I've been shooting night sky timelapse video with Canon 5D Mark II and 24mm f/1.4 prime lens in manual mode for more than a year, but always after dark with constant exposure dark night sky.

I thought I would try the Holy Grail of TL and shoot from dusk to night with the intention of changing the ISO a few times during the shooting period. This is the technique I read about on this forum. I thought I would start at ISO 100 and increase to 3200 during the shooting period. But I found when I started shooting at dusk, that with ISO 100, I had too much light shooting at f/2.8, f/1.4 was even worse.

For the dusk portion of the TL, I could add an ND filter but then I would have to adjust the ND filter and the ISO during the shooting period.

It seems to me the dusk to night dynamic range is so huge, that just changing the ISO isn't sufficient. I believe I would have to change the ND filter several times and the ISO several times for proper exposure and that's a lot of work and a lot can go wrong. I don't mind the work, but I can't help but think I am missing something.

Do I really have to change both an ND filter and ISO setting multiple times during a Holy Grail shoot? Can I really get away with just adjusting the ISO?

thanks,
Rich

Hi Rich! Just start adjusting Exposure Time in 1EV steps, than if it's long enough switch over to ISO!

Rich,

I just started to experiment with this a few weeks ago and ran into the same issues. Here's what so far seems to have solved it for me:

At dusk, I set the camera to ISO 100, stop down the lens, e.g. to f2.8, and expose for a short time. As it gets darker, I first increase exposure time until I get to where I want, e.g. 1/15 second. Next, I open up the lens step by step until I reach maximum aperture, e.g. in my case f1.8. By now it is quite dark already, and I start ramping up ISO until I hit what I think is the highest acceptable setting (depends, with modern cameras sometimes goes up as high as ISO 6.400, but I like to stick around ISO 1.600). Then, when it gets really dark, I usually increase exposure time again.

I don't fiddle with filters. It annoys me. :-)

HTH.

/Marcus

I as well would recommend not using filters but I would as well recommend not closing the aperture if avoidable because it introduces flicker and the change in depth of field might be visible as well. Just go for shorter times. Most bodies are pretty capable of doing 1/8000th, normally Exposure flicker (introduced by short times) is much less noticeable than aperture flicker.

Gunther,

that's of course correct. However, sometimes, especially when shooting directly at the setting sun, even 1/8000 second exposure is too long. With focus set to infinity, I have not seen any noticeable change in depth of field when changing aperture between f2.8 and f1.8, and LRTimelapse seems to do a terrific job deflickering. :-)

/Marcus

Thank you ;-), yes you are right, if have to go shorter than 1/8000 (especially with the f/1.4 lenses) you have to stop down... It's still way better then using filters!

Thank you for the reply and confirming that something more than ISO needs to be changed when creating a dusk to night TL. Tonight I will try what you suggest, start with changing the shutter speed and then as it gets much darker, the ISO.

I am used to starting a TL and walking away, shooting the Holy Grail is going to be more like baby sitting.

thanks,
Rich