Frequently asked questions about the Bonfoton Camera Obscura Room Lens


  • I have never heard of Camera Obscura, what is it?
  • Well, if you walk into a very dark room on a bright day and make a small hole to the window cover and look at the opposite wall you will see the scene outside the window transferred to the wall, only upside down!

    The words Camera Obscura comes from latin:

    Camera = Room

    Obscura = Dark

    This phenomenon can be explained by a simple law of physics. Sunlight travels in a straight line and when some of the sun’s rays reflected from a bright subject pass through a small hole in a thin material the direction of the rays do not scatter but cross and reform as an upside down image on a surface parallel to the hole.

    Using the Bonfoton lens you can make that small hole larger which allows more light to enter the room and the image will become much brighter and sharper!  

  • How and why should I use the Bonfoton Camera Obscura lens?
  • For me personally, the coolest way to experience the Bonfoton is in the mornings when I can wake up and see the weather outside even my curtains are closed. The light peering through the lens also helps me to wake up naturally.

    Lot’s of people use it for making a photoshoot background or they just want to see how their own room changes. We want to encourage people to take photos of their own Bonfoton rooms and post them with the hashtag #bonfoton to be eligible for future competitions!

    Other people have told us that they might listen to music etc. whilst in a Bonfoton room. Some just chill out, some do yoga and some just want to show the effect to their friends.

    Here’s a photograph of our son after a dip in the pool on our Greek holiday :)



  • Can I use the Bonfoton lens in any room with a window?
  • Yes, but keep in mind that the distance of the object (e.g. a house) reflected from outside is relative to the distance of the sharp image from the lens inside the room as explained in the chart below: 

    Distance of object (e.g. a house) from lens = p

    Distance of sharp image from lens = q 

    p = 10m > q = 6.7m
    p = 20m > q = 5.0m
    p = 40m > q = 4.4m
    p = 100m > q = 4.2m

    p = ~infinity > q = 4 m

    p = 32ft > q = 22ft 
    p = 66ft > q = 16.4ft
    p = 131ft > q = 14.6ft
    p = 328ft > q = 13.7ft

    p = ~infinity > q = 13.1ft

    The image will fill the whole room at any distance just the image sharpness will gradually soften as further it goes from the focus point. 

    The Bonfoton works best when it is sunny but the sunlight does not shine straight trough the lens. Straight sunlight will fade the image on the room. The Blackout Cover that comes with the Bonfoton lens should be used or the Bonfoton lens should be removed from the window when the sun shines directly into the room. 

    Here’s a photograph of the same room taken with an iPhone 6s with a cheap 3Fisheye lens to show how the Bonfoton image will fill a room:



  • How do I install the Bonfoton lens?
  • The Bonfoton Lens is easy to install. In the composite image below the stages of the Bonfoton Lens installation on to a Blackout roller blind are seen.

    Images 1. and 2. Use the logo sticker to draw a right size circle.

    Image 3. Cut a hole in the canvas (or other material you are using for room darkening).

    Images 4. and 5. On the backside of the Bonfoton Lens, there are four small metal plates with adhesive. Peel off the adhesive liners from the plates and press the Bonfoton over the hole. When you remove the Bonfoton the plates will be stuck onto the canvas. The Bonfoton has magnets on the back so it can be reattached to the plates. The blackout roller blind can still be rolled back up normally. The small metal plates will just roll inside the blind.

    Image 6. The Bonfoton comes with a Blackout Cover Plate that snaps onto the front magnets. The Blackout Cover Plate can be used to darken the room again when needed.

    Before cutting a hole to a Blackout roller blind you might want to test which is the best position for the Bonfoton Lens. A rule of thumb for the lens positioning: The higher the Bonfoton Lens is on the window the more sky you will get on your walls and the lower the Lens is, the more ground will be seen.

    The quickest room darkening method: The Tinfoil!
    Lightly spray the window screen with water and spread the tin foil roll over it. You can roll the tin foil over the frames of the window so no light will come through from the sides. Don't leave the tin foil on the window screen for too long. The drying water might leave stains that are hard to clean. This can happen in a day.


  • How do I darken my room and does it have to be completely dark?
  • You’re in luck since we have a whole page dedicated just to room darkening tips and tricks!

    How to darken your room for Bonfoton Camera Obscura Lens - link

    And no, the room doesn’t have to be completely dark. The Bonfoton Camera Obscura Room Lens can withstand quite a bit of stray light actually. Surely the image will look brighter and more colorful if the room is completely dark.

    Note! The Bonfoton Camera Obscura Room Lens needs sunlight (but not direct sunlight) to make the image on your walls. On full cast days, the image is dim.


  • I can make a pinhole camera without a lens so can I make a Camera Obscura room also without a lens?
  • Sure you can, but the image formed by the small hole will be blurred and quite dark. Using the Bonfoton Camera Obscura Room Lens the image formed on the wall will be sharper and brighter. 


  • Is it safe to shop on your site?
  • Yes. We understand that the safety of your personal information is extremely important to you. To protect your personal data and credit card information from unauthorized access Bonfoton.com uses Secure Sockets Layer (SSL) technology to provide you with the safest, most secure shopping experience possible. SSL technology enables encryption (scrambling) of sensitive information, including passwords and credit card numbers, during your online transactions.
    All of the forms on our site are secured with SSL technology so your personal information stays safe and out of malicious hands.


  • What is your ordering process?
  • Our order process is very simple – once you make your purchase through the checkout, you will receive an Order confirmed -email and as soon as we dispatch your order, we will send you a Your order is on the way -email to let you know it’s on its way.


  • What forms of payment do you accept?
  • We are happy to accept Paypal & most major credit cards such as Visa, MasterCard and American Express.


  • I can change the currency on the website, but I can only use US Dollars in checkout why is this?
  • The popular Shopify eCommerce platform that we are using as our storefront only enables us to use only one default currency at checkout. Sorry about that. But don't worry you can see the prices with different currencies on our storefront which are just converted at checkout to US dollars.



    How fast is your delivery?

    Orders are shipped from Turku, Finland. We are using the Finnish Postal Service (Posti) for shipping the product straight to your mailbox. The Bonfoton Camera Obscura Room Lens fits in an A5 size letter.

    Your order will be sent out as soon as possible after we have received your payment.  Please allow us 1-2 business days to process and package your order before shipping. The approximate shipping dates for different continents are:

    • Scandinavia and Central Europe: 2 - 5 working days
    • The rest of Europe: 3 - 6 working days
    • Rest of the World: 7 - 20 working days


  • Can I track my order?
  • Sorry, currently it is not possible. To be able to offer free worldwide shipping, we are using the Finnish postal service (Posti) envelope which does not include tracking.


  • Will I have to pay international taxes & duties?
  • If you are ordering within the EU you will not need to pay taxes in any case.

    If you are ordering from outside the EU, your order may be subject to import duties and taxes, which are levied once a shipment reaches your country. The general amount of the duties and taxes fee is about 5-20% of the dollar amount of the merchandise. However, this is just a general guideline and may vary depending on the country to which the order was shipped. Bonfoton (Boncomp Oy) cannot control and is not responsible for any duties/taxes applied to your package. You will be responsible for paying additional charges for customs clearance. Customs policies vary widely from country to country; please contact your local customs office for further information. Note, in rare occasions, customs agents may delay delivery of some packages.


    Are there any product safety issues that I need to be aware of?

    The Bonfoton comes with eight small attachment plates that small children could swallow. The neodymium magnets that are glued to the Bonfoton Lens are not super strong but they might damage some magnet strips or electronics if they get in close contact.

    The lens itself is made of plastic so it should not get broken as easily as a glass lens might.

    The Bonfoton lens is optically much weaker than average eyeglasses. It can project an image but it is very poor in concentrating heat. Projection of any scenery is always cooler than the real scenery due to the lens being unable to introduce any extra heat into the projection itself. 

    You would need approximately 15 Bonfoton Camera Obscura Room Lenses in order to make an average magnifying glass.

    Here’s an approximate scale indicating the heat concentrating properties of some similar optical materials:

    Bonfoton Relative Optical strenghts

    Even though the Bonfoton Camera Obscura Lens is weak in concentrating heat, we do advise to use the metallic Blackout Cover Plate which comes with the Bonfoton Lens or removing the Bonfoton Lens in direct sunlight, since it is possible that the projection of the sun (the bright spot on the wall in direct sunlight) might discolor or fade paintings, wallpaper etc. objects in the room. 

    Do not use the Bonfoton Camera Obscura Room Lens in a room that stores flammable liquids.