Voigtlander 50mm F/1.1 Nokton 

 If you are looking for a fast 50mm lens but don’t want to pay Noctilux money, then the Voigtlander 50mm F/1.1 Nokton is a great place to begin looking. This lens is one of the few fast 50mm's on the market that won't cost you a fortune and that will last a life time due to the fantastic build quality like all voigtlander lenses.  

This lens is a 50mm F/1.1 which means you will be able to shoot in low light conditions as well as create dream like backgrounds by shooting this lens wide open. The lens has seven elements in six groups and has ten aperture blades. This leads to excellent colour rendition and smooth bokeh. Because this lens is a F/1.1 it is quite large and heavy which is to be expected. The lens weighs 428 grams and has a 58mm filter thread, which is considered large for M – mount lenses. That being said, lens is very ergonomic with ridges in the focusing ring making it very quick and precise to focus this lens.  

Leica M5 + Voigtlander 50mm F/1.1 + Kodak Ektar

As far as 50mm lenses goes this is a great performer. I found this lens to have modern characteristics due to the modern lens design and coatings. When I was using this lens, I owned a Leica M5 at the time. The lens was a very good match to this camera as the Leica M5 is a slightly oddball Leica and is much larger than any other M film cameras. In the images below, you can see how the lens renders colour and contrast. Unlike older lenses this lens doesn't require much adjustment out of camera. 

Leica M5 + Voigtlander 50mm F/1.1 + HP5

Leica M5 + Voigtlander 50mm F/1.1 + HP5

Leica M5 + Voigtlander 50mm F/1.1 + HP5

After about four months of using this lens a great opportunity came about where I was able to swap my Leica M5 and this lens for a Leica M3 and a 50mm Summicron. Without a second thought I agreed to the swap and have never really regretted it. Though the Voigtlander 50mm F/1.1 is an amazing lens I wasn’t finding myself shooting it at f/1.1 that much. In most situations I would be shooting this lens between F/2 and F/8.  While the Voigtlander 50mm F1.1 Nokton is one of the cheapest fast 50mm lenses you can buy for your M system it isn't the only option. A few other potential lenses are the Canon 50mm F/1.2 ltm, the Voigtlander 50mm F/1.5 and the 7artisans 50mm f1.1. 

Leica M5 + Voigtlander 50mm F/1.1 + Kodak Ektar

Leica M5 + Voigtlander 50mm F/1.1 + Kodak Ektar

Leica M5 + Voigtlander 50mm F/1.1 + Kodak Ektar

The Canon 50mm f/1.2 is probably one of the more unique lenses as it is Leica Thread Mound (ltm) rather than Leica M mount. This lens is the baby brother to the legendary Canon 50mm f/0.95 TV lens. Though this lens can be had for about £100 cheaper than the Voigtlander I myself have purchased three of these lenses and all three were returned due to haze within the lens, this is a common issue with older Canon ltm lenses but if you can find a good copy then this lens can render some stunning classic dreamy images with a unique rendering which makes it quite special. The next lens to maybe consider is the Voigtlander 50mm f/1.5 nokton. This lens is much smaller than the f/1.1 nokton and renders images in a very classic way similar to older Leica lenses from the 1960's. This lens can also be had for about the same price as the f/1.1 nokton so if you dont need that extra stop of light this lens is another good choice. lastly we have the 7artisans 50mm f1.1. This is a new lens which costs below £300! Though I have not personally used this lens I have seen many people praising it due to the value for money. The only thing which puts my off buying this lens is the fact 7artisans include a tool to adjust the focus of the lens. This indicates that quality control and the labor that goes into this lens is rather low, that being said its a £300 lens so i guess you get what you pay for. 

https://www.voigtlaender.de/lenses/vm/50-mm-11-1-nokton/?lang=en