Do you remember Poinsettia?

[MacroLuv]

It is a plant which photos I've posted about four months ago. Poinsettia is also known as Christmas star. Here are two photographs of the very same plant (still in excellent condition) but captured with Canon and much closer.
Some technical data:
#1 photo - handheld, built in flash, (Canon Extension Tube EF25 II) + (Canon EF 85mm f/1.8 USM) + (Misumi +3 Diopter) - (possible max. magnification 0.13 + 0.29 + 0.33 = 0.75×)
#2 photo - handheld, built in flash, (Canon Extension Tube EF25 II) + (Canon EF 85mm f/1.8 USM) + (Misumi +10 Diopter) - (possible max. magnification 0.13 + 0.29 + 1.1 = 1.52×)
Did I calculate it right?
By the way, no cropping.



Model Canon EOS 400D DIGITAL
Date/time original 05.04.2007 15:48:27
Shutter speed value 1/1 s
Aperture value f/20
ISO speed ratings ISO 200
Focal length 85 mm



Model Canon EOS 400D DIGITAL
Date/time original 05.04.2007 15:55:06
Shutter speed value 1/1 s
Aperture value f/20
ISO speed ratings ISO 200
Focal length 85 mm

[beetleman]

Excellent pictures Nikola...and I must add that you are taking excellent care of the plant also. Usually they end up in the garbage can.

[Cyclops]

Excellent photos! By the look of it i'd say your magnification is quite a bit higher than you stated,they look really close as these true flowers are really small! I think the rules for calculating macro doesn't hold up for digital unless the sensor is 35mm sized.(24x36mm) I think with a smaller sensor (or smaller than 35mm film) the higher is the magnification for a given focal length as you need less extension to achieve lifesize. On a large format camera for example the equivalent of a 50mm lens might be as much as 250mm so you'd need a 250mm extension tube to get lifesize! Use that tube on a 35mm camera and you'd get 5x lifesize! (250/50)

[rjlittlefield]

Did I calculate it right?

Nikola, it's hard to predict exactly how these new asymmetric lenses respond to extension tubes and closeup lenses. I recommend to do less calculating and more measuring. You know how big your sensor is: 22.2 mm x 14.8 mm. Just photograph a ruler. If the photo shows 17 mm across the full frame, the lens magnification is then 22.2 / 17 = 1.3X.

But more important, you can tell us that "it's 17 mm across the image in the plane of focus". That's what most of us care about anyway. I don't even care if you crop -- that's like using a bit smaller sensor -- just tell me how big the subject is!

Cyclops, lens magnification does not depend on sensor size. But field of view and therefore total magnification does. Shoot 1:1 on 35mm film, you capture 36 mm x 24 mm at the subject. Do the same thing on 4"x5" film, you get 127 mm x 102 mm. On the Canon 400D, it's 22.2 mm x 14.8 mm. And on a Canon SD700 IS, it's only 5.76 mm x 4.29 mm. Display each of those at the same 8" = 200 mm wide on screen, and you'll have total magnification varying from less than 2X to more than 30X. The rules for calculating work just fine for digital. You just have to apply the real rules instead of the convenient shortcuts that people have worked out for 35 mm.

--Rik

[Cyclops]

But lets say you have a 14mm sensor,and you can remove the lens, then to get lifesize with extension tubes you would only need 14mm of extension. If you used the amount of extension you would use on a 35mm camera to get lifesize(50mm) you would get 50/14= 3.5X.

Its nothing to do with digital or film its to do with format sizes.

[rjlittlefield]

But lets say you have a 14mm sensor,and you can remove the lens, then to get lifesize with extension tubes you would only need 14mm of extension. If you used the amount of extension you would use on a 35mm camera to get lifesize(50mm) you would get 50/14= 3.5X.

Its nothing to do with digital or film its to do with format sizes.

I agree that digital vs film has nothing to do with it.

But I do not agree that "its to do with format sizes". Actually what you describe is to do with lens length. If the lens on that 14 mm sensor happens to be 50mm focal length, then adding 50mm extension will give 1X onto the sensor, same as using a 50mm lens in any other format size.

I think you're using the unstated assumption that lens length is roughly equal to the size of the film/sensor. Under that assumption, what you describe is correct.

But the assumption is certainly not true all the time. Examples include Sigma's 150 mm FL macro lens intended for formats of 35 mm and smaller, and Zeiss's 16mm Luminar macro lens intended for formats up to 4"x5" (on a long bellows). It's not even true for Nikola's current setup, using a lens with 85 mm focal length on a sensor whose size is only 22 x 15 mm.

--Rik

[Cyclops]

Oh bugger,I see my mistake! What I should have typed was if the lens on the digi was 14mm then one would only need 14mm of extension to get lifesize, which of course would not be enough to get even near half lifesize on a 35mm camera whose standard lens is 50mm.

and you say it doesnt depend on format but surely in a way it does! The standard lens on a 4x5 inch field camera is what 250mm? So you would need 250mm of extension.