Tokina RMC 17 f3.5 is not the fastest, but otherwise among the best. If interested, search for Ken Rockwell opinions and samples on this one and comparison to modern 17 mm lenses. This is almost a legend for photographers and works very well for video too. Flickr has many excellent sample images too.

@Vitaliy_Kiselev - Oops! Going on a GH2. I've got a LOMO and FD adapter but am willing to go for another adapter and lens as long as it sits in my budget.

@artistwar Depends on whether you want a high detail/high contrast look or a softer vintage look (as well as whether you plan on using AF, etc.)

Personally, without really having much to go on as far as the image quality of the LOMO, I would mention that the FOV of the 14mm (slightly wider than 28mm in 16:9) is VERY useful. I shot over 70% of my photos with that FOV (different focal length) for over a year and did some of my favorite work to this day.

Vitaliy - what do you think of 20mm 1.7 + wide converter ?

@bannedindv I use 20mm with Panasonic 46mm 0.8x wide angle converter and it is fantastic. I use it primarily during low-light shots and although there is a little softening at the edge at f 2.0, it still looks great. Razor sharp in the middle and it may actually improve the AF a little. I use half shutter AF to keep things from seeking constantly.

This effectively takes the lens down to 16mm which is a very film like 32mm in m43 in my opinion. 40mm equivalent is difficult to get shot sometimes i feel in cramped settings.

Pentax C60607KP 1/2" C Mount 6mm f/1.2 Manual Iris Lens

Price has risen waay beyond the $19.00 I paid for mine! But can be got cheaper on eBay.

http://www.ebay.com/itm/Cosmicar-Pentax-6mm-f-1-2-C-Mount-CCTV-TV-Camera-Lens-C60607-/190726239449

@nomad

This is the well-known C-Mount that we use in ETC mode. I know some have misgivings about ETC but the 6mm Pentax has become a classic so it has to be included. 12mm equiv, fast, cheap.

Low light you would have to keep ISO low, because of ETC, on that 6mm Pentax but for a 24mm equivalent and f 1.2, that is maybe worth trying out.

Difficult to focus though?

@ John: How do you set aperture on those?

@Nomad The lenses have no aperture control, the body had the aperture

but you can get adapters with 20 blades built in on ebay

or make filter sized aperture cards (black card with elliptical holes for pretend anamorphic :)

What sort of conditions will you be shooting in with the 14mm?

I thought it was the answer for providing wide enough shot in low light, but in extreme conditions (traditional disco lighting) it can require ISOs up to 1600 which in noise terms is just not good enough. Result looks cheap and bugs me big time. Although we use light to fill the scene in these circumstances, the lens just doesn't perform as well as 20mm. I can use the 20mm with the absolute bare minimum amount of light and the result looks terrific. I can't do this with the 14mm. It seems the difference of 0.5 is vast.

Excellent lens for work with good light, super sharp, AF a dream and hyper reactive, i find best results using f 2.8.

@artiswar .. interested in the Pentax 6mm
Watch this

If you are looking at cctv lenses then the Carl Zeiss Tevidon 2/10mm is hard to beat - new about $150