Is there an inverse to canon extenders? Is it even possible?

[Margus]

Hi!

Extenders as we know increase lenses reach at the cost of losing quite a bit of light. This makes sense, as to retain a particular f-stop as the focal length increases so must the lens itself get bigger.

So with the 2x extender, 70-200mm f/2.8 becomes effectively 140-400mm f/5.6

I was wondering if there is an inverse extender... like 0.5 extender, which would make it 35-100mm f/1.4


Now when I see the numbers, the quality would not be so wonderful I guess...

 

[480sparky]

There's a plethora of lenses that screw into a lens' filter threads that increase the FOV. IMPO, 99.999% of 'em are junk.

 

[o hey tyler]

Uhhh. You're never going to get anything larger than the maximum aperture of the lens. So this 35-100 f/1.4 wouldn't happen. If there were such a product, I'd expect it to halve the amount of light hitting the sensor.

 

[Big Mike]

You can get a wider view (0.7 adapter) but they are almost always a cheap lens that screws onto the front of the lens. And no, it won't give you a larger aperture.

Although....the F number is a ratio between the focal length and the entrance pupil. So if the 'effective focal length' is altered by the wide angle adapter, you could maybe say that the effective F stop is changed as well. But I'm not too sure about that. :scratch:

But yes, most/all of them are pretty crappy and not worth using if you care about image quality.

 

[Overread]

I think the market for a professional lens widener is just not there for there to be much work on developing a serious product for this. Teleconverters work because they take one lens and increase its focal length for a small cost - a 300mm to 600mm is a few £100 on a 2*TC as opposed to a few £1000 for a new lens. So at the long end there is a demand for such a product.

However at the wide end of the scale lenses are much cheaper, a few £100 on a lens widener and you're already half way or more to the cost of an actual wide angle lens. So the SLR game there just isn't a market for it; whilst in the point and shoot market there is some market, but because costs in that market are far less the quality goes out the window.

I can't recall ever seeing anyone reporting on a high quality lens widener.

 

[Destin]

The ONLY high quality lens widener I've ever heard of is the one that's made for Canon Camcorders such as the HF10 or HF11. Here's the adapter: Canon WD-H37 II 37mm Wide Angle Conversion Lens 3187B001 B&H
My videographer friend has one and has gotten good results in video.

But for still photos/DSLR's I've never heard of any of them working well.