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pinholeblender
12-28-2013, 08:03 PM
I made a collimator today following directions from a pamphlet by Edmunds Scientific called Fun With Optics. I can use it to check the focal lengths of all of the odd lenses I have. I'm using it with my fathers high school optical bench. Basically its a meter ruler with lens and projection screen holders. You can assemble multi element lenses in front of the collimator to test the resulting focal lengths. My snow globe has a focal length of 40mm and the jelly jar measured 210mm.

1635

1636

DaveBell
12-28-2013, 08:59 PM
I've loved those long-gone Edmund's booklets since, well, 1960?!? Wonderful learning tools.
Didn't have the money to buy many of them in the beginning, but a surprising amount of the pages could be read in the catalog, if your eyes were sharp.
A couple of years ago, I ran across an entire PDF collection of them on line.

Dave

JoeVanCleave
12-28-2013, 11:42 PM
Chris, that's a nifty project. I should think about making one. As for those Edmund's pamphlets, they were a great treasure for the DIYer - before the term DIY was coined!

~Joe

Tom Persinger
12-30-2013, 06:27 PM
Great tool and post Chris - thanks! I did a quick search and found this link that has quite a few of these as PDF for free download. If anyone grabs this and builds something please share it!

http://www.anchoroptics.com/documents/

pinholeblender
12-31-2013, 11:02 PM
Wow, great information Tom. I found a good chart on diopter focal lengths in the chipped lens kit pdf. This will help me make my reading glasses camera. Also much needed math formulas for the "Equivalent focal length of two lenses" on page 11 of Graphical Ray Tracing pdf. I never was good at math so this chart helps me understand focal lengths of multiple element lenses.

Ned.Lewis
12-31-2013, 11:41 PM
That first picture makes me want to remove the electrical cord and then put a candle ( or gaslight! ) in the box... then it would look like 100 years ago! Very nice setup.

Tom those are fun. I especially like the "opaque projector" one... it has a table with different kinds of lens configurations-- pages 4 and 5 have excellent information about lenses in general.

I've been contemplating the idea of building a reflective enlarger for paper negatives like this one:

http://www.photomemorabilia.co.uk/Gratispool/Paper_Negatives.html

The "opaque projector" pdf has all the information I could need....

Tom Persinger
01-01-2014, 10:05 AM
sounds like a great project Ned! if you build the project keep us posted - sounds great!

dwerg85
01-07-2014, 01:38 PM
any instructions on how to build one?

pinholeblender
01-12-2014, 11:30 AM
Page 6 of this pdf shows how to make one, http://www.anchoroptics.com/documents/download.cfm?id=14 The center bottom picture and paragraph below it tells how to use it. The other instructions are how to use it with telescopes. You can use anything on the target inside the collimator. After looking up collimator targets on the web all of the sites referred to using the "usaf 1951 test chart" but for your purpose anything will work. I printed my out on Vellum.

dwerg85
01-30-2014, 12:56 PM
Cool thanks.