Cosmicar 1.4/12.5: so whats the kb equiv after cropping?

[JanJordan]

Bought a Cosmicar TV lens with f1.4 12.5mm. I did expect it to vignette quite a bit but i figured that i would still get a useable wide angle lens after cropping, maybe equivalent to 35mm on 35mm film. After modifying it to fit into my c-mount adapter (had to file down quite a bit) i decided to compare it to my G1 kit lens at wide angle. I remember that the effective focal length of such a lens has been discussed here already without any real conclusion.

standard cat lens coverage test. This is an uncropped image, as you can see cat disaproves:

This is the kit lens at 14mm:

This is a 4:3 crop of the cosmicar image at roughly f5. The kit lens is sharper, but i am not sure if i reached infinity focus completely either. This is shot is mostly to see how much softer the lens gets wide open:

This is the cosmicar at wide open (f1.4) There is more darkening in the corner and it is quite soft, but i still like the result and its good enough for screen or small prints:

The effective focal length is only slightly larger then that of the kit lens, so depending on the aspect of the crop i would say it you get a lens equivalent to 28-30mm for 35mm film.

So here some other shots i did with it afterwards. It is quite good for moody pictures imho and should enable quite some nice low light shots (which i fancy currently). Even the cat approves now:

Jan

 

[Godfrey]

I always compose with mine for the central square, making a 9Mbyte image. That's about a 55x55 degree Field of View, minus a little bit of corner vignetting.

It's a cool little lens and makes nice photos. I like the fact of its very short focal length and very large aperture ... gives a lot of options. Here's one of my favorite photos with it from last year:

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Somewhere I have an FoV demonstration with three frames, one with it, the 20 and the Konica 40. If I can find it, I'll post it.

 

[JanJordan]

yes, i am very happy with it. Composition is imho possibly the biggest drawback, i have yet to find a good strategy here. And i need to find the time to take it on a field trip ;-)
Jan

 

[Godfrey]

focal length - fov example

Found it... same position, pointing the camera at similar scenes, the full frame for all three:

The 12.5mm is nicely wide even when cropped to the central square.

 

[apicius9]

This one looks really nice, much sharper toward the corners than some of the other ones I have seen.

Stefan

 

[JanJordan]

Stefan: i am fairly happy with it. Especially since the lens at first was was making clackering noises when i shook it. The front element was not correctly screwed in.

Godfrey: it is surprising how narrow the fov of the 40mm suddenly looks and even the 20mm...

 

[Godfrey]

... it is surprising how narrow the fov of the 40mm suddenly looks and even the 20mm...

Oh yes: once your eye gets into the 12.5mm world, the 40 seems a very long lens. I only rarely use longer than that anymore: 70mm is a very long view on FourThirds to me nowadays.

 

[kai.e.g.]

Until I was given the 9-18mm Olympus, the Cosmicar 12.5mm was the widest lens I owned for my E-P1 (well, I do have an Elgeet f/1.2 12.0mm, but it's pretty mushy 'round the edges of its image circle, to put it mildly). I like the Cosmicar. I mostly used it in square mode, but with certain images, it was possible to work with perspective distortions to create portrait-shaped images. Here's an example; first the original file, then the final file after messing with it.

 

[Godfrey]

Looks good! A creative and useful way to use warping tools.