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Thread: +10+3 and +4+10

  1. #11

    +10+3 and +4+10

    Man, that church has a lot of windows...must be very 'enlightened'.
    (yak, yak, yak)

    My first thought was holy cow, that's a lot of diopters!

    I don't know much at all about it but I wonder if all those curves have anything to do with a Petzval sum out in left field, with out of control field curvature...I don't know if symmetry alone addresses the high diopter factor.

    Nice experiment anyway.

    Lotsa surfaces (uncoated?) too as you noted...where's yo' lens hood?

    Probably not easy. but maybe "available spacing" needs experimentation too (but that'll change the f.l.).

    See hyperphysics site in Georgia, Gullstrand's Equation calculations (interactive calculator) to keep you from imploding your spacing (you'll see weird stuff happens with significant spacing).

    Whoaw, wait a minute...I thought you were doing PAIRS of these high diopter combos, that's what I was freakin' out about.

    I think you still need more spacing between the aperture and glass...1/5 - 1/7 of net f.l.in front of asymmetric lens (glass all on one side)

    Again, mechanically awkward,,,but two identical cells either side of stop may help the distortion

  2. #12
    500+ Posts Daryl's Avatar
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    +10+3 and +4+10

    Quote Originally Posted by Math Murray

    ..... anything to do with a Petzval sum out in left field........ high diopter factor.

    Nice experiment anyway.
    ........
    .........
    I think you still need more spacing between the aperture and glass...1/5 - 1/7 of net f.l.in front of asymmetric lens (glass all on one side)
    A agree with what I understood of all that.
    I'd like to get another identical set and try symmetrical pairs about the aperture, but coming up with some cheap and easy way to make sure they are centered is a problem. Something like a Copal Press shutter off of an old Polaroid threaded for stip-up rings.

  3. #13

    +10+3 and +4+10

    How about a block of wood drilled thru with a spade bit...OK, front & back may not be precisely parallel...

  4. #14

    +10+3 and +4+10

    Daryl, thanks for continuing with this journey, it's been very informative.

    I've had a similar problem of seeing the bed in the bottom of my images when using a plastic fresnel lens (credit card sized) magnifier as a camera lens on my Speed Graphic. It was wide angle enough to see the bed. I operated that rig stopped down to F/13 (i.e. a 1/4" wide hole.)

    What I like about your results is the sharpness of the image. The images from my plastic fresnel lens were 'interesting' to say the least.

    I'm thinking outloud here: you need to craft a sliding box tailboard camera, so you can attach experimental optics to the front and still have a functional variable focal length, without a drop-down bed getting in the way. See this link for just such an example from the George Eastman House online museum.

    ~Joe

  5. #15
    500+ Posts Daryl's Avatar
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    +10+3 and +4+10

    Laziness pays off.
    Check out my 17 Diopter thread - no hot spot.

    No Hot Spot!

    So, I was scratching my head over this and reviewed all my wide angle posts and noticed that I was using the 8banners shutter to hold laser drilled holes for my smaller apertures.

    DOH!

    The laser drilled holes are rather dull...... Attached files

  6. #16
    500+ Posts Daryl's Avatar
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    +10+3 and +4+10

    but they are so flat that the reflectance of perpendicular rays of light skyrockets and this particular set of close-up filters are close to being plano-convex.

    Attached files

  7. #17

    +10+3 and +4+10

    Wow , thats what I was dreaming . But only a dream which i do not know the way for accomplish. Shots are very good but i thought that what was the real lens , pinhole or glass ?
    I saw some pinhole + glass pictures at forums and it was also very good.
    What happens if you shoot with very big hole ? By this way , we could see the success of the glass design , am i wrong ?


    Umut

  8. #18

    +10+3 and +4+10

    See other similar postings by Daryl - he did this.

    Wide aperture is really going to reveal aberrations which is part of the fun here.

    They are simply close-up lenses, used not as intended, without a prime lens (probably design violation #1), assembled within the mechanical limitations of available mounting (violation #2).

    So I would lean toward calling this optical sculpture or optical alchemy (not sure if there's any lead in that glass). I mean that in a good way.

  9. #19
    500+ Posts Daryl's Avatar
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    +10+3 and +4+10

    Hi Mustafa!

    check out
    http://www.f295.org/DIYforum/cgi-bin/forum/Blah.pl?b-len/m-1186889463/
    http://www.f295.org/DIYforum/cgi-bin/forum/Blah.pl?b-bw/m-1185656643/
    and
    http://www.f295.org/DIYforum/cgi-bin/forum/Blah.pl?b-bw/m-1185656915/

    This kind of set up gives quite a desireable look and it is all primitive lenses.
    No achromat, no anistigmat - just simple positive miniscus

    Daryl

  10. #20

    +10+3 and +4+10

    Excellent , as Weston used a mexican made lens , someone can make miracles with these lenses.
    I believe every lens has some characters and it makes you successful if you walk with it. Portrait suggestion is correct .It would be lovely to use rolls of films and investigate the better sides of your lenses and my new lenses .
    I am collecting money to build luigi colani sailing yacht copy - very very small copy - and i want to see the thunders , strikes , shades of blue , black , grey , feel the wind ,rain , water .
    I watched a television program about a guy who have ocean kayaks and mountain equipment and travel my country. He saw some quite hippie , quite syhsophrene man at the sea cost of antalya at winter time and he followed him.
    Hippie man said i m seeing everything with my eyes and no need to record it.!
    My intention is to live in a photograph. I hope I one day see the ocean like Behrengis Little Black Fish. They call this storm chasing wow , what a wonderful hobby !

    Umut

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