Can 'auto ISO' be used when using a flash?

Scott Murray

Scott Murray

Senior Member
WayneF said:
Probably it can be done, but you may not want to.

Flash and Auto ISO on Nikon DSLR has gone through three variations (making explanations difficult).

1. Older ones, from D70 to D300, never increased ISO if flash was recognized with Auto ISO. They always stayed at lowest value, simply because we were using flash instead. Good plan, there is much to be said for that.

2. Then from D300S and later, it changed. I believe (not positive) your D3100 is in this group. Then Auto ISO did its thing, adjusting for the ambient light level (resulting in very high ISO indoors), and then the flash power level had to adjust for this high ISO situation. Several things wrong with that, flash pictures ought not always be high ISO. And the ambient incandescent light was orange, and caused white balance problems.

3. The very latest models (D800, D600, D7100, and I really don't know what else) would only advance ISO by two stops (for example, only to ISO 400) when flash was used. This was reasonable for bounce, and ceased doing the absurdly high ISO.

You can determine your cameras ISO mode this way: With flash turned off, and Auto ISO on, indoors where you need flash, compose your picture and half press shutter to see what ISO is. Probably pretty high ISO in dim places where flash is needed. Then reach up and turn the flash power switch On. What does ISO do at half press?
1) will stay the same, low. 2) will remain at the sky high value. 3) will advance only 2 stops over minimum (4x value).


2. Above should work, exposure wise, just with very high ISO, and possibly orange. We need more info, etc, to explore why not, but really, it seems a moot point. You surely do want to turn Auto ISO off with flash.
Click to expand...
My D800E still uses high ISO with Flash unless I specify manual ISO.
 
W

WayneF

Senior Member
Scott Murray said:
When I get home I will try to duplicate what I did, it most likely was user error lol
Click to expand...

If you can duplicate it, I would love to know specific details of how, your settings, etc.

But the few newest models (D800 is one) will only increase Auto ISO to two stops above Minimum ISO (like ISO 400) if flash is recognized.
That is speaking indoors, in dim light where flash is needed. In bright sun, I cannot get it above ISO 100. :)
 
P

paul_b

Senior Member
Not knowing too much about the mentioned orange CTO filters or gel thingies for the flash. Can anyone recommend some good ones, ideally on Amazon I suppose.
 
W

WayneF

Senior Member
There are extremely many colors of lighting filters. Even CTO (Color Temperature Orange, for converting flash to incandescent color, so Incandescent WB can be used) comes in shades, like 1/8, 1/4, 1/2, 3/4, Full CTO (all incandescent bulbs are NOT the same). And there are a few devices for holding the filter in front of the flash (I just use masking tape, but I am not a big user of filters).

See Four Flash Photography Basics - Color filters on flash first, for ideas.
 
P

paul_b

Senior Member
OK ive ordered my orange colour temp gel for my sb400 flash. One question that has since popped up in my mind though: won't the orange flash now make the ambient light even more orange? If so won't the colour difference ratio between flash light and ambient light therefore still be the same difference as before?
 
K

kluisi

Senior Member
paul_b said:
OK ive ordered my orange colour temp gel for my sb400 flash. One question that has since popped up in my mind though: won't the orange flash now make the ambient light even more orange? If so won't the colour difference ratio between flash light and ambient light therefore still be the same difference as before?
Click to expand...

The point of coloring the flash is to match the ambient light in the room. If all of the lights are the same, then you can easily correct the lighting for the entire picture by either setting the correct white balance in the camera, or modifying it in post (lightroom or any other editing software).
 
W

WayneF

Senior Member
Perhaps if the filter went on the camera lens?

But no, the orange filter goes on the flash head to make its light be orange too (the incandescent light is already orange). The filter does not affect the ambient coming from the light bulbs, just the flash. To mix light sources, the idea is match ambient color with the flash, so that then camera or Raw Incandescent WB is correct for everything. WB will never be perfectly correct, so if critical, we still need standard white card correction with the WB tool. But at least the two sources are near the same color.

Or, alternately (my own strong preference), we could instead use low ISO and faster shutter speed, to minimize any effect of the ambient at all (a black picture without the flash). Then Flash WB can be (near) correct, since it lights all we can see. Direct flash would see a darker background then (without ambient), but bounce flash will light the room too.
 
Top