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An iPhone/iPod touch application for photographers from hobbyist to pro.

NDTimer is an iPhone App useful for calculating and timing long exposures when using one or two neutral density (ND) filters.

Following is a typical scenario when using neutral density filters to achieve long exposures:
  1. Set your camera to “Aperture Priority” mode Nikon(A) and Canon(AV) and disable autofocus .
  2. Compose your shot, manually focus and meter the scene through your camera’s lens(TTL) without filter(s) installed and note the exposure time(shutter speed) displayed in your viewfinder or LCD if your camera is equipped with “Live View.”
  3. Launch NDTimer and dial in the given exposure(shutter speed) and filter of your choice. NDTimer will calculate and display the correct shutter speed or exposure time necessary to properly expose your scene. If you are using a second filter in combination with your first filter (stacking), simply tap the “stack filter” button, choose the filter you have staked on top of your first filter and NDTimer will calculate the necessary compensation and adjust the exposure time accordingly.
  4. Switch your camera from “Aperture Priority” to “Manual” mode, install filter(s) onto your lens and either dial your camera’s shutter dial to shutter speed displayed or set your camera to “bulb” mode and expose for the displayed time by simultaneously tapping “Start Timer” and opening your shutter with a remote trigger. The timer will countdown to zero and an alert tone will sound at the end of the exposure time. If your iPhone or iPod touch goes into sleep mode during your exposure, you will receive a “pop up” notification at the end of your exposure time

Note: Cover your eyepiece during long exposures to avoid light leaks.


Customer Reviews

I finally found this app! ????
by rejuvesite – Version 1.2 – Sep 12, 2013

This app works exactly as I had hoped. Take a shot without your ND and note the shutter speed your camera’s meter calculates. Then enter that speed into this app and boom, you’ve got your shutter speed when using the ND.


Useful app! ?????
by Truebritgal – Version 1.2 – Feb 13, 2012

This app has proven very useful to me when taking long exposure shots. Easy to use, and saves me from having to spend time calculating exposure times!


This One Works Well ????
by ShutterBob – Version 1.2 – Sep 10, 2011

Used this just this morning and it worked flawlessly. I was doing long exposures so a few seconds one way or the other didn’t matter, but I was happy to have this app so I wouldn’t have to embarrass myself by doing math on the iPhone calculator.


Great app! ????
by 01f4irider – Version 1.2 – Feb 10, 2011

I really like this app, especially the feature that allows you to get exposure times for stacked filters. Very cool. The only reason I gave the app 4 stars instead of five is because you are only given a countdown timer for exposures over 30 seconds. And, if this is to be the ND app to end all ND apps then the countdown timer is going to have to go all the way down to at least 1 second (like NDCalc does, an app which I also own). Add that in the next update and I’d be an extremely happy camper. Overall, an excellent app. Thanks guys!


Almost Perfect ?????
by MB1742 – Version 1.2 – Dec 22, 2010

Great alternative to doing the math in my head. Works as advertised. Has a nice UI, lets me stack my polarizer, and the countdown timer for exposures over 30 seconds is a nice touch. Wish it had a bulb mode where custom shutter speeds could be entered to be more useful with night photography.