550EX distance scale

[perror]

Hi all, I just got hold of a 550EX..and all in all I'm really happy with the results. However, I'm trying to make sense as to what the manual is trying to say, and one thing I am still unclear of is the distance scale on the flash LCD. From what I can see, it would seem to indicate in the manual that, it shows the range of distances the subject must be for the flash to achieve optimum coverage. Would I be right to say this? :oops: Also, as I understand it, the 550EX has an effective range of 55 meters...but the LCD seems to show only 18. Is the GN of 55 indicating an effective range of 55 feet? :?:

Hope you all can help me out on this..:) Thanks in advance..:D

[PaulB]

As a distance of 55 feet is 18 metres I think that the distance scale is set to show in metric.
To change from metric to imperial measurements - good old feet in other words - open the battery door on the 550EX and inside you will find a little switch...................It is in the manual, though not very obvious!

[scottbergerphoto]

Hi all, I just got hold of a 550EX..and all in all I'm really happy with the results. However, I'm trying to make sense as to what the manual is trying to say, and one thing I am still unclear of is the distance scale on the flash LCD. From what I can see, it would seem to indicate in the manual that, it shows the range of distances the subject must be for the flash to achieve optimum coverage. Would I be right to say this? :oops: Also, as I understand it, the 550EX has an effective range of 55 meters...but the LCD seems to show only 18. Is the GN of 55 indicating an effective range of 55 feet? :?:

Hope you all can help me out on this..:) Thanks in advance..:D
The 550EX has a Guide Number of 55 Meters at f/1.0, ISO 100.
The distance scale reflects the workable distance for a given f stop and ISO. The formula is Distance = Guide Number / F stop. So if your f stop is 5.6, and ISO 100, the max distance drops to about 10 meters. If you raise the Iso to 200, The distance increases by a factor of 1.4, at Iso 400 it increases by a factor of 2(from the value at ISO 100).
Questions?
Scott

[perror]

That's a really clear explanation..=D thanks everyone..=) So in this case, if let's say I'm using a 50mm at F1.8...so distance would be 55/1.8..which would give about 30 meters...in this case, how will the LCD show it? Or will the small right arrow blink or something like that?:)

[scottbergerphoto]

That's a really clear explanation..=D thanks everyone..=) So in this case, if let's say I'm using a 50mm at F1.8...so distance would be 55/1.8..which would give about 30 meters...in this case, how will the LCD show it? Or will the small right arrow blink or something like that?:)
30 meters at ISO 100. If you go to ISO 200, 42 meters,and ISO 400, 60 meters. The LCD shows a line from the min to max distance. There is a minimum distance you have to be from the subject as the flash can only shut down so quickly. The light from the flash drops off based on the inverse square law. When you double the distance, you get 1/4 the light delivered at the subject.
Scott

[perror]

Hi scottbergerphoto..thanks for the explanation..:) So if the range is 30 meters at ISO100...how will the LCD show it was the LCD max out at 18...so just kinda curious how it would appear on the LCD.. :oops:

[scottbergerphoto]

Hi scottbergerphoto..thanks for the explanation..:) So if the range is 30 meters at ISO100...how will the LCD show it was the LCD max out at 18...so just kinda curious how it would appear on the LCD.. :oops:
Check page 94 in the 550EX Manual. There is a bar that extends on the distance scale between the min and max distance.
Scott

[robertwgross]

The display shows a line from the maximum to the minimum distance, and it is shown in either feet or meters, depending on which way the switch is set inside the battery compartment.

If the line shows 5 feet to 15 feet, and if you are trying to shoot at 2 feet or 40 feet, then you have a problem, and you need to change the camera settings, such as the ISO, to rectify that situation.

---Bob Gross---

[Tom W]

I think what he means, Scott, is that the scale ends at 18 meters, so that anything beyond that range will be off scale.

[Sendide]

may be a stupid question but I'll throw it anyway :
I usually avoid to switch to "M"and keep the flash on ETTL cause I think if I swith to manaul, the calculation of the light the flsh has to deliver have to be somehow set by the user ?!!! where am I wrong?
you can also answer me by : "REEEAD YOUR BOOKLET :evil: , "
regards
Khalid

[scottbergerphoto]

I think what he means, Scott, is that the scale ends at 18 meters, so that anything beyond that range will be off scale.
Good point Tom. I'll check on that when I get home tonight. It looks like the scale is limited to an f/2.8 max. Curious?
Scott

[G3]

may be a stupid question but I'll throw it anyway :
I usually avoid to switch to "M"and keep the flash on ETTL cause I think if I swith to manaul, the calculation of the light the flsh has to deliver have to be somehow set by the user ?!!! where am I wrong?
you can also answer me by : "REEEAD YOUR BOOKLET :evil: , "
regards
Khalid

Normally, when using a manual flash such as a Vivitar 283, you will have to use the distance to the subject, ISO the camera is set for and the aperture. Normally flash is figured using X-synch shutter speed (1/60th of a second). For instance, if you set the dial on the flash at ISO 100, on the dial is marked the aperture you need to use for a particular distance range from the subject. So you focus on the subject, look at your distance scale on the lens and set the appropriate aperture. The Vivitar 283 also has an AutoThyristor circuit that will shut the flash down when it has put the appropriate amount of flash out if you have chosen one of the color modes other than M (manual).

The 550 EX works a little different. With the 550EX, you set the flash power at anything from full power (1/1) to 1/128 power. Then set the camera to either Av (and it will automatically choose 1/60) or to M (and it will automatically choose 1/60). The flash unit will read the ISO from your camera. Then you focus on the subject and look at the distance scale on the lens. Then look at the display on the back of the flash and it will display a bar over a distance scale showing you the min. and max. distances that the flash will cover at that setting. If the distance from the lens does not match the indicated distance on the flash, you need to either change the flash output or the aperture to make it match. The best way, by far, to get accurate flash exposure in manual mode is to use a hand-held flash meter.

[Sendide]

I love this forum ,
thanks a lot for such clear explanation G3
regards
Kh

[scottbergerphoto]

Sorry for the delay. As to the question about the fact that the distance scale is limited to 18 M, I checked the 550 EX Manual and the flash itself. When you choose an ISO and f stop combination that gives a distance greater then 60ft(18m), a little arrow appears to the right of the scale to let you know that it's beyond the pre defined scale. You have no choice but to use a flash meter or do a Guide Number calculation using:
Distance = Guide Number / f stop
So for example at ISO 100, at f/2.8, the maximum distance of the flash =
55M/2.8 = 18M
At ISO 200 : 55M/2.8 x 1.4 = 25M
At ISO 400: 55M/2.8 x 2.0 = 36M

Regards,
Scott

[scottbergerphoto]

The 550 EX works a little different. With the 550EX, you set the flash power at anything from full power (1/1) to 1/128 power. Then set the camera to either Av (and it will automatically choose 1/60) or to M (and it will automatically choose 1/60). The flash unit will read the ISO from your camera. Then you focus on the subject and look at the distance scale on the lens. Then look at the display on the back of the flash and it will display a bar over a distance scale showing you the min. and max. distances that the flash will cover at that setting. If the distance from the lens does not match the indicated distance on the flash, you need to either change the flash output or the aperture to make it match. The best way, by far, to get accurate flash exposure in manual mode is to use a hand-held flash meter.

G3,
A note about 1/60 sec and flash with the 10D and 1 series cameras. The shutter speed in flash photography is used to capture the ambient light. It has no effect on the flash as long as it is less then the max sync speed of the camera (1/200 for 10D). In P Mode and A-DEP mode, the camera sets a lower limit of 1/60 sec. If it's brighter out, the speed will increase anywhere between 1/60-1/200 to capture the ambient light. In Tv, Av, and M, there is no floor of or automatic setting of 1/60. You can set the shutter speed from 30secs - 1/200 to properly expose the background. People often forget this and wonder why they get blurred flash pictures. With the 10D you can lock the shutter speed at 1/200 in Av using Cfn 3-1. There is no automatic setting of the shutter to 1/60 in any of the exposure modes unless that is what the ambient light requires or the 1/60 limit of P or A-DEP has been reached. It is just a limit programmed into P and A-DEP modes so you don't get blurry pictures.
A note about a quirk in the 550EX and 10D combination. If you try to use a 550EX in M mode and the 10D in P mode, the camera locks a shutter speed of 1/200 and the f stop just blinks at f/22.
(Sorry about all the blue, it's just that kind of day!)
Regards,
Scott

[Sendide]

thanks scott, so as a chain , here come another question I usually wanted to ask :
in AV mode, I think I read somewhere that it makes automatically the flash fire wiht second curton, but even with that I get a very dark bakgroud behind the subject !!! any help on this issue

Regards

Khalid

[scottbergerphoto]

thanks scott, so as a chain , here come another question I usually wanted to ask :
in AV mode, I think I read somewhere that it makes automatically the flash fire wiht second curton, but even with that I get a very dark bakgroud behind the subject !!! any help on this issue

Regards

Khalid
I think your mixing apples and oranges. In Av mode, you set the Aperture for the depth of field you want and the camera will select a shutter speed to expose the ambient light properly. You need to use a tripod for shutter speeds longer then 1/lens focal length. In 1st curtain snc, usual mode, the flash fires with the opening of the shutter. If the subject moves with a long exposure, you will get trails in front of the flashed image. In 2nd curtain sync, which must be manually selected, the flash fires at the end of the exposure just before the shutter closes. This gives you trails behind a moving subject. The curtain you sync with doesn't determine the background exposure. The aperture and shutter speed does.
Scott

[Tom W]

Sorry for the delay. As to the question about the fact that the distance scale is limited to 18 M, I checked the 550 EX Manual and the flash itself. When you choose an ISO and f stop combination that gives a distance greater then 60ft(18m), a little arrow appears to the right of the scale to let you know that it's beyond the pre defined scale. You have no choice but to use a flash meter or do a Guide Number calculation using:
Distance = Guide Number / f stop
So for example at ISO 100, at f/2.8, the maximum distance of the flash =
55M/2.8 = 18M
At ISO 200 : 55M/2.8 x 1.4 = 25M
At ISO 400: 55M/2.8 x 2.0 = 36M

Regards,
Scott

You've given me the idea that I ought to make up an Excel chart. I'll probably never use it, as I tend towards E-TTL, but as a geek, it is something I need to do.

That is some good information, Scott. Thanks.

[scottbergerphoto]

You've given me the idea that I ought to make up an Excel chart. I'll probably never use it, as I tend towards E-TTL, but as a geek, it is something I need to do.

If you do, please e mail me a copy!
Regards,
Scott

[Tom W]

You've given me the idea that I ought to make up an Excel chart. I'll probably never use it, as I tend towards E-TTL, but as a geek, it is something I need to do.

If you do, please e mail me a copy!
Regards,
Scott

Awww, see, now I have motivation! :)

[G3]

The 550 EX works a little different. With the 550EX, you set the flash power at anything from full power (1/1) to 1/128 power. Then set the camera to either Av (and it will automatically choose 1/60) or to M (and it will automatically choose 1/60). The flash unit will read the ISO from your camera. Then you focus on the subject and look at the distance scale on the lens. Then look at the display on the back of the flash and it will display a bar over a distance scale showing you the min. and max. distances that the flash will cover at that setting. If the distance from the lens does not match the indicated distance on the flash, you need to either change the flash output or the aperture to make it match. The best way, by far, to get accurate flash exposure in manual mode is to use a hand-held flash meter.

G3,
A note about 1/60 sec and flash with the 10D and 1 series cameras. The shutter speed in flash photography is used to capture the ambient light. It has no effect on the flash as long as it is less then the max sync speed of the camera (1/200 for 10D). In P Mode and A-DEP mode, the camera sets a lower limit of 1/60 sec. If it's brighter out, the speed will increase anywhere between 1/60-1/200 to capture the ambient light. In Tv, Av, and M, there is no floor of or automatic setting of 1/60. You can set the shutter speed from 30secs - 1/200 to properly expose the background. People often forget this and wonder why they get blurred flash pictures. With the 10D you can lock the shutter speed at 1/200 in Av using Cfn 3-1. There is no automatic setting of the shutter to 1/60 in any of the exposure modes unless that is what the ambient light requires or the 1/60 limit of P or A-DEP has been reached. It is just a limit programmed into P and A-DEP modes so you don't get blurry pictures.
A note about a quirk in the 550EX and 10D combination. If you try to use a 550EX in M mode and the 10D in P mode, the camera locks a shutter speed of 1/200 and the f stop just blinks at f/22.
(Sorry about all the blue, it's just that kind of day!)
Regards,
Scott

Scott,
You are right....what I meant to put in those paerntheses was "synch speed", but I had that 1/60th stuck in my head from the little dissertation on the Vivitar flash (which in thinking about it had nothing to do with the question anyway).

Yes, when you are using flash, the shutter speed has no effect on the flash output other than if you choose a shutter speed faster than your camera can synch for. In that case, you will get a frame that is properly exposed for part of the frame and then the other part will be under exposed.....

I was trying to make my explanation as simplistic as I could...

For some reason I had the idea that the 10D would choose one synch speed in Av or in M and let you just change the aperture to suit your situation. You are right....in different shooting modes it reacts differently. I have mostly used mine indoors in relatively low light and in P mode with a wide open aperture, so I always saw 1/60. That's interesting, and opens up a whole new range of ways to use E-TTL without having to think about it. It just chooses the fastest synch speed it can for the ambient light...it was covering my butt and I didn't even think about it. In Program mode with E-TTL, I just never paid any attention to what it was doing...the results are always good so I didn't worry about it. The most I usually do if I'm using Program mode is shift the program to get the aperture I want.

Interesting points...I need to play with this thing a little more and pay attention to what it's doing in each mode. That Custom Function setting (CF-3) is pretty cool too...I haven't used that either. I'm going to try that tomorrow and see what it does for me. I'm still getting used to this 10D..it's a little different.

Thanks...