topic Re: NEX-5N Flash A,S,M Modes in Alpha & NEX interchangeable lens cameras

NEX-5N Flash A,S,M Modes

DNDNDN — Sun, 02 Sep 2012 23:37:16 GMT

Using a HVL-F20S flash.

When I use my NEX 5N in P mode, flash works perfectly - gives correct exposures automatically.

However when in A mode with Fill-in Flash, I have to manually set the aperture to get the right exposure.

I have to figure out the exposure from the tables supplied with the flash gun. Shouldn't the camera do this automatically for me?

Similar situation with S and M modes.

Strangely if I use slow flash, then exposures are always correctly set automatically,

Any ideas?

Re: NEX-5N Flash A,S,M Modes

Mick2011 — Mon, 03 Sep 2012 09:03:39 GMT

Hi, welcome to the Sony Forums

I can't test this as I don't have both units to hand, but I'd imagine the F20S will only work automatically in an Automatic (P) mode. Aperture & Shutter priority modes don't work in quite the same way as DSLT bodies and this may be normal behaviour with that flash.

Maybe someone with both units could try this out and see

Cheers

Mick

Re: NEX-5N Flash A,S,M Modes

cmosse — Mon, 03 Sep 2012 09:31:12 GMT

looking at the flash range table in the manual you will notice that flash range will drop drastically when ISO is set to a low value and aperture is closed some F-stops. E.g. with ISO set to 100 and aperture is set to 8 flash range is only 1.5m. The flash has a guide number (GN) of 14 in standard mode and you can calculate flash range (ISO100) by GN/aperture.

So when using the flash and you need to extend flash range just use AUTO-ISO or use a maual ISO setting (e.g. ISO 800). In P mode hte camerfa will automatically use a wide open aperture (e.g. F3.5 with kit lens), so do not close the aperture too much in the manual modes...

Re: NEX-5N Flash A,S,M Modes

DNDNDN — Mon, 03 Sep 2012 10:05:26 GMT

Thanks for the responses.

Actually I think that Cmosse has answered my question. Thanks

The camera/flash combination does work out the correct flash duration even when in A mode, However due to modest power of flash it always require a reasonably big aperture (small f number) to maintain correct exposure.

Did a few experiments pushing up the ISO speed to confirm this and it is as Cmosse explained.

When in A mode there doesn't seem to be any visible warning in viewfinder when Flash/Aperture/ISO combination will result in under exposure. I think I would have expected some warning.

Anyway, as Cmosse says when in a manual mode do not close the aperture too much.