RTS III / TLA360 flash compensation

[Pablo2000]

Please would someone more Contax-savvy than this newbie offer some guidance.

Using the above camera/flash combination in Av, I’m trying to figure out how to perform a flash compensation in a balanced lighting scenario. Following normal practice I would meter for the ambient exposure, apply AELock, then add TTL flash compensated for the subject reflectivity.

Obviously the ambient side of things is fine but I can’t figure out how to adjust the flash level. The TLA360 manual says: “TTL control is applied without regard to the film speed and aperture settings in the flash unit.” - so all settings in the flash are redundant (apart from fl spread). It also says: “In TTL auto mode, the output from this flash unit can be adjusted linked with the camera’s exposure compensation.”. The RTS III manual also says: “If you want to enhance the effect by adjusting the flash light, use the exposure compensation dial.”.

So, easy right? Lock in the ambient exposure (presumably before turning on the flash) and twiddle the compensation dial to increase/decrease the flash exposure once it’s charged. Makes total sense. But what I’m seeing in the viewfinder doesn’t make sense. I lock the ambient exposure, and the shutter speed starts flashing, at say 60. Turn on the flash unit and lightening symbol appears when charged. If I then twiddle the compensation dial, the shutter speed is changing - which of course alters the ambient exposure whether it adjusts the flash output or not. Same result if I lock the ambient, use a pre-flash TTL lock - adjusting the compensation dial causes the non-flash part of the exposure to change.

So my question is: what’s up with that? Can someone please tell me where I’m going wrong either in action or thought.

Thanks guys/gals

 

[pfharrison]

The TLA 360 does support on flash compensation, it is applied on the flash itself using the buttons on the flash and is an additional level of compensation to the camera body exposure compensation. the 2 are added together. It does not appear to be covered in the TLA 360 manual. It is covered in some of later camera body manuals, such as the AX manual. I suspect that it relies on the 5 pin hot shoe connector of the later Contax bodies, and as such may not work with the RTS 3 which only has a 3 pin hot show connector. You could give it a try with the RTS 3,

 

[Pablo2000]

Thanks for pointing me to the AX manual - it was very illuminating (pun intended).

Today I had some time to mess around with the flashes and my handheld flash meter and the following are my deductions:-

1) Because the AEL locks the EV not the aperture/speed (which is super useful and one of the things I love with this camera), any use of the compensation dial _always_ affects the speed. It does also vary the flash output.

2) If, instead, you make the ambient reading using match-meter in M mode, the compensation dial then only affects the flash output - exactly as I wanted.

3) This only works with my TLA30 (a 3 pin unit). This does not work with the TLA360 (a five pin unit).

4) The TLA360 will NOT allow access to it’s built in compensation setting unless on a five pin camera - presumably as a result of the camera communicating iso and aperture to the flash.

5) I’m sceptical that the TLA360 is even performing TTL controlled output at all on the 3 pin camera! My flash meter readings tend to indicate that the TLA360 on the RTS III is only usable as an “auto” or manual flash.

So, I have learned how to achieve the result I was after but very disappointed that the TLA360 will not function at least as well as the much older TLA30. Still, as we all no doubt know, Contax backward compatibility is a bit hit and miss. This one’s a definite miss. I bought the 360 for it’s significantly better bounce capabilities and the zoom head.

I hope someone finds my experiments and results useful.

 

[pfharrison]

1 I presume that you are using AV mode it probably adjusts the aperture in TV mode.

My understanding of the TTL flash, is that it only requires 2 of the three pins. It is an on / off system, the on signal is sent to fire the flash and the off is sent when the camera body determines the exposure is correct. The flash just does as it is told. This should work fine on the TLA 360 as it has the required pins, if it is not working then you may have an issue with the TLA360. The older contaxes used all 3 pins for TTL, but this was changed, and the third pin reserved for second curtain sync. This is why the later flashes do not work in TTL mode with the 137 and 139.
The extra 2 pins on the 5 pin hot shoe, are used to access the extra features of the TLA360 only, some features work with some camera bodies and not other camera bodies, only the autofocus SLR bodies give you the auto zooming of the flash head. I think that most if not all of the 5 pin hot shoe camera bodies transmit the aperture and speed, and so can display the valid auto range. The on flash exposure compensation only seems to work with some of the 5 pin hot shoe camera bodies. I think that you only get access to the full features of the TLA 360 with the N series or the 645.

 

[Pablo2000]

Good catch old chap!

I renounce points 3 and 5 above. I traced the issue to a dirty pin on the TLA360 making poor contact at the “flash off” pin.

It still isn’t really working as one might infer from the manual, but I’m happy enough with my workaround number 2 above - it’s behaving consistently now and I’ve still got the benefits of the 2 way bounce head and the zoom head (yes, I knew it wouldn’t autozoom).

 

[pfharrison]

Well that is progress, the Contax multi-flash TTL set up is fun to play with, I just mention that in passing. I did a set of 3 videos on Youtube about the Contax TLA Flash system, so I looked into it for them.