Aug 20, 2017
Hey folks,

Can i get some help here, i got a Canon 77D last week and Panasonic G7 last month but i want a better lens for both. Which lens should i buy for each or any lens that will work for both. I want 2 lenses with f1.7 or lower but it doesn't have to be zoom, i want them for mostly videos but they must have good low light and good video quality. I know about the Panasonic 25mm f1.7 that cost $148 on Amazon but i don't want it because the zoom is a lot for my needs, i want lenses that's between 10mm to 16mm with f1.7 or lower. Any lenses that cost $400 or lower?
First, those two cameras use different sensor sizes so their focal lengths are not comparable. The G7 uses a four-thirds sensor which is roughly half the size of 35mm film (which is actually 24x36mm) and yields a 2.1x focal multiplier (frequently rounded down to 2x by marketing). The 77D uses an APS-C sensor which yields a 1.61x focal multiplier (rounded down to 1.6x by marketing). So the focal length range you've listed is not comparable.

  • ■10mm on the G7 is equivalent to 21mm on full frame. 10mm on the 77D is equivalent to 16mm on full frame.
    ■17mm on the G7 is equivalent to 36mm on full frame. 17mm on the 77D is equivalent to 27mm on full frame.
Or put another way

  • ■10-17mm on the G7 is equivalent to 13-22.5mm on the 77D.
    ■10-17mm on the 77D is equivalen tto 7.6-13mm on the G7.
Second, you're splitting hairs with respect to aperture.

  • ■f/1.4 to f/2.0 is a full stop. A 1/60 sec exposure at f/1.4 becomes 1/30 sec at f/2.0.
    ■f/1.7 to f/1.8 is 0.12 stops. A 1/60 sec exposure at f/1.7 becomes 1/54 sec at f/1.8.
    ■f/1.4 to f/1.7 is 0.47 stops. A 1/60 sec exposure at f/1.4 becomes 1/41 sec at f/1.7.
    ■f/1.4 to f/1.8 is 0.65 stops. A 1/60 sec exposure at f/1.4 becomes 1/36 sec at f/1.8.
So there's very little difference between f/1.7 and f/1.8, and you're eliminating a lot of good f/1.8 lenses by arbitrarily setting f/1.7 as your limit. If you're serious about going wider than f/1.8, your target should be f/1.4 lenses.

Third, because the 77D's sensor is physically larger (22.3 mm x 14.9mm) than the G7's (17.3mm vs 13mm), at the same exposure, shutter speed, and video resolution, you should expect the 77D to produce cleaner output (less noise) in low light. Basically, at 1920x1080 resolution, the virtual pixels on the 77D are larger, so have more light to work with than the virtual pixels on the G7. So even when both cameras have the same exposure (same amount of light per square mm of sensor), the 77D's pixels are getting more light per pixel, and it should generate the cleaner image.

If you're serious about this, you should conduct your own tests with both cameras side-by-side in low light at the same exposure settings (doesn't have to be f/1.7 for the comparison, just make sure the ISO, shutter speed, and apertures for the two are the same). Then compare the image quality. If I'm right and the 77D's output is cleaner, crank down its exposure (keep the shutter speed the same, stop down the lens to a higher f-ratio, increase ISO to maintain image brightness). When you judge low light video quality to be the same on both cameras, compare the two f-ratios. That'll give you an equivalent f-ratio for the two cameras (for producing same-quality low-light video). e.g. If the 77D's video at f/3.5 matches the G7's video at f/2.8, then f/1.7 on the G7 is equivalent to (1.7)*(3.5)/(2.8) = f/2.1 on the 77D.


Lenses faster than F1.8 are expensive. You could get a Canon 50mm F1.4 for about $300+, that will be your cheapest fast lens. A 10 to 16mm lens for a 77D would be a VERY wide angle lens and probably have some barrel distortion.
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