Yoshizen's Blog

Jessop’s Fun-camera Lens

Jessop Funcamera-2-001

I found yet another fun-camera (One-time use Camera / Camera with Film)

in an Odds and Ends Box of a Camera shop. (for a couple of pounds)

Jessop Funcamera-1-001

This time it was a Jessop’s product though, since Jessops disappeared many years 

ago, this product was also pretty old.   Old enough to be rotten deep = supposed be 

an unused battery inside was completely corroded and the chemical has been leaked.

Branded Jessops though, it was a Chinese made = hence cheap battery was rotten.

This was an interesting product.   As a Chinese made, it could be a complete

Copy-cat product though,  the Jessops then was a well known English company 

= they could be an easy target of a lawsuit for a Copyright infringement.

So, they didn’t copy the lens by taking a mold —– instead, they put their own

Two-element Lens for this camera.     When Japanese film company, Konica,

Fuji, invented the disposable camera (one-time use camera), they designed the

omnifocus lens using pretty fancy aspherical design.

And to make the camera able to take photos under different lighting condition

with fixed shutter speed (about 1/60th second) on ISO 100~200 film, the

lens has to be about F4~3.5.  Especially after flash light was incorporated,

to have a reasonable picture for 3m, the lens can’t be smaller. = It’s mean,

pan-focus with smaller F-aperture was not an option, therefore, they had to

design sophisticated aspherical lens which could produce a reasonably well

focused image in any distance with F4 diameter (7~8mm).

—– But, without using aspherical lens, Jessops opted to the simple two lens

design with smaller F8 aperture setting, while taking advantage of the

higher ISO sensitivity of 400.

Jessop Funcamera-3-A09A2172 The trick here was,

 F4 x2 = F5.6  F5.6 x2 = F8    while

 ISO 100 x2 x2 = ISO 400 (the same)

 —– and F8 can give much deeper

 depth of the field

 (= Pan focus effect using ordinally 

 lens though, F8 is not enough for

 close focus). 

 I tested this lens attached with rather

 heavy concave lens to extend the 

 original 27mm focal-length to 44mm, 

in order to use on the Canon EOS, (Photo left)

(thus, 3.5mm lens diameter, now gives F13 = pretty dark to see the finder image)

 

—– Not only that, the image produced by this lens was utterly rubbish. = when F13

lens could make only trash image while having no fancy fuzziness (F13 couldn’t 

have any chance of nice fuzziness) = there wouldn’t be any point to use this lens.

—– Well, not all the experiment has been a successful one.   😀

[]

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2 Responses

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  1. Lemony (Gr)Egghead said, on July 20, 2015 at 12:52

    Still fun to experiment anyway! 🙂

    • yoshizen said, on July 20, 2015 at 13:00

      Thank you. Anyway it’s a harmless passtime. 🙂


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