Search found 273 matches

by mgoodm3
Tue Mar 26, 2013 2:57 pm
Forum: Equipment Discussions
Topic: Zoom Tube Lens for Numismatic Photography
Replies: 26
Views: 3780

I have also had no luck with much of anything under 2:1 mag with stacked lenses - vignetting also.

edit:

Why don't you just reverse a standard zoom lens? As long as you use an FD lens with an aperture ring, it will give you a magnification range in the area that you are looking.
by mgoodm3
Tue Mar 26, 2013 2:55 pm
Forum: Equipment Discussions
Topic: Zoom Tube Lens for Numismatic Photography
Replies: 26
Views: 3780

I haven't found zoom lenses to work well when stacked. USing an internal focus lens as you tube lens will work since they change their focal length with the focus ring. My 200/4 micro goes from about 200 to 100 mm from near to far focus and will give about a 2:1 magnification range. Anything shorter...
by mgoodm3
Sun Jul 29, 2012 1:43 pm
Forum: Equipment Discussions
Topic: Cheap way to photograph coins
Replies: 5
Views: 2284

Ray summed up things pretty well. I would tend to rank the cameras: barely OK - USB microscope (OK for close-ups of coin parts, not so good for a whole coin) adequate - compact camera best - SLR with macro lens I wrote an article on basic coin photography a few years back (I also have written a book...
by mgoodm3
Fri Feb 10, 2012 1:43 pm
Forum: Equipment Discussions
Topic: Useful Life for a Camera Body
Replies: 13
Views: 2556

I hvae about 10k on my D300 and no problems.
I have a D200 and the aperture control went out at about 60k. Go that fixed and still going strong at around 75k for the shutter.
by mgoodm3
Mon Dec 26, 2011 10:28 am
Forum: Macro and Micro Technique and Technical Discussions
Topic: idea to fight the diffraction?
Replies: 4
Views: 1618

Another problem with shoot images at a lower magnification than an objective is designed is that you may start to vignette the entrance pupil. With most high magnification objectives, you can only see the whole entrance pupil when you get very close to the objective (about the working distance). whe...
by mgoodm3
Thu Oct 27, 2011 10:09 am
Forum: Macro and Micro Technique and Technical Discussions
Topic: Does it really worth reversing enlarger lenses ?
Replies: 4
Views: 2443

my own experience with rev vs. normal mounting for enlarging lenses comes down mainly to focal length. Longer focal length, say 75 mm and above don't work any better reversed, and may work better normally mounted. 50 mm and below tend to work better reversed. The shorter the focal length the more im...
by mgoodm3
Wed Oct 05, 2011 5:52 pm
Forum: Equipment Discussions
Topic: Long CA effect on apparent color
Replies: 9
Views: 1461

I can certainly agree that long CA can affect the color seen on highlights and edges. In more complex areas you will probably see a little too much of the color in the fringe. In homogeneous areas it should all even out. I will also depend upon how much depth you have in the image. A stacked image w...
by mgoodm3
Sat Sep 17, 2011 9:16 am
Forum: Equipment Discussions
Topic: Silver componon 80mm F/5.6
Replies: 16
Views: 3792

I have an older schneider 80. Performs very well and a lot smaller than you would think.
by mgoodm3
Wed Aug 31, 2011 3:04 pm
Forum: Equipment Discussions
Topic: Pupil ratio of Sigma 150mm macro lens.
Replies: 3
Views: 1602

Another thing to think about:

The numbers that Sigma gave you are probably referred to infinity focus.

Since the 150 is an internal focus lens and the planes and pupils will move when the lens is focused closer. The pupillary magnification will probably change.
by mgoodm3
Wed Aug 31, 2011 7:51 am
Forum: Equipment Discussions
Topic: Canon TS-E 90 f/2.8
Replies: 16
Views: 4720

Tilt: tilts the focus plane. I use a Nikon 85 PC micro for my coin photography because it allows me to tilt the coin into the light while keeping everything in sharp focus. DOF is the same as always although the tilted focus plane makes the depth of field a cone shape (closer portions of the focus p...
by mgoodm3
Mon Aug 29, 2011 7:54 am
Forum: Equipment Discussions
Topic: Apochromatic and achromatic at the same time?
Replies: 3
Views: 1135

A second thought: most lenses that are called APO are not true APO's. It's an overused/misused term.
by mgoodm3
Sun Aug 28, 2011 5:10 pm
Forum: Equipment Discussions
Topic: Apochromatic and achromatic at the same time?
Replies: 3
Views: 1135

My own reading on the subject suggests that achromatic/apochromatic correction mainly deals with longitudinal CA (focal length variation with wavelength). Lateral CA (magnification difference with wavelength) is a different problem and requires a different process to correct. Achromatic is corrected...
by mgoodm3
Sun Aug 28, 2011 9:17 am
Forum: Equipment Discussions
Topic: Pupil ratio of Sigma 150mm macro lens.
Replies: 3
Views: 1602

If you know the position of the principal planes and the pupils, you can figure out the pupillary ratio. I think that the numbers are measured from the back focal point, the detector. The rear principal plane is at 146.5 - i.e. the focal length of the lens. The front principal plane is at 127.5 - th...
by mgoodm3
Wed Jul 20, 2011 9:16 am
Forum: Equipment Discussions
Topic: Optical test patterns
Replies: 1
Views: 646

I use one of their small chrome on glass patterns for all of my testing.
by mgoodm3
Thu Jul 14, 2011 10:52 am
Forum: Macro and Micro Technique and Technical Discussions
Topic: If I use flash, Is everything perfect?
Replies: 20
Views: 5194

So basically you can fire the shutter, wait for the vibration to die down, fire the flash, wait a second or two and close the shutter. Helping to decrease the shutter vibration in the image...

I can see where that would be helpful at very high mag.