LensFactor vs Message Viewer Pro
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
LensFactor
This app helps calculate lens factors, screen sizes, and projector distances based on known variables. It's a utility for professionals or enthusiasts needing precise measurements for display setups.
- Calculate lens factor
- Calculate screen size
- Calculate projector distance
- Input screen size and projector distance
- Input lens factor and projector distance
- Input lens factor and screen size
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LensFactor is an application for the iPhone OS which has 3 basic functions: - Calculate the lens factor when the screen size and projector distance is known - Calculate the screen size when the lens factor(s) and projector distance is known - Calculate the projector distance when the lens factor(s) and screen size is known
Message Viewer Pro
Easily view EML and MSG email files, including attachments, directly on your iOS or macOS device. Share or print attachments, or compose new emails using the content of your saved messages.
- View EML and MSG files
- Access attachments
- Share attachments
- Print attachments
- Compose new emails from viewed messages
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View both EML and MSG (Outlook) files on your iOS/macOS device, including attachments within them. These are usually emails saved in the EML or MSG format. Tap on an EML or MSG file in another app, "Open In..." and select Message Viewer to view your saved email. You may tap "open a sample EML" to see an example email open up. Attachments may be shared with other apps or printed. Tap the compose icon to open your EML/MSG as a new Mail message.
Screenshots
Verdict
The clearest difference is update cadence: Message Viewer Pro at monthly against LensFactor's every 24 months. LensFactor's advantage is price ($1.99 vs $3.99) and iOS requirement (11.0 vs 16.6). On rating, ratings volume, ads and in-app purchases there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
LensFactor costs $1.99 and Message Viewer Pro $3.99 up front. Neither carries in-app purchases, so what you see is what you pay.
On the App Store both sit at effectively the same score — 5.0 for LensFactor against 5.0 for Message Viewer Pro. Both are backed by a comparable volume of ratings — 2 and 1 respectively.
LensFactor ships an update every 24 months, Message Viewer Pro monthly. The most recent releases landed on September 21, 2026 and September 17, 2026 respectively.
| Parameter | LensFactor | Message Viewer Pro |
|---|---|---|
| Price | $1.99 — better | $3.99 |
| Rating | 5.0 (2 ratings) | 5.0 (1 ratings) |
| Positive reviews | 88.9% of reviews | — |
| Number of ratings | 2 — better | 1 |
| Update frequency | Every 24 months | Monthly — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Paid | Paid |
| Devices | iPhone, iPad, iPod — better | iPhone, iPad |
| Requires iOS | 11.0 — better | 16.6 |
| Further details — not scored | ||
| Size | 1 MB | 9 MB |
| Age rating | 4+ | 4+ |
| Developer | Bart van Stiphout | Matrix Logic Corporation |
Customer experience
LensFactor
Message Viewer Pro
In-app purchases
LensFactor
No in-app purchases
Message Viewer Pro
No in-app purchases
Questions
Is LensFactor free?
Is Message Viewer Pro free?
Which has better reviews, LensFactor or Message Viewer Pro?
Do LensFactor or Message Viewer Pro have ads?
Which is updated more often, LensFactor or Message Viewer Pro?
Other comparisons
