newbie SL3 questions

[DOUGWOLF]

Hello, I am a veteran VFX artist just starting out in shooting video. I have a Canon SL3 and was hoping someone could answer some (I hope) basic questions for me.

1. I have a 50mm lens and an 18-55mm lens and a 55-250mm lens, all Canon. I got a K&F variable ND filter to learn how best to use it in different situations. I found that the filter fits perfectly on the 18-55 and the 55-250, but wont fit on the 50. Am I missing something?

2.  When using the 50 mm lens, indoors for video I have very little problem setting the correct Fstop, white balance, ISO  etc to get the depth of field and look I want. But when I go outside, everythig is blown out white unless I go to the highest F stop, thus negating any DOF I would want. I have run up and down the scales on ISO, Fstop, white balance, etc and nothing seems to work to get and DOF which I can easily get indoors. Again, am I missing something?

Thank so much for any help.

[kvbarkley]

That is the point of the ND filter, to lessen the amount of light getting into the lens to allow for wide apertures in bright light.

You are not giving us enough info to say exactly what lenses you have but a quick glance for typical lenses shows that the 50 mm will have a 52 mm size filter ring while the 18-55 and 50 - 250 will have 58 mm. Filter ring sizes vary all over the place, there is no standard size.

[DOUGWOLF]

Gotcha.  Thank you for the info.

[rs-eos]

A very useful rule of thumb to learn is the 'Sunny 16' rule.  On a clear sunny day, an exposure within a proper ballpark is obtained with ISO 100, 1/100 (or 1/125) second, and f/16.

For video, a common setting to use is a shutter that's double the frame rate.  Assuming you're shooting at 30 fps, a shutter of 1/60 would be good.  So a "video sunny 16" would now need to be at f/22.

In order to open up the aperature, you'd use 3-stop, 6-stop or variable ND as you have.  e.g. a 6-stop ND would allow you to open up to f/2.8 (assuming ISO 100 and 1/60 shutter).

For the filter... as mentioned above, filter sizes are all over the map.  However, if your 50mm lens works with filter sizes  smaller than your K&F ND filter, you can pick up step-up adapters.   But this is only when going from small to large; not the other way around.   Pros is that you can save some cash.  Cons is that such a setup may interfere with lens hoods.  May also cause more vignetting.

[DOUGWOLF]

Great info! Thanks so much.

[kvbarkley]

Pedantic point of order. You want to use a shutter that is *half* of the frame rate, not double. 1/60 is half of 1/30.

[Waddizzle]

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@kvbarkley wrote:

Pedantic point of order. You want to use a shutter that is *half* of the frame rate, not double. 1/60 is half of 1/30.

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If you were shooting at 1/30 shutter speed, and someone said you need to "double your shutter speed", how fast would that be?

[kvbarkley]

1/15 of course. If you were at f/11 and someone said, "You need to double your aperture." what would you set it to?

Reciprocals are hard. 8^)

[Waddizzle]

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@kvbarkley wrote:

1/15 of course. If you were at f/11 and someone said, "You need to double your aperture." what would you set it to?

Reciprocals are hard. 8^)

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Shutter speed describes a unit vector.  At 1/15 of a second, did you double your speed, or did you double the period?

It I am traveling at 30 mph, doubling my speed would mean traveling at 60 mph.  Or, if I were traveling at 30 miles per second, doubling my speed would mean I am traveling at 60 miles per second.  Still with me?

At 30 miles per secon, the one mile unit vector is 1/30 of a second.  At double the speed, 60 miles per second, the one mile unit vector is 1/60 of a second.  Still with me?

[Ray-uk]

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@kvbarkley wrote:

 If  someone said, "You need to double your aperture." what would you set it to?

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This question only confuses many people because they don't differentiate between aperture and f number. Doubling an f number results in a smaller aperture, doubling an aperture results in a smaller f number.