topic Re: Speedlite 600 EX- RT in Speedlite Flashes

Speedlite 600 EX- RT

Sanjaydesai — Tue, 01 Aug 2017 09:47:16 GMT

I need to know if the speedlite 600 EX-RT is used off the camera in manual mode, is it possible to get flash distance to subject number on panel if f stop is dialed.Also if the power of flash is changed then the corresponding changes in flash distance to subject number is displayed. This feature is available in Nicon SB 900 speedlite

Re: Speedlite 600 EX- RT

jrhoffman75 — Tue, 01 Aug 2017 13:01:44 GMT

https://www.usa.canon.com/internet/portal/us/home/support/details/cameras/flashes/speedlite-600ex-rt?tab=manuals

Re: Speedlite 600 EX- RT

Sanjaydesai — Tue, 01 Aug 2017 13:19:11 GMT

Thanks for your response. I do have this manual. But I do not find what I am looking for. In manual mode of flash I need to dial f stop and the flsah to diplay flash to subject distance required for correct exposure.

Re: Speedlite 600 EX- RT

kvbarkley — Tue, 01 Aug 2017 14:56:24 GMT

You will have to do it the old fashioned way and create a cheat sheet.

Re: Speedlite 600 EX- RT

diverhank — Tue, 01 Aug 2017 21:58:48 GMT

@Sanjaydesai wrote:
I need to know if the speedlite 600 EX-RT is used off the camera in manual mode, is it possible to get flash distance to subject number on panel if f stop is dialed.Also if the power of flash is changed then the corresponding changes in flash distance to subject number is displayed. This feature is available in Nicon SB 900 speedlite

I don't think the 600 EX-RT display that but it's easy enough to estimate. The 600 - as the name suggests, has a Guide number of 60 which is the f/stop multiply by the distance in meters. So if you shoot an object at 10m your f/stop has to be f/6 at ISO 100 and the flash zoom at maximum (200mm) and power at 1/1. With a bit of practice you can figure all this out easy enough.

Re: Speedlite 600 EX- RT

Sanjaydesai — Wed, 02 Aug 2017 05:09:11 GMT

This is true but when the power is not 1/1 but other than that say 1/4 or 1/32 this becomes diffcult. it is all guess work then. Nikon SB 900 can display the distance flsat to subject for given power and f stop even if it is off the camera. Does 600 RT EX display if it is off the camera and in manual mode.

Re: Speedlite 600 EX- RT

diverhank — Wed, 02 Aug 2017 07:20:54 GMT

Short answer is no. IMHO, if you can't calculate these simple computations, you shouldn't be using the flash in manual mode. Or just get yourself a flash meter or just use the Nikon flash. In manual mode, any flash will do.

Re: Speedlite 600 EX- RT

TCampbell — Wed, 02 Aug 2017 12:19:22 GMT

I'm a bit confused by this....

Canon knows the distance to subject because the lens focusing mechanism reports it. But that is the focus distance for the CAMERA... not for an off-camera flash. When the flash is not on the camera, it doesn't know it's subject distance (not even for Nikon).

The illumination for a flash is based on subject distance (Inverse Square law), Flash power output, camera f-stop, and any light modifiers being used (reflectors, softbox, whether you are bouncing the flash, etc.)

When I worked with all manual flash we had only a few modifers and we knew what they did to the exposure when we used them. So it was fairly easy to know how much light we'd get from the flash for any giving subject distance and power level and we used that to dial in the appropriate f-stop.

Initially we had to work it all out and test it. But once you've taken hundreds of shots with the lighting setup you get to where you just know what exposures to use.

Re: Speedlite 600 EX- RT

diverhank — Wed, 02 Aug 2017 16:43:07 GMT

@diverhank wrote:
@Sanjaydesai wrote:
I need to know if the speedlite 600 EX-RT is used off the camera in manual mode, is it possible to get flash distance to subject number on panel if f stop is dialed.Also if the power of flash is changed then the corresponding changes in flash distance to subject number is displayed. This feature is available in Nicon SB 900 speedlite
I don't think the 600 EX-RT display that but it's easy enough to estimate. The 600 - as the name suggests, has a Guide number of 60 which is the f/stop multiply by the distance in meters. So if you shoot an object at 10m your f/stop has to be f/6 at ISO 100 and the flash zoom at maximum (200mm) and power at 1/1. With a bit of practice you can figure all this out easy enough.

On second thought, let me check into this tonight to confirm or deny it. Working off memory is a dangerous thing. When I shoot off camera, I almost always do mental calculation, trial and error or use a flash meter so I never looked. I'll give you a better report. I believe that the 600EX-RT does give you a distance for a given ISO and f/stop...not sure about off-camera.

Re: Speedlite 600 EX- RT

Sanjaydesai — Thu, 03 Aug 2017 04:48:50 GMT

Thanks for your response. I know pretty well that when the flash is on hot shoe and in manual mode it gives flash to distance reading for correct exposure for given power and Fstop but once the flash is off the hot shoe then it does not.

You are right if the flash meter is used then it gives information for the correct exposure but I was looking for if there is any setting on flash itself which shows the distance if it is off the hot shoe. I guess Nikon SB 900 or SB910 has that feature.

Regards,

Re: Speedlite 600 EX- RT

TCampbell — Fri, 04 Aug 2017 17:29:19 GMT

When you use the Nikon, are you having to manually dial in the distance to the subject to get the recommended settings?

The reason I ask is because I'm having difficulty understanding how the flash could reliably determine the distance on it's own.

The Canon flash is really a flash "system" and it uses data from the camera metering system and the lens' reported focus distance combined with what the flash knows. The camera can use the lens' reported focus distance to determine distance. But for an off-camera flash, it isn't safe to assume that the flash is at the same distance as the camera lens. Nor is it safe to assume the flash isn't mounted in a light modifier (when I use my 600EX-RT off-camera it's usually shooting into a soft-box ... so any assumptions about guide number would not be valid.)

I did photography for many years (decades now) using manual studio flash and even manual flash at events (weddings, etc.) with no automatic TTL systems. The math works based on the inverse-square law (light reaching the subject will appear exactly twice as bright or half-as bright (depending on closer or farther) anytime the distance changes based on the power of the square root of 2 (approximately 1.41). So if you have a subject at 10' and another at 14', the 14' subject will receive almost exactly half the light as compared to the 10' subject.

It turns out that if you divide the longer distance by the shorter distance (suppose one subject was 28' away and another was 10' away) you can get the number of stops. 28 ÷ 10 = 2.8

2.8 happens to be a full f-stop value on your camera and it is 3 stops down relative to f/1.0. That means the difference in light from a 10' subject as compared to a 28' subject is exactly 3 "stops" worth of light change.

With your actual f-stops you can set them in 1/3rd stop increments (or configure the camera to use 1/2 stop increments) but most flashes are only adjustable in full stops increments (1/1 = full power, 1/2 = one stop down, 1/4 = two stops down, 1/8 = three stops down... but there is no "1/6th power" setting (between 2 and 3 stops). So you set whichever is closest and your lighting will be within half a stop (you move the flash a bit closer or farther -- physically move the light) to obtain finer control if needed.

Changing the reflector position on the flash will of course change how much the light can scatter and that changes the guide number. This is why when you use a flash with a modifier (bouncing off a ceiling, using a soft-box, etc.) then you can't use the guide number anymore. But what you can do is test how much the modifier alters the light. You might determine, for example, that the fabric on the soft-box eats about 1 full stop of light. Once you know how much light it eats... that would be consistent for all situations when using that same modifier.

I use a Sekonic light meter that has the ability to meter flash in addition to ambient light. So I test my flashes both "with" and "without" modifiers and have my meter tell me how much I should adjust based on using that particular modifier. Knowing this, when I'm in the field I can make better decisions about flash settings and I don't necessarily have to pull out the hand-held meter because I've already tested my equipment and know the results.

Re: Speedlite 600 EX- RT

Sanjaydesai — Sun, 06 Aug 2017 08:26:09 GMT

Tim,

Thanks a lot for your explanation. I do not have Nikon flash. I am also having all canon equipments including 600 EX RT flashes.

I was going through a book in which Bryan peterson was explaining about Fstop and flash to subject distance reading displayed on back of flash panel even when the flash is in manual and off camera. So I was looking if the same is available in Canon 600 EX RT or not. I even do not know if Nikon SB 900 or SB 910 has this feature. I just took his words.

Regards,