See what any lens frames on your camera, before you buy it
Prospekt is an iPhone app that turns your phone into a viewfinder for a lens you don't own yet. Pick your camera body and a focal length from 14 to 300 mm, point the phone, and see the framing live.
$3.99 once. No subscription, no account, no ads. Works offline.
Get Prospekt on the App Store, $3.99 Try the free lens comparison tool
Is this for you?
- You're choosing between a 35 mm and a 50 mm, or a 50 and an 85, and want to see the difference before you spend the money.
- You have an APS-C or Micro Four Thirds camera and crop factor still confuses you.
- You're scouting a location and want to know if your 24-70 is wide enough, or if you need the 70-200.
- You're switching systems and want to know what your old lenses become on the new body.
- You're learning photography and want to feel what focal lengths look like.
How it works
- Pick your camera body. 59 are built in, from Canon, Sony, Nikon, Fujifilm, Panasonic, OM System, Leica, Hasselblad, Pentax and Sigma. You can add your own with any crop factor.
- Turn the wheel to a focal length from 14 to 300 mm. It clicks at the popular ones. Add a 1.4x or 2x extender if you use one.
- Point your iPhone. Prospekt switches between the ultra-wide, wide and telephoto cameras and sets the zoom so the frame matches that lens on that body.
- Take a snapshot. It's saved with a watermark showing the focal length, crop factor, full-frame equivalent and aspect ratio (3:2, 4:3, 16:9 or 1:1), so you can compare later.
Price
| Prospekt for iPhone | $3.99 once |
|---|
Everything: all 59 bodies, your own bodies, extenders, four aspect ratios, snapshots and future updates. No subscription, no in-app purchases, no ads.
Price in the US App Store. Other countries pay the local equivalent.
Privacy
Prospekt collects no data. There is no account, no analytics, no ads and no third-party code. The camera picture stays on your iPhone, and a photo is saved only when you tap the shutter, to your own photo library.
What it doesn't do
- It shows framing, not background blur. The bokeh of an f/1.4 lens is not simulated.
- Your iPhone's widest camera sets the widest framing you can preview: about 13 mm full-frame equivalent on iPhones with an ultra-wide camera.
- At long focal lengths the iPhone uses digital zoom, so the picture gets soft. The framing is still right.
- Perspective comes from where you stand, not from the lens. Prospekt shows the framing from where you are standing.
- iPhone only, iOS 17 or later. No Android or iPad version.
How it compares
| Prospekt | Field-of-view calculator websites | Director's viewfinder apps | Renting the lens | |
|---|---|---|---|---|
| Your real scene, live | Yes | No, a sample photo or a diagram | Yes | Yes |
| Knows your exact camera body | Yes, 59 bodies plus your own | Usually sensor size only | Yes, mostly cinema cameras | Yes |
| Shows bokeh and lens rendering | No | No | Some | Yes |
| Cost | $3.99 once | Free | More, built for film crews | A rental fee and a deposit |
| Works offline | Yes | No | Some | Yes |
Calculator sites are free and fine for quick numbers, our own lens comparison tool included. Renting is the only way to see bokeh and how a lens renders. Prospekt sits in between: the real scene, your body, a one-time price.
Questions
Is there an app that shows what a lens will look like before I buy it?
Yes. Prospekt shows the framing of any focal length from 14 to 300 mm on your camera body, live through your iPhone camera. It costs $3.99 once on the App Store.
How can I see the difference between 35 mm, 50 mm and 85 mm?
Pick your body in Prospekt and turn the wheel between the three while you point at the same scene. Without the app, compare them over a sample photo in our free lens comparison tool.
What does a 50 mm lens look like on APS-C?
It frames like a 75 mm lens on full frame, or 80 mm on Canon APS-C, which is a short telephoto. Every body has its own table on the camera pages.
What is crop factor?
It's how much smaller your sensor is than full frame, measured across the diagonal. Multiply a focal length by it to get the full-frame equivalent: 35 mm on a 1.5x body frames like 52.5 mm.
Does Prospekt work offline?
Yes. It never needs the internet, and there's no account to sign in to.
Does it simulate depth of field or background blur?
No. It shows what the lens frames, which is what decides most lens purchases. Bokeh depends on the aperture, the distance and the lens design, and a phone can't show it honestly.
Which cameras does it support?
59 bodies from 10 brands are built in, across full frame, APS-C, Micro Four Thirds and medium format. For any other camera, add it with its crop factor.
Is there a subscription?
No. You pay $3.99 once and every update is included.
Who makes Prospekt?
nakolini, a two-person studio: Vitalii Kikot and Dmytro Hryb. We also make Anonimo and Expenny.