Camera focus distance and macro lenses

[mikerr]

By now there's plenty of videos and distance shots out there, so I'm concentrating on closer in:

Fixed focus seems quite long and begins at 60cm+ anything closer is blurred:

20cm:



60cm away (those are 30cm rulers)



So I whipped out the cheapy clip on macro lens for my iphone, clipped it over the raspicam and here's the result:



That's at 2cm ..bit of a dusty pi

- now I need some middle ground

[pluggy]

Find a pair (or buy a pair - they are very cheap) of +2 or stronger reading glasses, pull one of the lenses out and mount it in front of the camera lens.

[alexeames]

I've got a +2 lens for slr (close-up screw on thingy.) Going to try that. Looks pretty good Mike. Where'd you get it?

[eckythump]

did something similar with a plastic eyeglass, decent pictures at about 12 cm but fairly poor closer or further away. (pictures posted but post awaits moderation), can you tell me which particular macro lens adapter you are using? there are some really cheap ones out there and some less cheap.

[eckythump]

did something similar with a plastic eyeglass, decent pictures at about 12 cm but fairly poor closer or further away. (pictures posted but post awaits moderation), can you tell me which particular macro lens adapter you are using? there are some really cheap ones out there and some less cheap.

[eckythump]

did something similar with a plastic eyeglass, decent pictures at about 12 cm but fairly poor closer or further away. (pictures posted but post awaits moderation), can you tell me which particular macro lens adapter you are using? there are some really cheap ones out there and some less cheap.

[mikerr]

Looks pretty good Mike. Where'd you get it?

..the iphone macro lens ? "youvue macro and wide angle lenses"
http://img208.imageshack.us/img208/9416 ... 161450.jpg

Find a pair (or buy a pair - they are very cheap) of +2 or stronger reading glasses, pull one of the lenses out and mount it in front of the camera lens.

Hehe, great tip - grabbed some reading glasses

Comical Pi with specs on:



20cm with reading glasses:

[pluggy]

That's just given me a tip about holding the camera - I have a set of helping hands somewhere......

[eckythump]

Find a pair (or buy a pair - they are very cheap) of +2 or stronger reading glasses, pull one of the lenses out and mount it in front of the camera lens.

Hehe, great tip - grabbed some reading glasses

Comical Pi with specs on:



20cm with reading glasses:

something very amusing about the picture with the specs on,

does it make any difference how far the glasses are from the pi-camera?

[pluggy]

They work best actually right over the lens, if there's a gap the contrast drops off with light coming into the camera from the gap. Pretty much like when you wear them for reading.

[mikerr]

You can see a reflection of the red camera LED in my first 2cm macro,
you can turn it off now:

disable_camera_led=1 in /boot/config.txt

[alexeames]

Looks pretty good Mike. Where'd you get it?

..the iphone macro lens ? "youvue macro and wide angle lenses"
http://img208.imageshack.us/img208/9416 ... 161450.jpg

Thanks Mike. Found one for £12 and another for £35. Worth a punt for £12. £35? No way. I want to be able to shoot close up video. Modified spectacles and the large slr close-up adaptor won't cut it for that.

[alexeames]

Just made some measurements, and according to my rough measurements, the close focus distance of the camera out of the box is ~ 47cm. Adding a +2D close-up makes it ~24cm.

Anyone would think that dioptre was the reciprocal of focal length or something.

Now all I need to do is find a way to mount the 52mm slr +2D lens to the PiCam without damaging either. At the moment it's sitting on top, pointing up, held in place by gravity.

[pluggy]

Cut a pair of acrylic reading glasses with an hacksaw and hot melt glue it over the lens. I wouldn't have thought the quality of a cheapish fixed focus camera module is going to suffer much in the process.....

[alexeames]

Cut a pair of acrylic reading glasses with an hacksaw and hot melt glue it over the lens. I wouldn't have thought the quality of a cheapish fixed focus camera module is going to suffer much in the process.....

That would surely do it. I'm wanting this for close-ups to possibly use in future videos for a second camera angle. It's got to be optically satisfactory. Sounds like it might work. Will acrylic be good enough? I wonder if I can nick a pair of my wifes old reading glasses to try out. I'm short sighted myself, so mine are -ve

[Ravenous]

If using old glasses, just make sure the wearer wasn't astigmatic! (The prescription might have zero in the cyl and sphere bits?)

I just mention it because I have quite a lot of it, though most people are more fortunate. You can tell by just holding the lens up to magnify something and rotating the lens in your hand. There shouldn't be any twisting distortion as you rotate it.

[mikerr]

I've just tried a clip on wideangle lens (iphone) and it did reduce the focus distance to 20cm, but wasn't as clear as the reading specs

[poing]

I've just tried a clip on wideangle lens (iphone) and it did reduce the focus distance to 20cm,
but wasn't as clear as the reading specs

Though much more pricey I'd guess

[pluggy]

Buy a pair of ready readers from ebay or a pound shop. They aren't prescription so don't have correction other than the focal length.

[pluggy]

I've just tried a clip on wideangle lens (iphone) and it did reduce the focus distance to 20cm, but wasn't as clear as the reading specs

Everything iPhone has a price premium and often isn't any better than cheap stuff.

[jbeale]

I've just tried a clip on wideangle lens (iphone) and it did reduce the focus distance to 20cm, but wasn't as clear as the reading specs

Although to be fair, an external wide-angle adapter has a different optical design than a simple close-up lens and does a different thing. It uses a minimum of two optical elements and gives you a wider field of view, greater depth of focus, and probably quite a bit more distortion. As a side effect, that allows you to get closer. The simple close-up lens gives you smaller field of view, and shallower depth of focus, and probably not much additional distortion.

I had a quick look at reviews of iPhone wide-angle adaptors and at least for the extreme wide-angle ones, they all get pretty blurry around the edges of the frame (using an iPhone, not a RPi camera- although I'm sure the RPi camera would do no better).

[alexeames]

something very amusing about the picture with the specs on,

He's promoting his new venture - Geek Boy Diaries.

[pluggy]

In answer to acrylic lenses, its easier to saw than glass and most prescription eye glass lenses are plastic nowadays. It lighter and the resultant glasses are less tiring to wear because there's less weight bearing down on the bridge of the nose. If the camera module was at all 'posh' it might be worth going to a lot of trouble and expense to get quality close up stuff, I think cutting up some cheap/old glasses is appropriate. (My 2 year old, cheap, bottom of the range Samsung Galaxy Ace phone has an auto focus lens , so the camera in the Pi's module isn't anything to write home about)

[alexeames]

In answer to acrylic lenses, its easier to saw than glass and most prescription eye glass lenses are plastic nowadays. It lighter and the resultant glasses are less tiring to wear because there's less weight bearing down on the bridge of the nose. If the camera module was at all 'posh' it might be worth going to a lot of trouble and expense to get quality close up stuff, I think cutting up some cheap/old glasses is appropriate. (My 2 year old, cheap, bottom of the range Samsung Galaxy Ace phone has an auto focus lens , so the camera in the Pi's module isn't anything to write home about)

OK fair enough. Horses for courses. I already have +2D (52mm thread)and +4D (62mm thread) glass optics for 35mm slr cameras. With +2D the results were superb when I tested them. I don't already have glasses I can cut up and my wife's old ones seem to be too "weak" to bother with. I'm not expecting miracles from this, and, yes I could probably use my Galaxy S2 or Nexus cameras to do the job. But I can't hack those - and touchscreens seriously suck for shutter release Cheap reading glasses might be worth a punt if I can find some.

[pluggy]

I wear these myself although they aren't the cheapest around :

http://www.tigerspecs.co.uk/item/51008