Crop Factor and Macro Ratio

alohadave · 08-12-2010, 11:16 AM

Originally posted by RioRico

Actually it's the other way around: D/FL

Nope, he's dead on.

F-number - Wikipedia, the free encyclopedia

stevebrot · 08-12-2010, 12:03 PM

Originally posted by alohadave

Nope, he's dead on.

F-number - Wikipedia, the free encyclopedia

This whole discussion is sort of silly. What I am waiting to read is the admission from one of the forum's macro shooters that their insect shots are cropped heavily even at 1:1 even with APS-C! Really people, this whole issue can be resolved by spending a few minutes with the actual equipment trying to fill the frame with a bug's eye.

Steve

Eruditass · 08-12-2010, 01:52 PM

Relevant analysis of the situation (see the discussion on the first answer):

Why do we talk about focal-length when frame sizes are different? - Photography - Stack Exchange
What is the difference between focal length and crop factor? - Photography - Stack Exchange

IMO, the attention needs to be taken AWAY from crop-factor and towards equivalent field of view of a 35mm lens. Some argue the confusing semantics of effective focal length and I agree to an extent.

I kinda like this approach:

http://petavoxel.wordpress.com/2010/01/08/35e/

Macro and 1:1 is a little trickier.. although they are physical properties just like focal length, there is no standard accepted format for conversion like 35mm focal lengths.

In the end, it is much less important than focal lengths and field of view because you are not going to be comparing similar setups across different formats, unlike focal lengths. Typically, you just want to reach a certain magnification for your subject.

RioRico · 08-12-2010, 01:58 PM

Originally posted by alohadave

Nope, he's dead on.

F-number - Wikipedia, the free encyclopedia

That entry is misleading. Think about it: f/d is a fraction. An f-stop like f/16 means that the iris opening is 1/16 the focal length -- that is the real ratio. The wikipedia entry formula calculates an f-number, but the reality is its reciprocal. That's why apertures are shown as f/(whatever).

[/nitpicking]

Marc Sabatella · 08-12-2010, 03:18 PM

Originally posted by Blue

Yes it will.

The confusion in this thread arises from the notion that macro photography is about filling the frame.

Well, to be precise, to quote the OP, it was about taking the same picture with two different cameras. And if you take pictures with the same magnification ratio on cameras with different format sizes, I guarantee they will *not* look like the same picture. The one on the larger format will show the subject smaller within the frame. That's just a fact. One can debate the relevance of that fact (I find pretty relevant, and apparently the OP does, but if others don't find it relevant to their own photography, that's fine). But there is no denying the fact itself - you need *different* magnification ratios to achieve the same shot between cameras of different format sizes, just as you need different focal lengths.

Quote:

You don't need macro to photograph a 72mm subject.

Call it what you want, but you need a magnification of 1:2 to fill the frame with a 72mm subject on FF, and since someone else brought up the idea of achieving results comparable to 1:2 on FF, I used that in my example as well.

Quote:

"crop factor" nor focal length will effect the 1:1 or 1:2 ratio.

Right - it affects the way the picture looks, which is the actual subject here, not the numbers that describe how the picture was taken.

Quote:

The only difference in the DA 35 and Sigma 105mm in my above example is the focus distance at 1:1. They are both 1:1 capable lenses and the format won't change that.

Well, sure, but no one was talking about comparing a 35mm lens to a 105mm lens. Of course they produce different images because their FOV's are different. That's why I used the example of a 35mm macro lens on APS-C but 50mm on FF - so the FOV's would match. That in turn means if you get the subject to match, the background will match, too. The physics of perspective won't allow it to be ny other way. And once you get subject and background to match, you'll discover that you're dealing with two different magnification ratios, just as I said.

Marc Sabatella · 08-12-2010, 03:22 PM

Originally posted by Lowell Goudge

The fact remains focal length is a property of a lens irrespective of format

In the same way aperture is the ratio of focal length over diameter and

Magnification ratio is the ratio of imigensize to subject size

None are changed by format only the vield of view changes

Of course. No one ever suggested otherwise. But as clarified by the OP, the discussion is really about taking pictures that *look* the same, not about taking pictures that happen to involve lenses of similar focal length or magnification ratios. If you want your picture to *look* the same between cameras of different format size, you need both different focal lengths *and* different magnification ratio to achieve this.

Quote:

Let's get on with talking about photography as opposed to trying to redefine physical lens characteristics just because we are using a smaller part of the image a lens projects

By talking about how a picture actually *looks* as opposed to physical characteristics of a lens like focal length or magnification ratio, I'd claim we *are* talking about photography.

Blue · 08-12-2010, 04:35 PM

Originally posted by Marc Sabatella

Well, to be precise, to quote the OP, it was about taking the same picture with two different cameras. And if you take pictures with the same magnification ratio on cameras with different format sizes, I guarantee they will *not* look like the same picture. The one on the larger format will show the subejct smaller within the frame. That's just a fact. One can debate the relevance of that fact (I find pretty relevant, and apparently the OP does, but if others don't find it relevant to their own photogrpahy, that's fine). But there is no denying the fact itself - you need *different* magnification ratios to achieve the same shot between cameras of different format sizes, just as you need different focal length.

Call it what you want, but you need a magnification of 1:2 to fill the frame with a 72mm subject on FF, and since someone else brought up the idea of achieving results comparable to 1:2 on FF, I used that in my example as well.

Right - it affects the way the picture looks, which is the actual subject here, not the numbers that describe how the picture was taken.

Well, sure, but no one was talking about comparing a 35mm lens to a 105mm lens. Of course they produce different images because their FOV's are different. That's why I used the example of a 35mm macro lens on APS-C but 50mm on FF - so the FOV's would match. That in turn means if you get the subject to match, the background will match, too. The physics of perspective won't allow it to be ny other way. And once you get subject and background to match, you'll discover that you're dealing with two different magnification ratios, just as I said.

What the OP asked was whether the so called crop factor applied to the macro ratio of a lens. It does not. At ratios greater 1:1 (life size) the distance between object and lens becomes less than the distance between the lens and film plane. At 1:1 the distances are equal. With closeups made at less than life size the distance between the sensor/film plane is less than the distance between the object and lens. The discussion you have been making is applicable to 1:10 standard photography. With true macro you do not have to get the FOV to match, just the image of the object. In short, my Sigma 105mm is 1:1 whether its on the MZ-3 or K-20d. What is different is the FOV.

alohadave · 08-12-2010, 07:00 PM

Originally posted by RioRico

That entry is misleading. Think about it: f/d is a fraction. An f-stop like f/16 means that the iris opening is 1/16 the focal length -- that is the real ratio. The wikipedia entry formula calculates an f-number, but the reality is its reciprocal. That's why apertures are shown as f/(whatever).

[/nitpicking]

You are getting in super fine splitting of hairs here.

You corrected something that wasn't wrong when you said that the formula is D/FL.

Nick Siebers · 08-12-2010, 07:19 PM

This thread is great! Everyone is arguing, and EVRYONE IS RIGHT! (Except maybe one of the D/FL:FL/D people, not following that.) The image IS the same size on different sensors. But it looks bigger on a smaller sensor relative to the rest of the picture, because some of the field is "cropped". A 1:3 macro on a APS-c DSLR will look like a 1:2 macro on 35mm, just like a 50mm lens looks like a 75mm lens. Whee!

**GregK8** · 08-12-2010, 10:04 PM

zOMG, I created a monster

Sorry I didn't mean to get so many people arguing over such a seemingly meaningless phenomena.

200th post btw

**Digitalis** · 08-13-2010, 05:04 AM

Just to drive the last nail in this argument:

top image: Tripod mounted D3s with Nikkor 105mm Micro-Nikkor f/2.8 VR @ 1:1
bottom image:Tripod Mounted D200 with Nikkor 105mm Micro-Nikkor f/2.8 VR lens @1:1 ( I know I didn't completely fill the viewfinder because the D200 doesn't have a 100% VF like the D3, this was a rush job)

ruler was moved to fill the viewfinder,these are the full captured frames. to get the same FOV with the D200 as the D3 I had to raise the central column and set the focus at 1:1.5... go figure....

Derridale · 08-13-2010, 05:10 AM

Well done Digitalis - at last someone has had the sense to post some actual images that show a meaningful comparison. As I have posted above a couple of times - it's all about the angle of view (or field of view if you prefer - same thing)

The crop factor is real (or magnification factor, format factor - call it whatever).

So, when another photographer on the same shoot as me is using a 70-200mm lens with a full-frame Nikon D3s, I use a Pentax DA* 50-135 which is as close as dammit to the same angle of view (multiplier of 1.5x). If we both shoot the same subject from the same spot, we should get the same view on the sensors.

Simple, really...

**Digitalis** · 08-13-2010, 05:15 AM

"Simple, really."

indeed, as a large format photographer with years of experience in this area, I found it very interesting to see some the arguments displayed here. when I need a tight macro shot on my 4X5 I often use a 67 rollfilm back, because then I don't waste so much film area, and I don't have the extend the bellows so much therefore I don't lose the ridiculous amounts of light you do when doing 1:1 magnification work on full frame 4X5.

Incidentally I don't refer to it as "crop factor" that term is completely misleading. I call it format factor, because that is what APS-C is, a format. So call it what is is damn it!

Blue · 08-13-2010, 08:08 AM

Originally posted by Digitalis

"Simple, really."

indeed, as a large format photographer with years of experience in this area, I found it very interesting to see some the arguments displayed here. when I need a tight macro shot on my 4X5 I often use a 67 rollfilm back, because then I don't waste so much film area, and I don't have the extend the bellows so much therefore I don't lose the ridiculous amounts of light you do when doing 1:1 magnification work on full frame 4X5.

Incidentally I don't refer to it as "crop factor" that term is completely misleading. I call it format factor, because that is what APS-C is, a format. So call it what is is damn it!

The fov wasn't the argument here between the two sensor/film sizes. My argument is that at 1:1 a 2mm subject forms a 2mm images on the sensor or film plane and that 1:1 doesn't automatically mean the subject will fill up the frame. It was whether the ratio changed from 1:2 to 1:1.3 from one to the other. I agree about the so called crop factor since it is a conversion determined by comparing the diagonal dimensions of the 2 formats being compared.

stevebrot · 08-13-2010, 09:07 AM

Originally posted by Digitalis

"Simple, really."

indeed, as a large format photographer with years of experience in this area, I found it very interesting to see some the arguments displayed here. when I need a tight macro shot on my 4X5 I often use a 67 rollfilm back, because then I don't waste so much film area, and I don't have the extend the bellows so much therefore I don't lose the ridiculous amounts of light you do when doing 1:1 magnification work on full frame 4X5.

Incidentally I don't refer to it as "crop factor" that term is completely misleading. I call it format factor, because that is what APS-C is, a format. So call it what is is damn it!

Ha! Ha!

I was going to mention that the idea of crop/format factor is well-known in large format circles and part of the general knowledge that goes with working in that space. Thanks for bringing your comment into the mix.

Steve

P.S. It might be good to notice the difference in FOV in the two example images that digitalis posted. After all, it is a ruler...)

08-12-2010, 01:52 PM	#33
Eruditass Veteran Member Join Date: Jul 2009 Photos: Gallery Posts: 2,207	Relevant analysis of the situation (see the discussion on the first answer): Why do we talk about focal-length when frame sizes are different? - Photography - Stack Exchange What is the difference between focal length and crop factor? - Photography - Stack Exchange IMO, the attention needs to be taken AWAY from crop-factor and towards equivalent field of view of a 35mm lens. Some argue the confusing semantics of effective focal length and I agree to an extent. I kinda like this approach: http://petavoxel.wordpress.com/2010/01/08/35e/ Macro and 1:1 is a little trickier.. although they are physical properties just like focal length, there is no standard accepted format for conversion like 35mm focal lengths. In the end, it is much less important than focal lengths and field of view because you are not going to be comparing similar setups across different formats, unlike focal lengths. Typically, you just want to reach a certain magnification for your subject. Last edited by Eruditass; 08-12-2010 at 01:59 PM.

08-12-2010, 03:18 PM	#35
Marc Sabatella Veteran Member Join Date: Sep 2006 Location: Denver, CO Photos: Gallery Posts: 10,685	Originally posted by Blue Yes it will. The confusion in this thread arises from the notion that macro photography is about filling the frame. Well, to be precise, to quote the OP, it was about taking the same picture with two different cameras. And if you take pictures with the same magnification ratio on cameras with different format sizes, I guarantee they will not look like the same picture. The one on the larger format will show the subject smaller within the frame. That's just a fact. One can debate the relevance of that fact (I find pretty relevant, and apparently the OP does, but if others don't find it relevant to their own photography, that's fine). But there is no denying the fact itself - you need different magnification ratios to achieve the same shot between cameras of different format sizes, just as you need different focal lengths. Quote: You don't need macro to photograph a 72mm subject. Call it what you want, but you need a magnification of 1:2 to fill the frame with a 72mm subject on FF, and since someone else brought up the idea of achieving results comparable to 1:2 on FF, I used that in my example as well. Quote: "crop factor" nor focal length will effect the 1:1 or 1:2 ratio. Right - it affects the way the picture looks, which is the actual subject here, not the numbers that describe how the picture was taken. Quote: The only difference in the DA 35 and Sigma 105mm in my above example is the focus distance at 1:1. They are both 1:1 capable lenses and the format won't change that. Well, sure, but no one was talking about comparing a 35mm lens to a 105mm lens. Of course they produce different images because their FOV's are different. That's why I used the example of a 35mm macro lens on APS-C but 50mm on FF - so the FOV's would match. That in turn means if you get the subject to match, the background will match, too. The physics of perspective won't allow it to be ny other way. And once you get subject and background to match, you'll discover that you're dealing with two different magnification ratios, just as I said. Last edited by Marc Sabatella; 08-13-2010 at 12:45 PM.

08-13-2010, 05:04 AM	#41
Digitalis Site Supporter Join Date: Mar 2009 Location: Melbourne, Victoria Photos: Gallery Posts: 11,694	Just to drive the last nail in this argument: top image: Tripod mounted D3s with Nikkor 105mm Micro-Nikkor f/2.8 VR @ 1:1 bottom image:Tripod Mounted D200 with Nikkor 105mm Micro-Nikkor f/2.8 VR lens @1:1 ( I know I didn't completely fill the viewfinder because the D200 doesn't have a 100% VF like the D3, this was a rush job) ruler was moved to fill the viewfinder,these are the full captured frames. to get the same FOV with the D200 as the D3 I had to raise the central column and set the focus at 1:1.5... go figure.... Last edited by Digitalis; 01-28-2015 at 12:36 AM.

08-13-2010, 05:15 AM	#43
Digitalis Site Supporter Join Date: Mar 2009 Location: Melbourne, Victoria Photos: Gallery Posts: 11,694	"Simple, really." indeed, as a large format photographer with years of experience in this area, I found it very interesting to see some the arguments displayed here. when I need a tight macro shot on my 4X5 I often use a 67 rollfilm back, because then I don't waste so much film area, and I don't have the extend the bellows so much therefore I don't lose the ridiculous amounts of light you do when doing 1:1 magnification work on full frame 4X5. Incidentally I don't refer to it as "crop factor" that term is completely misleading. I call it format factor, because that is what APS-C is, a format. So call it what is is damn it! Last edited by Digitalis; 08-13-2010 at 05:22 AM.

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08-12-2010, 11:16 AM	#31
alohadave Veteran Member Join Date: Jan 2008 Location: Quincy, MA Photos: Gallery \| Albums Posts: 2,024	Originally posted by RioRico Actually it's the other way around: D/FL Nope, he's dead on. F-number - Wikipedia, the free encyclopedia

08-12-2010, 12:03 PM	#32
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by alohadave Nope, he's dead on. F-number - Wikipedia, the free encyclopedia This whole discussion is sort of silly. What I am waiting to read is the admission from one of the forum's macro shooters that their insect shots are cropped heavily even at 1:1 even with APS-C! Really people, this whole issue can be resolved by spending a few minutes with the actual equipment trying to fill the frame with a bug's eye. Steve

08-12-2010, 01:58 PM	#34
RioRico Veteran Member Join Date: Jun 2008 Location: Limbo, California Posts: 11,263	Originally posted by alohadave Nope, he's dead on. F-number - Wikipedia, the free encyclopedia That entry is misleading. Think about it: f/d is a fraction. An f-stop like f/16 means that the iris opening is 1/16 the focal length -- that is the real ratio. The wikipedia entry formula calculates an f-number, but the reality is its reciprocal. That's why apertures are shown as f/(whatever). [/nitpicking]

08-12-2010, 03:22 PM	#36
Marc Sabatella Veteran Member Join Date: Sep 2006 Location: Denver, CO Photos: Gallery Posts: 10,685	Originally posted by Lowell Goudge The fact remains focal length is a property of a lens irrespective of format In the same way aperture is the ratio of focal length over diameter and Magnification ratio is the ratio of imigensize to subject size None are changed by format only the vield of view changes Of course. No one ever suggested otherwise. But as clarified by the OP, the discussion is really about taking pictures that look the same, not about taking pictures that happen to involve lenses of similar focal length or magnification ratios. If you want your picture to look the same between cameras of different format size, you need both different focal lengths and different magnification ratio to achieve this. Quote: Let's get on with talking about photography as opposed to trying to redefine physical lens characteristics just because we are using a smaller part of the image a lens projects By talking about how a picture actually looks as opposed to physical characteristics of a lens like focal length or magnification ratio, I'd claim we are talking about photography.

08-12-2010, 04:35 PM	#37
Blue Moderator Site Supporter Join Date: Jun 2008 Location: Florida Hill Country Photos: Gallery \| Albums Posts: 17,377	Originally posted by Marc Sabatella Well, to be precise, to quote the OP, it was about taking the same picture with two different cameras. And if you take pictures with the same magnification ratio on cameras with different format sizes, I guarantee they will not look like the same picture. The one on the larger format will show the subejct smaller within the frame. That's just a fact. One can debate the relevance of that fact (I find pretty relevant, and apparently the OP does, but if others don't find it relevant to their own photogrpahy, that's fine). But there is no denying the fact itself - you need different magnification ratios to achieve the same shot between cameras of different format sizes, just as you need different focal length. Call it what you want, but you need a magnification of 1:2 to fill the frame with a 72mm subject on FF, and since someone else brought up the idea of achieving results comparable to 1:2 on FF, I used that in my example as well. Right - it affects the way the picture looks, which is the actual subject here, not the numbers that describe how the picture was taken. Well, sure, but no one was talking about comparing a 35mm lens to a 105mm lens. Of course they produce different images because their FOV's are different. That's why I used the example of a 35mm macro lens on APS-C but 50mm on FF - so the FOV's would match. That in turn means if you get the subject to match, the background will match, too. The physics of perspective won't allow it to be ny other way. And once you get subject and background to match, you'll discover that you're dealing with two different magnification ratios, just as I said. What the OP asked was whether the so called crop factor applied to the macro ratio of a lens. It does not. At ratios greater 1:1 (life size) the distance between object and lens becomes less than the distance between the lens and film plane. At 1:1 the distances are equal. With closeups made at less than life size the distance between the sensor/film plane is less than the distance between the object and lens. The discussion you have been making is applicable to 1:10 standard photography. With true macro you do not have to get the FOV to match, just the image of the object. In short, my Sigma 105mm is 1:1 whether its on the MZ-3 or K-20d. What is different is the FOV.

08-12-2010, 07:00 PM	#38
alohadave Veteran Member Join Date: Jan 2008 Location: Quincy, MA Photos: Gallery \| Albums Posts: 2,024	Originally posted by RioRico That entry is misleading. Think about it: f/d is a fraction. An f-stop like f/16 means that the iris opening is 1/16 the focal length -- that is the real ratio. The wikipedia entry formula calculates an f-number, but the reality is its reciprocal. That's why apertures are shown as f/(whatever). [/nitpicking] You are getting in super fine splitting of hairs here. You corrected something that wasn't wrong when you said that the formula is D/FL.

08-12-2010, 07:19 PM	#39
Nick Siebers Veteran Member Join Date: Jun 2008 Location: Madison, WI Photos: Gallery \| Albums Posts: 2,165	This thread is great! Everyone is arguing, and EVRYONE IS RIGHT! (Except maybe one of the D/FL:FL/D people, not following that.) The image IS the same size on different sensors. But it looks bigger on a smaller sensor relative to the rest of the picture, because some of the field is "cropped". A 1:3 macro on a APS-c DSLR will look like a 1:2 macro on 35mm, just like a 50mm lens looks like a 75mm lens. Whee!

08-12-2010, 10:04 PM	#40
GregK8 Site Supporter Join Date: May 2008 Location: Western New York Photos: Gallery \| Albums Posts: 614 Original Poster	zOMG, I created a monster Sorry I didn't mean to get so many people arguing over such a seemingly meaningless phenomena. 200th post btw

08-13-2010, 05:10 AM	#42
Derridale Veteran Member Join Date: Jan 2008 Location: Brisbane, Australia Posts: 412	Well done Digitalis - at last someone has had the sense to post some actual images that show a meaningful comparison. As I have posted above a couple of times - it's all about the angle of view (or field of view if you prefer - same thing) The crop factor is real (or magnification factor, format factor - call it whatever). So, when another photographer on the same shoot as me is using a 70-200mm lens with a full-frame Nikon D3s, I use a Pentax DA* 50-135 which is as close as dammit to the same angle of view (multiplier of 1.5x). If we both shoot the same subject from the same spot, we should get the same view on the sensors. Simple, really...

08-13-2010, 08:08 AM	#44
Blue Moderator Site Supporter Join Date: Jun 2008 Location: Florida Hill Country Photos: Gallery \| Albums Posts: 17,377	Originally posted by Digitalis "Simple, really." indeed, as a large format photographer with years of experience in this area, I found it very interesting to see some the arguments displayed here. when I need a tight macro shot on my 4X5 I often use a 67 rollfilm back, because then I don't waste so much film area, and I don't have the extend the bellows so much therefore I don't lose the ridiculous amounts of light you do when doing 1:1 magnification work on full frame 4X5. Incidentally I don't refer to it as "crop factor" that term is completely misleading. I call it format factor, because that is what APS-C is, a format. So call it what is is damn it! The fov wasn't the argument here between the two sensor/film sizes. My argument is that at 1:1 a 2mm subject forms a 2mm images on the sensor or film plane and that 1:1 doesn't automatically mean the subject will fill up the frame. It was whether the ratio changed from 1:2 to 1:1.3 from one to the other. I agree about the so called crop factor since it is a conversion determined by comparing the diagonal dimensions of the 2 formats being compared.

08-13-2010, 09:07 AM	#45
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by Digitalis "Simple, really." indeed, as a large format photographer with years of experience in this area, I found it very interesting to see some the arguments displayed here. when I need a tight macro shot on my 4X5 I often use a 67 rollfilm back, because then I don't waste so much film area, and I don't have the extend the bellows so much therefore I don't lose the ridiculous amounts of light you do when doing 1:1 magnification work on full frame 4X5. Incidentally I don't refer to it as "crop factor" that term is completely misleading. I call it format factor, because that is what APS-C is, a format. So call it what is is damn it! Ha! Ha! I was going to mention that the idea of crop/format factor is well-known in large format circles and part of the general knowledge that goes with working in that space. Thanks for bringing your comment into the mix. Steve P.S. It might be good to notice the difference in FOV in the two example images that digitalis posted. After all, it is a ruler...)