Fill flash questions/observations

[canuck257]

D7200, shutter speed 1/500, aperture f6.3, ISO auto. Tamron 150-600 at 600mm zoom. SB 600 with diffuser set to TTL. Flash compensation was -0.7

I just made my first attempt at using fill flash photographing birds in shadow and I'm quite pleased with the results. There is much room for improvement but the shots are not as bad as I expected. I guess I should have used a fixed ISO (100?) as the shots do show some noise from the camera selecting 2500 and a degree of softness probably from the same source. I had the release mode set on CL because I did not think to change it consequently the camera/flash fired twice every time I pressed the shutter release. This is an assumption on my part but I cannot think of any other reason for multiple firings. I also noticed that I had to depress the shutter release a lot further to get the camera to fire. Is this normal?

Comments, advice, guidance and criticism are all welcome.

 

[singlerosa_RIP]

Nice work. I think you're right about getting off Auto ISO with flash.

 

[WayneF]

D7200, shutter speed 1/500, aperture f6.3, ISO auto. Tamron 150-600 at 600mm zoom. SB 600 with diffuser set to TTL. Flash compensation was -0.7

I just made my first attempt at using fill flash photographing birds in shadow and I'm quite pleased with the results. There is much room for improvement but the shots are not as bad as I expected. I guess I should have used a fixed ISO (100?) as the shots do show some noise from the camera selecting 2500 and a degree of softness probably from the same source. I had the release mode set on CL because I did not think to change it consequently the camera/flash fired twice every time I pressed the shutter release. This is an assumption on my part but I cannot think of any other reason for multiple firings. I also noticed that I had to depress the shutter release a lot further to get the camera to fire. Is this normal?

Comments, advice, guidance and criticism are all welcome.

By any chance, when at ISO 2500, could your Auto ISO Minimum ISO setting have been ISO 640?

I don't have a D7200 to verify it, but it is a very late mode, and I have assumed notions that it works like the other late models (since D800 in 2012), in that IF a hot shoe flash (not speaking of internal flash), if a hot shoe flash is recognized as in use, that recent Auto ISO will not advance more than 2 stops above Minimum ISO (4x the Minimum ISO setting).

So either I am incorrect, or your D7200 Minimum ISO was 640?

If you reset your Minimum ISO to ISO 100, my theory is that then (with hot shoe flash), D7200 Auto ISO would not increase above ISO 400 (2 stops above Minimum, on late model cameras, if with hot shoe flash). But this would reduce the flash range about 3 stops, or to about 1/9 range however.


Also, I suppose you know that your 1/500 second shutter speed is activating Auto FP to cause HSS flash mode (to allow the high shutter speed)... This is NOT regular speedlight mode, anything but... Instead, HSS mode reduces your maximum flash power to about 20% of maximum (to allow the faster shutter). I say 20%, its power is reduced about 2.3 stops. And the HSS flash has no motion stopping capability. Speedlight mode has a lot however, at power levels lower than absolute maximum.

SB-600 manual page 35 shows Guide Numbers for regular speedlight mode (max power at 85mm at ISO 100 is GN 131/feet) ...

and SB-600 manual page 76 shows Guide Numbers for Auto FP HSS mode (max at 85mm at ISO 100 is GN 26/feet). (this is at 1/300 second shutter speed, later flashes use 1/500 second as reference).

So at 1/300 second (the GN spec, page 76), and at f/6.3, HSS mode max power can do GN 26/6.3 = 4.1 feet distance.
However, at ISO 2500, the Guide Number 26 converts to GN 131, so that GN 131/f6.3 = 20.8 feet (and about double this range for a fill level down two stops.. not sure how bright your ambient is however, 40% more range for fill down one stop might be more reasonable?)

For HSS mode (flash becomes a continuous light), using 1/500 second is simply an Equivalent Exposure, so 1/500 second is about 2/3 stop less effective power used (than this 1/300 number computed).


In contrast, for regular speedlight flash mode (with shutter speed 1/250 second, to avoid Auto FP HSS mode),
then GN (page 35) is GN 131 already, at ISO 100.
(actually camera Auto FP (1/320) mode would allow 1/320 second shutter there too.


Lots of numbers, sorry....


But it means that since the flash mode changes drastically,

ISO 2500 at 1/300 second (FP HSS mode)

has exactly the same possible flash maximum distance range as

ISO 100 at 1/250 second (speedlight mode).
Or for example, ISO 400 would allow stopping the lens down two stops.
Or for example, ISO 400 would allow reducing flash power by two stops, which would be at least 1/3400 second motion stopping (SB-600 page 88).
Or maybe one stop of each, still 1/1600 second motion stopping at f/9.

That is pretty interesting to me.

And there are other interesting things that can also happen.

If using camera A mode with Auto FP on (with a hot shoe flash), normal light variations becoming brighter (if working around this 1/250 second threshold value) can let A mode increase shutter speed higher than the Auto FP speed, which of course suddenly shifts the flash to HSS mode, and we immediately notice that the flash loses about 80% of its power capability. So it might be sufficient power one moment, and next similar shot might be rather insufficient flash power, simply due to mild normal A mode variations. (we can turn Auto FP off however. )

Camera P mode will not allow that. Camera P mode will increase aperture to maximum f/22 or f/32 value before it will allow Auto FP to change the shutter speed and flash mode to HSS.

 

[canuck257]

By any chance, when at ISO 2500, could your Auto ISO Minimum ISO setting have been ISO 640?

I don't have a D7200 to verify it, but it is a very late mode, and I have assumed notions that it works like the other late models (since D800 in 2012), in that IF a hot shoe flash (not speaking of internal flash), if a hot shoe flash is recognized as in use, that recent Auto ISO will not advance more than 2 stops above Minimum ISO (4x the Minimum ISO setting).

So either I am incorrect, or your D7200 Minimum ISO was 640?

If you reset your Minimum ISO to ISO 100, my theory is that then (with hot shoe flash), D7200 Auto ISO would not increase above ISO 400 (2 stops above Minimum, on late model cameras, if with hot shoe flash). But this would reduce the flash range about 3 stops, or to about 1/9 range however.


Also, I suppose you know that your 1/500 second shutter speed is activating Auto FP to cause HSS flash mode (to allow the high shutter speed)... This is NOT regular speedlight mode, anything but... Instead, HSS mode reduces your maximum flash power to about 20% of maximum (to allow the faster shutter). I say 20%, its power is reduced about 2.3 stops. And the HSS flash has no motion stopping capability. Speedlight mode has a lot however, at power levels lower than absolute maximum.

SB-600 manual page 35 shows Guide Numbers for regular speedlight mode (max power at 85mm at ISO 100 is GN 131/feet) ...

and SB-600 manual page 76 shows Guide Numbers for Auto FP HSS mode (max at 85mm at ISO 100 is GN 26/feet). (this is at 1/300 second shutter speed, later flashes use 1/500 second as reference).

So at 1/300 second (the GN spec, page 76), and at f/6.3, HSS mode max power can do GN 26/6.3 = 4.1 feet distance.
However, at ISO 2500, the Guide Number 26 converts to GN 131, so that GN 131/f6.3 = 20.8 feet (and about double this range for a fill level down two stops.. not sure how bright your ambient is however, 40% more range for fill down one stop might be more reasonable?)

For HSS mode (flash becomes a continuous light), using 1/500 second is simply an Equivalent Exposure, so 1/500 second is about 2/3 stop less effective power used (than this 1/300 number computed).


In contrast, for regular speedlight flash mode (with shutter speed 1/250 second, to avoid Auto FP HSS mode),
then GN (page 35) is GN 131 already, at ISO 100.
(actually camera Auto FP (1/320) mode would allow 1/320 second shutter there too.


Lots of numbers, sorry....


But it means that since the flash mode changes drastically,

ISO 2500 at 1/300 second (FP HSS mode)

has exactly the same possible flash maximum distance range as

ISO 100 at 1/250 second (speedlight mode).
Or for example, ISO 400 would allow stopping the lens down two stops.
Or for example, ISO 400 would allow reducing flash power by two stops, which would be at least 1/3400 second motion stopping (SB-600 page 88).
Or maybe one stop of each, still 1/1600 second motion stopping at f/9.

That is pretty interesting to me.

And there are other interesting things that can also happen.

If using camera A mode with Auto FP on (with a hot shoe flash), normal light variations becoming brighter (if working around this 1/250 second threshold value) can let A mode increase shutter speed higher than the Auto FP speed, which of course suddenly shifts the flash to HSS mode, and we immediately notice that the flash loses about 80% of its power capability. So it might be sufficient power one moment, and next similar shot might be rather insufficient flash power, simply due to mild normal A mode variations. (we can turn Auto FP off however. )

Camera P mode will not allow that. Camera P mode will increase aperture to maximum f/22 or f/32 value before it will allow Auto FP to change the shutter speed and flash mode to HSS.

WOW!!! thank you Wayne (I think?) that's a huge amount of analysis and information. It will take me some time to understand and assimilate it all. I have something of a blind spot when it comes to flash guide numbers but, this was my first step on the road to understanding. I plan to persevere learning probably by trial and error which is always fun.

I can see that I will revisit this post many times in the next few weeks. Thank you again.:cheerful::encouragement:

PS on edit. The minimum ISO was set at 100.

 

[canuck257]

Any comments on the increased button travel required to fire the shutter?

 

[WayneF]

PS on edit. The minimum ISO was set at 100.

Oops! You have me worried now, and I could be wrong about D7200, and if so, I sure would like to know it. I wonder if you could verify that quickly? Real simple, you can do it now sitting in your computer chair, and it is not necessary to take a picture.

With D7200, with Auto ISO on, with Minimum ISO set at 100, and with hot shoe flash on camera, but flash NOT turned on yet.

Just aim camera at anything in the indoor room (which is dim compared to bright sun). Half press shutter. View finder should show a high or maximum ISO value, as expected indoors. Then reach up and turn flash on, half press again, and this ISO in viewfinder should drop to 400, specifically which is a maximum of 2 stops above whatever Minimum ISO is (if with flash).

D7100 should do that too, but a D7000 is older, a different version of Auto ISO, and it would read a high ISO either way (in this room indoors). And older cameras (D300 or older) would read Minimum ISO either way (with flash). There have been these three versions of Auto ISO with flash. The "middle age" cameras screwed it up, but the recent models have fixed it again.

I am assuming TTL flash mode. Auto ISO will never advance if a manual mode flash is detected (manual flash cannot react to ISO changing).

It does seem important that we realize that turning Auto FP on (menu E1) will allow flash shutter speeds faster than Maixmum sync speed (1/250 second on D7200). Which then (assuming a camera and flash capable of HSS mode) enables HSS flash mode, which drops maximum power capability to about 20%, and removes all flash motion stopping capability. This tends to be noticeable. In practice, it tends to be done only to allow closeup portraits in bright sun at f/2.8 to blur the background. Otherwise, speedlight mode runs circles around HSS mode. We can turn Auto FP off.

More description of HSS flash mode at Auto FP and HSS - What is it?

Sorry, I don't know about having to press shutter harder. Should not be any affect on the button, but sometimes finding focus is harder in dim light, esp with a f/6.3 lens, and then (in normal modes) shutter and flash will not trigger until it it can focus (maybe causing sort of a delay). I've noticed then that I do try pressing shutter harder. Next time pressing doesn't work, notice if the green "in focus" dot is visible in viewfinder, at bottom left.

 

[singlerosa_RIP]

With flash, isn't is easier just to go manual ISO? All those numbers give me a headache (no offense Wayne). I normally start at 100 and work my way up as needed.

 

[WayneF]

With flash, isn't is easier just to go manual ISO? All those numbers give me a headache (no offense Wayne). I normally start at 100 and work my way up as needed.

I agree, I like manual ISO. And a manual flash mode absolutely requires fixed ISO. Bounce flash can typically need maybe ISO 400, but higher ISO just captures the orange incandescent light, which is no plus.

 

[Whiskeyman]

With flash, isn't is easier just to go manual ISO? All those numbers give me a headache (no offense Wayne). I normally start at 100 and work my way up as needed.

No kidding. I'm fairly sure that I had classes in college that didn't get to that level of technicality. I'm going to have to read WayneF's posts over again to try to understand them. But I do plan on understanding them when I'm done!

WM

 

[WayneF]

Sorry guys, I don't mean to be unclear. Writing does seem hard, and I wish I had more literary skills. In school, when a choice of literature or shop, I always made ashtrays. I just keep hammering on it until it makes sense to me. But the details do seem important. Above, I really only quoted what was in the manuals.

 

[canuck257]

Oops! You have me worried now, and I could be wrong about D7200, and if so, I sure would like to know it. I wonder if you could verify that quickly? Real simple, you can do it now sitting in your computer chair, and it is not necessary to take a picture.

With D7200, with Auto ISO on, with Minimum ISO set at 100, and with hot shoe flash on camera, but flash NOT turned on yet.

Just aim camera at anything in the indoor room (which is dim compared to bright sun). Half press shutter. View finder should show a high or maximum ISO value, as expected indoors. Then reach up and turn flash on, half press again, and this ISO in viewfinder should. drop to 400, specifically which is a maximum of 2 stops above whatever Minimum ISO is (if with flash).

I will answer in this manner to cover all the points you mentioned. I tried as you suggested above with the flash turned off. 1/2 pressing the shutter release makes no difference in the display, it continues to flash ISO AUTO. With the flash turned on I get the same result.

 

[canuck257]

Additional to my last post, with manual ISO set at 100 I do not get any ISO information in the viewfinder. Should I?

 

[WayneF]

Additional to my last post, with manual ISO set at 100 I do not get any ISO information in the viewfinder. Should I?

Oops again, my mistake not being familiar with D7200. Checking the manual, I see now that D7200 does not show current ISO in the viewfinder. My D300 and D800 do, and I assumed also true of D7200, but now it appears those models with an Auto mode do not show current ISO value in the viewfinder.

So sorry, in that case, it will require clicking off a picture (in those situations) to record ISO used, in the Exif data shown on the rear LCD after taking it. Showing the last picture, and then one of the screens there shows the Exif data with the ISO value that it used.

Same idea then, the presence of a TTL hot shoe flash ought to prevent ISO increase from being more than 2 stops (4x)... on about a dozen of the latest models.

 

[canuck257]

My rear LCD does not show ISO so--------these do. SOOC

 

[Moab Man]

I am not a bird guy, but my approach would be to set up my shot to expose for the background sky, then turn on my flash and adjust the power up or down to dial in the exposure of the subject.

Again, I do not really shoot birds, but this is how I shoot people. Maybe this might help.

 

[WayneF]

My rear LCD does not show ISO so--------these do. SOOC

That seems pretty clear. I hate it when I'm wrong. I can't test the models I don't have, but I sure thought I had it figured out. But if the D7200 does that (Auto ISO still goes high with a hot shoe flash), obviously I'm still missing something. I can't think what it could be though. Maybe it's only the most top end models? I am very puzzled, but it looks like I must be wrong. This Auto ISO action with hot shoe flash is one detail that Nikon does not put in the specs.

What camera mode was that? A,S,P,M, or Auto? I suppose it had to be camera M mode, to duplicate your previous bird settings?

I wish I could get at your Exif data, but the web site appears to strip it out (of the file).

You are still at 1/500 second and HSS flash mode, but that has no effect on Auto ISO here (other than needing a lot more ISO).

Thanks for the examples... time for me to rethink it.



Regarding seeing ISO for your pictures on the rear LCD, you can.

The "playback" of the previous image can show several screens about the image, one of which shows settings like ISO. The horizontal selector buttons step trough the images, and for any one image, the up/down buttons selects one of these several screens. This from page 234 of the D7200 manual. The one in top right shows mode, shutter speed, aperture, and ISO. I think it is one down button click, but it is there somewhere.

Actually, the Info button may show the current ISO? At least it appears to do this on my models, although it seems a little shakey.

 

[canuck257]

Wayne, again my thanks for your input. With your guidance above I can now see the ISO in my LCD and you are correct in assuming that I was in M mode. I was actually using U2 which I have set up for BIF.

Given that there are so many inter connected parameters in the camera system it is highly likely that you are correct. I probably have something set different to the "norm" which is affecting the ISO settings in Auto. My Info. screen does show the maximum and minimum ISO as well as the flashing "AUTO" but, it does not show the actual.

I would like to get your analysis of the exif. data, is there some way to get it to you? I hope you are enjoying this conundrum as much as I am.

 

[canuck257]

I am not a bird guy, but my approach would be to set up my shot to expose for the background sky, then turn on my flash and adjust the power up or down to dial in the exposure of the subject.

Again, I do not really shoot birds, but this is how I shoot people. Maybe this might help.

This method certainly has merit however, birds tend not to stand still as long as people do. I will try it though in one scenario. There is a tree whose shaded branches they feed in after leaving the feeders. I can expose for the highlights in that scenario then set the flash for the shade where they are perching.

 

[WayneF]

Thanks, I would welcome your emailing the second mage with flash to me if OK with you. Or any one like it, meaning with auto ISO and hot shoe flash. The subject is not important to me.

SOOC please, because Adobe strips all the Manufacturers section, even if it keeps the general part.

To bypass any spam harvesters, I have sent my email via PM.

Thanks

I wouldn't bet on much "analysis" but would like to see it all for myself. I will contact you back, via return email if OK.