How to measure and time long exposures at dusk or dawn.

[mongole]

Hi,

I enjoy long exposure photography very much. I do some of it in digital, which is quiet easy. But at changing light and considering Schwarzschild effect, it get's more complicated.

I use a Sekonic L-758 for metering. Most of the time incident, but sometims spot metering. I am to slow on spot metering, have to practice it more :D
Then I use two Android apps to do the compensation. ND Filter Calc to get the compensated time and then Exposure Assistant, which calculates the Schwarschild effect for several film brands and ISOs.

From the technical point it's straigt forward and clear, although I would wish to have an app, which could somehow take over the metering and do both compensations. But that's another story...

Where I struggle now is how to compensate for the changing light during dusk and dawn. How do you handle this? Also passing clouds are not that easy to handle. Do you have any rules of thumb how to compensate?

[steveo]

The easy, expensive, option is to use Fuji films, Acros and Provia both have exceptional reciprocity response and need very little adjustment for very long exposures.

Alternatively you can not worry too much about it, realise its very hard to over expose once you're into Schwarzschild territory and use a compensating developer to help. If you are scanning you can get away with quite a lot, its not ideal but it is amazing what you can get away with.

[Jac@stafford.net]

It is faster to set the lightmeter's ISO to compensate for the ND filter, or any other filter. Those factors will not change, so you need read only once. No conversion necessary. Regarding reciprocity failure, a simple small card giving ranges is adequate, as stevo mentioned.

Changing light will become easier to compensate with experience. When a huge cloud moves into a significant part of your scene with a very long exposure, just let it be, make the picture and prepare to make another.

[Lachlan 717]

If you have an IPhone, consider Reciprociry Timer app. (Not sure if it's available for Android).

[mongole]

Thanks for the tips.

@steveo
Acros and Provia prices are really hefty! 25 sheets above 80€ compared to 50€ for Deltta 100.... But the advantage is tempting.

@Jac
You are right, i also think it's an experience thing. It's a pity, it's that seldom I manage to get out shooting! I really should try to do the iso compensation. It's one step less and there are plent left! :D

@Lachlan
Thanks for the tip, but it's not available for Android. But Exposure Assistant is doing exactly the same. So no problem here.

In meantime, I also found this very interesting thread: http://www.largeformatphotography.info/forum/showthread.php?10497-Exposure-measurement-at-dawn-dusk
They discuss the same topic and also have some interesting tips.

Let the brighter sun compensate for the most of Schwarzschild during morning Hours. But there is no tip for me for the evening hours.

[mongole]

What I do not fully understand. In my understanding, a compensating developer holds back the light areas and pushes the dark ones resulting an a less contrasty image. Wouldn't this strenghten the Schwarzschild effect, as it tends to underexpose?

[Corran]

I don't know how long of a timed exposure you are doing. But I've done some real long exposures, up to 10-20 minutes in abandoned buildings. I usually pulled the development 10-15% for every extra "stop" I gave the exposure to correct for reciprocity.

I found some adjusted times online and used them. They worked fine. I don't use silly phone apps, I just remember correction values.

More importantly than any of this discussion is just trying it out. Shoot a few sheets and see what works for you.

[Greg Miller]

Where I struggle now is how to compensate for the changing light during dusk and dawn. How do you handle this? Also passing clouds are not that easy to handle. Do you have any rules of thumb how to compensate?

The good news is the actual exposure time with long exposures isn't all that critical. For example, if you determine your exposure should be 2 minutes, a full minute underexposure is only 1 stop off, and full minute overexposure is only (about) 1/2 stop off. So for long exposures I just count in my head. I have practiced and I am rarely off by 10 seconds or less, and that amount of time is inconsequential for exposures of a minute or longer. For really long exposures i just look at the time on my phone. The most you are going to be off is one minute (on average it will be 30 seconds) and that is meaningless on a 30 minute exposure.

As for clouds, if you have the time, meter when the cloud cover is close to what you want for the actual photo. Then wait some more until the clouds get right again and make the photo. This won't work if you happen encounter a unique cloud that you want to photograph, or you are short on time. But it works pretty well most of the time.

[Vaughn]

I think the best way is to bracket, keep notes and from the results you'll have hard facts and experience to last you the rest of your days.

But as starting points, from info by Michael Kenna: For Tmax400 and Tri-X.

[Lachlan 717]

I found some adjusted times online... I don't use silly phone apps


Why is an app "silly", yet "online" is okay?

[Corran]

Why is an app "silly", yet "online" is okay?

Because I don't want to be messing with my phone while trying to enjoy photography. I oftentimes leave my phone in the car, unless I'm (sigh) "on-call" for work.

I don't much care for any phone app.

[Andrew O'Neill]

Where I struggle now is how to compensate for the changing light during dusk and dawn. How do you handle this? Also passing clouds are not that easy to handle. Do you have any rules of thumb how to compensate?

No rules of thumb other than to not worry about it too much. Just make sure your exposure has taken into consideration factors such as reciprocity, filters, bellows extension, etc. You should have an image that you can work with. Personally, I don't use any apps in the field. I've done it so many times, with the same films, for many years, it's in me head. Get out there and just do it!

[Steve Sherman]

Why is an app "silly", yet "online" is okay?

I wouldn't use an app for reciprocity but I do use the phone to record the camera as it relates to the scene. I use the voice recorder to keep specific notes about exposure, development, scene contrast and then send the audio file along with a still pix or even a video to File Maker Pro program you can design specifically to your needs. The notes about the shot are on my home computer before I even return home.
Just turn the ringer off on your phone if in the Zone !

[Lachlan 717]

What is this phobia/dislike of smart phone applications?

They are simply a different representation of information in (IMO) a bloody handy format.

The creator of the reciprocity tool put many, many hours into collecti and collating reciprocity information and then spent many more creating an easy-to-use interface.

Bryan's comment about not wanting to mess with his phone whilst trying to make photographs just seems priggish; first, smart devices (apps are not always on phones) seems no less tedious or fiddly than looking through hand written notes. Second, put your phone on aeroplane mode. It will still work with the apps without receiving calls.

Steve, I can understand if you wrote "I don't use an app", but I certainly think "I wouldn't use an app" a strange philosophy. If you read the thread about the reciprocity app by Boizo, you'll get to understand the vast amount of work he put into its creation. Can you please explain this view further?

[Andrew O'Neill]

I wouldn't use an app, either... I'm quite happy using the data that I generated myself. And like I said, it's all in my head after using it for years. If other people want to use an app, that's their business and it doesn't bother me in the least. There certainly are some pretty cool apps out there! To each his own! :)

[Corran]

Lachlan, what is the big deal? Are you personally insulted that I don't use the Reciprocity Timer? Get over it. Your accusation of priggishness is really unnecessary. I didn't imply at all that you, or anyone, shouldn't use an app, just that I don't care to.

Look, I like my smartphone. Having access to the internet 24/7 is pretty cool. I listen to podcasts with it as well as mp3s (I can still remember buying my first mp3 player with 16 megabytes of storage). It's a great waster of time. But I don't really care to bother with my phone while I am enjoying my alone time in the woods, or whatever. I tried some corrections for my usual film and found what works for me, and then memorized it. Done. To be honest I did have a cheat-sheet of basic values for a while in a memo on my phone that I referred to once or twice.

It's all for the best that I don't care to mess with most apps as my preferred phone for simplicity and UI is a Windows phone, which the Reciprocity Timer doesn't support anyway.

[StoneNYC]

Personally, when doing dusk and dawn photos, we are sometimes talking an hour or two exposure not just 10 minutes.

In this case, with the changing light what I do is meter from time to time and see if the light has changed, if it has I either adjust the time I shoot for, or adjust the aperture to compensate for the change in light. Depends on the circumstance.

Knowing your film and experience really are the key however.

I also use Acros100 for sure whenever possible as its with the extra time, as I've said before it can be the difference between taking 3-5 exposures and taking only 1 in a single day because the other films that take longer to expose mean that by the time the first one is finally exposed, the light is GONE, but with Acros100's reciprocity characteristics (schwarzschild) you can take more shots.

"Bracketing" is a joke I think? You don't bracket in these kinds of long exposures with changing light unless you set up 3 cameras and fire them simultaneously and then stop them at different times. Lol.

When shooting 8x10 long exposures, I really can't afford to have a bad sheet so I only use Acros100.

[dave_whatever]

What is this phobia/dislike of smart phone applications?

They are simply a different representation of information in (IMO) a bloody handy format.



.....that is entirely battery dependant, and almost impossible to use when wearing gloves. Quick show of hand anyone who's ever had their phone die unexpectedly, especially towards the end of the day? I'm guessing thats most of you.

[Doremus Scudder]

Personally, when doing dusk and dawn photos, we are sometimes talking an hour or two exposure not just 10 minutes.

In this case, with the changing light what I do is meter from time to time and see if the light has changed, if it has I either adjust the time I shoot for, or adjust the aperture to compensate for the change in light. Depends on the circumstance.

Knowing your film and experience really are the key however. ...

"Bracketing" is a joke I think. You don't bracket in these kinds of long exposures with changing light unless you set up 3 cameras and fire them simultaneously and then stop them at different times. ...

Ding, ding, ding!!! We have a winner. If the time allows, re-meter and adjust. Err on the side of overexposure for negative materials. It's really hard to overexpose to the point of not being able to print a negative once you reach reciprocity failure. Of course, there's a build up of contrast, but you take care of that by reducing development.

Best,

Doremus

[Steve Sherman]

Steve, I can understand if you wrote "I don't use an app", but I certainly think "I wouldn't use an app" a strange philosophy. If you read the thread about the reciprocity app by Boizo, you'll get to understand the vast amount of work he put into its creation. Can you please explain this view further?

142575

First, let me state, by in large the contributors on these forums are seasoned and knowledgeable LF photogs whose opinions I value, those who are not usually distinguish themselves very soon into their contributions.

As you point out Lachlan a poor choice of words, I do use apps but in the case of Reciprocity conversions, I have seen over the years photogs fumbling thru their backpack for their R. Chart and then converting to the meter and then onto the lens adjustments. To my way of reasoning, the ONLY time I need the chart is when the meter is in my hand, a simple 90 degree turn of the meter and I know what my exposure will be base on the R. chart I use.

Also, before a Flame War begins as to my corrected times, when in a situation where the EV value falls below 5; I have to cut the corrected Reciprocity time by 30 %. These numbers have worked for me for years and scores if not hundreds of long high contrast exposures, as I think about I am in a reciprocity situation more than I am not.

My appreciation for the smart phone grows every time my kids come home. Miss you Steve Jobs !!

[tgtaylor]

Like Stone, I shoot Acros - especially for night scenes. A few years back several of us got together for a 4am meetup at Sutro Bath ruins on the San Francisco coast. Everyone was shooting digital SLR except for me: I was shooting Acros with a Pentax 67II. The Pentax digital spot meter read "0" everywhere for the EI. I asked Steven who was nearby what he was getting with his camera. "It's a little blown-out at 7 minutes at ISO 100 and f..." Seven minutes on a CCD chip is seven minutes on Acros and all 10 frames turned out well exposed but several were "ruined" by ships suddenly exiting the Golden Gate (you can't see what's coming around the bend) and ships entering turn their lights on well offshore and leave streaks of light across the horizon. Packing a small digital camera solves the exposure problem in those instances: You can get an accurate idea of the correct timing as long as you are using a film like Acros.

zthomas

[BetterSense]

At "integrating" meter can be created which adds up the exposure. I am unaware of any commercial examples but I made one a long time ago that filled up a capacitor. You could set the dark current separately so sort of compensate for schwarzchild.

[John Kasaian]

"ONE Deardorff, TWO Deardorff, THREE Deardorff...." I find to be accurate enough.:)