On 10/13/2020 7:57 AM, Wayne Shumaker wrote:
At 10/12/2020 09:41 PM, Moose wrote:
On 10/8/2020 4:42 PM, Ken Norton wrote:
This is by focal length shortening and thus reduction in working distance--not
always conducive to chasing critters but results in less light loss than
extension.
There is, of course, one other method and that's to use a diopter on
the lens. That can be through the use of a designed-for-macro-use
diopter,
Jim knows about that, although we haven't seen anything from his 135 Takumar with
Olympus IS/L Lens A-Macro H. Q. Converter f=40cm dia. 49mm for a while.
This is far my preferred method. So light, so quick, so easy, no lens changing
and lens/tube/body juggling - and excellent results.
In a place like a botanic garden, I may be found palming one, on magnetic
filter holder, and popping it on and off.
The problems are two:
Not all AC-U lenses work well with all lenses. And there's no way to tell but
trial and error, other than copying Moose. ;-)
The selection is not ideal. Many of these lenses are discontinued, and some are
hard to find. The Pentax 67 T132 is so important to me that I had a watch on
the 'Bay for ages before snagging a back up.
( There is an apparent difference between older and newer AC-U lenses. the older ones seem to
generally have stronger curvatures. The diopter is simply the difference between front and read
"powers". My suspicion is that most older ones are designed to minimize reflections
between AC-U and main lens. Later ones have MUCH better coatings, and flatter curves. Oly's latest,
for smaller µ4/3 lenses is a bit like looking into a black hole.)
or a reversed 50/1.4 sitting on the front of another lens.
Optically a fine option, practically, a big, unnecessary pain.
Getting Closer Moose
As you say, highly unlikely to come across a Pentax T132 (+0.76 d) or the T226
(+0.44 d).
I have the Sigma AML72-01 (+1.74 d) and is too much diopter for my use. The
less than +1.0 achromatic diopters seem to be rare indeed. Price usually puts
them out of practicality also.
I found this list of achromatic close-up lenses:
http://fuzzcraft.com/achromats.html
I have, or have used, a significant subset of these:
Brand Model Diopter Thread
Olympus MCON-P02 ~+3.6 46 & 37
Olympus iS/L Lens A-Macro H.Q. Converter f=40cm. 2.50 49
Olympus iS/L Lens A-Life Size Macro H.Q. Converter f=13cm. 7.70 55
Olympus iS/L Lens B-Macro H.Q. Converter f=40cm. 2.50 55
Olympus Close-up Lens 80mm Macro f=170mm 5.90 49
Nikon 3T 1.50 52
Nikon 5T 1.50 62
Nikon 6T 2.90 62
Canon 500D 2.00 72
Minolta No. 0 0.90 55
Minolta No. 1 2.00 55
Minolta No. 2 3.80 55
B&W 67E NL 0,5 0.50 57
Pentax T132 0.76 67
Pentax T226 0.44 67
Sigma Achromatic Macro Lens AML 72-01 1.74 72
I returned the Canon 500D when testing showed it didn't resolve as well on the PLeica 100-400 @ 400mm as the Pentax
T132. Whether downsampling the Canon or upsampling the Canon to the same size, the Pentax was better.
The B&W was an experiment to see if, at very low diopters a single element lens
might work - no.
>From this list there is also a Minolta close-up lens (+0.33 d) 72mm thread.
One on echBay for only $500.
Having tried the various AC-U lenses on various primary lenses, I think I can safely say that there is a fairly narrow
range of really useful diopter for each primary lens/FL.
One factor how close the primary lens focuses on its own. For the PL 100-400, 0.44 diopter is so weak that it adds
nothing to using the lens alone. On an old MF lens with poor minimum close focus, it might be of value. This means the
expensive 0.33 diopter lens is not a good choice for the 100-400.
OTOH, as you point out, Sigma AML72-01 (+1.74 d) is too much diopter, and perhaps not as well matched for optical
performance as the T132. Using it side by side with the T132, I found
the shorter working distance problematic for bugs, and had trouble getting good
shots.
For shorter focal length lenses, smaller filter thread and higher diopter,
there are more options. Perhaps the Minolta No. 0 (+0.94 d) (52mm) only $30 on
the 'Bay.
The Minolta no. 0 works well on a Panny ZS200, using the Lensmate adapter to
get a filter thread.
The Nikon 5T is perfect on the PLeica 12-60; 6T is too strong. The PL has quite
good close focus on its own.
Years ago I experimented with the OM 180/2 with extension and 1.4X
teleconverter with somewhat OK results. The faster 180/2 lens helped with that
combination. Working distance was great.
Working distance is sacrificed with the diopter option. I only try using the
close-up filter option for static subjects, while working distance is more
valuable for me in the field.
Mileages vary . . . Of course I'm using the semi-unobtanium T132, but I use it extensively in the field. As Jim has
confirmed, magnetic filter holders are an integral part of the package for field use.
BTW, working distance at infinity primary lens focus of an AC-U lens is its focal length - from the front of it. So add
distance from front of lens to focal plane to that, to compare to other options.
For now I use my Zony zoom lens at 0.35x or PL 100-400 at 0.25x. The Olympus
50-200mm f/2.8-3.5 ED SWD has 0.21x and worked good with the E-1:
These are not comparable numbers. Shoot a US quarter, 24 mm diameter with a .35x lens on FF and again with a .25x lens
on 4/3 sensor. Print the full frames on 8x10. The FF quarter is 2.8" in diameter, the 4/3 is 3.7"
It gets weirder, when Mega-Pickles are considered. Testing the OM 600/5.6, I found that the pixel dimensions of the
target on 24 MP FF were almost identical to those of a shot @ 400 mm on 20 MP µ4/3. The interaction of different
physical and MP dimensions of the sensors and of actual, vs. nominal, FLs of the lenses made them in effect equivalent.
Relative Sizes Moose
--
What if the Hokey Pokey *IS* what it's all about?
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