# BTZS ExpoDev

> Companion app for BTZS Plotter to calculate B&W film exposures and development times. (iPhone/iPad app by TinyOctopus, LLC.)

- Source: https://appshunter.io/ios/app/btzs-expodev/id507385770 (this page in markdown: same URL + `.md`)
- Developer: [TinyOctopus, LLC](https://appshunter.io/developer/507385773)
- Category: Photo & Video, Utilities
- Price: $24.99
- Rating: 4.80/5 from 5 App Store ratings · 6 written reviews indexed
- Age rating: 4+
- Requires: iOS 13.7 · 16 MB
- Released: 2012-03-10
- Data updated: 2026-08-29
- Monetization: paid
- User reviews in markdown: https://appshunter.io/ios/app/btzs-expodev/id507385770/reviews.md

## What is BTZS ExpoDev?

BTZS ExpoDev is the companion app for BTZS Plotter for Windows that allows you to more accurately expose traditional B&W films using film test data from BTZS film tests.

"BTZS meets the iPhone. It's the perfect match of Phil Davis' BTZS with the same device that the rest of my life is on." - Robert Levittan

"It has liberated me from having to worry about my negatives, so that I can direct my attention to the important process of making a photograph." - Laura Campbell

"Liberation for the traditional film photographer." - Bill Waldron

*** Note: This app cannot be used without having your own BTZS Film Profiles that have been analyzed and exported by the BTZS Plotter for Windows application. ***

BTZS ExpoDev is the newest generation of ExpoDev for Apple iOS devices. ExpoDev allows you to use your BTZS test Film Profiles to accurately calculate B&W film exposures in the field for consistently exposed negatives that are easier to print in the darkroom. ExpoDev was designed for Large Format film photographers working in any traditional or alternative process (including hybrid processes such as film scanning).

Among the many features in BTZS ExpoDev are:

    ◆   An exposure record keeping system to keep track of all of your film exposures, allowing you to view the exposure details and the development time to use when back from the field

    ◆   Manages your lists of Film Profiles, lenses, and filters for fast & easy selection when making exposures

    ◆   Support for both BZTS Incident and traditional Zone System metering methods

    ◆   Interactively calculates the SBR, Average Gradient, and the EFS for each scene while metering

    ◆   Support for user-specified filter factors and Large Format bellows extension compensation

    ◆   A powerful Depth of Field calculator with selectable Circle of Confusion that supports 3 DOF calculation modes (Aperture/Distance, Near/Far Distances, and Focus Rail Spread)

    ◆   DOF calculator supports both metric and imperial measurement modes

    ◆   Calculates exposure by either selecting the Aperture or Shutter speed to use

    ◆   Supports Apertures down to f/2048 (perfect for pinhole work) and Shutter speeds up to 6 hours

    ◆   An integrated exposure timer than can handle exposure times up to 12 hours

    ◆   Sophisticated reciprocity failure adjustments for both exposure and development time that are based on lab-produced data for over 90 film and developer combinations

    ◆   and more...

Note: Sample Film Profiles are available for experimentation but they are not a substitute for personal film testing.

## Key features

- Exposure record keeping
- Film Profile, lens, and filter management
- Incident and Zone System metering support
- Depth of Field calculator
- Reciprocity failure adjustments
- Integrated exposure timer

## Recent user reviews (6 of 6)

All indexed reviews: https://appshunter.io/ios/app/btzs-expodev/id507385770/reviews.md

### 4/5 — Using as I write...

*2020-07-12*

I trust this app when I shot which is generally 5 days per week.  Exposures are 99% spot on as with development.
For the analog photographers this should be a must have app.
James M Locke
Alexandria, Va

### 1/5 — Issues with this app

*2020-01-17*

Be aware the app requires you purchase additional software that only works on PC. The sample files don’t work and support does not respond. How do I get a refund?

**Developer response:** Sorry that you are having issues - we’d like to help. Please email support@tinyoctopus.net for app support.

### 5/5 — Great, could be better

*2014-08-28*

I used ExpoDev on a Palm, but it’s really nice to be able to use it on my iPhone and iPad.

Given how nice it is, it would be even nicer if Plotter were integrated into the app for use on an iPad. This would require a lot of work, but it would simplify things. If it were designed well, with integrated Plotter, it would be an excellent way for people to learn about BTZS(I know I’m dreaming.) I bet Phil would like such a creation. As it is now, even with a good film testing service available, I can imagine only BTZS veterans using it.

The input method for EV seems clumsy, I can’t help but feel scrolling is the way to go.

For Mac users: Plotter for Windows works great using Wineskin. No need for Windows.

All this being said, it is a great app that does what I need it to do. In this age of high priced film, it is worth learning BTZS, doing the film and paper tests and buying this app.

### 5/5 — BTZS Expo/Dev is a godsend

*2013-08-26*

For those still interested in using a view camera, the BTZS Expo/Dev App is a great tool.  It allows you to import film test data, which can be done with the help of Fred Newman at The View Camera Store in Fountain Hills, Arizona.  Once the film data is imported into the app, your I-phone becomes a very accurate and simple to use calculator for exposure and development.  It also calculates filter factors, bellows factor and adjusts the exposure for reciprocity failure.  In addition, the app helps you set the desired depth of field and keeps a record of all pertinent data for each exposure in your I-phone.  Further, the expo/dev screens prompt you so you don't forget to calculate for various factors which could throw the exposure calculation way off.  In short, for the price of a lunch and a couple of days of film testing you can have perfect exposures every time.  BTZS is a godsend and a no brainer for any serious large format photographer.

### 4/5 — Finally

*2012-05-25*

Expo dev finally ported to iOS. This app is a fabulous tool for BTZS 
users and zone system users alike. You will need your film data from the BTZS Plotter program or you can have the view camera store expose and test your developed film.  My previous film data imported flawlessly into the program . If you are a large format photographer, don't leave home without it. I am thrilled with this program.

### 5/5 — A remarkable app that will take your photography to the next level

*2012-03-11*

ExpoDev is truly a remarkable tool to have in the field. The app, combined with my personal film test data, has in a sense automated the process of large format photography for me. It has liberated me from having to worry about my negatives, so that I can direct my attention to the important process of making a photograph. With the ExpoDev app, a hard day's work in the field pays off in the form of an easily printable negative.

## Frequently asked questions about BTZS ExpoDev

### What is BTZS ExpoDev?

BTZS ExpoDev is a mobile application designed to assist traditional film photographers in accurately calculating black and white film exposures and development times. It requires custom film test data analyzed and exported by the BTZS Plotter for Windows application.

### Can I use BTZS ExpoDev without BTZS Plotter for Windows?

No, this app cannot be used without having your own BTZS Film Profiles that have been analyzed and exported by the BTZS Plotter for Windows application. It is a companion app.

### What metering methods does BTZS ExpoDev support?

BTZS ExpoDev supports both BTZS Incident metering and traditional Zone System metering methods, offering flexibility for different photographic workflows.

### Does BTZS ExpoDev have a depth of field calculator?

Yes, it features a powerful Depth of Field calculator with selectable Circle of Confusion and supports three different DOF calculation modes. It also includes metric and imperial measurement options.

### How does BTZS ExpoDev handle reciprocity failure?

The app provides sophisticated reciprocity failure adjustments for both exposure and development time. These adjustments are based on lab-produced data for over 90 film and developer combinations.

### What is the price of BTZS ExpoDev?

BTZS ExpoDev is a paid application, priced at $24.99. This one-time purchase grants access to all its features.

### What devices is BTZS ExpoDev compatible with?

BTZS ExpoDev is available for Apple iOS devices, specifically iPhones and iPods. It requires iOS 4+ and has an age rating of 4+.

### How often is BTZS ExpoDev updated?

The latest version of BTZS ExpoDev is 1.1.7, which was last updated on August 31, 2023. Updates typically include bug fixes and feature enhancements.

## Version history (last 5 releases)

### 1.1.7 — 2023-08-31

Fixes for Dark Mode UI

### 1.1.6 — 2023-05-11

General compatibility improvements

### 1.1.5 — 2018-12-11

v1.1.5

This is a minor compatibility update

*** Note: ExpoDev now requires iOS 11.0 or later ***

v1.1.4

This is a minor compatibility update to support iOS 9

*** Note: ExpoDev now requires iOS 8.0 or later ***

v1.1.3

This is a minor compatibility update to better support iOS 8

v1.1.2

This is a minor update with improvements

*** Note: ExpoDev now requires iOS 5.0 or later ***

◆ ExpoDev now supports filter factors up to 65536 (i.e. 16 stops)
◆ Improved the Check DOF accuracy for very near subjects
◆ Improved support for the iPhone 5.0's larger screen size
◆ Fixed crash when viewing saved records with metering notes

Previous updates:

V1.1.1

◆ This update fixes a rarely experienced situation with some exposures that require reciprocity adjustments. These exposures are now checked to ensure that they do not exceed the film's development range.

V1.1.0

◆ Support for apertures down to f/2048 (for pinhole work)
◆ Support for lenses up to 2000 mm
◆ Bellow extension factor now supports calculation by Distance, Extension, or Magnification

### 1.1.4 — 2015-10-09

v1.1.4

This is a minor compatibility update to support iOS 9

*** Note: ExpoDev now requires iOS 8.0 or later ***

v1.1.3

This is a minor compatibility update to better support iOS 8

v1.1.2

This is a minor update with improvements

*** Note: ExpoDev now requires iOS 5.0 or later ***

    ◆   ExpoDev now supports filter factors up to 65536 (i.e. 16 stops)    
    ◆   Improved the Check DOF accuracy for very near subjects
    ◆   Improved support for the iPhone 5.0's larger screen size
    ◆   Fixed crash when viewing saved records with metering notes

Previous updates:

V1.1.1

    ◆   This update fixes a rarely experienced situation with some exposures that require reciprocity adjustments. These exposures are now checked to ensure that they do not exceed the film's development range. 

V1.1.0

    ◆   Support for apertures down to f/2048 (for pinhole work)
    ◆   Support for lenses up to 2000 mm
    ◆   Bellow extension factor now supports calculation by Distance, Extension, or Magnification

### 1.1.3 — 2014-10-08

v1.1.3

This is a minor compatibility update to better support iOS 8

*** Note: ExpoDev now requires iOS 7.0 or later ***

v1.1.2

This is a minor update with improvements

*** Note: ExpoDev now requires iOS 5.0 or later ***

    ◆   ExpoDev now supports filter factors up to 65536 (i.e. 16 stops)    
    ◆   Improved the Check DOF accuracy for very near subjects
    ◆   Improved support for the iPhone 5.0's larger screen size
    ◆   Fixed crash when viewing saved records with metering notes

Previous updates:

V1.1.1

    ◆   This update fixes a rarely experienced situation with some exposures that require reciprocity adjustments. These exposures are now checked to ensure that they do not exceed the film's development range. 

V1.1.0

    ◆   Support for apertures down to f/2048 (for pinhole work)
    ◆   Support for lenses up to 2000 mm
    ◆   Bellow extension factor now supports calculation by Distance, Extension, or Magnification

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## More apps by TinyOctopus, LLC

- [PNW Current Atlas](https://appshunter.io/ios/app/pnw-current-atlas/id1456020312)

All apps by TinyOctopus, LLC: https://appshunter.io/developer/507385773

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-08-29.*