# Flash for a 70-200 and 300mm lens



## Deleted member 381342 (Jun 28, 2019)

Greetings folks, I have at the moment the option to get a Speedlite 430EX III RT however, I am not familiar with them. Will work to give some fill light when I am using my 70-200 F4.0 and 300 f2.8 or it is only going to be of use for my 24-70 f4.0 as it is under 105mm?


----------



## YuengLinger (Jun 28, 2019)

The 600ex-rt would give you more power when bouncing (plus a full 360 degrees of swivel) and is definitely a great match for 200mm. 

But if you can get it very cheap, the 430ex, being smaller, is handy in a pinch. And from what I understand, the newer one swivels a bit more than the version II, but still not a full 360 degrees. I can tell you version II feels compact compared to the 600ex-rt!

Here's a good review, and there are many others:









Canon Speedlite 430EX III-RT Flash Review


Canon-Speedlite-430EX-III-RT-Flash




www.the-digital-picture.com


----------



## Deleted member 381342 (Jun 28, 2019)

I have read a few reviews including the one linked. However, I am still at a loss for understanding the power to lens length and subject distance. With the 430 will it work with a 200mm lens on a subject a good 5 meters away?


----------



## neuroanatomist (Jun 28, 2019)

Codebunny said:


> I have read a few reviews including the one linked. However, I am still at a loss for understanding the power to lens length and subject distance. With the 430 will it work with a 200mm lens on a subject a good 5 meters away?


It will work well enough. Without going into an exhaustive discussion of guide numbers and the inverse square law, as an approximation the 600 flash will give you about 35% more distance than the 430, or about a stop more light at the same distance. For example, the light delivered at 15 m by the 430EX is what the 600EX delivers at ~20 m. Or if you prefer, you could shoot at 15 m with the 430 at a given aperture and ISO, while the 600 would allow you to use a stop narrower aperture or a stop lower ISO (or use 1/2 flash power, which would mean faster flash recycling).


----------



## Deleted member 381342 (Jun 29, 2019)

neuroanatomist said:


> It will work well enough. Without going into an exhaustive discussion of guide numbers and the inverse square law, as an approximation the 600 flash will give you about 35% more distance than the 430, or about a stop more light at the same distance. For example, the light delivered at 15 m by the 430EX is what the 600EX delivers at ~20 m. Or if you prefer, you could shoot at 15 m with the 430 at a given aperture and ISO, while the 600 would allow you to use a stop narrower aperture or a stop lower ISO (or use 1/2 flash power, which would mean faster flash recycling).




Thanks for that, I'll give is a go and see if I can make use of it. I don't really want to invest in a 600 and find I never used it, especially given for the last 10 years I have been flash free with my 5d mk II and while my 7d had a built in one, I kept it off. £200 is not a lot of money to loose if it ends up not being of use.


----------



## scottkinfw (Jun 30, 2019)

Codebunny said:


> Greetings folks, I have at the moment the option to get a Speedlite 430EX III RT however, I am not familiar with them. Will work to give some fill light when I am using my 70-200 F4.0 and 300 f2.8 or it is only going to be of use for my 24-70 f4.0 as it is under 105mm?


Look into a Better Beamer to attach to your flash. You will need to set the flash to 50mm. You can google it or look at the lenscoat website. I am not sure how far, but the better beamer will extend the reach of your flash with a frensel lens.

scott


----------



## Kit. (Jun 30, 2019)

Codebunny said:


> I have read a few reviews including the one linked. However, I am still at a loss for understanding the power to lens length and subject distance. With the 430 will it work with a 200mm lens on a subject a good 5 meters away?


It should be enough for Sunny-16 fill flash in X-sync mode, but a bit short in power in HSS mode, unless you find a way to move the flash closer to the subject.


----------



## Deleted member 381342 (Jun 30, 2019)

Kit. said:


> It should be enough for Sunny-16 fill flash in X-sync mode, but a bit short in power in HSS mode, unless you find a way to move the flash closer to the subject.


Will see how it goes. It can always end up as a slave to a 600 at a later date


----------

