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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

Sharper slow motion image

Linda Barzini

Linda Barzini

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When I shoot 23.98 4k with my 100mm Schneider Xenon FF prime, I get outstandingly sharp images. When I shoot at 100fps at 4k with a shutter speed of 1/200, the images are just ok. I don't want motion blur.

Is there any way to get the supersharp images in slow motion? I assume I will need what seems like an excessive amount of light, especially to shoot at ISO 800 at t4.0-5.6.
 
But if you're saying that your images are less sharp at 100FPS and 1/200 Shutter than 24FPS at 1/48 Shutter, that is simply not possible... if all else is equal... i.e. if the subject is moving more or less the same and you have the same time and ability to nail focus and the lens is the same and depth of field based on aperture settings is the same. There is nothing inherent about faster FPS and shutter that makes images LESS sharp... the opposite is true. Stills from any moving subject at 24FPS/180 deg shutter are generally soft with motion blur. One fun reason to shoot HDRx is to use the X-track images for stills. The frames on the x-track are a few stops darker (based on settings) but are sharper because the shutter was faster on the X-track. Faster shutter will give sharper images if all else is equal.
 
Girls doing hair whips at 1/200th is soft. I think I'll try 1/500th, good idea.

Here is a girl dancing in a club. It is not as sharp as I would like. I would need be able to add quite a bit of light to capture girls dancing in a club in slow motion. I guess everything has its limitations. If you can't add light, you just can't capture sharp slow motion in the dark.

ashley.jpg
 
add all the light you can find... flicker free. and then shorten exposure time to as little as possible.
 
It is possible to film sharp, slow motion images in low light. In this instance, I think its your choice of 100mm lens for this type of shot. It results in a decision to film at an f4-5.6 aperture to retain background detail. Personally, I would film with a wider angle lens to retain similar background detail while adjusting the aperture. Or film the existing image as an establishing shot, then move much closer to the subject at the fastest possible aperture. Are you viewing the image in the monitor at full magnification?
 
This was with a Xenon FF 50mm at 2.2 (the 100mm was outside) with maximum compression for 4k at 100fps.
 
If you get sharp images with the Xenon at the same aperture as when shooting soft slow motion it's not the lens. First off, if you want sharper images you need a faster shutter. Compression at lower resolution is key and not going under 4K. Even shooting at 4K will make 4K look soft since there's no downscaling involved. I would actually say that I do not consider Red to be more high speed than what 5K can give you, going under that you are rapidly lowering the debayer downscaling improvements in post.

Another thing is the quality of the light. If you shoot tungsten it will be more muddy than daylight, higher ISO as well. If you want super sharp images in slomo, shoot at 5K or 4,5K, with as low ISO as possible, in 5000K and above, at aperture T4.0, compression as low as you can (preferably with minimags) and with a faster shutter. If that's not crisp there would be something wrong with the hardware.
 
This is slightly unrelated but I did a test a little while ago with my Dragon and found that I'm better of increasing the compression than lowering the resolution.

https://www.dropbox.com/sh/gv944j3sl6wm6yc/AABHs4mBU_-whT86Unu0xgHIa?dl=0 (DOWNLOAD this and watch on your computer, don't watch it on Dropbox!)

I agree with Christoffer Glans that going much lower than 5K for slo-mo is not very good. I was doing some slo-mo at 2K and was pretty disappointed with the quality. Fuzzy and muddy looking.
 
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