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Ping Pong Ball diffusers
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NikonUser



Joined: 04 Sep 2008
Posts: 2560
Location: southern New Brunswick, Canada

PostPosted: Thu Oct 22, 2009 9:03 am    Post subject: Ping Pong Ball diffusers Reply with quote

EDIT: title was "1st Ping Pong Ball image"

Finally found a box of table tennis balls "halex No. 1" (made in England) at a local yard sale (=boot sale in UK).

Cut a hole that was slightly too large (unintentional) for a snug fit on the 10x Nikon CF N Achromat so I taped the barrel of the lens with green masking tape (say goodbye to the labels). Now the ball is a snug fit and readily adjustable.

Top is the actual setup used to capture an image of the head of a small fly.

Head:122 frames @0.01mm ZS PMax, max eye width 0.56mm; some cropping.

NU09215

NU09217
EDIT: 400px image of entire fly
ON THIS PAGE
_________________
NU.
student of entomology
Quote – Holmes on ‘Entomology’
” I suppose you are an entomologist ? “
” Not quite so ambitious as that, sir. I should like to put my eyes on the individual entitled to that name.
No man can be truly called an entomologist,
sir; the subject is too vast for any single human intelligence to grasp.”
Oliver Wendell Holmes, Sr
The Poet at the Breakfast Table.

Nikon camera, lenses and objectives
Olympus microscope and objectives


Last edited by NikonUser on Fri Oct 23, 2009 5:13 am; edited 1 time in total
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rjlittlefield
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Joined: 01 Aug 2006
Posts: 19972
Location: Richland, Washington State, USA

PostPosted: Thu Oct 22, 2009 11:16 am    Post subject: Reply with quote

Neat -- I think this is the first we've seen posted showing more than half a ball.

One issue to consider... Given the large aperture of a microscope objective, and depending on where your subject is within the ball, the bottom edge of that pingpong ball may intrude into the field of view. It's hugely OOF, of course, but it will still be bright. This may not be a problem with light gray backgrounds, but it will definitely interfere with darks. So for other cases, you may need to make that bottom hole bigger.

For reference, the angle between two sides of the entrance cone of an objective is 2*arcsin(NA). For NA=0.30, that's about 35 degrees; for NA=0.40, about 47 degrees. In contrast, the in-focus subject for that 10X Nikon objective spans less than 6 degrees. I've been caught more than once seeing things in far background that looked at first glance to be way outside the field.

--Rik
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NikonUser



Joined: 04 Sep 2008
Posts: 2560
Location: southern New Brunswick, Canada

PostPosted: Thu Oct 22, 2009 12:18 pm    Post subject: Reply with quote

Thanks for the comment.
I replaced the gray background with a sheet of black Protostar.
Single image, full frame, no processing except to re-size to 800px.
Seems OK.

NU09218
_________________
NU.
student of entomology
Quote – Holmes on ‘Entomology’
” I suppose you are an entomologist ? “
” Not quite so ambitious as that, sir. I should like to put my eyes on the individual entitled to that name.
No man can be truly called an entomologist,
sir; the subject is too vast for any single human intelligence to grasp.”
Oliver Wendell Holmes, Sr
The Poet at the Breakfast Table.

Nikon camera, lenses and objectives
Olympus microscope and objectives
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rjlittlefield
Site Admin


Joined: 01 Aug 2006
Posts: 19972
Location: Richland, Washington State, USA

PostPosted: Thu Oct 22, 2009 12:31 pm    Post subject: Reply with quote

Agreed, looks great.

Reviewing your first image, and comparing it with my copy of that objective, I now get the idea that the fly shown here is only a few mm above the hole in the bottom of the pingpong ball. Is that correct?

If so, then it seems you've created a design that allows a lot of flexibility by mounting the subject on a long pin and sliding the ball along the objective to surround it. I must try this the next time I have that lens out...

--Rik
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NikonUser



Joined: 04 Sep 2008
Posts: 2560
Location: southern New Brunswick, Canada

PostPosted: Thu Oct 22, 2009 12:52 pm    Post subject: Reply with quote

Luckily I haven't changed the setup, the distance between the fly and the hole is about 6mm.
The ball has plenty of room to slide up and down the barrel of the lens.
_________________
NU.
student of entomology
Quote – Holmes on ‘Entomology’
” I suppose you are an entomologist ? “
” Not quite so ambitious as that, sir. I should like to put my eyes on the individual entitled to that name.
No man can be truly called an entomologist,
sir; the subject is too vast for any single human intelligence to grasp.”
Oliver Wendell Holmes, Sr
The Poet at the Breakfast Table.

Nikon camera, lenses and objectives
Olympus microscope and objectives
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DaveW



Joined: 04 Aug 2006
Posts: 1702
Location: Nottingham, UK

PostPosted: Thu Oct 22, 2009 2:25 pm    Post subject: Reply with quote

If the diffuser is kept more spherical would it not also act like an integrating sphere as used in some enlargers? Or as it is lit from the outside would that not apply?

http://en.wikipedia.org/wiki/Integrating_sphere

I found this explanation on the Web but it is beyond the comprehension of a humble carpenter! Laughing

http://www.precisionphotometrics.com/pdf-files/Int_Sphere_Technical-guide.pdf

DaveW
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Eric F



Joined: 11 Nov 2008
Posts: 246
Location: Sacramento, Calif.

PostPosted: Thu Oct 22, 2009 4:16 pm    Post subject: Reply with quote

Nice images NU, and nice setup with the full sized ping ball diffuser. I think the lighting of your first fly shot is especially nice! I believe you have some special light dispersion that is different from the customary half ping pong ball diffuser (which is more of a shield); yours does act like the integrating sphere that Dave mentions.

Do you like your new Beljan cone? Have you put some Prostar on the inside base (the area underneath the white-labelled part in your photo)?

Eric
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NikonUser



Joined: 04 Sep 2008
Posts: 2560
Location: southern New Brunswick, Canada

PostPosted: Thu Oct 22, 2009 6:49 pm    Post subject: Reply with quote

Thanks Eric, ball did a nice job on the eyes - no bright shiny reflecttive facets
Love the cone. Protostar: Yes, I followed your advice:
BOTTOM OF PAGE
_________________
NU.
student of entomology
Quote – Holmes on ‘Entomology’
” I suppose you are an entomologist ? “
” Not quite so ambitious as that, sir. I should like to put my eyes on the individual entitled to that name.
No man can be truly called an entomologist,
sir; the subject is too vast for any single human intelligence to grasp.”
Oliver Wendell Holmes, Sr
The Poet at the Breakfast Table.

Nikon camera, lenses and objectives
Olympus microscope and objectives
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Graham Stabler



Joined: 20 Dec 2007
Posts: 209
Location: Swindon, UK

PostPosted: Fri Oct 23, 2009 3:19 am    Post subject: Reply with quote

I've also been experimenting with almost complete balls. My object movie rig needs to give reasonable lighting no matter what angle the object it tilted at so I ended up with this. The ball is held in place by one of my Gorrilla pod mounts, basically a section of one of the legs held to a base plate (steel coated in black flocking) by a strong magnet (taken from cheap magnetic pick up tool).

Obviously normal folks don't need the slot.

I also wondered about making a box around the ball, lined with silver foil or just painted white to use with a flash or two to try and get a very even spherical lighting.



Graham
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NikonUser



Joined: 04 Sep 2008
Posts: 2560
Location: southern New Brunswick, Canada

PostPosted: Fri Oct 23, 2009 5:12 am    Post subject: Reply with quote

Neat-looking rig. I'm trying to picture where the subject goes; on a pin and then through the slot?
Does the ball have a hole in the bottom or is it complete and the ball bottom forms the background for the image?
The lens 'looks through' the top hole?
_________________
NU.
student of entomology
Quote – Holmes on ‘Entomology’
” I suppose you are an entomologist ? “
” Not quite so ambitious as that, sir. I should like to put my eyes on the individual entitled to that name.
No man can be truly called an entomologist,
sir; the subject is too vast for any single human intelligence to grasp.”
Oliver Wendell Holmes, Sr
The Poet at the Breakfast Table.

Nikon camera, lenses and objectives
Olympus microscope and objectives
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View user's profile Send private message
Graham Stabler



Joined: 20 Dec 2007
Posts: 209
Location: Swindon, UK

PostPosted: Fri Oct 23, 2009 6:02 am    Post subject: Reply with quote

Sorry my choice of angle was not great. The subject is on the end of a pin (in fact a 1mm drill blank, a posh pin) in the centre of the sphere generally. The pin can rotate and also be tilted (hence the slot) and go up and down for stacking. There is indeed a hole in the bottom which provides the background which is the same black flocking and the lens looks in from above. I use this with a 50mm enlarger lens reversed.

Because the pin is vertical at times in my rig I have flocking at it's base so there is always a black background. I'm considering flexible paper backgrounds which will scroll with the system but for my needs it is not so critical.

Graham
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Eric F



Joined: 11 Nov 2008
Posts: 246
Location: Sacramento, Calif.

PostPosted: Fri Oct 23, 2009 9:55 am    Post subject: Reply with quote

Thanks NU; I somehow had missed your response last week. Glad the Beljan cone is working so well.

Graham: nice ping pong diffuser setup!

Did you guys know that there are different sized ping pong balls? Normal ones are now 40mm in diameter (though 10 years ago the standard was 38). There are also 44mm ones and 55mm ones (latter called Gorilla Balls!). These odd size balls are much more expensive than the 40mm standard -- though there is a push to make 44 the new standard (slower game, easier to televise), so presumably the price will drop for those. I found a source for a sample of each (Google: "JOOLA BALL SET 3/2/2 Table Tennis Balls") for about $7; otherwise, the 55's cost $80 for a box of 32 (half of which are yellow!). I'm curious about how the 55's will work as diffusers, so I've ordered a Joola Ball set...

Eric
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NikonUser



Joined: 04 Sep 2008
Posts: 2560
Location: southern New Brunswick, Canada

PostPosted: Fri Oct 23, 2009 11:39 am    Post subject: Reply with quote

Wow, 40mm - mine are exactly 37.4mm

I would love to get hands on those larger balls but they must have some military significance - Amazon will ship them only within the USA Sad
_________________
NU.
student of entomology
Quote – Holmes on ‘Entomology’
” I suppose you are an entomologist ? “
” Not quite so ambitious as that, sir. I should like to put my eyes on the individual entitled to that name.
No man can be truly called an entomologist,
sir; the subject is too vast for any single human intelligence to grasp.”
Oliver Wendell Holmes, Sr
The Poet at the Breakfast Table.

Nikon camera, lenses and objectives
Olympus microscope and objectives
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View user's profile Send private message
Eric F



Joined: 11 Nov 2008
Posts: 246
Location: Sacramento, Calif.

PostPosted: Fri Oct 23, 2009 1:07 pm    Post subject: Reply with quote

Oops ... should be Elephant Balls, rather than Gorilla. We'll have to keep looking for sources for these 55mm balls -- if the 1 white one I will get shows promise. The 40mm ping pong balls I have are a fairly recent purchase from Target. An internet site said that the legal "Table Tennis" size was changed in 2000 from 38 to 40mm. I imagine that most of the old ping pong balls that are lying around in garages, etc. are the 38mm size.
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ChrisR
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Joined: 14 Mar 2009
Posts: 8369
Location: Near London, UK

PostPosted: Fri Oct 23, 2009 3:27 pm    Post subject: Reply with quote

Polystyrene balls, 30 to 500mm diameter.
Possibly too thick:
http://stores.shop.ebay.co.uk/Modelling-Magic__W0QQ_armrsZ1QQ_fsubZ8

I did find some balls in halves, intended to have matchheads or somesuch stuffed in them to make grenades - not there now!
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