iISO flash shoe

Minolta/Sony iISO flash shoe - Minolta Maxxum 9 specimen pictured
Pre-1985 Minolta ISO 518 hot-shoe - Minolta X-500/X-570 specimen pictured

iISO (intelligent ISO) flash shoe (aka "reversed" hotshoe) is the unofficial name for the proprietary accessory flash attachment and control interface used on Minolta cameras since the i-series introduced in 1988, and subsequently Konica Minolta and later Sony α DSLRs and NEX-7 up to 2012. Sony called it the Auto-lock Accessory Shoe (AAS). In order to speed up and enhance attachment, detachment and latching, it departs from the conventional circa-1913 mechanical design that is now standardized as ISO 518:2006[1] and used by other camera systems, including Canon, Nikon, Pentax, Olympus, and Leica.

History

The mechanical design of the accessory shoe now common on most cameras dates back to 1913, when Oskar Barnack, the inventor of the Leica, devised it for attaching an accessory viewfinder.[2] By 1940's, with the addition of the central contact, the design became commonly used for attaching and triggering accessory flashes and known as the "hot-shoe". Prior to 1988, Minolta has used that familiar, common hot-shoe design, adding, just like the other makers, its own proprietary contacts for enhanced control.

In 1988, Minolta introduced the iISO flash shoe in its new i series of cameras. Reportedly conceived with the input from Herbert Keppler in 1987, the new Minolta patented design[3] featured a push-button latching mechanism, for the purpose of easier and faster flash attachment and removal and a more secure hold.

On 12 September 2012, Sony introduced a new 21+3-pin metal-based hotshoe with mechanical quick locking mechanism, called Multi Interface Shoe. At first sight it resembles a standard ISO 518 hotshoe with just the middle contact and chassis and without any vendor-specific extra contacts, but additional contacts are hidden under the front of the hotshoe. The new hotshoe is mechanically incompatible with the iISO hotshoe, but electrically backwards compatible. The first cameras to use the new hotshoe are the SLT-A99, NEX-6, NEX-VG900, NEX-VG30 and DSC-RX1. An ADP-MAA adapter to the iISO flash shoe is however provided with the Sony SLT-A99, and the newest flash Sony HVL-F60M, which uses the new hotshoe comes with a reverse adapter ADP-AMA for older Sony and Minolta cameras.

The last cameras introduced utilizing the iISO hotshoe in 2012 were the SLT-A37 and NEX-7 as well as the Hasselblad Lunar.

Design

Mechanical

The use of the button-operated latch, besides facilitating a quick, one-handed flash attachment and detachment, also eliminates the possibility of the flash gradually working itself loose and shifting in the shoe, which on camera systems using the ISO 518 hot-shoe can lead to certain contacts being broken, contacts with the wrong pins being made, or in extreme cases the flash sliding off the hot-shoe entirely.

Electronic Contacts

Listed top-to-bottom (looking at the flash shoe socket as pictured above, or with the camera positioned with the lens pointing up):[4] The electrical interface and protocol is backward-compatible with the older Minolta hotshoe, except for that it does not support the F4 signal, which was provided by the first generation of Minolta AF SLRs to control the AF illuminator, as this function became part of the digital protocol.

Pin Wire Analog Digital
F3 black TTL OK Clock
F2 white Ready Bidirectional serial data
G blue Ground Ground
F1 red Sync / trigger flash --

Variations

Criticism

The iISO hot shoe's introduction left few informed users indifferent - some photographers loved it, while others hated it. The sentiment revolves around these areas:

iISO flash accessories

List of Sony flashes for Auto-lock Accessory Shoe:

Model VX code Hotshoe Guide number [m] ISO Manual steps Released Comments

HVL-F20AM Auto-lock Accessory Shoe (iISO) (4-pin) 20 100 2009 similar to HVL-F20M; not to be confused with HVL-F20S

HVL-F36AM Auto-lock Accessory Shoe (iISO) (4-pin) 36 100 - (not manually configurable) 2006 identical to Minolta Program Flash 3600HS(D)

HVL-F42AM VX9039 Auto-lock Accessory Shoe (iISO) (4-pin) 42 100 1/1-1/32 in 1/1 EV steps 2008

HVL-F43AM Auto-lock Accessory Shoe (iISO) (4-pin) 43 100 1/1-1/128 in 1/3 EV steps 2011 not to be confused with HVL-F43M

HVL-F56AM VX8950 Auto-lock Accessory Shoe (iISO) (4-pin) 56 100 1/1-1/32 in 1/1 EV steps 2006 identical to Minolta Program Flash 5600HS(D)

HVL-F58AM VX9010 Auto-lock Accessory Shoe (iISO) (4-pin) 58 100 1/1-1/32 in 1/1 EV steps 2008 similar to HVL-F60M

HVL-MT24AM Auto-lock Accessory Shoe (iISO) (4-pin) 24 100 2006 Macro twin flash similar to Minolta Macro Twin Flash T-2400 with Minolta Macro Flash Controller MFC-1000, but lacking the jack for the Minolta Macro Ring Flash R-1200/1200AF

HVL-RLAM ISO-518 (0-pin) 2006 LED ring light, not a flash; mechanical mount adapter FA-SA1AM supplied with HVL-RLAM[8]

References

  1. 1 2 Photography -- Camera accessory shoes, with and without electrical contacts, for photoflash lamps and electronic photoflash units -- Specification, 2006 revision
  2. "Speaking Frankly" PopPhoto blog by Herbert Keppler, January 10, 2007 post "Inside Straight: Shoe Fetish"
  3. Matthias Paul: Article at Minolta-Forum detailing the Minolta hotshoe patents
  4. Matthias Paul: Article at Minolta-Forum on trigger circuit voltages, also describing the evolution of the Minolta hotshoe pinout over the decades
  5. Matthias Paul: Article at Minolta-Forum on the Minolta flash protocol - first known public description of parts of the digital data format
  6. Matthias Paul: Article at Minolta-Forum on various camera and accessory pinouts - first known public description of the various hotshoe signals, origin of naming conventions
  7. Matthias Paul: Article at Minolta-Forum detailing the Minolta FS-PC internals
  8. 1 2 Paul, Matthias (2009-07-11). "Name of Sony mount adapter for HVL-RLAM ring light". Retrieved 2015-06-28.

External links

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