Shutter Speed Look Not What I Expected

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Denniscasey

Well-known member
With thanks to patient coaching from this forum regarding my ongoing efforts to improve my videos of race cars, I am wondering why I don't see a very noticeable change in the motion "look" I get when I shoot at different shutter speeds. Applied to video I think I understand that if each frame has some blur (slower shutter speed) the human eye uses that to "smooth" frame to frame movement. If each frame is very sharp (fast shutter speed) human eye can give a strobing look to frame to frame movement. I have also watched You Tube and similar video "teaching" about shutter speed, but my internet speed I think affects way video looks.

When I critically viewed video from last race car event I shot at 1/60 I thought there was too much blur. Going to another race September 7 so did following experiment today which I thought would define upper limits to shutter speed I could use and still get normal motion look:

Went to nearby highway, stood about 20 feet back at right angles to cars passing at around 55 miles per hour. Background was wooded area. Filmed cars as they came towards me, selected a car and panned with it as it crossed in front of me (had set zoom so car almost filled frame as it passed in front of me then did not touch zoom), and continued panning with car as it drove away. That is typical shot angle/pan I get at races. Selected 720 60P format; put camera on manual setting (but left exposure and focus on default auto setting for simplicity); and then varied shutter speed; 1/60; 1/120; 1/250; 1/500 and 1/1000. Viewed experiment results on 46 inch HD TV with SD card inserted in Panasonic Blu-ray player.

I have to say the overall motion effect looked quite similar and "normal" even at 1/1000 (no noticeable stuttering or jerky motion) for all shutter speeds greater than 1/60 (which still had some blurring). In fact I wondered if camera was really using shutter speeds I selected but there are differences in exposure settings camera chose which I monitored at each shutter speed; sharpness of cars when I pause player (blurred at 1/60, progressively sharper at faster shutter speeds) and wheels turn forwards at some shutter speeds and "backwards" at other shutter speeds (which could be considered to give abnormal look, but it is overall look I am interested in); background blurs more with panning at slower shutter speeds, etc. I will continue some experimenting at race next week, but most of that footage needs to be "good." So, my questions are:

1. Did all my reading and theory just cause me to expect a more dramatic difference than I saw? Are differences just subtle ones?

2. Were cars just moving too slowly (55 mph) to create very noticeable difference among shutter speeds?

3. Do some Blu-ray players have software/hardware that "smooths" motion when it detects a stuttering condition so it "normalized" motion effect among all the shutter speed settings? Doubtful, but had to ask.

4. Was my particular shooting/panning angle one that led to minor changes in look as I changed shutter speed?

5. Or something else going on?

Thanks in advance for any comments that would help me with this, Dennis
 
Upload your test footage to Vimeo or somewhere and we can tell. There should be a huge diff between 1/60 and 1/1000. And yes, some TVs definitely do have a motion-smoothing algorithm which totally ruins motion rendition.
 
Hey Dennis

Panning with the vehicle is actually giving the camera less motion to deal with...have you tried a fairly wide shot with the car passing at right angles so the motion is at maximum?? I've done test shoots with cars passing in our street at 1/50th with no blur but then again they were hardly doing racecar speeds. AFAIK the moment you change shutter speeds the autoiris SHOULD be disabled as in autoiris the shutter can auto change from default right up to 1/2000 in bright light. Barry, of course, would know the answer that the manual doesn't tell you so what actually occurs if you set a shutter of say 1/120th and leave autoiris running??? Does the auto circuitry then recognise the manual setting and only adjust exposure down to where you have set it???

Chris
 
Dennis motion blur and the 180 degree rule does give you a unique pleasant look in normal action speeds , but , at least in my experience some times you have to use speeds somewhere between 120 and 500 to look well
in particular sports , Not always is possible to follow the car or subject at a low speed to cause a blurry background and a sharp subject, If you shoot race cars and the look fine at 500 go for it, as you know some rules are made to be broken
is very different the look you get with a proper video camera like the HMC40 where this speed effect doesn't look jerky at high speed than a DSLR for example where if you increase the speed looks really bad, I guess has something to do with
camera construction where Barry Green is a Bible.
 
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Barry_Green said:
Upload your test footage to Vimeo or somewhere and we can tell. There should be a huge diff between 1/60 and 1/1000. And yes, some TVs definitely do have a motion-smoothing algorithm which totally ruins motion rendition.
Click to expand...

Barry, I will admit I am from the 8mm film generation so am not native Vimeo/You Tube. Thank you for offer to look at this and I will set aside some time to learn Vimeo or something. Dennis
 
ChrisHarding said:
Hey Dennis

Panning with the vehicle is actually giving the camera less motion to deal with...have you tried a fairly wide shot with the car passing at right angles so the motion is at maximum?? I've done test shoots with cars passing in our street at 1/50th with no blur but then again they were hardly doing racecar speeds. AFAIK the moment you change shutter speeds the autoiris SHOULD be disabled as in autoiris the shutter can auto change from default right up to 1/2000 in bright light. Barry, of course, would know the answer that the manual doesn't tell you so what actually occurs if you set a shutter of say 1/120th and leave autoiris running??? Does the auto circuitry then recognise the manual setting and only adjust exposure down to where you have set it???

Chris
Click to expand...

Hi Chris,
Regarding iris behavior, my understanding from p40 of PDF manual is that setting functions to manual mode is actually a two step action if you are switching from auto to manual mode. First slide switch to manual mode--at that point all functions stay in auto mode. Step two is selecting functions you want to change to manual mode and change them to manual--i.e. press iris dial, press focus button. In an old post I had asked if HMC40 had something like Aperture Priority or Shutter Priority and Greg Smith and others told me, if I paraphrase correctly, that I could do something like Shutter Priority by sliding switch to manual and adjusting shutter speed while leaving iris set in auto mode--when I would change shutter speed iris would automatically adjust exposure to fit new shutter speed.

Agree that panning with car (like I do at races) does give camera (and viewer) less motion to deal with --and that is where panning technique can be important I guess. I did try a few shots as you suggest where I did not pan, but they were close shots with short duration so did not see big changes. I will try wider shots without panning and see what that does at various shutter speeds. Dennis
 
Felipe Henao said:
Dennis motion blur and the 180 degree rule does give you a unique pleasant look in normal action speeds , but , at least in my experience some times you have to use speeds somewhere between 120 and 500 to look well
in particular sports , Not always is possible to follow the car or subject at a low speed to cause a blurry background and a sharp subject, If you shoot race cars and the look fine at 500 go for it, as you know some rules are made to be broken
is very different the look you get with a proper video camera like the HMC40 where this speed effect doesn't look jerky at high speed than a DSLR for example where if you increase the speed looks really bad, I guess has something to do with
camera construction where Barry Green is a Bible.
Click to expand...

Felipe,

Good points and thinking about other experiments I have done I should realize look can vary with subject: (1) shooting ceiling fan the look of spinning blades was distinctly different at different shutter speeds; (2) shoots of tree leaves blowing in wind did not look distinctly different at different shutter speeds; (3) I expect that if I do the well known shot of waterfalls at different shutter speeds I will again see distinct differences in look at various shutter speeds. Still, I was surprised that I did not see more differences in looks when I did experiment yesterday--however as you and others state, there actually is subtle difference in looks with background having more or less blurring as I panned with cars (I was just looking mostly at effect on car motion). Dennis
 
Hey Dennis

Quite correct ... I call that semi-auto mode cos the cam is in manual but functions are still in auto...yes, if you reset shutter speeds and leave the iris wheel in auto it will simply adjust iris for that shutter speed..obviously this is fine outdoors on the racetrack but you do need to remember to set back to 1/60th if you are going to lower light situations. The other thing to remember is the the patterns created by not only motion but also by spinning blades, picket fences and the rest are seen by ourselves as terrible!! However the average viewer would not even notice then because they are not looking for them...same as the bit of blur on your car shots are only considered critical by you...others will think it's a great video!! We tend to often beat ourselves up over technical issues with our work that isn't at all necessary and seriously, the whole thing was pretty much perfect to everyone else except us which is really silly....that's why we have forum discussions ...it's mainly about the tech stuff BUT don't let it get to you!!

Chris
 
ChrisHarding said:
Hey Dennis

Quite correct ... I call that semi-auto mode cos the cam is in manual but functions are still in auto...yes, if you reset shutter speeds and leave the iris wheel in auto it will simply adjust iris for that shutter speed..obviously this is fine outdoors on the racetrack but you do need to remember to set back to 1/60th if you are going to lower light situations. The other thing to remember is the the patterns created by not only motion but also by spinning blades, picket fences and the rest are seen by ourselves as terrible!! However the average viewer would not even notice then because they are not looking for them...same as the bit of blur on your car shots are only considered critical by you...others will think it's a great video!! We tend to often beat ourselves up over technical issues with our work that isn't at all necessary and seriously, the whole thing was pretty much perfect to everyone else except us which is really silly....that's why we have forum discussions ...it's mainly about the tech stuff BUT don't let it get to you!!

Chris
Click to expand...

Hi Chris,

Good philosophy and good perspective. Regards, Dennis
 
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