Strobist: AF in the dark - advice needed

Hugh_C

Hi,

I'm doing a load of strobist stuff these days in a space where there's very little ambient light - the problem I'm having is that there's so little ambient light that my autofocus system is having a really hard time latching onto anything, even with the AF assist beam on. I'm using Cactus triggers so there's no TTL stuff happening with the flashes, in any case the light is being bounced off umbrellas and other surfaces, so the flashes' AF beams are pointing the wrong way to help.

Any suggestions how to illuminate the scene sufficiently to get the AF working well but without compromising the strobe lighting?


Thanks, Hugh

Nikon system & flashes btw

swingking

Could u use a maglite torch to light the area for focusing purposes

From my photowalks, I've got the focused locked in under better conditions and then flicked the lens to manual to take the shot. This locks the lens when its sharp and lets you shoot away without loosing it.

sheesh

there is also manual focusing but that can be hit and miss unless you have sharp eyesight

so If i could I would light the area focus switch to manual to lock the focus and photograph.

your a pretty experienced photographer so I imagine you would have probably thought of that so is there any way you could calibrate your lens so that you could if you knew the distances you could dial it in

ie put marks on th focusing ring for a range of distances and set manually

its the way they used to do it in the old days

melekalikimaka

swingking got in in one

kjt

Hey Hugh,
Yup, as Stephen(Swingking) has already said. Use a tourch. I recently shot in the Wicklow Gaol after dark and as you can imagine there was little/no light. I had one shot with two strobes setup within a cell that was absolutely pitch dark (we literally couldn't see a thing). The model was put in position and given direction while I got to my spot with a bit of stumbling around. I then had the model shine a tourch on her face where I would autofocus, switch the camera to manual focus, ask the model to hide the tourch, get ready, 1-2-3 Click, take 2-5 shots and repeat a good few times. It can be tedious but when you have no other choice, it does the job

Here's the shot with no lights.... (haha)


Shot with one strobe firing and model using light to help me focus


Flash setup




Finished shot using the same method in a different cell with no available light.


Hope that helps my man!!
Kyle

pullandbang

kjt wrote: »

Here's the shot with no lights.... (haha)

LOL

Seriously though, that's good stuff Kyle. A very informative post.

DaireQuinlan

Can't you mount a strobe on-camera and just use its AF assist lamp ? Without triggering the strobe during the shot ? AFAIK the AF-assist on the strobes is much more powerful than the small one on the camera itself, so they should have the range.

There is also some Nikon hotshoe mounted AF assist only accessory I've seen, but I can't for the life of me track it down at the moment.

.Longshanks.

I've seen a video where David Hobby (from strobist.com) where he puts a small LED torch onto to the side of this shoe mounted wireless transmitter with elastic band. He doesn't bother to turn it off either, uses the light from the torch to autofocus and and the power of the strobes overpower any light from the torch

PopeBuckfastXVI

A tungsten lit room will be pretty much black at iso100 1/200s at any aperture, you could bring a little lamp to focus by, try a few by shooting with enough light to focus, but that you still get a completely black image when the flashes are switched off.

Shutter speed controls the ambient level, aperture controls the flash level, by making your shutter speed faster, you reduce the ambient without affecting the flash.

swingking

kjt wrote: »

I recently shot in the Wicklow Gaol after dark

Isn't that place like haunted or something :eek:

oshead

+1 for what popebucketfast said. The ambient would have to be mighty strong to affect the image in any way. So just bring a lantern with a good wide spread with you if you've absolutely no light to work with and you should be fine.

Hugh_C

Huge thanks to ALL for all the great suggestions - I have just the Maglite attached to my keys - I guess it's going to be re-purposed,

Thanks again,

Hugh

PS just for the craic, here's a result from the near-dark ambient when I did get the focus right

model: Sarah H | mua: Agnieszka Pietrzak | photog: Hugh_C

.

Slidinginfinity

Beautiful hues, Hugh.:D

But seriously, just beautiful.

FoxT

I feel your pain & in the past I have had the following MO:

1 - use a torch to light the subject, then focus using AF.

2 - switch lens to Manual focus & shoot.

This is a pain b/c you and your model have to stay still, and you will have to recompose, and it is just awkward in general. So, A better way is ( with a canon 40D at least,I am sure other SLRs have a similar function)

1 - using custom functions, configure the camera so that the shutter button does no AF, and the separate AF button triggers AF.

2 - use torch & focus using the AF button

3 - shoot.

This method has the advantage of not having to constantly mullock with the lens, switching between AF & MF.

And finally, the ne plus ultra of shooting in the black dark is....

1 - using custom functions, configure the camera so that the shutter button does no AF, and the AF button triggers AF.

1a - take your cactus trigger off the hot shoe & fire it with the x-sync cord instead ( so you can use your camera's inbuilt flash)

1b - Note that when you do this you cannot do 2nd curtain sync ( on a 40d at least), but this is unimportant unless your subject is in motion.

2 - configure the camera so it will use its internal flash (assuming it has one) in 'AF-Assist' mode

3 - focus using the back button. When you focus, the camera flash will give a short burst of 3-4 flashes

4 - once focused, pop down the internal camera flash if you dont want it

5 - shoot.

I have found that
The 3rd method works well if your aperture is at f/4.0 or smaller ( ie f/5.6. f/8, etc) . AF assist flash is not as good as a bright torch - but it is good enough @ smaller apertures.

The 2nd method works best if focus accuracy is absolutely critical ( f/2.8 or wider)

And finally
- If using method 2, use a bright torch, the brighter the better.
- 'focus bracket' - ie focus, shoot, lean forward about 5-10cm, shoot again , lean back 5-10 cm & shoot gain. Do the 2nd & 3rd shots without refocusing between shots. This guarantees that you will have 2 shots out of 3 slightly oof, but the 3rd one will be spot on.


Good luck!

FoxT

Hugh_C

Great suggestion FoxT, I'll have to dig out my manual to see how to configure the Nikon to do this if I can - I know I can set it to only allow the shutter open under certain focus conditions.

I'm mostly in the range 3.5 to 5.6, seldom stray below 2.8 for the strobist stuff I do.

I'm using a 50mm 1.8 for most of the beauty stuff I do but am considering a Nikkor 50mm f/1.4 - the opportunity to rent out some of my kit and take payment in kind (i.e a 1.4) might be coming up soon, and I'm hoping that the threefold price increase over the 1.8 might mean a better AF system. Not sure if the optics are three times as good as the 1.8

We'll see.

Thanks for all the suggestions again.

FoxT

I hope it helps you! I make suggestions on boardsie partly to try help others & partly to get critique so I can learn, too. So, I am interested to see how it works out for you. Living in Canon Land as I do, I cannot comment on the Nikon 50mm f/1.4. I am sure it is a good lens.I have a canon 50 mm f/1.8 & while the lens is great value for money it focuses erratically in poor light. I am reluctant to go for the canon 50mm f/1.4 b/c it is reputed to be soft at wide apertures. The Sigma 50mm f/1.4 has been getting good reviews but it is heavy & expensive. Nevertheless it would be my upgrade choice. Having said all of that, I am really impressed with the photo you posted - far more impressive than anything I have done to date unfortunately!

-FoxT