[VisualDarkness]

ok I rest my case you photography geeks :P

It's the former natural science student that is itching inside, not the photographer

[pagu66]

What a response!
After reading all your answers, I think I will go for 50mm extension tube track, Ebay next stop!

The Link to Cambridge in Colour was great, thank BrianR!

Thanks /Patrik
Stockholm
Sweden

[vonBaloney]

Similar with macro - you get more magnification , despite the lens being 1:2 - you will get an equivalent of something around 1:1.5

No, NOT similar with macro. With discussing macro, magnification is magnification, no crop factors. (As others have been saying.) Macro photography is an area where the people that shoot it and talk about it have been able to do so without crop factor nonsense muddying the waters. Let's keep it that way. "Life-size" or "1:1" is a pretty easy concept to grasp, and it should be obvious it either is or isn't no matter the sensor size that is capturing it.

[manntax]

It's the former natural science student that is itching inside, not the photographer

Ok, that makes more sense now :P

No, NOT similar with macro. With discussing macro, magnification is magnification, no crop factors. (As others have been saying.) Macro photography is an area where the people that shoot it and talk about it have been able to do so without crop factor nonsense muddying the waters. Let's keep it that way. "Life-size" or "1:1" is a pretty easy concept to grasp, and it should be obvious it either is or isn't no matter the sensor size that is capturing it.

If I was going to explain to an inexperienced photographer how to doeal with macro and magnification I would rather stick to my simplified view , than go for *exact* science. Let's imagine we have an old film photographer who knows how to do macro on film. he wants to photograph an object let's say 35mm wide - exactly frame wide , for which he needs a lens that offers 1:1 magnification. But when he switched to APS-C digital, he suddenly realises that he needs to back a little , or change the lens, because object now at 1:1 macro lens setting is not fitting the frame - thus in his mind exceeding the 1:1 magnification ( although it is not obviously). This case for me clearly explains that macro magnification is also affected by sensor crop factor - in this case adding to focal length 50% , and so for simply minded photographer , similarly to easy to grasp the idea of equivalent focal lengths between APS-C and 35mm, it applies to macro magnifications.
If lens used had no helicoid and had fixed focusing point, it would not allow to photograph whole object 35mm wide on an APS-C sensor , because of (one saying it ) the sensor is cropping the externals of frame, or (another way saying it ) sensor is adding 50% of magnification making object appears larger in the frame than the photographer used to 35mm film frames , would expect.

Anyway at least this is how I simplify things on the subject

[vonBaloney]

Ok, that makes more sense now :P



If I was going to explain to an inexperienced photographer how to doeal with macro and magnification I would rather stick to my simplified view , than go for *exact* science. Let's imagine we have an old film photographer who knows how to do macro on film. he wants to photograph an object let's say 35mm wide - exactly frame wide , for which he needs a lens that offers 1:1 magnification. But when he switched to APS-C digital, he suddenly realises that he needs to back a little , or change the lens, because object now at 1:1 macro lens setting is not fitting the frame - thus in his mind exceeding the 1:1 magnification ( although it is not obviously). This case for me clearly explains that macro magnification is also affected by sensor crop factor - in this case adding to focal length 50% , and so for simply minded photographer , similarly to easy to grasp the idea of equivalent focal lengths between APS-C and 35mm, it applies to macro magnifications.
If lens used had no helicoid and had fixed focusing point, it would not allow to photograph whole object 35mm wide on an APS-C sensor , because of (one saying it ) the sensor is cropping the externals of frame, or (another way saying it ) sensor is adding 50% of magnification making object appears larger in the frame than the photographer used to 35mm film frames , would expect.

Anyway at least this is how I simplify things on the subject

I think you are making it less clear, as anything to do with "crop factor" usually does. Especially for anyone that does macro already, film or not. You are actually just making it nonsense by bringing in concepts of magnification and then saying "you're getting such-and-such magnification" when you flat-out are not, it is technically a lie. If you want to simplify it, tell him to look at the ratio given on his macro lens at his focus point, most of them still say "1:3", "1:2", "1:1", etc on the barrel. If you want to say, "you can fill the frame with this object from a farther distance on APS-C than on FF", then just say that. It has nothing to do with magnification. This is not splitting hairs so we get EXACT science, it is apples & oranges; and insisting to call one the other will never help clarity...

(Sorry for going a little off-topic here, btw. I'm done.)

[gofour3]

What a response!
After reading all your answers, I think I will go for 50mm extension tube track, Ebay next stop!

The Link to Cambridge in Colour was great, thank BrianR!

Thanks /Patrik
Stockholm
Sweden

This will do the trick, the Pentax K 50mm Auto Extension Tube. I use it on my K100/4 Macro.

PENTAX Auto Extension Tube K 50mm reviews - Pentax Camera Accessory Review Database

Phil.

[Sagitta]

The easiest way to explain crop factor is this:

The trucks are the full frame image, the bridge is the cropped sensor.

Youtu.be

Youtu.be

[Not a Number]

As the manuals say you need a 50mm extension to get 1x at minimum focus with 100mm f/4 M or A lenses

Downloads & Literature - RICOH Imaging
Downloads & Literature - RICOH Imaging

But what a minute... don't you need extension equal to the focal length of the lens to get 1:1?

If it were a non-macro lens yes, but the extension factor needed is based on the primary optical plane (often called the optical center) of the lens. Since the macro gives 1:2 at minimum focus or maximum extension of 50mm only an additional 50mm is needed to achieve 1:1.

[Zephos]

Ok maybe I wasn't precise enough - of course life size is property of lens , or the object for that matter. If an insect is 23mm long , it will fit perfectly into your APS-C frame at 1:1 magnification. BUT if you use the same lens on a film camera - it will not be full frame, but part of it - still life size of course However, for most purposes we do apply the 1.5x crop factor - so instead of x4 magnification of 200mm lens we say it is x6 times - right. Why ? Because you will fit less into the frame, thus achieving more magnification.

Similar with macro - you get more magnification , despite the lens being 1:2 - you will get an equivalent of something around 1:1.5 - why ? because your sensor is adding you magnification by.. precisely , cropping out the rest of the frame

in practical life it mean you get 1:1.5 with 1:2 lens

Cropping does not magnify. It simply crops, then the smaller cropped image is often viewed (blown up) at the same size as a regular full frame image to make it LOOK like it's magnifying, but really you are just blowing it up and losing resolution. So you don't get 1.5x, its still 1.2 but the edges are cropped off and what's left is smaller than a full frame image if you view them both at a 100% zoom. When they say a 200mm on an APS-C gets magnified, its false.The image circle is the same regardless of the camera, and the only way to magnify is to make the image circle show less of the image (not the sensor). So what they really mean is that on APS-C you can fill the frame with LESS of the image circle, but your not really magnifying anything because the image circle still shows the same thing. You just have less pixels to fill.

[old4570]

As the manuals say you need a 50mm extension to get 1x at minimum focus with 100mm f/4 M or A lenses

Downloads & Literature - RICOH Imaging
Downloads & Literature - RICOH Imaging

But what a minute... don't you need extension equal to the focal length of the lens to get 1:1?

If it were a non-macro lens yes, but the extension factor needed is based on the primary optical plane (often called the optical center) of the lens. Since the macro gives 1:2 at minimum focus or maximum extension of 50mm only an additional 50mm is needed to achieve 1:1.

The lens is already 1:2 , it needs to be taken to 1:1 , 50mm should do this nicely ..
If the lens was a standard non macro lens , then you would need 100mm of tube ..

[BrianR]

In general, a 100mm lens won't need 100mm of extension tubes to hit 1:1 magnification. It will be less, how much less depends on how close it can focus natively. See the Cambridge in Colour link, though it's assuming your lens is 'inert' so it may be off for more modern designs that involve lens elements moving around internally as you focus.

This case for me clearly explains that macro magnification is also affected by sensor crop factor - in this case adding to focal length 50% , and so for simply minded photographer , similarly to easy to grasp the idea of equivalent focal lengths between APS-C and 35mm, it applies to macro magnifications.

It's not the worst to think of it this way, but you should absolutely be clear to not in any way imply that the magnification of the lens has changed. This will just confuse people to no end when they find all other sources contradict how you're using the terminology. In any case, you should check again on how the crop factor would apply to translate to a "35mm effective magnification" and make sure you get the math right. A 1:2 lens will fill an APS-C frame with something 32x48mm in size. This is the same area you'd get with a 1:1.333 lens on a Full Frame camera, not 1:1.5.

Personally, I think it's simplest to just explain what magnification means, then draw a bunch of little rectangles that will 'fill the frame' at different magnification ratios for the users sensor size. If multiple formats are a concern, do the same for each format. This approach seems to work well, it's nice and physical and even non-math minded people seem to get it pretty quick especially if you have a macro lens on hand they can aim at the little rectangles.

[Dewman]

The lens is already 1:2 , it needs to be taken to 1:1 , 50mm should do this nicely ..
If the lens was a standard non macro lens , then you would need 100mm of tube ..

O.K., Matt..... if I wanted to go to..... um..... oh..... let's say 2:1 or 3:1 using my new-to-me FA 50mm f:2.8 macro, how much extension tube would I need to achieve this? Is there a formula? Also, by doing this, will I lose any IQ?

[old4570]

O.K., Matt..... if I wanted to go to..... um..... oh..... let's say 2:1 or 3:1 using my new-to-me FA 50mm f:2.8 macro, how much extension tube would I need to achieve this? Is there a formula? Also, by doing this, will I lose any IQ?

The lens is 50mm 1:1
So 50mm of tube should take you to 2:1
To go 3:1 would probably be 100mm of tube ..


I would suggest there is little point going past 2:1 .. as the focus distance is short enough as it is ..


I would also suggest lens stacking if you wanted to try something different , pop a 28mm reversed in front of your 50mm for almost 2:1 , or a 24mm if you have one ..
This way you can keep all the functionality of the 50mm lens ..

[BrianR]

O.K., Matt..... if I wanted to go to..... um..... oh..... let's say 2:1 or 3:1 using my new-to-me FA 50mm f:2.8 macro, how much extension tube would I need to achieve this? Is there a formula? Also, by doing this, will I lose any IQ?

See the calculators here: Macro Extension Tubes & Close-up Lenses or here Lens Magnification and Depth of Field Calculator. The second one also gives depth of field and makes some assumptions that may end up a little more accurate for the more complicated modern lens designs (though won't make a big difference for your 50mm).

[Nass]

Yes this is easily calculated - see Macro Photography Calculators, including extension tube, bellows, closeup lens and stacked lens calculators
Feel free to drop other requests for macro calculators on the site (it's mine), I'm on a calculator binge at the moment.

Fwiw: cropping most definitely does not add magnification, Zephos explained it best. And 50mm of extension tube will make a 100mm 1:2 to a 1:1