Not an issue! Possible colloboration

[NightFlyer]

I didn't know how else to contact you.

I'm working on an exposure calculator to help with long exposure photography - basically, you tell the app the shutter/aperature/ISO/ND filters you've got on when doing a "high ISO exposure test", then you lock in that EV and can then play with the values in the app to determine what you should set your camera to.

I thought that wrapping it up with Field Tools would be great -- one tab could be Depth of Field, another tab would be Exposure Equivalence. Information about the camera & lens that DoF has would also be useful for exposure equivalence (knowing the max/min allowable aperatures, whether the camera supports 1/2 or 1/3 EV stops, etc.) So, in addition to avoiding having to have a separate app, there is some synergy there as well.

If you don't like that idea, then I'll just finish the app & publish it as a separate app.

[bradsokol]

Hi Tim,

Thanks for the interest. I've thought from the beginning the Fields Tools could be enhanced with other capabilities, but I have been focused on depth of field so far. I'm curious about your suggestion and would like to better understand it.

Can you point me to a some more info on long exposure photography and the types of calculations that the app would do? I'd like to better understand how the app could supplement the capabilities of the camera's light meter. If you're willing, one or two screenshots of your app, showing the inputs and results of calculations, might help me quickly understand.

Thanks for the interest.

Brad

On 2012-05-30, at 1:35 PM, Tim wrote:

I didn't know how else to contact you.

I'm working on an exposure calculator to help with long exposure photography - basically, you tell the app the shutter/aperature/ISO/ND filters you've got on when doing a "high ISO exposure test", then you lock in that EV and can then play with the values in the app to determine what you should set your camera to.

I thought that wrapping it up with Field Tools would be great -- one tab could be Depth of Field, another tab would be Exposure Equivalence. Information about the camera & lens that DoF has would also be useful for exposure equivalence (knowing the max/min allowable aperatures, whether the camera supports 1/2 or 1/3 EV stops, etc.) So, in addition to avoiding having to have a separate app, there is some synergy there as well.

If you don't like that idea, then I'll just finish the app & publish it as a separate app.

---

Reply to this email directly or view it on GitHub:
#1

[NightFlyer]

On 5/31/12 4:56 PM, Brad Sokol wrote:

Hi Tim,

Thanks for the interest. I've thought from the beginning the Fields
Tools could be enhanced with other capabilities, but I have been
focused on depth of field so far. I'm curious about your suggestion
and would like to better understand it.

Can you point me to a some more info on long exposure photography and
the types of calculations that the app would do? I'd like to better
understand how the app could supplement the capabilities of the
camera's light meter. If you're willing, one or two screenshots of
your app, showing the inputs and results of calculations, might help
me quickly understand.

Thanks for the interest.

I'm not a UI person (obviously), but here's a screen shot of what I'm
currently playing with. The major part of the screen shows the "exposure
triangle" of f/Stop, shutter speed, and ISO, with the Exposure Value
(EV) in the middle. Each of these values can be locked by sliding the
switch to "on". (Eventually it would be a lock icon). The text field at
the top allows quick entry of whatever is specified in the choice
selection immediately below it -- in this case, the user is entering an
f/Stop. There are also +/- steps to easily increase/decrease to the next
value. In general, all values are unlocked, the user enters the f/Stop,
shutter speed, and ISO from their camera and then locks the EV. They can
then experiment by changing f/Stop, shutter speed, or ISO and see how
the other values need to change to maintain the same EV.

When doing long exposure, you often take a high-ISO test shot to see if
the composition is correct and to see if you're getting the correct
general exposure where you care about it. You then reduce the ISO to a
value which will decrease noise to a reasonable amount and adjust the
shutter speed to compensate. People use charts like this:
http://www.thenightskye.com/wp-content/images/High-ISO-test.pdf
or the one in the middle of the page here:
http://www.bulbexposures.com/long-exposure-tutorial-old/

to help them quickly convert. For example if you're shooting a canon
camera and set the ISO to 6400 and your test shot takes 3 seconds to
properly expose, then the chart shows that if you set the ISO to 100,
then the shutter speed needs to be 3 minutes. However, if you can set
your camera to a higher ISO, then this chart doesn't apply without
modifications. Or, if at ISO 6400 the shutter speed is 1/8th of a
second, then the chart doesn't help (since it only goes down to seconds).

Here's the way I envision a photographer will use my stuff:

1. take a picture at high ISO (so the exposure time is short). Check
   composition and whether the appropriate items in the picture are exposed
   correctly for you -- you've got detail where you want it, nothing blown
   out that you care about, etc.

2. Record those values into the app by setting the shutter speed, ISO,
   and aperature used in the shot. The App will show you the EV (in the
   center of my screen shot).

3. Now, LOCK the EV. (Right now, that's the slide switch below EV which
   is showing that it isn't locked).

4. If you now change the ISO, then since the EV is locked, the app will
   change the shutter speed automatically to keep the EV the same.

5. The photographer will set their camera settings to the aperature,
   shutter, ISO that the app is displaying. They will now take a picture.

The benefit of the app is that you don't have to worry about using
special ISO values (one that gives you a quick translation from seconds
to minutes as shown in the paper at the above link). You can also more
easily modify the different components. For example, you might do your
high-ISO test shot with a wide open aperture just to make the exposure
faster to take, but then want to adjust both the aperture and ISO and
determine what the equivalent shutter speed needs to be.

Of course, you can do all this by keeping track of how many stops you're
changing things, but that takes time & is just a hassle.

Also, modern cameras allow (or choose) EV values in 1/3 or 1/2 steps,
not just full steps. Thus, I can set the aperture to f6.3, which further
complicates the whole calculation if I decide to go from f4.5 to f6.3!

Here's where the integration with Field Tools comes in: the user is
already specifying what lens they are using (giving the min/max
aperature of the lens), so the Exposure Equivalence calculator would use
that information and only allow valid values within that range --
otherwise the user might inadvertently choose an f/stop that isn't
available on that lens. (I also see that the Exposure Equivalence might
do the equivalent of "shutter priority" and modify the aperture rather
than shutter speed). Also, I would add an "EV Steps" field to the camera
information, where you specify whether your camera is set to only full
EV steps, 1/2 EV steps, or 1/3 EV steps. This information would also be
used in ensuring that calculations are carried out correctly. And, of
course, the ISO range is specific to each camera model.

In the App, ND stands for Neutral Density filter. During daytime long
exposures, you often add ND filters to arrive at a slower shutter speed
in order to have the desired shutter speed (if you want people to blur,
but still be visible, the shutter speed is on the order of seconds, but
if you want people to completely disappear, the shutter speed is on the
order of 30 minutes or so). Photographers might use the app to decide
how much ND filtration they need to add to get to the shutter speed they
want. So, that's an additional item that plays into the EV.

I hope that this makes sense! If not, I can try to find some other way
to describe things, or spend some time looking for good articles which
show some of what goes on.

[bradsokol]

Hi Tim,

Sorry for taking so long to get back. I had a busy week :)

Thanks for the explanation. I've learned something that will be helpful for my photography. I think your idea is a good one. The tables you linked to definitely have their limitations. And there is some synergy with the camera settings already in Field Tools.

One of my goals for the depth of field calculators in Field Tools was to create a UI that required a minimum number of gestures (taps, slides, etc.) in order to perform common tasks such as changing camera settings or selecting cameras and lenses. I'm curious to see what you've come up with as I think consistency in the UI will be important for any enhancements to Field Tools.

Unfortunately your screen shots didn't make it through. GitHub strips attachments. I'll send you a private email with my contact info and hopefully you can re-send the screen shots.

[asettico]

Hi,

I'm also interested in long exposure with ND, I'm using other app, but I find it not so usable as your.

I'm a programmer with many experiences, I'm able to work on Apple IOS, I've already developed an iPad app for a business customer (distributed as ad-hoc application for internal use only).

So I can collaborate to help you to add new functionalities.

contact me if I can help.