Flash on a 100-400 - Can I do it?

swag72

swag72

Suspended / Banned
Messages
7,969
Name
Sara
Edit My Images
Yes
Further into my flash journey - Before actaully getting the thing! - I am thinking of ways I can use it. So, maybe a stupid question, apologies if it is.

I am getting a 580exII and will be using it for macro work, using a set up similar to stan the man (velcroed to the hood, with an off shoe cord). My dumb question is whether I will be able to use the similar thing on my 100-400 as I have read that the flash only 'goes up to 100mm'. I am thinking of pics of flying dragons at 400mm, so would need high speed synch (?) and would the flash reach for 6 ft?

Or - Am i being a total idiot and have got it all wrong?!!:thinking:
 
I've used a 580II with my 70-200mm ok, just watch the lens hood doesn't get in the way.
 
So what does 'Lens Coverage: 24mm - 105mm' mean? Can I not use it automatically above 105mm?

Were you using it at 200mm admirable?
 
Tried to find a sample pic but don't have any to hand. I used it at my daughters riding school inside a large arena that wasn't completely dark. It worked fine just to light them up a bit, more of a fill flash I suppose.

I live 5mins from a park with nice gardens/flowers etc and is a target for wedding togs, I often see a girl there with a 70-200 and a flash on top doing wedding stuph.

It depends what you want to light up. I could do some test shots tonight in the dark if you want.
 
swag72 said:
So what does 'Lens Coverage: 24mm - 105mm' mean? Can I not use it automatically above 105mm?

Were you using it at 200mm admirable?
Click to expand...

It simply automatically ensures (providing you're using a lens within those focal lengths) that the flash will illuminate the scene as seen by the lens without wasting flash energy. For example: if you manually set the flash to 100mm but used a 24mm lens, the edges of the shot would not be illuminated by the flash because the flash would project a beam with a field of view suitable for a 100mm lens. Equally if you manually set the flash to 24mm and used a 100mm lens you would waste a lot of flash power illuminating more of the scene than the lens can see. You can use longer lens than 105mm perfectly well (providing your inside the range of the flash of course) but if you do, some of your flash power will be wasted illuminated parts of the scene the lens can't see.
 
You should look at a Better Beamer flash extender (FX-3 version for a 580EX). It focusses the flash beam to improve range and concentrate (within limits) the flash to the area covered by the lens.

Bob
 
Gofer has it spot on. As for the question about coverage to 6' that should be no problem. The 580EX has a Guide Number of 58m or 191' when used at the 105mm setting. That means that the flash will reach 191' at 100 ISO and f/1.0. At f/8, as an example, simply divide the distance by 8 to give a range of 191/8 = 24'. f/11 would give a range of 191/11 = 17'. f/16 would give 191/16 = 12'. f/22 would give 191/22 = 8.7'.

If you should need more range then each time you increase the ISO by 1 stop you increase the distance covered by 1.4X.

You probably should not use high speed sync. If you kill the ambient and use only flash then you will get a shorter flash duration without HSS. If you use HSS you can actually get more subject blur as the flash is illuminating for longer. I don't know if the data here is accurate but the principle is sound - http://www.photosbykev.com/wordpress/2008/07/12/canon-580ex-flash-duration/.

This may help - http://www.naturephotographers.net/articles0703/jm0703-1.html.
 
As Bob says, a Better Beamer, or one of the Chinese clones would help - Fracster might be able to shed more light (sorry :shake:) on the subject, he has/had one....
 
What sort of distance are your dragonflies from the lens?

I use a kirk flash x-tender with my 300mm and I'm sure it mentioned in the instruction leaflet that there was a minimum recommended distance. Maybe you would be better off with a flash bracket and a softbox?

On a sidenote, I love the flash x-tender it makes a huge difference to my shots where a little extra light is needed. The two below were shot on a dully murky day over on inner farne
http://www.scruffywhippet.com/talkphoto/rts/2009-05-23-farne/IMG_8425.jpg
http://www.scruffywhippet.com/talkphoto/rts/2009-05-23-farne/IMG_8491.jpg
 
You must log in or register to reply here.
Back
Top