Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 69,924   Posts: 1,522,105   Online: 786
      
Page 1 of 3 123 LastLast
Results 1 to 10 of 26
  1. #1
    Newt_on_Swings's Avatar
    Join Date
    Mar 2011
    Location
    NYC
    Shooter
    Multi Format
    Posts
    1,782

    Pinhole with an Epoxy Droplet Lens?

    So just before sunset today I was playing with my chocolate box pinhole camera using 5x7 paper and litho film, and a thought occurred to me.

    Would it be possible to use clear epoxy to create a droplet lens on top of a pinhole. The surface tension should create a nice smooth and round surface as long as you can center it on the hole, I think it should work.

    I just put a few drops on a very thin piece of adheasive foil tape (my current pinhole medium) and they are drying. They do form a nice round shape, and by accident one has even formed a tiny bubble under the epoxy right above the pinhole.

    I tried doing some google researching, but have not come across any info on such a process. Anyone ever do something like this before? or read about it? Would the droplet lens be able to form a picture? How would such an image come out?

  2. #2
    Rick A's Avatar
    Join Date
    Mar 2009
    Location
    north central Pa
    Shooter
    Multi Format
    Posts
    5,820
    Images
    31
    To answer your question, I don't know. Since you have some made try them out. Can't wait to see what you get.
    Rick A
    Argentum aevum
    BTW: the big kid in my avatar is my hero, my son, who proudly serves us in the Navy. "SALUTE"

  3. #3
    Nicholas Lindan's Avatar
    Join Date
    Sep 2006
    Location
    Cleveland, Ohio USA
    Shooter
    Multi Format
    Posts
    2,372
    Images
    4
    The focal length of a sphere is about equal to its radius. I'd guess your epoxy drop has a focal length of a few mm.

    If your camera has a pinhole-to-film distance of 100mm then a 10 diopter close-up lens is about right. The lens out of an old box camera might have a convenient focal length. You might find coverage isn't as great, though, as at large angles a meniscus lens will produce lots of aberrations.
    DARKROOM AUTOMATION
    f-Stop Timers - Enlarging Meters
    http://www.darkroomautomation.com/da-main.htm

  4. #4
    Worker 11811's Avatar
    Join Date
    Jan 2010
    Location
    Pennsylvania, USA
    Shooter
    Multi Format
    Posts
    1,620
    Try some super glue. I think you'll find its optical properties to be a bit better.
    Randy S.

    In girum imus nocte et consumimur igni.

    -----

    http://www.flickr.com/photos/randystankey/

  5. #5
    SMBooth's Avatar
    Join Date
    Jun 2008
    Location
    Melbourne, North/West
    Shooter
    Multi Format
    Posts
    964
    Images
    7
    Won't it also seep through the pinhole and create another lens on the back....

  6. #6
    Newt_on_Swings's Avatar
    Join Date
    Mar 2011
    Location
    NYC
    Shooter
    Multi Format
    Posts
    1,782
    This has been a bit tricky, well I tried super glue, but it was way too runny, the liquidity of it caused it to not form a high meniscus. The epoxy I am using is branded Duco Cement and it dries very clear.

    The problem is that when the droplets are drying they collapse and shrink down. I have had the most success with forming a bubble within the epoxy which acts as a support for the material to dry on and take shape. Also suspending it upside down helped it dry into a better shape as well.

    I have been trying to get some exposures indoors, and flashing a test subject with a strobe, and leaving it sitting on a chair for awhile but I am not getting anything close to usable. I think the focus is off. They are 5mm wide, and 2-2.5mm high, I think the correct terminology is plano convex for the lens shape. The box back/paper/film surface is 4cm away from pinhole.
    Click image for larger version. 

Name:	1.JPG 
Views:	57 
Size:	259.4 KB 
ID:	49451Click image for larger version. 

Name:	2.JPG 
Views:	71 
Size:	280.7 KB 
ID:	49452
    Sorry for the images I didnt want to setup the macro lens and tube for these 2 shots. I'll have to try in daylight tomorrow if I have time.

  7. #7
    Worker 11811's Avatar
    Join Date
    Jan 2010
    Location
    Pennsylvania, USA
    Shooter
    Multi Format
    Posts
    1,620
    The reason I mentioned Super Glue is because it was invented by Eastman Kodak as a material to make optical gun sights but the stuff was too sticky to be useful.

    When one of the scientists working on the project accidentally glued a set of refractometer prisms together, trashing several thousand dollars worth of lab equipment, they decided to abandon the project and, subsequently, they decided to market the stuff as "Kodak #910" because it took them 910 tries to perfect it before they gave up and repurposed the stuff.

    Sorry, I didn't think about how runny Super Glue might be. I was only thinking of the optical qualities.

    Regardless of the glue that's used, cyanoacrylate or otherwise, what do you think about building it up in thin layers to get the shape and thickness you want?
    Randy S.

    In girum imus nocte et consumimur igni.

    -----

    http://www.flickr.com/photos/randystankey/

  8. #8
    paul_c5x4's Avatar
    Join Date
    Apr 2009
    Location
    Ye Olde England
    Shooter
    Large Format
    Posts
    1,415
    Images
    23
    Superglue (or cyanoacrylate adhesive) comes in a variety of types depending on it's intended use. Some are water thin and good for seeping in to thin joints that have already been assembled. Other grades are viscous with good gap filling properties. For forming a lens, I'd suggest one of the thicker grades to produce a droplet.

  9. #9
    Newt_on_Swings's Avatar
    Join Date
    Mar 2011
    Location
    NYC
    Shooter
    Multi Format
    Posts
    1,782
    I will have to check for different brands of superglue next time I'm in the store. I did get to play around with the camera and lenses today at around the same time and lighting conditions.

    The lenses that dried to the bubble shape did work. I had to go back with a needle and pierce the hole again as a tiny film of glue covered it. So I had to be careful to not pierce the lens when doing it.

    The results? Well not amazing lol. I have used the same size pinhole for all of them, using the same needle. The standard pinhole image fills a 5x7 image area almost fully. The one with my bubble epoxy lens, makes an image circle a little smaller than half that size. All are kinda fuzzy, I think thats more me than the hole, or lens, as the box is a cardboard chocolate box, with a film canister cap for a lens.

    I will upload images after dinner. I kinda messed up the contact prints. I did them rushed and wet with a quick wash of the original negative image and using water to hold them together and squeegeed them flat. I have a piece of glass somewhere, but it wasn't in the darkroom.

  10. #10
    Newt_on_Swings's Avatar
    Join Date
    Mar 2011
    Location
    NYC
    Shooter
    Multi Format
    Posts
    1,782
    Here are the results:
    1st Standard Pinhole for baseline.
    Click image for larger version. 

Name:	pinhole resized .jpg 
Views:	81 
Size:	103.6 KB 
ID:	49486
    2nd Close up Performance with Epoxy Lens
    Click image for larger version. 

Name:	pinhole 2 resized.jpg 
Views:	80 
Size:	199.9 KB 
ID:	49487
    3rd Subject at Infinity with Epoxy Lens
    Click image for larger version. 

Name:	pinhole 3 resized.jpg 
Views:	79 
Size:	188.1 KB 
ID:	49488

    As you can see there is a fair amount of softness. There are probably a bit to many variables to really say whats causing it, the stability of the box, the edges of the pinhole, the size and curvature of the epoxy bubble, the light transmission properties of the epoxy, and user induced movement when opening can closing the lens cover. All I can say for sure is that the epoxy lens makes a smaller image circle within a similarly sized box than a standard pinhole.

    I think it was a interesting experiment, and future experimentation should be looked at though different materials such a other brands of clear epoxy or superglue.

Page 1 of 3 123 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Contact Us  |  Support Us!  |  Advertise  |  Site Terms  |  Archive  —   Search  |  Mobile Device Access  |  RSS  |  Facebook  |  Linkedin