# Manual, Auto ISO, and Flash- how does this work?



## scottkinfw (Mar 29, 2014)

I am going to shoot a the cattle drive in Fort Worth, TX today at 4PM, which of course is outdoors. This occurs on most weekends at 11 AM and 4PM. I have shot this before but obviously, the timing of the event isn't the best for lighting. Specifically, there is a lot of contrast not only in the longhorn color, but also the shadows and bright sunlight areas (obviously). Today I am going to try to shoot again, this time with my new (yippie ky eyeee) 300 2.8 IS II lens on my 5DII body.

In thinking about how to augment the shadows, I though I would use a better beamer for fill and set flash to ETTL (using a single 580 EXII). I haven't used auto ISO, so I thought I would try that with appropriate manual camera settings.

I would appreciate if anyone can provide me insight for this situation. How does this work? Will the flash control the ISO? What will the camera logically use as priority to set the ISO? Should I make exposure compensation changes or set the flash to manual? I could just set it and forget it I guess, but I really want to understand what is going on inside the camera.

To all who answer, I thank you in advance.

sek


----------



## ahab1372 (Mar 29, 2014)

I haven't tried in a while, but I believe Auto ISO will be set to 400 when using on camera flash. That is probably not what you want it to do in this case.


----------



## neuroanatomist (Mar 29, 2014)

ISO is fixed at 400 with flash. I assume you want to be using action-stopping shutter speeds, which means you also need to use H mSS on your flash. Even with the power loss from that, you'll have enough for fill with the better beamer.


----------



## scottkinfw (Mar 30, 2014)

Here is what I discovered. 

I initially set the camera on manual with auto ISO, flash to ETTL. The flash was always set to HSS. The ISO WAS fixed at 400.

The pics were way over exposed so I went to manual and set ISO to around 160, played with settings until I got a good exposure. I also lowered the flash output as needed. 

So here are some sample shots.


----------



## scottkinfw (Mar 30, 2014)

Here are a few more



scottkinfw said:


> Here is what I discovered.
> 
> I initially set the camera on manual with auto ISO, flash to ETTL. The flash was always set to HSS. The ISO WAS fixed at 400.
> 
> ...


----------



## scottkinfw (Mar 30, 2014)

And finally, bringing up the rear



scottkinfw said:


> Here are a few more
> 
> 
> 
> ...


----------



## neuroanatomist (Mar 30, 2014)

Nice!


----------



## ahab1372 (Mar 30, 2014)

I agree, nice job. Thanks for sharing.


----------



## Marsu42 (Mar 30, 2014)

scottkinfw said:


> I would appreciate if anyone can provide me insight for this situation. How does this work?



Use Magic Lantern, the stable v2.3 or a wip auto_iso module for nightly (incidentally written by me ) fixes this braindead crippling... 2/3rd of my shots are taken with flash+autoiso. The module also adds ec in m which is otherwise only available on 1dx.


----------



## scottkinfw (Mar 31, 2014)

Thanks Marsu42.

I learned a lot, hopefully, others did too.

sek


----------



## Mt Spokane Photography (Mar 31, 2014)

Using a better beamer throws off any auto setting, and Magic Lantern will not correct this.

Doing it the way you did is fine.

You can also use your better beamer with TV and exposure compensation.


----------



## Marsu42 (Mar 31, 2014)

Mt Spokane Photography said:


> Using a better beamer throws off any auto setting, and Magic Lantern will not correct this.



Ugh? Why's that? I'm not using the better beamer but the 600rt @200mm zoom, and at least that works just fine with ML, auto iso and ettl.


----------

