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02-01-2016, 07:40 PM   #1
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Practical shutter speed limits?

Just curious, are there any mechanical limitations (lens) when trying to shoot a 1/8000 sec shutter speed? I've tried to search this topic but it must be a dumb question since I couldn't find anything on this topic.

I'm trying to snap a picture of air bubbles in a clear pipe containing a flowing, two phase liquid (air/water) and want to get a representative snap shot of the size/concentration. Perhaps a stretch with my K-5iis or K3 w/o getting specialized equipment?!?

Thanks in advance,
Z

02-01-2016, 07:55 PM   #2
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Upload a picture of what you got. 1/8000 should be sufficient.
02-01-2016, 08:00 PM   #3
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There are no lens-induced limitations other than you need a lot of light and hence a "fast" lens (large aperture).

It might be better to use a powerful external flash. The light emitted by the flash has a very brief duration.

Some camera systems with leaf shutter lenses have limitations where you can't combine a fast shutter speed with a large aperture. DSLRs do not have such limitations.
02-01-2016, 08:08 PM   #4
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I would think so also. So what I'm trying to inquire about is whether the hardware (i.e. shutter) is up to the task. This one I took with my daughter's K-3: 1/6400s, SMC 50 1.8 lens (manual), +5 exp, ISO 3200. Fluid flow from orange adapter to yellow - hand drawn square was my area (1" square) to count/analyze.

http://i310.photobucket.com/albums/kk424/TZellers/ERIN4976.jpg

---------- Post added 02-01-16 at 08:25 PM ----------

Perhaps said another way, what are the limitations to a system (camera body and lens) to achieve, say, 1/1,000,000 sec Av? Just an extreme example.

02-01-2016, 08:27 PM   #5
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QuoteOriginally posted by Ole Quote
It might be better to use a powerful external flash. The light emitted by the flash has a very brief duration.
But ironically, a lot of compact external flashes aren't all that fast at full power, you need to turn the power down to get to really high speeds. Unless you are using an expensive high power monobloc flash head which can be quite fast at 1:1 - but the really fast ones with 1:1 durations as short of 1/8000~1/12000th can cost megabucks.
02-01-2016, 08:32 PM   #6
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Things working against you for a clear picture:

-High ISO
-Low depth of field
-Shooting through plastic/glass
-Having to make a large crop to the area you're sampling

Do you have any lenses that can give a higher magnification? Or extension tubes? Can you get more light on the bubbles (for lower iso and higher f-stop)? An external hot shoe flash is probably the easiest solution here, you can tuck it in pretty close to keep the power levels low for a short motion freezing flash duration.
02-02-2016, 03:23 AM   #7
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Try to turn of the light in the room, or cover the device with something that blocks the light, then add a flash close to the bubbles and angle it so the light hits the glass surface in a low angle. Choose very low flash power output (1/64 or less). Take relatively long exposures, mainly in dark, just lit up by that short flash. Try this, I think it will work.

02-02-2016, 04:31 AM - 1 Like   #8
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The physical shutter mechanism on a Pentax DSLR has a limit of about 1/180 second.
The extra "speed" comes from the reduced space between the "first curtain" and "second curtain" to create a light-limiting effect of 1/8000 shutter speed.
This cannot capture very fast moving objects in the same manner as an actual shutter sped of 1/8000. i.e. you may get smearing, tearing or bending of objects as they move through the frame.

Better to capture with relatively long shutter speed, low to no ambient light and a very quick flash duration.
02-04-2016, 06:41 PM   #9
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Thanks for the input! In my limited photo aptitude, I chose a fast lens (50mm 1.4 if I recall correctly) to allow as much light as I could with short duration, intending to get as much stop action. I realize the plastic reflection, distance between the two plastic surfaces (upper and lower), "thickness" of the water stream, etc would be a challenge. I just did not get the stop action I was seeking. For reference, I was using a 500 watt spotlight (the ones that get really hot) to generate some light to help shorten the exposure time. So hopefully, you can see the "primitive logic" I used including high ISO.

I'll try a few more variations but do not have much in the way of flashes to use and fear the reflective issue.

Just for reference, while the pressure is relatively low (10 psi at most), converting the nominal pipe area to a relatively thin "flat" section for this purpose exacerbated the load on the clear acrylic sheet (surface area increase x pressure per area = more force). I blew out my first attempt rather quickly. For this one, I used my 3D printer to make the adapters and the spacer manifold between the clear sheets. Worked pretty well for that intent.

And I've downloaded the 3D files to print a medium format, pinhole camera. That should be interesting...

Thanks again,
Z
02-04-2016, 08:19 PM   #10
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QuoteOriginally posted by HomeMadeSin Quote
Thanks for the input! In my limited photo aptitude, I chose a fast lens (50mm 1.4 if I recall correctly) to allow as much light as I could with short duration, intending to get as much stop action. I realize the plastic reflection, distance between the two plastic surfaces (upper and lower), "thickness" of the water stream, etc would be a challenge. I just did not get the stop action I was seeking. For reference, I was using a 500 watt spotlight (the ones that get really hot) to generate some light to help shorten the exposure time. So hopefully, you can see the "primitive logic" I used including high ISO.
One thing you can try is simply use the pop-up flash on your camera.
As you say there is an issue with reflection. But this might be something you can work around.

Since you're interested in only a small area, you can push that far off to one side of the field of view.
This way the camera, and flash, is off center and not directly in line to cause a visible reflection.
You can then use some white paper or foam-core as a reflector to bounce some of that light from the flash back to the rig.
With the camera being off center, any reflections from your flash will be at such an angle that they will remain out of sight.

I do this all the time for photographing paintings/photos behind glass when I do not have the luxury of getting them into a proper studio-lighting type environment.
It is also how you would photograph a mirror straight on without your own reflection. :-)

Hopefully the flash will be fast enough to stop the action.
At least it is simple enough to be worth a try.

Last edited by amoringello; 02-04-2016 at 08:25 PM.
02-04-2016, 11:57 PM   #11
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I don't know about pop up flashes, but years ago, I had an issue with optical electronic devices being susceptible to light. The most reliable source I could get, was my sunpak auto zoom 3000 flash, which at minimum power had a 20 microsecond burst duration. That's 1/50,000 of a second, flash power is simply achiecpved by increasing time not light intensity,

There are several posts here in the forums, where people have birds in flight at feeders, using a relatively short lens (50mm for example) mounted close to the feeder, and a flash at minimum power, also very close to the feeder. The whole setup is triggered by either remote or an infra red beam that is broken by the bird

The reason to be mounted close is because light falls off with the square of the distance, so to keep the power at minimum, the camera and flash need to be close,mand the birds don't seem to mind
02-05-2016, 08:27 AM   #12
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QuoteOriginally posted by HomeMadeSin Quote
So hopefully, you can see the "primitive logic" I used including high ISO.
The high iso and low f-stop made perfect sense for your purpose and the light you had available, they just don't help the cause for clarity.

QuoteOriginally posted by HomeMadeSin Quote
I'll try a few more variations but do not have much in the way of flashes to use and fear the reflective issue.
Do you have any external flashes available at all? The flash off to the side can take care of reflections (as mentioned by amoringello). You can probably get by without any fancy triggering options if the room is dark enough (and it probably is).
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