Apparent V absolute magnification

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Cyclops
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Apparent V absolute magnification

Post by Cyclops »

Here's the thing. When for example I set my scope up to 40x and look thru the eyepiece I see a large circle with my image within and everything magnified to 40 diameters,to use old terminology(i love that use of diameters!) But then I decide to get a photo and all I have available is my cell phone which takes a mean pic! Only thing is I get a much smaller circle surrounde by black and have to zoom in some to get a good size circle,or zoom in further to get a full borderless image. So the question is is the image I see before zooming still 40x and by zooming I'm increasing the mag. or is zooming bringing it closer to 40x?
Canon 5D and 30D | Canon IXUS 265HS | Cosina 100mm f3.5 macro | EF 75-300 f4.5-5.6 USM III | EF 50 f1.8 II | Slik 88 tripod | Apex Practicioner monocular microscope

Cyclops
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Post by Cyclops »

Here's a couple of examples of images as seen on the phone's screen

Image

Image
Canon 5D and 30D | Canon IXUS 265HS | Cosina 100mm f3.5 macro | EF 75-300 f4.5-5.6 USM III | EF 50 f1.8 II | Slik 88 tripod | Apex Practicioner monocular microscope

rjlittlefield
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Post by rjlittlefield »

I don't think your question has a simple answer. It might be "yes", "no", or "maybe", depending on exactly what you mean.

So let's talk about what that phrase "40x" really means.

On your scope, "40x" means that the optics change the angles of the light so that a subject spans a 40 times larger angle when viewed through the ocular, than it would if you looked at it with your naked eye at 10 inches viewing distance. In other words, it appears to be 40 times larger, even though there's no real image where you could measure that number.

On a print, "40x" means that the image of the subject really is 40 times larger than the real subject. The field diameter of that scope is probably around 4 mm, so a "40x" print would mean printing the circle at 4 x 40 = 160 mm diameter.

What "40x" means with a digital camera is subject to a wide range of interpretations. The actual sensor in your cell phone may be only 4 mm wide, so imaging the entire scope field at maximum size without vignetting would be only 1x on the sensor! Yet the pixels on the sensor may be so small that it can capture all the detail the scope can provide, allowing you to make that honest-to-goodness 40x print, at 160 mm diameter, and still have it look good. In fact, the pixels on some sensors (probably not the one in your cell phone) may be so small that they can capture all that detail in an even smaller area, still allowing you to blow up the circle to 160 mm and see all the detail that the scope provided.

Bottom line, you'll have to decide how you want to think about "40x".

Absent any other information, I generally interpret "40x" as meaning "This is about what you would see through a microscope at 40x." If the image is printed, that means it has to be at least 40x life size, proportionally more if say it's a poster or billboard that I'm supposed to view at a distance. If the image comes through an ocular, for example via those cute little TV goggles, then the subject has to appear 40 times larger, same rule as in a microscope.

Does this help?

--Rik

Cyclops
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Post by Cyclops »

Err thanks Rik,i think lol
You lost me on the print bit but i get the gist. Basicaly 40x in my scope(10x eyepiece/4x objective) means nothing really whether its viewed with the naked eye or a sensor.
Canon 5D and 30D | Canon IXUS 265HS | Cosina 100mm f3.5 macro | EF 75-300 f4.5-5.6 USM III | EF 50 f1.8 II | Slik 88 tripod | Apex Practicioner monocular microscope

rjlittlefield
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Post by rjlittlefield »

Cyclops, it's a lot of words, I know, I'm sorry. Sometimes that happens when I try to be careful and precise. Try picking it apart a few words at a time.

"...means nothing really..."

I think it means something very important: how small detail you can see.

Most microscopes these days will show you an image that looks sharp. In that case, "40x" means that you can see detail that is 40 times smaller than just by eye, without the scope.

If something in the photographic process degrades the image so that you can't see such fine detail, then you get what's called "empty magnification" -- the subject may look 40 times bigger, but maybe it's so fuzzy that you could see the same detail at only 10 times bigger.

--Rik

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