technical references surrounding Minolta/Sony flash equipment.

ISO flash shoe (old version)

The original AF series of cameras and flashes used a variant of ISO flash shoe. Here's the pinout:

ISO flash shoe, top is front

Signal NameIOComment
GGground (blue)
F1sync / fire flash (connect G and F1) (red)
F2flash ready signal / data (white) [also: bidirectional serial data line “F2OUT”, “F2IN”]
F3TTL OK signal / clock (black) [also: serial data output: “F3L” + “F3H”]
F4AF assist light control (only on 9000AF, 7000AF and 5000AF)

iISO flash shoe (new version)

Later cameras and flashes used a new flash shoe which sometimes is called “iISO”. Sony calls this flash connector “Auto-lock Accessory Shoe”. Here's the pinout:

iISO flash shoe, top is front

Signal NameIOComment
GGground (blue)
F1sync/fire flash (connect G and F1) (red)
F2flash ready signal/data (white) [also: bidirectional serial data line “F2OUT”, “F2IN”]
F3TTL OK signal/clock (black) [also: serial data output: “F3L” + “F3H”]
F5/VDD1Pflash power, regulated (+5V) & control (only on Dynax/Maxxum 3000i/Alpha 3700i)
F7/PGNDGpower ground (only on Dynax/Maxxum 3000i/Alpha 3700i)
F8/VDD0Pflash power, unregulated (+6V) (only on Dynax/Maxxum 3000i/Alpha 3700i)

Note that F5, F7 and F8 are only present on the Dynax/Maxxum 3000i/Alpha 3700i and are used to power and control the D-316i and D-314i flashes.

Multi Interface flash shoe

A new flash shoe was introduced by Sony with the SLT-A99, NEX-6 and other cameras. It has an ISO-like layout, but with additional contacts underneath the front rim.

Multi Interface flash shoe, top is front

There are several functions on the MI shoe:

The pinout (seen from top/rear) is:

23 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 24

(pins 23 and 24 are connected to the frame, pin 22 is the center contact)

As you can see in the table below, many pins have multiple functions, so you can only connect one type of device at a time.

FunctionPin #IOSignal NameComment
Power and ground7GREG_GNDlogic ground
15GREG_GNDlogic ground
13PLOGIC_VDDregulated power at 3.15 V
17PUNREGunregulated battery power, fused at 1.6 A
21GPGNDunregulated battery ground
Accessory ID1ID3accessory ID bit 3
2ID2accessory ID bit 2
3ID1accessory ID bit 1
Analog microphone4GMIC_GNDmicrophone ground
5MIC_Lleft channel
6MIC_Rright channel
14MIC_Ccenter/correction channel
GPS8GPS_PWR_CTRLGPS power control
9GPS_CTSGPS handshake
10GPS_RTSGPS handshake
11GPS_UART_TXDGPS data out
16XGPS_RSText. GPS reset
9WLAN_SD_D0WLAN data 0
10WLAN_SD_D1WLAN data 1
11WLAN_SD_D2WLAN data 2
12WLAN_SD_D3WLAN data 3
16XWLAN_RSText. WLAN reset
Audio output14AUDIO_Laudio output, left channel
16AUDIO_Raudio output, right channel
Flash18F3flash F3
19F2flash F2
20F1flash F1
22XISO_SHOE_Xflash center contact, connected to FG when flash fires. Corresponds to F1 on older shoes.
23GISO_SHOE_FGframe ground, also connected to REG_GND
24GISO_SHOE_FGframe ground

Accessory types are identified by the device by connecting the ID pins either directly to logic ground (●) or via a 470 kΩ resistor to logic ground (○).

Known accessory IDs are:

ID1ID2ID3accessory type

Flash connector

This round connector is found on some flashes and all cables and connectors. Here's the pinout:

Connector, male socket

Signal NameIOComment
GGground (blue)
F1sync / fire flash (connect G and F1) (red)
F2flash ready signal / data (white) [also: bidirectional serial data line “F2OUT”, “F2IN”]
F3TTL OK signal / clock (black) [also: serial data output: “F3L” + “F3H”]

The current Minolta AF/Sony Alpha flash system has grown quite complex, and it is not very well covered in the manuals. That's because this would involve to cover some very basic concepts, and there are many combinations of cameras and flash units with different capabilities that would have to be documented. What I try here is to explain how the Minolta flash system works in detail. This compendium assumes that you have some basic knowledge of photography, ie. you know that an aperture is and you know how a shutter works. Sony has taken over further development of the Minolta A mount (now Sony Alpha mount) and has also kept the Minolta AF flash system with their new DSLRs. When this compedium says "Minolta", the same is true for "Sony Alpha", too, except when noted otherwise.