Focusing help

[steveo]

This is the Forth Bridge a big Victorian over designed railway bridge near Edinburgh, I've had a few attempts at this and can't quite seem to get it quite right I'd like the whole structure in (reasonably) sharp focus but I'm trying to shoot it at night to fit in a series of architectural night shot. I'm trying not to stop right down because I'm cheap I've not got any Acros in 54 so I've been making do with delta and the reciprocity gets really silly really quickly.

Would any movements help bring this into focus or will I need to either stump up for acros or wait for a flat calm day and stand there for 10 minutes.

Forth Bridge Evening by Steven, on Flickr

Forth Bridge Night by Steven, on Flickr

[Nathan Potter]

If you want maximum sharpness in the bridge then treat the bridge itself as a pretty flat Schiempflug plane running from right foreground to left end of bridge. Thus you could use backplane tilt by moving the right edge of the rear standard slightly backward (toward you) such that the entire length of the bridge is in focus with the lens wide open. To the degree that you want the area to the left and right of the bridge in focus you'll have to then use a smaller aperture especially at the left and right edge of the image.

Nate Potter, Austin TX.

[steveo]

I was using a little bit of front tilt, I take it that would not have the same effect? I'll need to get down in day time I think to be able to more clearly see the changes but it would be helpful to have where I've messed up pointed out to me.

[rbultman]

Front swing to get the bridge in focus front to back and a little forward tilt to get the foreground? Sorry, total newb here, so feel free to discard.

You might return to the site during the day with a loupe and a darkcloth. That might help you understand the movements you need to acheive the focus you want.

[Jac@stafford.net]

I was using a little bit of front tilt

I would stick to Nathan's suggestion. Just a few degrees should do the trick. And regarding standing for 10 minutes, take it as time to relax. It is worth it, and a smaller stop might help with the light-source interference.

[steveo]

I would stick to Nathan's suggestion. Just a few degrees should do the trick. And regarding standing for 10 minutes, take it as time to relax. It is worth it, and a smaller stop might help with the light-source interference.

I meant swing not tilt but the advice stands. I'll give it a try.

Problem with the very long exposures is camera shake, the bridge is over and estuary and it gets pretty windy even when it's basically flat calm inshore.

[Jac@stafford.net]

Problem with the very long exposures is camera shake, the bridge is over and estuary and it gets pretty windy even when it's basically flat calm inshore.

Of course. I wasn't thinking. I've used an umbrella to help shield a camera from the wind. Sometimes it even works.

Best of luck to you.
I look forward to your final picture of that scene.

[Doremus Scudder]

A little tilt (front forward with the back plumb if you want no perspective change) combined with swing (rear or front depending on if you want to emphasize the closer part of the bridge or not) should help some.

Choose focus points near and far as well as left and right and check focus spread between them as you apply movements. The position with the least focus spread is what you're after. Keep in mind that applying tilt will throw the nearest high areas out of the plane first and that swing will affect the left foreground first, so make sure you choose those areas for a couple of your focus points.

FWIW, to beat the wind, you might try stopping down and then making a series of shorter exposures that add up to one longer one. Make your exposure when the wind is calm, close the shutter when it comes up again, and repeat till you have reached your total exposure time. I've done this successfully a number of times for exposures up to 15 or 20 minutes.

Best,

Doremus

[tgtaylor]

The foreground in the first looks reasonable sharp but it has too much black for my taste. I would bring the camera up a little to eliminate most of the black at the very bottom and start the composition with the little promontory at thee center. That way you will have alternating bands of darkness and light in the immediate foreground instead of mostly darkness.

I did a similar composition of the San Francisco Bay bridge from the SF side to Treasure Island with a 150mm apo-Sironar-S and IIRC I focused on one of the bulbs hanging from the cables. Back then the decorative lighting on the Bay Bridge was done with something like large light bulbs if you will which were hung from the suspension cables. I then stopped down to f16 to make sure that all the vertical cables running up to the large suspension cable were sharp. I forget what the actual exposure time was - no doubt on the order of a full minute with Acros. But the long exposure smoothed the currents in the bay and I got a nice black bay with streaks of silver - which was exactly what I was looking for. You can do it with Delta or other Ilford films but you need to have the Ilford reciprocity curve which I have found to be very accurate with you.

You don't have bulbs to focus on but you have the actual structure itself which is well-lit instead. A little front tilt for the foreground should do it: focus on the X and tilt for the Y is the drill.

Thomas

[Jim Jones]

Shooting a little earlier on an overcast evening could provide a hint of detail in the shadows and a shorter exposure. Wait until the artificial lights are on to provide the feeling of a night shot. Make sure your lens is perfectly clean and don't stop down so far that diffraction smears the bright lights.