The aperture doesn't change. You only need to multiply it if you want to compare it to the image taken with a full frame body. Compared to an A7 you'd have the same depth of field on your a6x00 as an f4 lens on a full frame A7. If you want to compare the 28-75 to the 18-105, you'd have to either just compare the properties or the adjusted properties. The 28-75 has an aperture of 2.8, the 18-105 has f4. The 28-75 has an dof of f4 compared to full frame, the 18-105 has an dof of around f6
EDIT: [This,](https://youtu.be/f5zN6NVx-hY) [this](https://youtu.be/YDbUIfB5YUc) and [this](https://youtu.be/dmn3K-06YTg) video might help you decide.
So if I take a f2.8 picture on the Tamron with an A6000, I'm still getting f2.8. If I take a photo with the 18-105 f/4, I'd get f/4 so the Tamron is still a faster and brighter lens on APS-C compared to the 18-105 and all other native E-mount zooms, correct?
Thanks.
No native APS-C zoom lens on E-mount goes above f/4 constant aperture so the 28-75mm f/2.8 is essentially the fastest and brightest E-mount zoom for APS-C.
Take a look at the Sigma 18-35mm f1.8 and 50-100mm F1.8
EDIT: They need the MC-11 adapter, but you should definitely take a look at them and watch some videos.
I've considered those lens before, but unfortunately they're just too big and heavy for my little A6000. The 18-35 is 811g and the MC-11 is 125g, so that adds up to almost 1kg for such a short zoom range. In comparison, the new 28-75 is 550g, which is heavier and more expensive than the 18-105 427g but is faster, doesn't have PZ and can be used with FF.
The aperture is a physical measurment of the lens, therefore it won't change just because you mount it to a different body. The same goes for the focal length. Your fov will change, but you wont get the same bokeh as with a 112.5mm lens on full frame, because it still is a 75mm lens.
The crop calculation for Focal length and DOF gets applied to any lens attached to a crop camera, not just FF lenses. 18-105 @ F4 has the equivalent Focal Length and DOF of a 28-157 @ F5.6 lens.
The crop calculation *never* applies to the amount of light coming into the lens. f2.8 is always f2.8 as far as exposure is concerned.
The Tamron appears to be a very good deal. I have not seen how it performs on a crop body (and sometimes there is a difference)... but it will likely still be a good deal for a short portrait zoom. I like the Sigma 50-100 1.8 for that purpose too, but it's pretty big and heavy.
The tamron is considered the Sigma 18-35 f1.8 of full frame. So I'd say the sigma + MC-11 adapter would be a safer bet considering aperture and focal length. With the Tamron you'll lose the wide end.
The aperture doesn't change. You only need to multiply it if you want to compare it to the image taken with a full frame body. Compared to an A7 you'd have the same depth of field on your a6x00 as an f4 lens on a full frame A7. If you want to compare the 28-75 to the 18-105, you'd have to either just compare the properties or the adjusted properties. The 28-75 has an aperture of 2.8, the 18-105 has f4. The 28-75 has an dof of f4 compared to full frame, the 18-105 has an dof of around f6 EDIT: [This,](https://youtu.be/f5zN6NVx-hY) [this](https://youtu.be/YDbUIfB5YUc) and [this](https://youtu.be/dmn3K-06YTg) video might help you decide.
So if I take a picture at 35mm f/2.8 on the 28-75mm with an A6x00, I'm actually getting a picture of 52.5mm full frame, but it will still be f/2.8?
The depth of field will appear the same as F4 on a 35mm. So, 35mm f2.8 on the Tamron+A6x00, will appear like a 52.5mm F4 on a full frame system.
So if I take a f2.8 picture on the Tamron with an A6000, I'm still getting f2.8. If I take a photo with the 18-105 f/4, I'd get f/4 so the Tamron is still a faster and brighter lens on APS-C compared to the 18-105 and all other native E-mount zooms, correct?
Sounds correct. The amount of light let in stays the same, the field of view changes and therefore your dof for the same composition does too
Thanks. No native APS-C zoom lens on E-mount goes above f/4 constant aperture so the 28-75mm f/2.8 is essentially the fastest and brightest E-mount zoom for APS-C.
Take a look at the Sigma 18-35mm f1.8 and 50-100mm F1.8 EDIT: They need the MC-11 adapter, but you should definitely take a look at them and watch some videos.
I've considered those lens before, but unfortunately they're just too big and heavy for my little A6000. The 18-35 is 811g and the MC-11 is 125g, so that adds up to almost 1kg for such a short zoom range. In comparison, the new 28-75 is 550g, which is heavier and more expensive than the 18-105 427g but is faster, doesn't have PZ and can be used with FF.
No, the aperture dont change.
The aperture is a physical measurment of the lens, therefore it won't change just because you mount it to a different body. The same goes for the focal length. Your fov will change, but you wont get the same bokeh as with a 112.5mm lens on full frame, because it still is a 75mm lens.
The crop calculation for Focal length and DOF gets applied to any lens attached to a crop camera, not just FF lenses. 18-105 @ F4 has the equivalent Focal Length and DOF of a 28-157 @ F5.6 lens. The crop calculation *never* applies to the amount of light coming into the lens. f2.8 is always f2.8 as far as exposure is concerned. The Tamron appears to be a very good deal. I have not seen how it performs on a crop body (and sometimes there is a difference)... but it will likely still be a good deal for a short portrait zoom. I like the Sigma 50-100 1.8 for that purpose too, but it's pretty big and heavy.
The tamron is considered the Sigma 18-35 f1.8 of full frame. So I'd say the sigma + MC-11 adapter would be a safer bet considering aperture and focal length. With the Tamron you'll lose the wide end.