WTD: Stock Optics 35 or 50mm IR M12 Board Lens

[Clunge]

I'm sure some of you will have one or two of these lenses in your spares/old projects bins.

They are the f2.5 1/2" format IR lenses which will be equivalent of 50 and 75mm when used on 1/3" sensor.

They are 41 and 50 quid new, but you could use - say - 25 or 35 beer tokens for your discarded project lens, couldn't you?

PS. If you've used one for an E700 based spotter, what are your thoughts? (Needed for FAC air/Rimfire ranges).

[subzeer0]

50mm .... these are available via fleabay for around £18 from china.and arrive fairly quick...and are just the same as had both from there and off a night vision seller

the work fine but be prepared to grind...file whatever off the e700 mount down to the lock screw to get the lens to focus

used on a spotter they are quite good, very clear and easy to focus

someone will be along shortly to offer more

[some bloke]

They work well and are indeed less focus fussy than a 50mm F1.4 C mount TV lens, expect them to be a bit wobbly in the camera neck but a few turns of PTFE tape on the thread should work well, or a 12mm coil spring, or both.

The 50mm lens is IMO too tight a FOV for air and rimfire range rabbits, the 35mm one's are better suited for close work but budget builders will need an extension for the E700 neck - which then needs trimming down because the E700 neck is too short but the extender is too long.

The spotter in this photo has a 35mm board lens fitted in a lens adaptor I have made for them so its less likely the lens and camera will shift if the lens gets a hard knock because my bespoke adaptors screw to the box - and the lens doesn't meet the camera. Its more expensive but more reliable.


This is my bespoke 35mm board lens adaptor - it is not suitable for the other focal length board cameras. The E700 is tacked into the back of it with glue but the camera is protected from knocks because its inside the box, not very heavy and isolated from knocks to the lens.



I have made this one up with a 50mm board lens screwed directly into an E700 - but it feels much more fragile and I suspect it will not take a knock like an adaptor that's screwed to the box would. Being significantly longer than the 35mm lens it is also more likely to get moved during handling. There are people who seem happy enough to have a lens fixing reliant on glue though.


When fitting lenses that are likely to take an occasional knock because they extend well in front of the spotter directly into the E700, I have concerns that there seems no practical and durable way to fix the E700 body inside your box unless you all but bury the camera in glue and faff about a lot to aim the IR beam to its best position before and or while it sets. The appearance of the camera fixing is not going to be much of an issue for anyone building a sealed box type project but I feel it will look too untidy for my spotters that have flip out, relocatable monitors.

All in all I think the 50mm board lenses are too exposed and vulnerable for spotters unless they can be almost buried into a very deep box.

[Clunge]

Thanks Sub and Dave. Some very good info to chew on.

More leaning towards the 35mm then.

Also wondering if the 50mm could be used for a very compact scopeless.

(Sure I posted this earlier today, but maybe I didn't press submit.)

[some bloke]

Would be OK for subsonic ranges, I think 'Pitch Black' used them in their rigs.