mikerr
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Camera focus distance and macro lenses

Thu May 16, 2013 3:22 pm

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:

Image

60cm away (those are 30cm rulers)
Image


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

Image

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

- now I need some middle ground
Last edited by mikerr on Fri Jun 07, 2013 10:19 pm, edited 2 times in total.
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pluggy
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Re: Camera focus distance and macro lenses

Thu May 16, 2013 3:27 pm

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.
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alexeames
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Re: Camera focus distance and macro lenses

Thu May 16, 2013 3:39 pm

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?
Alex Eames RasPi.TV, RasP.iO

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Re: Camera focus distance and macro lenses

Thu May 16, 2013 3:41 pm

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.

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Re: Camera focus distance and macro lenses

Thu May 16, 2013 3:42 pm

eckythump wrote: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.
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eckythump
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Re: Camera focus distance and macro lenses

Thu May 16, 2013 3:44 pm

eckythump wrote:
eckythump wrote: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.
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mikerr
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Re: Camera focus distance and macro lenses

Thu May 16, 2013 3:47 pm

alexeames wrote: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
pluggy wrote: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:

Image

20cm with reading glasses:

Image
Last edited by mikerr on Thu May 16, 2013 3:55 pm, edited 2 times in total.
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pluggy
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Re: Camera focus distance and macro lenses

Thu May 16, 2013 3:53 pm

That's just given me a tip about holding the camera - I have a set of helping hands somewhere......
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Re: Camera focus distance and macro lenses

Thu May 16, 2013 3:54 pm

mikerr wrote:
pluggy wrote: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:

Image

20cm with reading glasses:

Image
something very amusing about the picture with the specs on,

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

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Re: Camera focus distance and macro lenses

Thu May 16, 2013 4:06 pm

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. ;)
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Re: Camera focus distance and macro lenses

Thu May 16, 2013 4:12 pm

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
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Re: Camera focus distance and macro lenses

Fri May 17, 2013 7:11 am

mikerr wrote:
alexeames wrote: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.
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Re: Camera focus distance and macro lenses

Fri May 17, 2013 8:36 am

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. :roll:

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. :D
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Re: Camera focus distance and macro lenses

Fri May 17, 2013 2:24 pm

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.....
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alexeames
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Re: Camera focus distance and macro lenses

Fri May 17, 2013 4:03 pm

pluggy wrote: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
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Re: Camera focus distance and macro lenses

Fri May 17, 2013 4:22 pm

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.

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Re: Camera focus distance and macro lenses

Fri May 17, 2013 4:30 pm

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 ;)
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Re: Camera focus distance and macro lenses

Fri May 17, 2013 4:31 pm

mikerr wrote: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 ;)

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Re: Camera focus distance and macro lenses

Fri May 17, 2013 4:33 pm

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.
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Re: Camera focus distance and macro lenses

Fri May 17, 2013 4:37 pm

mikerr wrote: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.
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Re: Camera focus distance and macro lenses

Fri May 17, 2013 4:45 pm

mikerr wrote: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).

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Re: Camera focus distance and macro lenses

Fri May 17, 2013 5:19 pm

eckythump wrote:something very amusing about the picture with the specs on,
He's promoting his new venture - Geek Boy Diaries. :lol:
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Re: Camera focus distance and macro lenses

Fri May 17, 2013 6:33 pm

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)
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Re: Camera focus distance and macro lenses

Fri May 17, 2013 6:56 pm

pluggy wrote: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 :lol: Cheap reading glasses might be worth a punt if I can find some.
Alex Eames RasPi.TV, RasP.iO

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Re: Camera focus distance and macro lenses

Fri May 17, 2013 7:05 pm

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

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