Crop mode

Peter C.

Peter C.

Veteran
Does shooting in crop mode on a full frame camera effect exposure? The A7IV can crop in so I can logically understand that in editing if you cropped only the framing would be effected but on the other hand I thought full frame cameras are better in low light because they are taking in more light due to the larger sensor so that would lead me to believe cropping into the sensor should let in less light… Which is it?
 
Crop mode does not affect exposure. Sometimes things might appear different in brightness because depth of field varies compared to full frame for same field of view when using same f-stop.
 
Peter C. said:
Does shooting in crop mode on a full frame camera effect exposure? The A7IV can crop in so I can logically understand that in editing if you cropped only the framing would be effected but on the other hand I thought full frame cameras are better in low light because they are taking in more light due to the larger sensor so that would lead me to believe cropping into the sensor should let in less light… Which is it?
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The noise in your image will be enlarged when you crop. So, the image will appear noisier. In that sense, you can get away with a higher ISO when using it full-frame mode vs cropped. But the exposure will look identical. And what you see is what you get in terms of increased noise, so it's easy to decide how far you want to push the ISO when you're cropping.
 
That makes sense, Full Frame performs better in low light because it makes noise smaller. I also noticed on a recent shoot I didn't get a shallow dof because I was using crop mode to zoom in more with 20-40mm lens. Which wasn't a bad thing but something to be aware of. I'm still thinking of getting a longer telephoto to compliment that lens. I'm considering the 28-70 sigma because it light, small and relatively cheap although I'm not crazy the wide is only 28mm. There is the Art 24-70 but it's big and heavy.
 
Peter C. said:
That makes sense, Full Frame performs better in low light because it makes noise smaller. I also noticed on a recent shoot I didn't get a shallow dof because I was using crop mode to zoom in more with 20-40mm lens. Which wasn't a bad thing but something to be aware of. I'm still thinking of getting a longer telephoto to compliment that lens. I'm considering the 28-70 sigma because it light, small and relatively cheap although I'm not crazy the wide is only 28mm. There is the Art 24-70 but it's big and heavy.
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I think it's slightly different with a full frame camera compared to a crop sensor camera, vs cropping in on the full frame camera itself. A full frame camera has larger photosites than the crop sensor camera, and I think that's how it achieves a stronger signal to noise ratio at matching ISO, or something like that. But when you crop in on a full-frame camera, you're getting the same signal and noise as you were when using the entire sensor because you're working with the same photosites. It's just that the noise that's there is larger and blockier because you're magnifying the entire image. But you get a similar result either way -- the full-frame camera can go about a stop higher in ISO than a cropped sensor camera or full-frame camera cropped to APS-C.

And then with the DOF, cropping in on the sensor looks exactly the same as using a crop-sensor camera. You would have to back up to get the same framing on the same lens with the crop as you would full-frame. And you get more DOF when focusing farther away. Or however you want to look at it.

What type of lens are you looking for? Something like the 20-40 but with a faster aperture?
 
How I'm using it would result in a shallow dof. For example at the party to achieve closeup shots I would crop in. My current lens is only 40mm on the telephoto side, cropping in gives me 60mm but it still retains dof of a 40mm, but if I got a longer telephoto lens manually zooming in 60mm would result in a shallower dof.
 
Peter is correct. If he can get the same field of view using either a 40mm (and cropping the sensor) or a 60mm then he will get shallower DOF with the 60mm.

Do you have the opportunity to change lenses? I have the tamron 70-180 f/2.8 and it's really sharp and very lightweight for a telephoto and costs about $1k.

if you want a 24-70 f/2.8 that's lightweight then it seems like the Sony gm 24-70 ii is the one to get but it's very expensive. I have the sigma 24-70 f/2.8 and like you said, it's heavy.

The samyang 75 f/1.8 is supposed to be really nice and is very lightweight and inexpensive.
 
ahalpert said:
Peter is correct. If he can get the same field of view using either a 40mm (and cropping the sensor) or a 60mm then he will get shallower DOF with the 60mm.

Do you have the opportunity to change lenses? I have the tamron 70-180 f/2.8 and it's really sharp and very lightweight for a telephoto and costs about $1k.

if you want a 24-70 f/2.8 that's lightweight then it seems like the Sony gm 24-70 ii is the one to get but it's very expensive. I have the sigma 24-70 f/2.8 and like you said, it's heavy.

The samyang 75 f/1.8 is supposed to be really nice and is very lightweight and inexpensive.
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At least for my work I don't need as much reach as the 70-180 and above 70 gets hard to hold steady.
Sony gm 24-70 ii is a dream but cost prohibitive. I'd sooner spend the money on a second camera body

I've narrowed down to
Sigma 24-70 f/2.8 (like you suggested) it's heavy but that might not be a bad thing for steadier hand held filming. I also like 24 on the wide.
Sigma 28-70 is lighter, smaller less expensive ($500) used, and I've read less focus breathing but I don't like 28mm wide. I can use the Tamron 20-40mm for gimbal or when I need the wider angle for 60p crop slowmo.

The fast primes are tempting but in my experience I've seldom used primes for event work they sit on the shelf 99% of the time. Once you get into the flow of an event job you don't want the hassle of caring a fanny pack to keep the lens on you then have to pull off a swap in a crowded venue and risk getting dust on the sensor.
 
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Peter C. said:
Does shooting in crop mode on a full frame camera effect exposure? The A7IV can crop in so I can logically understand that in editing if you cropped only the framing would be effected but on the other hand I thought full frame cameras are better in low light because they are taking in more light due to the larger sensor so that would lead me to believe cropping into the sensor should let in less light… Which is it?
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No light loss. The same amount of light is arriving at each photo site whether you are using one pixel, crop or all of them in FF. The lens I'm finding incredibly versatile as a one lens solution in both full frame and crop on the A7iv is the Sony 24-105 mm. In crop mode, that becomes a 36-158 mm lens. Add Sony's Clear Image Zoom, which goes up to 2 x, and you effectively have a 72-316 mm lens which is a constant F/4.0 regardless of what zoom length you are using. Most importantly, the lens has OIS and on top of that with a very slight crop it has Active Stabilization. With OSS and IBIS combined, this lens can be held very steadily at quite long zoom lengths. The fact that it uses Sony's breathing compensation feature on the A7iv is also a plus. It's also sharp. $$$ value for performance, it's a pretty hard combo to beat. Check out a really comprehensive real world experience with some samples using this 24-105 mm lens. YT link below.

Sure, everyone raves on about it's not F/2.8. When you really analyse the facts and figures of F/2.8 vs F/4.0 with modern high sensitivity cameras, where at F/4.0 you can get the same depth of field but at slightly, and I mean slightly longer distances, the question is quite moot in my mind. The extra zoom reach flexibility along with lens OSS working in conjunction with IBIS far outweighs the sole advantage of F/2.8 on a non-stabilized lens. In fact, for interviews on the 24-105 mm I'm getting less DOF at F/4.0 at 2 meters where the DOF is 0.08 of a meter up against my F/2.8 Tamron 28-75 mm which at 70 mm at 2 meters is delivering a DOF of 0.13 meters.

Regarding the quality difference in crop mode and FF on the A7iv it's virtually indistinguishable. Unless you are an absolute pixel peeper!

Chris Young

DOF table 2.8 vs 4.0

70 mm f2.8 @ 2.0 meters DOF = .13 meter
70 mm f2.8 @ 2.5 meters DOF = .21 meter
70 mm f2.8 @ 3 meters DOF = .31 meter

70 mm f4.0 @ 2.0 meters DOF = .19 meter
70 mm f4.0 @ 2.5 meters DOF = .30 meter
70 mm f4.0 @ 3 meters DOF = .43 meter

105 mm f4.0 @ 2 meters DOF = .08 meter
105 mm f4.0 @ 2.5 meters DOF = .13 meter
105 mm f4.0 @ 3 meters DOF = .19 meter

 
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Peter C. said:
At least for my work I don't need as much reach as the 70-180 and above 70 gets hard to hold steady.
Sony gm 24-70 ii is a dream but cost prohibitive. I'd sooner spend the money on a second camera body
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I think that if I were you, I would buy the sigma 28-70. In many situations, it's going to be all you need. For some scenarios, such as following people through hallways and elevators, you may choose to use the 20-40 instead.
 
Peter C. said:
That makes sense, Full Frame performs better in low light because it makes noise smaller. I also noticed on a recent shoot I didn't get a shallow dof because I was using crop mode to zoom in more with 20-40mm lens. Which wasn't a bad thing but something to be aware of. I'm still thinking of getting a longer telephoto to compliment that lens. I'm considering the 28-70 sigma because it light, small and relatively cheap although I'm not crazy the wide is only 28mm. There is the Art 24-70 but it's big and heavy.
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In terms of DOF, using crop mode will be the same as changing to an equivalent longer lens (assuming that distance to subject remains the same).
 
cyvideo said:
With OSS and IBIS combined, this lens can be held very steadily at quite long zoom lengths. The fact that it uses Sony's breathing compensation feature on the A7iv is also a plus. It's also sharp. $$$ value for performance, it's a pretty hard combo to beat. Check out a really comprehensive real world experience with some samples using this 24-105 mm lens.
Click to expand...

The 24-105 is an excellent lens and the lack of IBIS on the FX6 means I rarely use anything else for doc work. I wish it was wider though. I'd sell my left earlobe for a version of the new Sony 20-70 f/4 with OSS. I can use crop mode and Clear Image Zoom if I need to go longer in an emergency and I've got longer, prettier lenses for interviews anyway.

In short, I can't fault your reasoning about the utility of crop mode and CIZ but my conclusions are different. If we can easily hack together a narrower field of view (with an amazing lack of visual compromise) then a 2023 midrange zoom should be wider than 24mm.
 
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Thanks for the suggestions. The 24-105 was on my list it can be had for around $650 used. I’ve used it in the past and was happy with it’s versatility and relatively light weight. The f4 isn’t an issue and sometimes a benefit with more DOF latitude when zoomed in. It’s not perfect in low light contrast situations…

I’m leaning towards the Sigma 24-70 I rather have the extra stop of light but the 24-105 is worthy option. I’d prefer the contemporary form factor but 28 isn’t wide enough.
 
Holy smokes -- Tamron is coming out with a 20-50mm f/2. I don't know how heavy it will be (though I bet it's less heavy than the sigma 24-70) and I don't know how much it will cost (probably around $1k I'm guessing). But that sounds like it would be a great lens for you. It can widen out to 20, you get extra light-gathering power and shallower DOF. And then if you need to crop in, you're going to end up with the same DOF and about the same noise level as if you were using the sigma 24-70 at 70 uncropped. This is a best of both worlds lens

https://www.sonyalpharumors.com/lea...tamron-20-50mm-f-2-0-full-frame-e-mount-lens/
 
ahalpert said:
Holy smokes -- Tamron is coming out with a 20-50mm f/2. I don't know how heavy it will be (though I bet it's less heavy than the sigma 24-70) and I don't know how much it will cost (probably around $1k I'm guessing). But that sounds like it would be a great lens for you. It can widen out to 20, you get extra light-gathering power and shallower DOF. And then if you need to crop in, you're going to end up with the same DOF and about the same noise level as if you were using the sigma 24-70 at 70 uncropped. This is a best of both worlds lens

https://www.sonyalpharumors.com/lea...tamron-20-50mm-f-2-0-full-frame-e-mount-lens/
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Interesting. I already have the 20-40 but I agree if it's not too big also another excellent candidate. Dam too many options!
 
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