Amateur Question: Full Frame vs Crop Sensor

[Marcepstein]

I thought I had read a thread here recently about the difference between full frame vs crop sensors for macro photography but can’t seem to find it. Rik suggested I start a new thread for discussion. I’m considering upgrading my Canon 1DM4 (1.3x crop, APS-H sensor) to a newer body for macro but not for micro. I had read an article or some discussion about the advantages/disadvantages of full frame vs crop sensors for Macro. I seem to recall discussion about more light needed to cover the larger FF sensor, better suited with FF lenses and cropping reducing pixel density. I think the conclusion of the thread was the crop sensor was probably better in the long run but could not find the thread again to confirm.

I was looking at a Canon R7 but a friend suggested a R6 might be better, or the 5D Mark 4. I just have 2 macro lenses; an EOS ef100mm f2.8 L and the EOS MP-e65 f2.8 1-5x, also extension tubes and teleconverter. The bodies are within the same price range + on ebay. Im not planning on upgrading my ef lenses.


Im leaning more towards the R7 because its a newer system or the 5D for image quality. The R7 (APS-C sensor & 1.6 crop factor) has EFCS and the 5D has silent mode (full-frame CMOS sensor & mirror lockup continuous shooting).

Any thoughts would be much appreciated.
Marc

[chris_ma]

hi Marc,

it probably depends on your preferences and shooting style.

for maximum image quality, FF (and larger) still gives a benefit over APS, but things get heavier and more costly, and there's diminishing returns because you're fighting depth of field and diffraction.

there's also the question if you'd like to have features like in body stacking etc.

personally if I'd have to get maximum image quality on a budget, I'd probably get a used Sony A7rII, and I'd definitely upgrade your lenses to a laowa 100mm 2x and a laowa 25mm 2.5-5x

but maybe best if you describe a bit what your typical subjects, shooting scenarios and image preferences are and what you're planning to do with the images afterwards.

[bbobby]

My 2 cents... if the choice is between R7 and 5Dm4 you probably will be wiser to spend the money on newer system.

As a general rule the smaller sensor is losing some dynamic range and noise levels are higher - this is for sensors made with the same technology. But difference is not really so big and may not be a real issue for most people. I am not familiar with R7 maybe it is with newer sensor and the technology could narrow or completely eliminate the difference. And there are ways around these obstacles, especially in studio settings.

In macro DOF and diffraction are almost always an issue... and the framing difference (for the same field of view) between full frame and crop sensor will be a plus for the crop.

At about the same pixel count crop sensor will have more pixels per area so it can capture more details.

Another plus for the crop is that you will be using only the central portion of the full frame lenses - less vignette, less distortion, more sharpness...

I am guessing here (and you have to check) but R7 should be smaller and lighter - no mirror and crop sensor are the clues here - which is preferable in most cases.

Electronic viewfinder will allow for better focusing.

In-body stabilization if you do not always use tripod is a blessing too.

If R7 have fully electronic shutter mode - meaning no use of the mechanical one in this mode - this is also in most cases a plus: no vibrations, no wear and tear, faster frame rate.

If you do not plan to make enormous prints (enlarging image from R7 20 times will give you 12"x17" print at 300 dpi and you will need to enlarge the image from full frame only 13 times for the same size print) or if you do not really need better battery life of DSLR I see no reason to chose 5DM4.

Now if you have the inclination to go with full frame mirrorless Sony (like 7RIII or 7RIV), maybe it will be another story, especially if you are fan of the pixel shift technology and looking for more quality. You will need adapter for Canon lenses, of course, but you will need one for R7 anyway to mount EF lenses...

[Lou Jost]

Also, what is the focus of your non-macro photography? If you are doing astrophotography, for example, you'd be best served by FF rather than APS, because for the same field of view and exposure, the FF camera captures about twice as much light, so it has lower noise than APS.

[Marcepstein]

Thanks for the questions and discussion, it’s very helpful.

My photography style - photography as art with emphasis on nature and biology (if that’s a style?)

Image stacking in the new bodies - sure but I also just received a CamRanger Mini that has that feature. There are not many used R7’s on eBay but many 5DM4’s. So I agree the newer bodies would be wise.

I’ve had Olympus, Nikon and presently Canon. If I was starting over I’d go with Sony. But I see what you are saying from a budget standpoint. Something to consider.

I’ll take pictures of almost anything but lean towards biological subjects, studio or outdoors. I’ll keep the 1DM4 for wildlife, landscape, family images. Image quality is a priority. Images will probably just be amateur-hobby oriented. Macro photography is very challenging- I like it.

Hope that helps.

[rjlittlefield]

Image quality is a priority.

I'm curious, what do you mean by those words "image quality"?

The reason I ask is that for most purposes the only advantage of a larger sensor is that it can give less pixel noise, but only if you fill up the pixel wells by shooting at base ISO.

If you shoot the FF above base ISO, then you can get the same result on a smaller sensor by tweaking the ISO and aperture settings appropriately.

Does the physical feel of the camera matter to you? That can go either way.

--Rik

[Marcepstein]

I'm curious, what do you mean by those words "image quality"?

The reason I ask is that for most purposes the only advantage of a larger sensor is that it can give less pixel noise, but only if you fill up the pixel wells by shooting at base ISO.

Image quality - better image resolution/detail and visual clarity.... Im presently shooting the 1DM4 at iso 50 to get the best resolution I can squeeze out of it.

Does the physical feel of the camera matter to you? That can go either way.

The 1D is a Tank so a larger body Im used to. I can go with a smaller body and newer feel, either way. The Canon M6ii was also brought to my attention but it may be a little too compact.

[chris_ma]

I'm curious, what do you mean by those words "image quality"?

Image quality - better image resolution/detail and visual clarity....

well, in that case I think it's safe to say that a Sony A7rII with the Laowas I mentioned will easily outperform both, the 5DmkIV and the R7 with your existing lenses.

If the options are strictly 5DmkIV or R7, then with your existing lenses the 5DmkIV has probably a slight edge due to the lenses being too soft for the R7, while with some modern lenses like the Laowas I imagine the difference might be not really significant between the two cameras. In both cases I would go with whatever cameras is more comfortable to use for you since that will be the much bigger factor than differences in image quality.

[Lou Jost]

"The reason I ask is that for most purposes the only advantage of a larger sensor is that it can give less pixel noise, but only if you fill up the pixel wells by shooting at base ISO."

Rik, is that always true? Even though I am a longtime proponent of small sensors for most work, I' now see how useful FF sensors are for astrophotography and other low-light imaging. For a given FOV and aperture the full frame system has much less shot noise than a smaller sensor, and this is especially true when you are not close to filling the wells. Take the extreme case of a standard micro four thirds (MFT) sensor, which is easier to calculate than the odd APS sizes. For fixed aperture and FOV, you need four times as much exposure to get the same noise level in the MFT photo as in the FF photo. When exposures are on the order of hours or days, as in astrophotography, that's huge. For a given FOV and exposure, the MFT photo only uses 1/4 the number of photons as FF. Anyway this is an extreme application, but noise sometimes limits macrophotography too, especially extreme macro or fluorescence photography.

[rjlittlefield]

"The reason I ask is that for most purposes the only advantage of a larger sensor is that it can give less pixel noise, but only if you fill up the pixel wells by shooting at base ISO."

Rik, is that always true? Even though I am a longtime proponent of small sensors for most work, I' now see how useful FF sensors are for astrophotography and other low-light imaging. For a given FOV and aperture the full frame system has much less shot noise than a smaller sensor, and this is especially true when you are not close to filling the wells. Take the extreme case of a standard micro four thirds (MFT) sensor, which is easier to calculate than the odd APS sizes. For fixed aperture and FOV, you need four times as much exposure to get the same noise level in the MFT photo as in the FF photo. When exposures are on the order of hours or days, as in astrophotography, that's huge. For a given FOV and exposure, the MFT photo only uses 1/4 the number of photons as FF. Anyway this is an extreme application, but noise sometimes limits macrophotography too, especially extreme macro or fluorescence photography.

The second part of what I wrote is also important:

If you shoot the FF above base ISO, then you can get the same result on a smaller sensor by tweaking the ISO and aperture settings appropriately.

The "appropriate tweak" is to scale ISO in proportion to the sensor area, and scale effective aperture in proportion to the sensor linear dimension. Do those two things, and you'll capture the same number of photons over the same FOV in the same light intensity in the same time. If you also keep the entrance pupil in the same position (by using a suitable focal length lens), then both sensor sizes end up capturing equivalent images, including same DOF, same diffraction blur, and same amount of shot noise. At same pixel count, you literally cannot tell which size sensor shot each image.

As Lou points out, large sensors do work better for low light imaging. But the fundamental reason for this is not the sensor, it's the lens. At same FOV, the larger sensor demands a longer focal length, and at same f-number, that longer focal length gives a proportionally larger entrance pupil. It's that larger entrance pupil that lets you capture more light in the same time. If you could use the same size entrance pupil with the smaller sensor, then you could get the same result in same time, but for astro this runs into the problem that for example you can buy a suitably sharp 80 mm f/1.8 lens and that just doesn't scale down nicely to 40 mm f/0.9.

So yeah, big sensor allows big entrance pupil allows lower light. It also allows shallower DOF and more blurred backgrounds, which can be important in some cases.

But I don't see any of those issues playing a role in what Marc says he wants to do, hence my comment.

--Rik

[Marcepstein]

I think it is all great information, very educational. I appreciate the helpful comments and discussion.

I looked at the Laowas website and they do have Canon RF mounts for macro lenses among others. Something to consider going forward as I am still leaning towards the R7. I noticed there were several Laowas lenses on Ebay.

Marc

[Adalbert]

Hello Marc,

If I were you, I would go with the R7.
APS-C fits very well with the microscope lenses.
And the fully electronic shutter is perfect for macro/micro photography.

Best, ADi

[blekenbleu]

FWIW, having played with macro, but more with micro and wildlife,
I agree with ADi, particularly if you will continue using those Canon EF lenses.
Be aware that Canon has blocked other lens manufactures from offering autofocus lenses in RF mounts.
Since only a fixed amount of light power comes from any subject,
sensor size matters relatively little, compared to how many pixels are on subjects.
More pixels on subjects allow better filtering, both for noise reduction and antialiasing.
For moving subjects with electronic shutter, faster readout speed reduces rolling shutter distortion.
Readout speed is mostly a matter of pixel count,
but larger sensors for the same pixel count and technology tend to have slower readout.
For sensor stabilization, smaller sensors in larger bodies have an advantage,
which can improve hand-held macro image keeper rate.
Mirrorless camera bodies, with smaller flange to sensor distance,
can more easily be located on some microscopes at their intermediate image plane, preempting photo relay lens.
That intermediate image plan image circle usually better fills APS-C than 35mm sensors.

[Doppler9000]

Another camera to consider is the Fuji X-H2, which offers 40 MP on an APS-C sensor. The X-T5 has the same sensor. Either adds a little more pixel density. You can easily add Canon EF lenses which will autofocus with an appropriate adapter.

[Marcepstein]

Be aware that Canon has blocked other lens manufactures from offering autofocus lenses in RF mounts.

That's a good point. I had forgotten that.