| Author |
 Replies: 13 / Views: 2,050 |
|
|
Pillar of the Community
United States
4038 Posts |
I just got a new piece of old glass in the mail Saturday and threw it on the bellows. Here is what I get. First image is a full-sensor shot at around 4-5x, downsized 4x. Second image is a 1600x1600 crop from the first image, downsized 2x.   This is the best I've been able to achieve at 4x so far. Anyone care to guess what the "new piece of old glass" is? |
|
|
|
Moderator
United States
56855 Posts |
No clue. Those pics are WOW,color me jealous  John1  |
|
Pillar of the Community
United States
627 Posts |
The images and the magnification are stunning! I have no idea on the lens, but I am excited to find out! Maybe a 28mm lens with an f of 2.8 or faster? Just a (not-so-educated) guess.  |
|
Pillar of the Community
United States
1745 Posts |
All I know is "those pictures are crazy good"!!
|
|
Pillar of the Community
United States
1374 Posts |
What kind of set up you got going there, rmps?
|
|
Bedrock of the Community
United States
10045 Posts |
Nice shots, as always!  |
|
Pillar of the Community
 United States
4038 Posts |
This was taken with my standard setup, but instead of the 75ARD1 I used a Nikon CF Plan 4x 0.13 objective. I also used a new Director I built just for the purpose, with a tiny tip that fits nicely between the coin and objective even though there is only 14mm working distance...Ray
Contact me for photographic equipment or visit my home page at: http://macrocoins.com |
|
Pillar of the Community
United States
3076 Posts |
Very very nice Ray, and as always your research on lighting really shines!  I was going to guess the missing E86 lenses your collecting...G |
|
Pillar of the Community
United States
627 Posts |
Quote:
Nikon CF Plan 4x 0.13 objective Care to expand on what this is and what all of the "jargon" means? |
|
Pillar of the Community
United States
4038 Posts |
Sorry, I love acronyms and jargon...
This is a microscope objective. Basically I attached a microscope objective to the bellows and made a mini-microscope out of it.
CF = Color Free, ie requires no color correction from the rest of optical system
4x is the optimized magnification
0.13 is the NA or Numerical Aperture. You can convert to effective aperture by calculating Feff = M/2*NA. So the effective aperture of this beast is f15, which is not bad at 4x. You can convert back to infinity aperture to compare to a normal lens by calculating Finf=Feff/(1+M) or Fin=3 for this lens.
|
|
Pillar of the Community
United States
3076 Posts |
some times MATH has its virtue, and to many its out of this world LOL......I need to travel space...  |
|
Pillar of the Community
United States
627 Posts |
Ray, thanks for the detailed information -- I love jargon too, and I even love formulas more! Now, care to explain any of the details about how one attaches such a "lens" to a bellows? Are there standard threads for such lenses and/or adapters? Is this in the pricing ball park of a Printing Nikkor or an EL-Nikkor 80mm?  -- or somewhere in between? |
|
Pillar of the Community
United States
4038 Posts |
Most of these objectives are "RMS" thread, which is 20mm in diameter. You can get RMS adapters to fit onto M42 bellows that are either flat or tapered (which are really cool looking) and you can also get RMS to 52mm reversing adapters for objectives that are "infinity" corrected (another discussion entirely). A lot of optical systems used RMS, and in fact the smaller Nikon Macro-Nikkors used RMS threads. So it's not terribly difficult to adapt, and if you have M42 bellows you are in great shape. The gold standard for 4x objectives is the Nikon Plan Apo 4x 0.2. These will cost you at least $1k if you can find one. The one I bought is not an Apo and only has NA 0.13, but still does pretty well. I bought it on ebay for $125. I have a few "run of the mill" 4x 0.1 objectives in the mail to test. I am not sure if they will give that great a result since their Feff=20, but they were cheap and I wanted to find out how good an image they can produce. Contact me for photographic equipment or visit my home page at: http://macrocoins.com |
|
Pillar of the Community
United States
627 Posts |
Very cool. The first thing I noticed on your image was that it was ridiculously sharp and the DOF was immense for that magnification. I figured possibly a 28 f/2.8 lens, as you'd be able to get to 4x and if you left it wide open you'd be shooting at Feff = 2.8(4+1) = f/15. Nonetheless, this is a whole new world of lenses for super-mag coin images. I love reading your posts! Thanks for all the info!
-Brandon
|
| |
Replies: 13 / Views: 2,050 |
|
Posted 02/13/2012 11:03 am
