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04/19/2005 03:33:35 PM · #1 |
| Does anyone know for sure if the 100mm 2.8 canon macro is 1X life size or 1.6X life size on the 20D. does the 1.6x play a part? |
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04/19/2005 03:41:20 PM · #2 |
The lens is designed for a 35mm frame and your camera sensor is a subset of that frame size. The image scale remains the same but your sensor sees only the center portion of the image. You will enlarge a smaller portion of the macro image to whatever size you like. In the case of the 20D your sensor is smaller by a factor of 0.625 (1.6X multiplier).
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04/19/2005 03:43:54 PM · #3 |
| yep...and seriously, I never really realized how much that 1.6was compared to FF, I went from a 300D to a 1DsMkII and my wider angle lenses (16-35 and 14) are now so wide that I just can't use them due to the image distortion. |
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04/19/2005 04:05:18 PM · #4 |
A 1:1 Macro shot was originally defined as one where the image as reproduced on film is life-size. IN other words, shoot a dollar bill at 1:1, process the film, and you can overlay the part reproduced onto the bill with perfect alignment.
Now, a lens that's capable of producing 1:1 is always capable of it; the only question is, how wide is the angle of view? So depending on the sensor in your camera, you are effectively cropping more or less of the center of the subject from the "finished image" in camera, but the actual size of the elements common to both pictures is identical.
Does this make sense? It's like, with 4x5 film I can shoot nearly the whole bill at 1:1 with lens "x", and George is centered in the film. Now I slip a piece of 2 1/4 film onto the film plane, and I see a LOT less of the bill, but George's face is still the same size. And by the time I get down to the smaller CCDs like my prosumer uses, I might not even see all of George's face at 1:1, the "crop" is so extreme. So the same lens that gave me a "wide" angle macro on 4x5 film is a "normal" angle macro on 2 1/4 film, a slight telephoto macro on 35mm film, and a true telephoto on a small CCD, practically speaking.
When you're doing macro work, there's nothing "magic" about 1:1 reproduction, precisely because of the above. You can't shoot an object bigger than your sensor at 1:1, regardless of how capable the lens is. And contrariwise, shooting objects significantly SMALLER than your sensor requires either a lot of cropping or an extension tube set so you can go from 1:1 to 2:1 or even 4:1; which, of course, is beginning to approach MICROphotography.
That 1.6:1 ratio mentioned earlier is the conversion factor that shows the 35mm equivalent of a lens fitted down to your smaller-than-35mm sensor; a 100mm lens on a 1.6:1 digicam is the equivalent of mounting a 160mm lens on a 35mm camera, as far as angle of coverage goes.
Robt.
Message edited by author 2005-04-19 16:06:09.
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04/19/2005 04:07:36 PM · #5 |
Thank you.
Originally posted by bear_music:
A 1:1 Macro shot was originally defined as one where the image as reproduced on film is life-size. IN other words, shoot a dollar bill at 1:1, process the film, and you can overlay the part reproduced onto the bill with perfect alignment.
Now, a lens that's capable of producing 1:1 is always capable of it; the only question is, how wide is the angle of view? So depending on the sensor in your camera, you are effectively cropping more or less of the center of the subject from the "finished image" in camera, but the actual size of the elements common to both pictures is identical.
Does this make sense? It's like, with 4x5 film I can shoot nearly the whole bill at 1:1 with lens "x", and George is centered in the film. Now I slip a piece of 2 1/4 film onto the film plane, and I see a LOT less of the bill, but George's face is still the same size. And by the time I get down to the smaller CCDs like my prosumer uses, I might not even see all of George's face at 1:1, the "crop" is so extreme. So the same lens that gave me a "wide" angle macro on 4x5 film is a "normal" angle macro on 2 1/4 film, a slight telephoto macro on 35mm film, and a true telephoto on a small CCD, practically speaking.
When you're doing macro work, there's nothing "magic" about 1:1 reproduction, precisely because of the above. You can't shoot an object bigger than your sensor at 1:1, regardless of how capable the lens is. And contrariwise, shooting objects significantly SMALLER than your sensor requires either a lot of cropping or an extension tube set so you can go from 1:1 to 2:1 or even 4:1; which, of course, is beginning to approach MICROphotography.
That 1.6:1 ratio mentioned earlier is the conversion factor that shows the 35mm equivalent of a lens fitted down to your smaller-than-35mm sensor; a 100mm lens on a 1.6:1 digicam is the equivalent of mounting a 160mm lens on a 35mm camera, as far as angle of coverage goes.
Robt. |
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04/19/2005 04:21:18 PM · #6 |
Originally posted by bear_music:
That 1.6:1 ratio mentioned earlier is the conversion factor that shows the 35mm equivalent of a lens fitted down to your smaller-than-35mm sensor; a 100mm lens on a 1.6:1 digicam is the equivalent of mounting a 160mm lens on a 35mm camera, as far as angle of coverage goes.
Robt. |
But ultimately, I think the only thing the average macro shooter really cares about when evaluating lenses is "how big is the image going to be."
I think the relegation of the 1.6 issue to an afterthought in discussing macro lenses is a mistake. The simple fact is that an image taken with the same lens, say 100mm macro, will produce an effectively closer macro image than the same lens on a 35mm film camera. Discussion of how the lifesize factor has not changed, to me, is secondary to this fact and is also somewhat misleading. The 1.6 digital crop is relevant and affects the captured image (just like it does for any other lens).
Just my 2 cents.
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04/19/2005 04:33:18 PM · #7 |
Originally posted by bledford:
Originally posted by bear_music:
That 1.6:1 ratio mentioned earlier is the conversion factor that shows the 35mm equivalent of a lens fitted down to your smaller-than-35mm sensor; a 100mm lens on a 1.6:1 digicam is the equivalent of mounting a 160mm lens on a 35mm camera, as far as angle of coverage goes.
Robt. |
But ultimately, I think the only thing the average macro shooter really cares about when evaluating lenses is "how big is the image going to be."
I think the relegation of the 1.6 issue to an afterthought in discussing macro lenses is a mistake. The simple fact is that an image taken with the same lens, say 100mm macro, will produce an effectively closer macro image than the same lens on a 35mm film camera. Discussion of how the lifesize factor has not changed, to me, is secondary to this fact and is also somewhat misleading. The 1.6 digital crop is relevant and affects the captured image (just like it does for any other lens).
Just my 2 cents. |
The original poster was expressing confusion between the two ratios. My answer was an attempt to clarify that they are entirely distinct things. The 1.6:1 ratio is a function of the SENSOR size, the 1:1 ratio is a measure of IMAGE size thrown.
I somewhat disagree with your conclusion re: "efefctively closer macro image", because if you use the same lens with a larger sensor (difference between a 300D, say, and a 1DS) then you get identical results by cropping the larger image down. Your camera position is the same: as close as the lens allows it to get. So your actual image size for the portion of the subject captured by both sensors is the same. If your larger sensor were to have a lower resolution than the smaller one, there'd be a difference, sure, but in reality the larger sensors give BETTER detail, so it does no harm in this case to use just the central portion of the captured image. Only up to a point, of course, but still...
Robt.
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04/19/2005 04:36:36 PM · #8 |
I agree and have previously posted that I thought the magnification factor was misleading in today's world of varying sensor size. A simple thought exercise to imagine shooting a macro at 1:1 with a 1Ds, a 20D, and a prosumer digicam. They all magnify at 1:1, but on th 1Ds an object 36mm long will fill the frame, on the 20D a 22mm object will do so and on the prosumer cam an object maybe 7mm long will fill the frame. That's a huge difference.
Nonethelss, the subject magnification is still an important thing to know if you want to do any calculations regarding actual size of the subject on a given print size, as well as other image-related calculations.
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04/19/2005 06:09:16 PM · #9 |
Originally posted by bear_music:
The original poster was expressing confusion between the two ratios. My answer was an attempt to clarify that they are entirely distinct things. The 1.6:1 ratio is a function of the SENSOR size, the 1:1 ratio is a measure of IMAGE size thrown.
I somewhat disagree with your conclusion re: "efefctively closer macro image", because if you use the same lens with a larger sensor (difference between a 300D, say, and a 1DS) then you get identical results by cropping the larger image down. Your camera position is the same: as close as the lens allows it to get. So your actual image size for the portion of the subject captured by both sensors is the same. If your larger sensor were to have a lower resolution than the smaller one, there'd be a difference, sure, but in reality the larger sensors give BETTER detail, so it does no harm in this case to use just the central portion of the captured image. Only up to a point, of course, but still...
Robt. |
I don't see how the discussion of other format cameras with varying sizes of sensors or film helps the original poster understand what I believe to be his question...which I read as follows:
"Does putting a 100mm macro lens on my camera, a 1.6 crop factor digital, make a Norwegian fuzzy backed tangerine catepillar appear 1:1 (35mm equivalent) or 1.6:1 (35mm equivalent) when I view the darn JPG on my 'puter monitor"
I would answer 1.6. Am I wrong? Maybe that's not what he's asking. |
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04/19/2005 06:16:19 PM · #10 |
Nevermind. I think I get it now. 1:1 lifesize is really not a function of any resulting image size. It's merely a measure of the image circle being shown on the sensor of the camera. That sensor could be of any resolution or size, which affects the resulting image size/resolution, without changing the 1:1-ness of the lens.
Yumm, took my medicine and I feel better. |
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