Hello, everyone! Tonight we're going to be doing something different
I'm gonna be capturing that tree back there
And hopefully, some star trails behind it, that's the idea
It's obviously gonna be a long exposure of around an hour and a half, something like that
That's what I'm aiming for
I'm gonna be using film for this, I find film to be much better for exposures this long
so I have the Bronica back there, it's already set up
I did it a while ago when there was still light out
I find it much easier that way
I just need to figure out the settings
It's a little bit complicated, this is about reciprocity failure and things like that
I'm gonna just show you a few videos and then hopefully the final image
and then I'll be talking about how I figured out the settings for this
we're gonna be talking about reciprocity failure and how to make long exposures with film in general
All right, so the image kind of worked
it wasn't the best subject because it was lit by a streetlight
so it was going to be hard to capture that lit tree and the star trails in the background
I had to work a little bit in Lightroom to bring those star trails back
It got a little bit cloudy too as you can see here, above the tree
But what matters here for this video, what I wanted to talk about is about the exposure
and how I figured out the settings to use with the Bronica for this shot
So for those who don't know, I have a whole a book about long exposure photography
that I'm gonna link in the description down below, it's free so you can download it
it's a PDF, almost a hundred pages
And I talk about everything that you might need to know for long exposure
from camera gear to the subjects that you can capture, why to do it and how to do it with both digital and film
So as I said earlier, I prefer film over digital for exposures this long, for many reasons
We have to keep in mind reciprocity failure, that's something that happens with film
and that happens because film is made of chemicals and those chemicals become
less and less sensitive to light the longer we are exposing an image
So we have to compensate for that, and the way to do it is to expose that film for even longer
What this theory means in practice is that we need to adjust the shutter speed and make it much longer
I exposed this image for an hour and half, to get to a shutter speed as long as that one with a digital camera
I'd have to use ND filters, but I didn't need them at all with the film camera, thanks to the reciprocity failure
Reciprocity failure is different for every film stock and there are usually tables that you can find online
or even apps, I think that Ilford has an app
For this, I used HP5 and I have a table that I've been using for years
So I know that if I wanna get an exposure of an hour and a half, I need to meter for 10 minutes
So, to get this exposure, to get this brightness with a digital camera
I'd have to have the shutter open for 10 minutes
but to get the same brightness with film, I need to have it open for an hour and a half
I'm gonna show you really quick how I did the math for this
as we said, this is gonna be a 1h30min long exposure
when we look at the reciprocity failure table for HP5, that is in equivalent of
10 minutes when we meter with a digital camera or a light meter
I took a photo with my digital camera and the values that I got were
one second, f/1.4 and ISO 1600
the ISO is the same that I was using for film, I was pushing HP5 2 stops
so that is done, we can't change that value with film
We need to somehow transform this 1 second into 10 minutes
as you saw in the video, probably, I was using an orange filter
I need to compensate 2 stops for that orange filter, so that changes the shutter speed to 4 seconds
The lens I was using, the 80mm, the maximum aperture is f/2.8, that's another 2 stop difference
so, f/2 would be 8 seconds, and another stop, 16 seconds at f/2.8
The shutter speed is getting slower and slower, but still pretty far from the 10 minutes
The only option that we have here is to keep stepping down the lens
So if we do step it down to f/4, that'd mean 32 seconds
if we step it down to f/5.6, that means 1min and 4 seconds
To f/8, that's 2 minutes and 8 seconds
To f/11, that means 4min and 16secs
and finally, f/16, that means 8min and 32secs
and this is what I went with, settings of f/16, pushing HP5 to 1600, 8 and a half minutes
but that would be for digital, we need to compensate for reciprocity failure
so I eyeballed this, if 10 minutes were an hour and a half
8:30 I assumed it was going to be around 1h and 15mins
that's what I did and the image turned out pretty well when it comes to the exposure values
this is how I did the math
This is what I wanted to share about this
Some people had asked me in the past about this topic
It's a little bit complicated to explain, but I hope that this helps someone
If it's still not clear for you, please leave a comment down below
I'll try to get back to you or send me an email from my website and I'll try to help you
and now, some of my favorite long exposure images I've made at night
Thank you so much for watching, and see you in the next one!