Techniques

ND filter maths for Bedok Jetty sunrise — what am I doing wrong?

@bestlight · 2mo ago

Trying to smooth the water at Bedok Jetty before sunrise and my numbers keep coming out wrong. With a 6-stop on at f/11 ISO 100 I metered 10s and the frame came out about two stops hot by the time the shutter closed. I think the problem is that it is getting brighter the whole time I am exposing, which never happens when I shoot sunsets. Do you just meter again between every frame, or is there a smarter way?

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@bestlight2mo ago

You are not doing anything wrong, the light is just moving under you. Pre-sunrise gains roughly a stop every ten to twelve minutes here, so a 10s frame metered at the start is already wrong by the time it finishes. What works: meter, then deliberately underexpose by about a stop, and shorten as you go. My Bedok sequence usually runs 15s, then 10s, then 6s, then 4s over about twenty minutes at f/11 ISO 100. Same filter throughout.

@bestlight2mo ago

The descending ladder works at Lorong Halus too — same east-facing water. I start one stop shorter because the bridge rail glows earlier than the sky.

@bestlight2mo ago

Film shooter here so take this how you like, but the descending ladder is exactly what you do on a light meter with no screen to check. You are just doing manually what your histogram would have told you. Write the ladder on tape and stick it to the back of the body. Sounds primitive, works at 6am when you are not thinking clearly.

@bestlight2mo ago

That was it. Ran the descending ladder this morning and got four keepers instead of one. Thank you both.