dual iso with flash photo mode

[visiono]

Has anyone tried this? Is it doable?

[Ottoga]

Why not  just try it and find out for yourself.

[R]

I've been shooting DISO and flash for a while and I like the results.

[nikfreak]

Care to share the results?

[DeafEyeJedi]

Care to share the results?

+1

[Ottoga]

As "R" has indicated, Yes, it works. The following links are a quick test performed this evening with my 7D (hand held).

This is the control photo:   f3.5, exp: 1/60 (using the built-in flash), iso: 800, Auto WB
https://www.dropbox.com/s/t8yb7rcdqzq5f48/IMG_4481.CR2?dl=0

This is the original Dual_ISO CR2 file:  f3.5, exp: 1/60 (using the built-in flash), iso: 800/1600, Auto WB
https://www.dropbox.com/s/yi5mm4t9qweic8h/IMG_4482.CR2?dl=0

This is the processed DNG image created with BarracudaGUI using the -cs2x2 and -amaze-edge command line parameters.
https://www.dropbox.com/s/66gja8ipjuh74u5/IMG_4482_Amaze.DNG?dl=0

And its console output file
https://www.dropbox.com/s/0ekv02t3oczggvk/IMG_4482_cr2hdr.log?dl=0

I can see a scenario where you may want/need to use the flash for a foreground subject whilst still wanting to bring the detail of a shadowy background out as well where a flash/dual_ISO combo could be useful. I'm sure that greater minds than mine can come with many more as well as alternate ways of capturing the image without dual_iso.

[a1ex]

Didn't download the images (slow network), but I don't expect any improvement at ISO 800/1600 over ISO 800.

You can expect noticeable improvement at ISO 100/800 or ISO 100/1600, if the control photo is taken at ISO 100, is exposed to the right, but still has very dark shadows. Also, considering the typical DR curves of Canon sensors, the biggest improvement will be on full frame cameras.

Regarding the original question, I don't expect the flash to affect dual ISO in any way (it's just an extra light source).

[R]

For me, as archt/int photographer, is the fastest way to capture backlit rooms getting data enough to edit the image comfortably and quality enough to be able to sell the picture. The room is illuminated by one or more flashes while the exterior seen through the windows is controlled by the lowest ISO.

In most scenes I find 200/1600 and 100/1600 the best settings. If there's a window or a door those photos are most likely to be shot using DISO+flash.

Check this ramonclemente.com/portfolio/casas/ or this ramonclemente.com/portfolio/apartamentos/

[visiono]

So there is no special trick then? If you are using radio triggers its just like any other flash photo?
Ramon, I don`t see why you don`t just shoot bracketted exposures and keep everything at 100 iso, then blend in post. some of your outdoor exposures could still be brought down a bit. just use a tripod.

I`m mostly for portraits, wedding couples , maternity, people stuff.  The flash is more for beauty light but sometimes I`d like to not try to fight the sky exposure. So say i fire the flash for like 1600 iso exposure on the person but i need 100 iso for the sky to be blue.
If i was to use only flash with no dual iso, my flash would have to be 4 stops more powerfull to meet the sky. If i was to use only dual iso and no flash, i would get ok exposure on everything just not an intersting beauty light on the person. Angle and quality is what the flash gives me regardless  of what`s around. Sure i could use reflectors but that`s still not quite as good and powerful and introduces the squinting eyes problem.

[R]

So there is no special trick then? If you are using radio triggers its just like any other flash photo?
Ramon, I don`t see why you don`t just shoot bracketted exposures and keep everything at 100 iso, then blend in post. some of your outdoor exposures could still be brought down a bit. just use a tripod.

No special trick visiono.

I just treat continuous light as if I were working with the low DISO and flash with the high DISO. I keep the brightest exterior area I want to have reasonable color accuracy around zone IX and below that if I also want to retain a bit of texture.

My starting point is 200/1600. If exterior exposure needs faster shutter speed than 1/160 then I go for 100/800. If the interior needs more light, as I keep my flashes relatively low (1/16), to avoid casting noticeable shadows in opposite direction of natural light, I try 100/1600.

(BTW, I always use tripod and I don't know what made you think I don't use it.)

I have several reasons why I rather use DISO for most of my shootings than bracketing, many of them related with productivity.

- One take for scene is better than three or four takes.
- Less files equals faster imports.
- In Lr there's no HDR batch processing. Let's say I need to process 20 HDR scenes for job and group them. With the bracketing method I would have to repeat 20 times x (select images -> ctrl+h -> select deghosting level -> click ok -> select images -> ctrl+g). But using DISO I just need to do once ctrl+a -> export cr2hdr. That's all.
- Lr HDR deghosting is waayyyy to sensitive and unpredictable. Using it ends up with weird deghostings in the exterior areas seen through windows. DISO solves that; one picture no ghosting.


I definitely would give ML DISO a try for portraits. I would start with a 400/100 setting if you want sky recovery and 800/100 for dramatic effects. I'd make sure that my main subject falls between zone V-VI to avoid the inherent resolution loss of DISO in HL and SH.

Post some images if you finally try it.

[Danne]

Those are nice looking examples. Are you exposing for highlights in dualiso? Flash exposure on the high iso setting for instance 1600 in an 100-1600 example?

[R]

Those are nice looking examples. Are you exposing for highlights in dualiso? Flash exposure on the high iso setting for instance 1600 in an 100-1600 example?

Danne, look my last reply to visiono: http://magiclantern.fm/forum/index.php?topic=17705.msg171333#msg171333.

Using base ISO for calculations, I keep highlights around zone IX (90%) if I want to keep just HL colors. If shutter speed allows it I put HL under zone IX if I want to bring back its textures. Then, using the exposure meter I check my midtones. Multiplying exposure meter x DISO factor I know in which zone midtones are going to fall.

Usually I use 200/1600 DISO, that's three extra stops but I never push the exposure 3 stops in postpo. I usually add about 2 stops; strobes help midtones to fall around zone VI. Keeping in postpo the exposure push below the DISO factor helps avoiding ugly noise in shadows and the appearance of that  pattern that cr2hdr creates due to the different odd/even rows ISO.

There's more noise in DISO shots than in normal shots so it's a good idea to push the NR more than what you do in normal shots. In my 5DmkII I keep luminance NR between 10-20 and chroma between 20-30. Above that textures get washed for my taste. But my clients use my images for web so, displaying a 20Mpx photo at let's say a maximum of 1440px wide creates the false illusion of almost no noise at all.

I use 100/1600 DISO for extreme DR scenes. But keeping in mind that the more you push DISO the more noise, fringing and pattern you get, I then shot a normal bracketing in case I need to compose an HDR in Photoshop.

[Danne]

I will try this out one day. Been working real estate photography every now and then. Always been stacking and enfusing in lightroom but if it can be done with one exposure instead of two or three it,s worth a shot.