Hacking an old SLR lens to a P&S camea

[ramses]

Has anyone ever considered pulling the lens off of a cheap point and shoot (or maybe a Casio HS one) and securing an SLR lens to the body.

I mean, with the crop factor, a 50mm lens could have an EFL of 300mm, a 135mm an EFL of over 800mm. You could get a ton of light in, too, considering 50/1.4 and 135/2.8 lenses are available very cheaply on ebay.

[Hotwired]

I certainly wouldn't try it on a decent compact camera.

A fair bit of what you pay for requires it to still have the lens it came with.

Just found a hack for sticking a SLR lens to a phone camera: http://blog.cow.mooh.org/2009/12/phone- ... es-to.html

Picture quality seems dubious, you get SLR effects but you'd have to have some serious precision in bodging the lens on to fix the artefacts.

[MrCrowley]

I've thought about it in passing. There was a tutorial somewhere that took apart some point-and-shoot Canon so as to clean the sensor. I'm sure with a dremel, some epoxy and a custom machined fitting it would be possible. Whether it is worth the hassle, I doubt it unless you have an unwanted camera laying around.


Edit: It'd be much easier to attach a film lens to a webcam and see what the performance is like. I recently modded a Microsoft Livecam Cinema 720p (30fps) for my microscope which involved removing the webcam lens and filters.

[MRR]

You could get a ton of light in, too, considering 50/1.4 and 135/2.8 lenses are available very cheaply on ebay.

The objective lens sure helps but the main factor is the CMOS chip. Compared to a p&s the chip of a DSLR is gigantic. I have a bridge camera with a rather large objective and it is still bad in low light situations.

[ramses]

All right, let me clarify what I meant by "a ton of light." Obviously, when you crop the image projected by the lens, you only get that little bit of light. The light let in would be the same as the stock lens if the stock lens would go to f1.4 (or whatever). Most point and shoot lenses go to around f2.7 at wide open, which is a focal length of about 4mm. (and like 28mm field of view)


The primary advantage of large sensors is that the pixels are bigger. When you put 16MP on some tiny sensor, each pixel receives next to no light. If you had a ~1MP camera with a sensor 1/18 the area of the 7d, you would theoretically see about the same amount of noise in 100% crops. Using the same exact lens on both cameras, the crops should be identical (except the p&s is probably CCD)

The main advantage here is magnification. I can't think of a single point and shoot that goes to 300mm at f1.4. The HS20EXR maxes out at 720mm and f5.6. This would be something like 800mm at f2.8, or 2 stops faster.

One thing I did notice with all the other attempts is that they left the stock lens on. I was thinking something more like this:

Now off to find a discarded P&S with manual mode.

[Technician1002]

Hmm, I have a couple of old school video cameras at home, big tube jobs from before CCD cameras. The zoom lenses are motorized for both zoom and apature. Only focus is manual. Putting a decent multi megapixel sensor behind that would make a decent zoom. Cameras are 1980's vintage.