So I've been reading a lot on this forum to improve the quality of my pictures. Of course, shooting RAW is a no brainer. Also read about the bracketing to create good HDR shots. That's all great. What I am more concerned about is to have the focus right. Switched to MF yesteday, and I have to admit the macro to infinity wheel is kinda confusing. So I wanted to see if someone finally nailed it to find the hyperfocal distance. Also, best procedure to get it?

Oh, and would you leave the ND filters on for a picture? CP, ND8, ND16..

Don't know the hyperfocal distance but why do you need it? Use AF for your footage and you should be good to go. Just re-focus before you take the shot.

CP is a great filter and you can use it for photos - but - you need the right angle to the sun to take advantage of the CP effect. If you want to take long exposure than you can use the ND for photos. But normally you didn't need NDs for photos because you can adjust the exposure with shutter speed. (not really possible in video because you have a fixed shutter speed)

Sorry, I haven't calculated the exact hyperfocal distance. But with the small sensor and short 4.7mm focal length of the lens, the depth of field is HUGE. The exact value of hyperfocal distance depends on how you define the "circle of confusion" (how sharp is needed). But I would say you can focus at 5m (and probably closer) and get everything sharp from a bit closer and until infinity.

In practice for video I use autofocus (but importantly with AFC off) and just focus at the shortest distance I expect to need anything sharp (usually that is no closer than 5m) in the beginning of my recording. I will have everything sharp in my video then.

For photography, I just (auto)focus at the closest object I need to have sharp before shooting.

No need for trouble using manual focusing as long as AFC (continuous focusing) is off.

You have to focus on something VERY CLOSE before you get in trouble with distant objects.

StigNygaard Posted at 2017-6-15 07:17
Sorry, I haven't calculated the exact hyperfocal distance. But with the small sensor and short 4.7mm focal length of the lens, the depth of field is HUGE. The exact value of hyperfocal distance depends on how you define the "circle of confusion" (how sharp is needed). But I would say you can focus at 5m (and probably closer) and get everything sharp from a bit closer and until infinity.

In practice for video I use autofocus (but importantly with AFC off) and just focus at the shortest distance I expect to need anything sharp (usually that is no closer than 5m) in the beginning of my recording. I will have everything sharp in my video then.

Thank you for this. So let's say I'm up in the air (125m) and want to do a landscape shot. How do I focus on something at 5m?

dimgo Posted at 2017-6-15 06:56
Don't know the hyperfocal distance but why do you need it? Use AF for your footage and you should be good to go. Just re-focus before you take the shot.

CP is a great filter and you can use it for photos - but - you need the right angle to the sun to take advantage of the CP effect. If you want to take long exposure than you can use the ND for photos. But normally you didn't need NDs for photos because you can adjust the exposure with shutter speed. (not really possible in video because you have a fixed shutter speed)

Shouldn't a ND16 help when the sun is out and bright just to make sure it doesn't end up overexposed and crushed details?

vinnyhofx Posted at 2017-6-15 07:44
Thank you for this. So let's say I'm up in the air (125m) and want to do a landscape shot. How do I focus on something at 5m?

I don't see why you would want to focus on something 5m away if you are 100m up in the air? Just focus on the ground, you don't need the hyperfocal distance for anything if you don't have anything very close in your landscape shot.

Hyperfocal distance is a focus-distance used when you want to have the largest possible depth of field. Ie., you want both near and far subjects to be sharp at the same time. If you only have far objects in your shot, just focus on a far object.

If you don't need anything closer than at X meters distance to be sharp, there's no need to have focus at closer distance than X meter.

vinnyhofx Posted at 2017-6-15 07:45
Shouldn't a ND16 help when the sun is out and bright just to make sure it doesn't end up overexposed and crushed details?

No, ND filters are not meant to be about how bright your image should be. You can adjust the exposure for that. In automatic exposure mode, use the EV control to brighten or darken image.

ND filters is to "smoothen" your video by using longer exposure-times for each frame. A rule of thumb for cinematic look, is that the shutter should be open 50% of the time. That means as for 30fps video you aim for 1/60s exposure time pr. frame. In other words: Yes, ND filters blocks some light, but the idea is that you extend the exposure to compensate for that (using longer exposure time). So ND filters (used this way) doesn't change the brightness of your footage, but introduce some motion blur in each frame making the final video look more smooth. If you are using automatic exposure, the camera will automaticly compensate for the light the ND filters "steal" by chosing a longer exposure time for each frame.

Normally you will avoid using ND filters for photography.

I can add that there's a lot of misleading "experts" posting instruction or test videos on YouTube, who clearly hasn't understood the purpose of using ND filters for video. So I understand the confusion.

StigNygaard Posted at 2017-6-15 08:42
No, ND filters are not meant to be about how bright your image should be. You can adjust the exposure for that. In automatic exposure mode, use the EV control to brighten or darken image.

ND filters is to "smoothen" your video by using longer exposure-times for each frame. A rule of thumb for cinematic look, is that the shutter should be open 50% of the time. That means as for 30fps video you aim for 1/60s exposure time pr. frame. In other words: Yes, ND filters blocks some light, but the idea is that you extend the exposure to compensate for that (using longer exposure time). So ND filters (used this way) doesn't change the brightness of your footage, but introduce some motion blur in each frame making the final video look more smooth. If you are using automatic exposure, the camera will automaticly compensate for the light the ND filters "steal" by chosing a longer exposure time for each frame.

It's what I thought! Thank you very much! I'll only use CP filters when necessary.

StigNygaard Posted at 2017-6-15 08:28
I don't see why you would want to focus on something 5m away if you are 100m up in the air? Just focus on the ground, you don't need the hyperfocal distance for anything if you don't have anything very close in your landscape shot.

Hyperfocal distance is a focus-distance used when you want to have the largest possible depth of field. Ie., you want both near and far subjects to be sharp at the same time. If you only have far objects in your shot, just focus on a far object.

I noticed that when I am up in the air (100M) and I focus on the ground (a house for instance in the middle of a farm or forest), the trees around will be more blurry.. as if the only focus was the house but in face I want everything to be in focus (hence the reason I was wondering about hyperfocal)

StigNygaard Posted at 2017-6-15 08:28
I don't see why you would want to focus on something 5m away if you are 100m up in the air? Just focus on the ground, you don't need the hyperfocal distance for anything if you don't have anything very close in your landscape shot.

Hyperfocal distance is a focus-distance used when you want to have the largest possible depth of field. Ie., you want both near and far subjects to be sharp at the same time. If you only have far objects in your shot, just focus on a far object.

Makes perfect sense to me.

vinnyhofx Posted at 2017-6-15 09:52
I noticed that when I am up in the air (100M) and I focus on the ground (a house for instance in the middle of a farm or forest), the trees around will be more blurry.. as if the only focus was the house but in face I want everything to be in focus (hence the reason I was wondering about hyperfocal)

I'm sure this isn't related to focusing. It sounds like some other problem. Maybe the problem that the camera sometimes seems to have too aggressive noise-reduction smearing details in video and jpgs. This is especially a problem when setting sharpening is at a low value (partly already at 0, but a bigger problem at -1 or below). Often very visible in trees.

Maybe post an example?

Maybe also see my JPG (sharpening -1) vs. DNG comparision at: http://forum.dji.com/thread-94609-1-1.html (The 2nd illustration in 1st post). Does the JPG look unsharp the way your photos does?

I think I see what you are asking. StigNygaard is correct but let's consolidate your questions.

Hyperfocal: It seems that what I have read on the net and my own calculations put the hyperfocal distance around 12m for the mavic. Fly up 12m high, tilt camera to ground, lock focus and then point your camera wherever you want and you will have everything in focus from about 5m to infinity. This is helpful if you simply are busy flying and forget to hit the auto focus reticule on your device - or the mavic got focus lock on some grass just in front of it as it was sitting on the ground before take-off and you forgot to re-focus.

Setting to hyperfocal also means as you fly and are capturing video you aren't getting focus shift as the mavic tries to get focus lock on different objects OR as you hit the focus reticule.

BUT, having said that - and you kind of hinted at this in a comment above - because everything is in focus from 5m to infinity, you are sacrificing some ARTISTIC control over your footage. You may be 100m away from your subject and want to focus on that and have the foreground a bit blurry to really draw attention to the subject. Hyperfocal won't give you that effect because everything is sharp. In this case you would lock focus on the subject 100m away and thus the stuff in front and behind will fall off from/to blur. (Note - you are dealing with a very small lens so the effect isn't as dramatic compared to a big zoom lens or prime lens - but still, you work with what you have got).

So there is a place for hyperfocal - just want to fly and not worry about focussing all the time OR you are shooting a landscape style pic and want as much as possible to be in focus - foreground to background.

There is a place for constantly re-focussing or auto focussing - to draw attention to a subject by focussing just on it and using the artistic blur (as much as the lens allows) to draw your eye to it.

CP and ND filters: Let's talk ND (neutral density) side first - the filter will reduce the amount of light hitting the sensor which means you can use a slower shutter speed to get that cinematic feel. In short, a slower shutter speed allows fast movement to have a bit of motion blur which gives that nice cinemagraphic feel. Simply dial in the iso you want to use on the mavic, slap on one of your ND (cp) filters and see what shutter speed it gives you. If the shutter speed is too high for your liking then put on a darker ND until you get it right (or lower the ISO) - you get the idea.

Beware: if you put on a very dark ND or CP you may find your shutter speed drops to 1/24s and your footage looks blurry - this is because the movement in your shots is too fast or you're flying too fast so the 1/24s was too slow. Either crank up the iso or land and put on a more suitable ND until you get the right shutter speed going on.

BTW - I am assuming you are filming in manual mode and not auto (where the camera chooses the iso, shutterspeed etc).

Now Polarising Filters

Polarising filters cut the glare - but that depends on the ANGLE the light is hitting the subject relative to the direction your drone is facing. This bit is very important. (polarisers also cut a bit of light and some filters have ND and Polarising in them but we're just dealing with polarisers).

In STILL photography, you put your camera on the tripod, frame your shot, then rotate the polariser until the glare is gone. Then take the shot. If you find there is still glare you either move the light source or move your camera.

On the Mavic: Here's my workflow - I have CP that are also ND so I dial in my ISO, then put try different filters until I get the good combination of ND and shutterspeed. Then I take my polarised ND off the mavic and bring it up to my eye. I then face the direction that I intend to do most of my filming and rotate the filter in front of my eye until I see the polarising effect kick in - I then hold the filter with my index on the top and then put it on the mavic exactly the same way/orientation. So my index is on the top of the filter when I take it from my eye and my index finger will be on the top when I put it on the mavic.

Take off, and shoot my subject and let the ND and Polariser do their magic.

You will notice as you turn the mavic in different directions the polarising effect will diminish, return, diminish etc as you move around. This is because the polariser needs to be set for the direction and light source you are shooting.

Generally a polariser works best with light hitting your subject at an angle but you do have to rotate the filter to get the maximum effect - if your light direction changes or your shooting position changes then you may have to re-adjust the filter. Easy to do on the ground, hard to do in the air.

There are good youtube videos on how to use polarises etc. that will make more sense.

In short, experiment. I took some great footage of a boat with my polarised ND one day and the footage was awful because my ND was too strong and my shutter speed was too slow plus I forgot to set my polariser filter for the direction I was shooting - in short, I rushed to get the shot and the drone in the air and totally screwed the pooch.

This wouldn't have happened in my regular photography because everything is right in front of me and I'm used to using my camera gear - practice makes perfect.

fans193195a1 Posted at 2017-6-15 14:33
I think I see what you are asking. StigNygaard is correct but let's consolidate your questions.

Hyperfocal: It seems that what I have read on the net and my own calculations put the hyperfocal distance around 12m for the mavic. Fly up 12m high, tilt camera to ground, lock focus and then point your camera wherever you want and you will have everything in focus from about 5m to infinity. This is helpful if you simply are busy flying and forget to hit the auto focus reticule on your device - or the mavic got focus lock on some grass just in front of it as it was sitting on the ground before take-off and you forgot to re-focus.

Very detailed answer. Thank you so much! Yeah, I'm trying to get breathtaking landscape shot, so all in focus is what I am mostly interested in, less the artistic blur around a subject. I'll try the hyperfocal stuff over the weekend.

fans193195a1 Posted at 2017-6-15 14:33
I think I see what you are asking. StigNygaard is correct but let's consolidate your questions.

Hyperfocal: It seems that what I have read on the net and my own calculations put the hyperfocal distance around 12m for the mavic. Fly up 12m high, tilt camera to ground, lock focus and then point your camera wherever you want and you will have everything in focus from about 5m to infinity. This is helpful if you simply are busy flying and forget to hit the auto focus reticule on your device - or the mavic got focus lock on some grass just in front of it as it was sitting on the ground before take-off and you forgot to re-focus.

In only a few lines you have given me answers to questions I didn't even know I had... Specially around the issue of focus/auto focus etc. Most of my videos are at distance and suffer from me forgetting to hit the autofocus button regularly etc!!

Also, your explanation on filters is thought out extremely well.

Thanks!

Have you tried using the Peak Focus Threshold. The high setting is probably the best as it does not create too many red lines but it does show you what is in focus.

My 2 cents..
> Learn about, find and turn on "Peak Focus", as it's very useful when flying a drone and time is a factor.
> With DoF, due to the sensor size, using an aperture above f4 will reduce your DoF (due to laws of physics)
> Using f4 with a 1/2.3 sensor means everything is going to be in focus with FP of 5m (in theory).
- "It seems that what I have read on the net and my own calculations put the hyper-focal distance around 12m for the Mavic"
This I find interesting, using what aperture?

- "sacrificing some ARTISTIC control over your footage", totally agree, and it's a point often missed.
The most important thing about a picture or video is not its technical perfection, however the story or emotion it communicates.  As long as technical imperfections don't distract from this they should not be worried about.

Other points on DoF
Finally DoF also changes in presentation (as focus is a perception apart from a really thin line).  What may look like a wide Dof on a smart phone can look all soft on A0 print.

CP and ND has been covered well already, however just to be clear "cinematic feel" just means more natural looking when a little motion blur is included as it aids in the elimination of subtle flickering during movement.

Youtube is full of "experts" trying to get revenue through advertising, however I love this forum.. it's got some cracking people on it.

Looking forward to seeing your landscapes.. :-)
Happy days..

PS. This has some helpful stuff on it regarding DoF etc...
http://www.cambridgeincolour.com ... era-sensor-size.htm

Depth of field: The distance-interval where objects are perceived as sharp.
Hyperfocal distance: The shortest focus distance where objects at infinitive distance still are perceived as sharp.

In general small sensor cameras has lenses with very short focal lengths, giving you are much wider depth-of-field than for example 35mm cameras.

When calculating the hyperfocal distance, a lot of people makes the mistake of putting the 35mm equivalent focal length into equations requiring the REAL focal length. Using the 35mm equivalent focal length will give you a much narrower depth-of-field and much further hyperfocal distance.

But there's no single truth when it comes hyperfocal distance, because there's one "subjective" parameter in the calculations, the "Circle of confusion" telling how sharp is "sharp enough". So in general I would suggest people do their own practical testing to find a hyperfocal distance that works for them.

But lets do a calculation anyway...

The official specifications says Mavic has a camera with a 28mm (35mm equivalent) focal length lens and a 1/2.3" sized sensor (Sony IMX377). However the specification also says the lens has a 78.8° field-of-view, which sounds like a bit wider focal length than that.
I think Adobe gets it right (they have implemented lens-correction for it, so they probably did a thorough analysis) when they say the 35mm equalent focal length is 26.3mm and the true focal length of 4.7mm. The camera in Mavic has a fixed aperture of f/2.2 (f-number). Like on a lot of other small sensor cameras, the aperture can not be changed.


The equation:

H = (f^2 / N * c ) + f

H = Hyperfocal distance (mm)
f = focal length (mm)
N = f-number
c = Circle of confusion (mm)

To make a conservative calculation, lets set focal length to 5mm. As Circle-of-confusion I'll use 0.007mm as calculated suggestion from http://www.studiojpic.com/calculators/circle-of-confusion-calculator/ (for a 8.8x6.6mm sensor).

The result:

H = (5^2 / 2.2 * 0.007) + 5 = 1628mm = 1.6m

The short hyperfocal distance of 1.6m will probably come as a surprise for a lot of people. But if you forget to focus, the camera might have focused on the grass half a meter in front of camera when taking off. And then you are in trouble if you doesn't correct the focus.

Note, atmospheric disturbance (like "heat haze") can introduce some error in this calculation. So in practice I would probably set focus a bit beyond that if I was to use one fixed focus distance for all use. But also, if you don't plan to have any objects closer that 5m when filming, there's no need to set focus closer than 5m. You always get better sharpness by setting focus-distance closer to the distance you are shooting at.

EDIT: I just see there's some inconsistence between the sensor diagonal size I find in specificatios and the sensor diagonal you get by using a 8.8x6.6mm sensor in linked calculation of circle-of-confussion. If I adjust sensor size to a diagonal of approx. 7.81 mm, I get a suggested Circle-of-confusion value of 0.005. If I redo above calculation with this value I get:

H = (5^2 / 2.2 * 0.005) + 5 = 2278mm = 2.3m

But still very short distance. But again, do your own testing to find the closest distance where far objects still appear sharp to you...