September 18, 2014, 08:19:09 AM

Author Topic: Crop sensors better than full frame for macro photography?  (Read 11053 times)

privatebydesign

  • Canon EF 300mm f/2.8L IS II
  • *******
  • Posts: 2342
  • Ermintrude says "moo"
    • View Profile
Re: Crop sensors better than full frame for macro photography?
« Reply #30 on: February 25, 2014, 03:09:50 PM »
Ok,

I accept actually reading an entire article that explains everything in a few pages is too much for practically everybody, and shouting your ignorance at the top of your voice is far more fun (Carl!). So here is a concise version.

If you can get the framing you want with the lens you have with either camera the FF camera will give you the better image. You will have more pixels on target and any adjustment needed to match dof because the camera is closer can be done with iso for a neutral noise and dof equation.

If you can get the framing you want with the crop camera but not the ff one (you can't get close enough and/or the subject is too small), the crop camera will give you the better image. But only because the crop camera will put more pixels on target, if you crop the ff image to match the crop camera image the dof, noise, and everything else is identical.

These two examples assume you need the maximum amount of pixels on target, if you don't, and most of us don't 99.9999999999% of the time, there will be very little difference between the two. In most real world shooting, including macro, a ff camera will best a crop camera at everything to do with image output quality, the reasons for this are many and varied, but who, for instance, accepts that a crop camera needs over 1.6 times the support of a ff camera? Yep. you should use a more expensive and sturdier tripod for your smaller sensor. Equivalence needs to take shutters speed into account where you are limited by hand holding not subject motion, but it doesn't, this is very relevant to macro shooting. Most of the time these differences are small enough to not impact the average output.

People that think a crop camera gives you anything for free are sadly mistaken. You don't get "free" reach, dof, noise, or any other quantifiable image metric from using a crop camera.
The best time to plant a tree is twenty-five years ago. The second best time is today.

canon rumors FORUM

Re: Crop sensors better than full frame for macro photography?
« Reply #30 on: February 25, 2014, 03:09:50 PM »

Marsu42

  • Canon EF 400mm f/2.8L IS II
  • *******
  • Posts: 4527
  • ML-66d / 100L / 70-300L / 17-40L / 600rts
    • View Profile
    • 6D positive spec list
Re: Crop sensors better than full frame for macro photography?
« Reply #31 on: February 25, 2014, 03:31:52 PM »
People that think a crop camera gives you anything for free are sadly mistaken. You don't get "free" reach, dof, noise, or any other quantifiable image metric from using a crop camera.

I'd disagree in one select special case, and that happens to be a macro situation... but please correct me if I'm getting it wrong:

If you have the same framing on crop and ff, the ff nears to the subject (the famed working distance). If the crop is still outside the macro distance and can use the full aperture, and the ff is inside it (meaning the usable aperture drops to rock bottom) the ff needs to use a *higher* iso setting to get the *same* exposure - that's how macro lenses work if you increase magnification and the macro mechanism is engaged.

This effect means that depending on the lens-object distance, the crop camera has less noise disadvantage than usual, or it might even have an advantage - the latter is my personal, subjective experience and part of the reason why I'd prefer to shoot fireflies with crop.

privatebydesign

  • Canon EF 300mm f/2.8L IS II
  • *******
  • Posts: 2342
  • Ermintrude says "moo"
    • View Profile
Re: Crop sensors better than full frame for macro photography?
« Reply #32 on: February 25, 2014, 03:45:22 PM »
People that think a crop camera gives you anything for free are sadly mistaken. You don't get "free" reach, dof, noise, or any other quantifiable image metric from using a crop camera.

I'd disagree in one select special case, and that happens to be a macro situation... but please correct me if I'm getting it wrong:

If you have the same framing on crop and ff, the ff nears to the subject (the famed working distance). If the crop is still outside the macro distance and can use the full aperture, and the ff is inside it (meaning the usable aperture drops to rock bottom) the ff needs to use a *higher* iso setting to get the *same* exposure - that's how macro lenses work if you increase magnification and the macro mechanism is engaged.

This effect means that depending on the lens-object distance, the crop camera has less noise disadvantage than usual, or it might even have an advantage - the latter is my personal, subjective experience and part of the reason why I'd prefer to shoot fireflies with crop.

I'm sorry I don't understand this bit "If the crop is still outside the macro distance and can use the full aperture, and the ff is inside it (meaning the usable aperture drops to rock bottom)"

If the two cameras are at different distances for the same framing the crop camera aperture number will be lower to get the same shot. If they are both wide open the dof of the ff camera will be less but it will gather over twice as much light on it's over twice as large sensor, this will result in less noise. So stop the ff camera down and raise the iso to get the same noise (but even then the ff camera actually comes out better) for the same dof.

The only situation where you can't do dof equivalence is stopping right down, if your crop camera is at f32 you can't (with most lenses) stop down to f64 for the ff shot, but you have long since passed the limits of diffraction and would be better off focus stacking anyway.
The best time to plant a tree is twenty-five years ago. The second best time is today.

neuroanatomist

  • CR GEEK
  • ********
  • Posts: 14391
    • View Profile
Re: Crop sensors better than full frame for macro photography?
« Reply #33 on: February 25, 2014, 04:04:03 PM »
If you have the same framing on crop and ff, the ff nears to the subject (the famed working distance). If the crop is still outside the macro distance and can use the full aperture, and the ff is inside it (meaning the usable aperture drops to rock bottom) the ff needs to use a *higher* iso setting to get the *same* exposure - that's how macro lenses work if you increase magnification and the macro mechanism is engaged.

This effect means that depending on the lens-object distance, the crop camera has less noise disadvantage than usual, or it might even have an advantage - the latter is my personal, subjective experience and part of the reason why I'd prefer to shoot fireflies with crop.

I'm sorry I don't understand this bit "If the crop is still outside the macro distance and can use the full aperture, and the ff is inside it (meaning the usable aperture drops to rock bottom)"

I suspect what Marsu42 is referring to is the decrease apparent aperture, the light loss you get as magnification increases.  There's no 'magic number' for that, there's no 'macro mechanism', and it's not the case that 'outside macro distance' there's no light lost.  At 0.2x mag you lose ~0.67-stops of light, at 0.5x mag you lose ~1.33-stops, and at 1x you lose ~2-stops.  The decrease in magnification when matching framing means a differential loss of less than 2/3-stop more with the FF sensor at 1:1, and that's likely not enough to make a significant difference, particularly since recent FF bodies tend to give more than the size-predicted 1.33-stop noise benefit over APS-C. 
EOS 1D X, EOS M, and lots of lenses
______________________________
Flickr | TDP Profile/Gear List

privatebydesign

  • Canon EF 300mm f/2.8L IS II
  • *******
  • Posts: 2342
  • Ermintrude says "moo"
    • View Profile
Re: Crop sensors better than full frame for macro photography?
« Reply #34 on: February 25, 2014, 04:12:35 PM »
Ok, the old extension tube bellows light loss thing. Yes, as you say, because the ff tends to outperform the numbers I would expect the same thing, the ff camera would still give a "better" image.

Back in my film days I actually used to know how to work all that out, my class project was to take a picture of a hand on a watch face, I filled the (FF) image with the width of the minute hand, I used two sets of bellows at full extension and either a 50mm or 32mm lens. But that was a long time ago.
The best time to plant a tree is twenty-five years ago. The second best time is today.

faustino

  • Power Shot G16
  • **
  • Posts: 18
    • View Profile
Re: Crop sensors better than full frame for macro photography?
« Reply #35 on: February 25, 2014, 04:25:41 PM »
I would like to thank you all for your replies.

At this point I feel the duty to summarize my learnings from your posts:

For macro photography, there are two meaningful ways to compare crop vs. full frame sensors:

1)
The comparison can be made trying to achieve the same image in terms of perspective and depth of field.
* In order to get the same image in terms of perspective (related to distance) and framing, the smaller sensor shall be coupled with a shorter lens. If we put a 100mm lens on the full frame, something in the range of 60mm lens should be mounted on the crop sensor camera (assuming a 1.6 crop factor).
* In order to get the same depth of field, the aperture on the full frame camera shall be roughly one stop smaller. The smaller aperture would loose one stop of light, that would be compensated by the "one stop higher" light gathering capacity of full frame sensors.
* Identical framing is achieved with the same distance to the subject.
==> In such first comparison the output from the two setup is theoretically very similar. Anyhow, in practice, as pointed out by Neuro and proved by Mackguyver, the image from the full frame sensor would be visibly sharper. Since there is a proof, I would say this conclusion is incontrovertible.

2)
The comparison can be made keeping the same lens on both full frame and crop camera.
In this case the distance to the subject can be either be selected to be the same (2.1), or we can move the crop camera further away (2.2) to get some sort of "same composition" (will never be the same composition because perspective would be different)

2.1) keeping the same distance:
The crop sensor would capture exactly the same image that would be obtained from the full frame sensor cropping in post production.
==> The advantage of crop camera would be in pixel count, allowing more latitude for further cropping (if ISO is not pushed up too much) - as Neuro was writing elsewhere, the subject image is captured with more pixels.
==> The advantage of the full frame would be a larger angle of view, which is potentially important for multiple reasons (e.g. easiness of composition)

2.2) moving the crop camera further away from the subject.
Such scenario would could be considered less important; a full frame owner could move his camera further away as well, then crop in post production, and get the same image that could be obtained by an APS-C camera owner (except from pixel count).

In this latter scenario (2.1 and 2.2), the crop camera have actually the advantage of capturing the same cropped image that a full frame camera can capture, but with more pixels (usually it is the case with current cameras, may not be true with future cameras). This is unquestionable an advantage, if the ISO is "low". It is not and advantage, and can be a disadvantage, if the ISO needs to be pushed up.

Besides the above, there are some advantages of current crop cameras that I am not considering, e.g. swivel screen, weight, and some sort of better autofocus (7d coupled with 100mm f2.8L IS USM).
« Last Edit: February 26, 2014, 08:28:27 AM by faustino »

CarlTN

  • Canon EF 300mm f/2.8L IS II
  • *******
  • Posts: 2227
    • View Profile
Re: Crop sensors better than full frame for macro photography?
« Reply #36 on: February 25, 2014, 08:54:03 PM »
==> The advantage of crop camera would be only in pixel count, which is a questionable advantage.

Questionable how?  Not from the standpoint of putting pixels on the subject.  50MP vs. 22 is quite a difference.

canon rumors FORUM

Re: Crop sensors better than full frame for macro photography?
« Reply #36 on: February 25, 2014, 08:54:03 PM »

CarlTN

  • Canon EF 300mm f/2.8L IS II
  • *******
  • Posts: 2227
    • View Profile
Re: Crop sensors better than full frame for macro photography?
« Reply #37 on: February 25, 2014, 09:02:50 PM »
Let me get this straight. You're saying that a crop sensor will have shallower depth of field than a full frame sensor, given the same subject distance from the lens?  So, if that lens cannot focus at closer than 35 inches (as in the case I described), somehow I'm going to get shallower depth of field with a crop sensor, than with a full frame camera?  Why?  Because the subject is relatively tiny in the center of the (full) frame, and is represented by larger (and thus fewer) pixels over its area?  So what?  I still say with a 100mm macro lens, if ultimate detail and subject magnification is what you want, a crop sensor will be better.  To get the same subject magnification with a full frame camera, the distance will be closer, and then the depth of field will be SHALLOWER than it was with the same framing on the crop camera, not deeper.  It's you who doesn't understand relevant concepts here.  Get off my back.
That's exactly what I'm saying - with the same focal length, aperture and subject distance, a crop sensor will have a shallower depth of field.  The 'deeper DoF with a crop sensor' applies only when considering the same framing, where to match the FoV with the smaller sensor you are either further away or using a shorter focal length.  Also, crop sensors don't magnify, they just use a much smaller portion of the image circle (less than 40% of the FF area) - optical magnification of the subject isn't changing. The 'magnification' you're talking about is solely a function of pixel density, which is usually, but not always, higher on crop sensors.  If you frame the subject the same with both formats, the 'advantage' of pixel density is reversed (in general with current sensors). If you keep the distance the same you get more pixels on target with the crop sensor (in general with current sensors) – however, the DoF will be shallower, not deeper...and the smaller pixels of the crop sensor mean a greater effect of diffraction as you stop down, costing you more sharpness.


So I do understand relevant concepts here, and am not just looking to argue and make myself look like an idiot...not this time anyway.  But somebody sure is...
Sorry, but no, you don't.  Don't feel bad, you're not the first to be lost inside the circle of confusion, and you won't be the last.  Instead of calling people names, you could do some reading on the subject, or simply try going to an online depth of field calculator (such as DoFMaster), pick a focal length, aperture, and subject distance, then without changing any other settings switch back-and-forth between a full frame body and a crop body in the camera selection, and see which one has the shallower depth of field.  Then you can come back here and tell us who looks like what…

What names did I call anyone?

What you are saying, does not make sense with the experience I have had.  For example, a wide angle lens.  How is it that I have to use a smaller aperture on a wide angle lens on a full frame camera, to get the same depth of field, as with an aps-c camera?  For example, a 24mm lens closed to f/5.6 on a full frame camera, has much shallower depth of field on a full frame sensor, as does a 15mm lens closed to the same aperture on a Canon aps-c camera.  You're going to say this isn't true also?

When I look through the viewfinder, even my own eye (which is seeing deeper depth of field than the full frame sensor does)...seems to see far less "deep focus" with say my 58mm Voigtlander f/1.4 lens (even though the angle of view is wider on the full frame)...than it did on the previous crop camera I had.

How is it that a compact camera with a tiny sensor, can get very deep focus (within its angle of view) even when zoomed into a full frame equivalent of 300mm, at an aperture of only say f/6.3...whereas if I put a 300mm lens on my 6D, I need to close it to f/20 or smaller to get a similar "deep focus"??

 

CarlTN

  • Canon EF 300mm f/2.8L IS II
  • *******
  • Posts: 2227
    • View Profile
Re: Crop sensors better than full frame for macro photography?
« Reply #38 on: February 25, 2014, 09:06:04 PM »
If you can get the framing you want with the lens you have with either camera the FF camera will give you the better image. You will have more pixels on target and any adjustment needed to match dof because the camera is closer can be done with iso for a neutral noise and dof equation.

Who's calling names now?  You're calling me ignorant, and you're also falsely accusing me of shouting at the top of my lungs....THIS IS SHOUTING DUDE...not this...

You can't actually get more pixels on subject if the pixel count is the same, as in a 70D vs 6D, both have 20 MP.  22 MP isn't that much more pixels...and in any case I have my doubts at your prowess of being a macro photographer.  Is that supposed to be your specialty?  If so I wasn't aware of it.

neuroanatomist

  • CR GEEK
  • ********
  • Posts: 14391
    • View Profile
Re: Crop sensors better than full frame for macro photography?
« Reply #39 on: February 25, 2014, 09:21:47 PM »
What names did I call anyone?

Insult by implication is still insult. 

On the off chance that you're actually interested in the understanding the relevant concepts...

What you are saying, does not make sense with the experience I have had.  For example, a wide angle lens.  How is it that I have to use a smaller aperture on a wide angle lens on a full frame camera, to get the same depth of field, as with an aps-c camera?  For example, a 24mm lens closed to f/5.6 on a full frame camera, has much shallower depth of field on a full frame sensor, as does a 15mm lens closed to the same aperture on a Canon aps-c camera.  You're going to say this isn't true also?

If you're comparing a 24mm lens on FF to a 15mm lens on APS-C, of course the DoF will be deeper with APS-C at the same aperture.  The shorter focal length means less subject magnification, it's the same as increasing the distance in term of effect on DoF.

When I look through the viewfinder, even my own eye (which is seeing deeper depth of field than the full frame sensor does)...seems to see far less "deep focus" with say my 58mm Voigtlander f/1.4 lens (even though the angle of view is wider on the full frame)...than it did on the previous crop camera I had.

First off, your viewfinder is showing you the DoF of ~f/2.5-2.8 with the stock viewfinder.  You only see the true DoF of faster lenses if you have installed an appropriate focusing screen (such as the Eg-S). 

But while I know the technical reasons for what you should be seeing, I really have no idea what you're actually seeing…  If I had to guess, you're comparing the same framing - being further away with APS-C means deeper DoF.

How is it that a compact camera with a tiny sensor, can get very deep focus (within its angle of view) even when zoomed into a full frame equivalent of 300mm, at an aperture of only say f/6.3...whereas if I put a 300mm lens on my 6D, I need to close it to f/20 or smaller to get a similar "deep focus"??

Focal length again.  When 'zoomed into a full frame equivalent of 300mm,' what's the real focal length of the lens?  For example, if that compact camera is the SX50, the FF equivalent of 300mm is a real 53mm lens.  The DoF is determined by the actual focal length of the lens, not the FF equivalent of that focal length.  Compare the DoF of a 50mm lens on your 6D with a 300mm lens on your 6D, at the same subject distance.  Which has the deeper DoF?
EOS 1D X, EOS M, and lots of lenses
______________________________
Flickr | TDP Profile/Gear List

Hillsilly

  • 1D Mark IV
  • ******
  • Posts: 760
    • View Profile
Re: Crop sensors better than full frame for macro photography?
« Reply #40 on: February 25, 2014, 11:23:15 PM »
....At this point I feel the duty to summarize my learnings from your posts...

That's a good summary.  Overall, it is difficult to argue that crop sensors will produce a better image than a full frame sensor.  But given that we're on page 3 with vocal proponents on each side and the "Full Frame vs Crop Sensor" topic is up to page 13, you could take that to mean that a crop sensor will produce excellent results and that you will probably only notice a difference if comparing two images side by side.  In the real world, where an image stands on its own, a crop sensor produces images that are more than acceptable to everyone.
1000FN | 7E | 3000 | 3 | LS-100TS

Marsu42

  • Canon EF 400mm f/2.8L IS II
  • *******
  • Posts: 4527
  • ML-66d / 100L / 70-300L / 17-40L / 600rts
    • View Profile
    • 6D positive spec list
Re: Crop sensors better than full frame for macro photography?
« Reply #41 on: February 26, 2014, 01:28:02 AM »
I suspect what Marsu42 is referring to is the decrease apparent aperture, the light loss you get as magnification increases.

Indeed, but it's not "apparent" but for real, unlike Nikon Canon just chose to hide the fact that a f2.8 lens @1:1 doesn't get f2.8 light through anymore... that's why the shutter speed gets longer like by black magic. I just read up about it again, it's called "effective f-stop": http://www.cambridgeincolour.com/tutorials/macro-lenses.htm

There's no 'magic number' for that, there's no 'macro mechanism'

Imho there is, it's the "extension" that only a real macro lens has.

At 0.2x mag you lose ~0.67-stops of light, at 0.5x mag you lose ~1.33-stops, and at 1x you lose ~2-stops.

Ah, thanks, that were exactly the numbers I was looking for. Now I'd only need to calculate how much effective f-stop difference there is for crop vs. ff for some scenes, but what you wrote indicates ff still has a slight advantage, though to a much smaller degree than at non-macro distances. But *plus* you still need a smaller aperture to get a usable dof, so that means even higher iso on ff for the same framing.

That, the dr loss at the higher iso for ff, the working distance & swivel screen still make me use the 60d :-)

CarlTN

  • Canon EF 300mm f/2.8L IS II
  • *******
  • Posts: 2227
    • View Profile
Re: Crop sensors better than full frame for macro photography?
« Reply #42 on: February 26, 2014, 01:40:25 AM »
Insult by implication is still insult. 

What the hell?  Um, Dr. John…you of all people should know you’re guilty of the above, especially in my case (but in the case of most people you get on your high horse with on here), if not outright insults…many many times over on this forum.  So let’s call a spade a spade.  People in glass houses…Mr. "I'm so smart I will make a cartoon character out of you in pink tights, but no that is not an insult, because I said so, and I own this website".


First off, your viewfinder is showing you the DoF of ~f/2.5-2.8 with the stock viewfinder.  You only see the true DoF of faster lenses if you have installed an appropriate focusing screen (such as the Eg-S). 

But while I know the technical reasons for what you should be seeing, I really have no idea what you're actually seeing…  If I had to guess, you're comparing the same framing - being further away with APS-C means deeper DoF.

I know the reason too, and it's not all that technical.  The reason I'd need a focusing screen, is because my pupil is much smaller than the sensor.  Sure there is more to it than that (the path reflected through the prism and magnified by the eyepiece, etc)...but that's the gist of it. 

In any case, my original point is something you have done your best to ignore.  I was not arguing so much that equal framing with the two sensor sizes would produce superior results with a crop sensor.  I was arguing that you get more effective magnification due to the smaller pixels of the crop sensor...WITH THE SAME LENS and same distance to the subject.  I.E., regardless of whether the framing is "ideal" with either sensor size...just given the same lens...one that perhaps cannot focus on a subject that is touching the front lens element...but rather needs inches or a foot or three distance from the element.
« Last Edit: February 26, 2014, 01:43:15 AM by CarlTN »

canon rumors FORUM

Re: Crop sensors better than full frame for macro photography?
« Reply #42 on: February 26, 2014, 01:40:25 AM »

faustino

  • Power Shot G16
  • **
  • Posts: 18
    • View Profile
Re: Crop sensors better than full frame for macro photography?
« Reply #43 on: February 26, 2014, 03:19:38 AM »
==> The advantage of crop camera would be only in pixel count, which is a questionable advantage.

Questionable how?  Not from the standpoint of putting pixels on the subject.  50MP vs. 22 is quite a difference.

I agree, it is not that much questionable. I changed my mind about this specific point, and changed my previous post accordingly.

There is only one consideration about pixel count that I believe should be taken in account:
at higher ISO, considering current sensor technology, lower pixel count sensors produce better images than higher pixel count sensors.

wsheldon

  • EOS M2
  • ****
  • Posts: 150
    • View Profile
    • sheldon-photo
Re: Crop sensors better than full frame for macro photography?
« Reply #44 on: February 26, 2014, 08:20:21 AM »
==> The advantage of crop camera would be only in pixel count, which is a questionable advantage.

Questionable how?  Not from the standpoint of putting pixels on the subject.  50MP vs. 22 is quite a difference.

I agree, it is not that much questionable. I changed my mind about this specific point, and changed my previous post accordingly.

There is only one consideration about pixel count that I believe should be taken in account:
at higher ISO, considering current sensor technology, lower pixel count sensors produce better images than higher pixel count sensors.

True, but we're talking about macro here where tripods and low ISO are the order of the day. At ISO 100 I'm very happy with the IQ of the 15MPx covering the subject from my 50D at 100mm, and the extra working distance compared to my 6D is extremely helpful when shooting critters and flowers.
Canon 6D & 50D, nice set of lenses

canon rumors FORUM

Re: Crop sensors better than full frame for macro photography?
« Reply #44 on: February 26, 2014, 08:20:21 AM »