ST-E3-RT Focus Assist Add-on

[mikehiga]

Since the ST-E3-RT doesn't have a focus assistance beam, is there a reliable alternative?  I've heard of YN-E3-RT, but also have heard that its focus beams don't align with the focus points of the camera.

Is there a such thing as an addon device that is specificaly for low light focusing assistance?  Kind of like an add-on to the ST-E3-RT.  Or perhaps a Version 2.0 of ST-E3-RT which includes focus assistance?

[TCampbell]

Well... the "alternative" would be to use another 600EX-RT on-camera as the focuser and transmitter (you can disable the flash).  That's actually what I initially did.

The pattern of the focus beam will look different depending on the focal length of the lens.  e.g. if you use a really wide angle lens (e.g. such as a 14mm) then the outer focus points will probably be looking at a target far enough away from the beams that they don't benefit from it.

[mikehiga]

Thanks for the response.  I was hoping I can get a focus assistance device without resorting to purching another 60ex-rt.  I just can't really justify the cost.

My lens range from 17-40mm, 50mm and 70-200mm. On 5D III.