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default K3 lens, 17-69 ?


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#1 Curtis Bouvier

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Posted 26 April 2009 - 09:05 PM

Ok, my nikon d70 lens is 17-70MM

i get a nice wide look on 17 and a decent zoom look on 70mm

on my K3 lens, set for 17, it has the same look as my nikon lens at 70mm...

the K3 lens has the same zoom range as a nikon 70-200mm lens

is this because the K3 lens is actually 17-69 FEET? not mm?

i'm kind of confused as to whats going on here..

i was planning on picking up some cheap m42 lenses off ebay, but now i'm not sure what to buy lol
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#2 Ian Cooper

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Posted 27 April 2009 - 02:14 AM

The focal length of a lens is its focal length, that is a fundamental characteristic of the lens and in itself does not affect the angle of view that lens produces as an image. The K3 meteor zoom lens is indeed measured in 'mm', the same as the Nikon.

Where the differences lie is in the size of the imaging sensor, it doesn't matter whether that is a digital sensor, a slice of film, a sheet of tracing paper, or a wall in a camera obscura.

Imagine a traditional 35mm stills camera, as most people are fairly comfortable with that. A 'normal' lens is taken as having a focal length equal to the diagonal of the frame dimensions. A 35mm still frame is 36mm x 24mm, this means the diagonal is 43mm, usually rounded up to 50mm. This will give a horizontal angle of view of about 39 degrees. (43mm would give 45 degrees)

However, if you imagine inside the camera, the lens is actually projecting an image that is larger than the 36x24 piece of film, it's just the film is only 'seeing' a small portion of that image. If you were to place that 50mm focal length lens on a medium format camera with a piece of film 56mm x 42mm large, the horizontal angle of view would be 58 degrees. Therefore the same focal length lens appears to be 'wide angle'.

The diagonal dimensions of the 56x42mm film is 70mm, and using that focal length lens has a horizontal angle of view of 43 degrees, (much the same as 45 degrees from a 43mm lens on 35mm format). In practice the 70mm is usually rounded up to 80mm, which actually gives 38 degrees, which is even closer to the 39 degrees produced by the rounded up 50mm normal lens on 35mm format.


If we return to the 35mm stills camera. If we now imagine a 50mm focal length lens projecting an image on our film, but crop out only the centre part of the image. The angle of view produced will be reduced - it is the opposite effect from using a larger sensor area.


Ok.
Now the D70 has a 'DX' sensor size of 23.7mm x 15.5mm. The diagonal of that is 28mm, which would again produce a horizontal angle of view of 45 degrees.

Standard 16mm film has dimensions of 10.26mm x 7.49mm, giving a diagonal of 12.7mm, and once again that lens would give an angle of view of 43 degrees.

Hopefully you can see that as the dimensions of the sensor decrease, the focal length of the lens required to give a fixed angle of view also decreases. Your 17-70mm lens on your D70 gives angles of view from 69 degrees through to 19 degrees. To achieve the same angles of view on a 16mm camera would require a lens with focal lengths from 7.5mm (68 deg) through to 32mm (18 deg).

As the meteor zoom is 17-70mm, the same as your Nikon zoom, you would get exactly the same angles of view if you were able to mount the Meteor on the D70. In practice you'd probably find the Meteor would vignette quite badly as it isn't designed to cover the larger area, but the principle still holds true that the angle of view would be unaltered. In the same way that mounting your Nikon 17-70mm zoom on the K3 would give exactly the same angles of view as the standard Meteor 17-70mm already does.

The M42 mount on the K3 camera is great if you envisage doing 'long lens' work with the camera, as it allows a wide range of lenses designed for 35mm stills cameras to be used. The problem arises when you want wider angles of view, because what is considered 'wide angle' in 35mm still photography terms is still a 'long' lens in 16mm terms!

Although the 'standard' focal length for a 16mm camera is 12.7mm, for various reasons often quoted to do with average viewing distances, the 'normal' lens is actually taken to be 25mm. This gives an angle of view of 23 degrees, the same as about a 90mm lens on a 35mm stills camera. A 12mm lens in 16mm terms is considered to a be 'wide angle', dispite only giving the same angle of view as a 'standard' 35mm stills lens.

What all this boils down to is that to find a 7.5-32mm zoom in M42 mount for your K3 to give the same views as a 17-70mm on a D70 is going to be all but impossible. The M42 mount and lenses were designed for 35mm stills cameras. A 7.5mm lens on 35mm stills format would give a 134 degree angle of view - exceedingly wide angle! To get the same on your D70 would require about a 4mm lens! Zoom lenses simply weren't produced that wide for 35mm stills cameras.

There are a few prime lenses in M42 mount at the wide end. There is the Peleng 8mm lens which is often mentioned on these boards, but after that the focal lengths are already covered by the 17-70mm standard zoom. The quality of the Meteor zoom appears to be a little variable, some people find it sharp and good quality, others find not so good examples. Your best bet is to test it for yourself and see if you're happy with the results.

As a rough guide, divide the focal length used on your D70 by 2.2 to find the focal length required to give the same view on your K3. It has nothing to do with different lenses - it's just a smaller imaging sensor in 16mm, so is only 'seeing' the middle bit of the D70 frame.


Hope I've made things a bit clearer?

Edited by Ian Cooper, 27 April 2009 - 02:18 AM.

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#3 Kristian Schumacher

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Posted 27 April 2009 - 10:08 AM

Hi Curtis,

Your d70 projects onto a 24x18mm frame, while your k-3 projects onto a 10.5x7.5mm frame. That is why it looks so different. If you were able to fit your Nikon zoom to your K-3, it would pretty much match the Meteor zoom.


Kristian

P.S. I perfectly agree with IanĀ“s reply, this was just my explanation.


Ok, my nikon d70 lens is 17-70MM

i get a nice wide look on 17 and a decent zoom look on 70mm

on my K3 lens, set for 17, it has the same look as my nikon lens at 70mm...

the K3 lens has the same zoom range as a nikon 70-200mm lens

is this because the K3 lens is actually 17-69 FEET? not mm?

i'm kind of confused as to whats going on here..

i was planning on picking up some cheap m42 lenses off ebay, but now i'm not sure what to buy lol


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#4 Curtis Bouvier

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Posted 27 April 2009 - 09:57 PM

wow thank you for taking the time to give me that response my friend, its perfectly clear.

this one guy mentioned an 8mm m42 lens that would offer a decent look for this k3 (has a fish eye look for 35mm, but supposedly not too bad on 16mm!). but it was a little pricey, i guess i'll have to see!
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#5 Ian Cooper

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Posted 28 April 2009 - 12:50 AM

...this one guy mentioned an 8mm m42 lens that would offer a decent look for this k3 (has a fish eye look for 35mm, but supposedly not too bad on 16mm!). but it was a little pricey, i guess i'll have to see!


If you have a trawl through the archives of the 16mm and the Russian 16mm sections of the board you'll find some examples of the M42 Peleng 8mm used on a K3. I think general opinion is that's the only M42 wide angle lens you're likely to find.
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#6 Will Montgomery

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Posted 28 April 2009 - 01:52 PM

this one guy mentioned an 8mm m42 lens that would offer a decent look for this k3 (has a fish eye look for 35mm, but supposedly not too bad on 16mm!). but it was a little pricey, i guess i'll have to see!

Pricey is relative. A Peleng 8mm goes for about $375 new. It is very wide of course but not very sharp. Nice for what it is but only for a specialized application. A Kiev 16mm is a good lens for the K3. Wider than the stock lens and it covers the whole Super 16 area; probably sharper than the Peleng.
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#7 Olex Kalynychenko

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Posted 29 April 2009 - 05:53 AM

Pricey is relative. A Peleng 8mm goes for about $375 new. It is very wide of course but not very sharp. Nice for what it is but only for a specialized application. A Kiev 16mm is a good lens for the K3. Wider than the stock lens and it covers the whole Super 16 area; probably sharper than the Peleng.


I porpose to check information about Kinor-16 SX-2M camera and set of lenses.
Kinor-16 SX-2M camera can have super wide angle lens 6 mm, 10mm, 15 mm.
The zoom lens can be 7.5-75 mm ( 16OPF-12-1 10-100mm with 0.75 front wide adapter )
the image will have better result from K-3 with Peleng.
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