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F/stop correction for Telephoto Lens ?
- Thread starter fl64776
- Start date
Yes.If a telephoto lens and external flash are used, is F/stop
correction required to match the flash F/stop? I'm using Tiffen 2x
telephoto and Sunpak 383 flash.
Thanks,
fl
If you are using it on a Canon (or any other electronic) camera, see http://www.botzilla.com about strobe trigger voltages. The Sunpak may or may not zap your camera.
Many non-Canon flashes will not function properly on the G1/G2. GKL
Mike K
Veteran Member
If a telephoto lens and external flash are used, is F/stop
correction required to match the flash F/stop? I'm using Tiffen 2x
telephoto and Sunpak 383 flash.
Thanks,
fl
Mike K
Veteran Member
Sorry for MT message,
If you are using the G-1 or G-2 with the Tiffen megaplus, the camera has through the lens (TTL) metering thus no additional corrections are required for available light shots. if the Sunpak works ok, it will flash with full intensity as the camera will only control Canon 420EX and 550EX flashes. If the Sunpak has an intesity control, use it, otherwise exposure control on the camera is all you have to adjust exposure.
Mike K
If you are using the G-1 or G-2 with the Tiffen megaplus, the camera has through the lens (TTL) metering thus no additional corrections are required for available light shots. if the Sunpak works ok, it will flash with full intensity as the camera will only control Canon 420EX and 550EX flashes. If the Sunpak has an intesity control, use it, otherwise exposure control on the camera is all you have to adjust exposure.
Mike K
If a telephoto lens and external flash are used, is F/stop
correction required to match the flash F/stop? I'm using Tiffen 2x
telephoto and Sunpak 383 flash.
Thanks,
fl
Just one comment on this advice: if the Sunpak has its own auto sensor then it will can adjust its output accordingly. These sensors usually have 2 or 3 user-selectable f-stops. (These f-stops change when you change the camera's ASA setting). In order to use these f-stop settings you will have to set the G2 to the correct fstop in Av mode. If you have a telextender on the lens, then you have to divide the flash f-stop setting by the magnification to get the fstop you would set on the G2, which is the question asked in the original post.Sorry for MT message,
If you are using the G-1 or G-2 with the Tiffen megaplus, the
camera has through the lens (TTL) metering thus no additional
corrections are required for available light shots. if the Sunpak
works ok, it will flash with full intensity as the camera will only
control Canon 420EX and 550EX flashes. If the Sunpak has an
intesity control, use it, otherwise exposure control on the camera
is all you have to adjust exposure.
Mike K
All of the above assumes that the flash will trigger on the G2. I don't have a Sunpak, but I tried another well-known non-Canon brand and the flash triggered before the shutter went off. GKL
Thanks for the advise.
I missed the camera information: it's G2, with Tiffen megaplus 2X, Sunpak 383 flash.
The Sunpak 383 flash has 5-step intensity control and a sensor to automatically control the flashing time based on F/stop setting. The important thing is to tell flash which F/stop is set on the G2, so flash can control exposure. Everthing works OK.
If a telephoto lens is attached to the camera, at the same F/stop, the light reaching CCD will be different, so how to make the compensation and to set the flash.
Frank Liu
I missed the camera information: it's G2, with Tiffen megaplus 2X, Sunpak 383 flash.
The Sunpak 383 flash has 5-step intensity control and a sensor to automatically control the flashing time based on F/stop setting. The important thing is to tell flash which F/stop is set on the G2, so flash can control exposure. Everthing works OK.
If a telephoto lens is attached to the camera, at the same F/stop, the light reaching CCD will be different, so how to make the compensation and to set the flash.
Frank Liu
Just one comment on this advice: if the Sunpak has its own autoSorry for MT message,
If you are using the G-1 or G-2 with the Tiffen megaplus, the
camera has through the lens (TTL) metering thus no additional
corrections are required for available light shots. if the Sunpak
works ok, it will flash with full intensity as the camera will only
control Canon 420EX and 550EX flashes. If the Sunpak has an
intesity control, use it, otherwise exposure control on the camera
is all you have to adjust exposure.
Mike K
sensor then it will can adjust its output accordingly. These
sensors usually have 2 or 3 user-selectable f-stops. (These f-stops
change when you change the camera's ASA setting). In order to use
these f-stop settings you will have to set the G2 to the correct
fstop in Av mode. If you have a telextender on the lens, then you
have to divide the flash f-stop setting by the magnification to get
the fstop you would set on the G2, which is the question asked in
the original post.
All of the above assumes that the flash will trigger on the G2. I
don't have a Sunpak, but I tried another well-known non-Canon brand
and the flash triggered before the shutter went off. GKL
Frank, the answer was in my previous post. See below. GKLThanks for the advise.
I missed the camera information: it's G2, with Tiffen megaplus 2X,
Sunpak 383 flash.
The Sunpak 383 flash has 5-step intensity control and a sensor to
automatically control the flashing time based on F/stop setting.
The important thing is to tell flash which F/stop is set on the G2,
so flash can control exposure. Everthing works OK.
If a telephoto lens is attached to the camera, at the same F/stop,
the light reaching CCD will be different, so how to make the
compensation and to set the flash.
Frank Liu
change when you change the camera's ASA setting). In order to use
these f-stop settings you will have to set the G2 to the correct
fstop in Av mode. If you have a telextender on the lens, then you
have to divide the flash f-stop setting by the magnification to get
the fstop you would set on the G2, which is the question asked in
the original post.
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