Author Topic: Extracting still images  (Read 948 times)

rdemyan

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Extracting still images
« on: April 25, 2020, 07:15:52 PM »
I am thinking about purchasing a Chronos camera.  I need super slow motion video, but I also need 1 microsecond still images.  I have emailed Sebastian at Kron and he replied as follows:

"I think the best method of extracting a still image from the camera is by saving the file as cinemaDNG.  This will create a folder on your card containing a number of still adobe dng images that can be opened as a single image in your preferred photo post processing software or as a video sequence in your preferred NLE software by importing the whole folder.

One note when saving cinemaDNG files on the camera, they are much more data heavy (h.264 is up to 60Mbps, cinemaDNG is 1258Mbps) and the save time will be much longer.  I recommend using a SSD if you wish to save cinemaDNG files since the transfer rate is much faster than the SD card."

Has anyone tried this?  How good is the resolution of the image.  Another choice I have is to try  to buy a Vela One flash (as low as 0.5 microsecond), but they are not producing flash units at the moment.  I feel confident that the Vela one will provide a very good image, but I thought I should maybe consider the Kron cameras since I would like to have super slo mo video as well.

Any advice is appreciated.  Thanks.

Nikon1

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Re: Extracting still images
« Reply #1 on: April 25, 2020, 08:17:29 PM »
Hi, there is quite a number of people using the Cinema DNG format for video, since it will give the Highest Quality Output data possible and even allow for heavy Image Manipulation in Editing afterwards.
Since Video is Basically just a lot of still images, and the Cinema DNG format will give very high Quality, you will be able to extract still images from the Footage with no problem.
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 I am Not familliar and havent even heard about that other camera brand you mentioned, but Sharpness / Resolution of Still images on an Chronos Camera comes down to a number of factors. One of the More important ones is the choice of Lens, use of Proper setting and use of enough light. You will need quite a lot of light if you want to shoot at one µs Exposure!
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 For highest Image Resolution and Quality i can reccomend buying an Chronos 2.1 HD, this will give you an 1920x1080px Resolution image at ~1000fps. You didnt Mention, if you need Color for your Application, but if it is more important to you to get the sharpest, Highest Quality Image Possible, i would highly reccomend thinking about getting a Monochrome Version of the Camera. The Monochrome Version will give you an very Sharp image, while the Color Version will be a tic less sharp (this is due to the basics of Bayer-Sensors, which are used in any Color Camera today... If you want to know more about that, i can explain in detail).
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 As far as Minimum Exposure Time (1µs) goes, the Hardware /Sensor in the Chronos Cameras, should be, as far as i Recall, able to do way shorter exposure Times than 1µs. It is just limited to this value because of legal reasons and i think it is because you will need an very special official permit to export cameras that go beyond 1µs (Like about any other Camera like this), i dont know how much work it would be, but you can ask the Krontech Staff, if they would sell/ Modify an Special camera firmware / Camera unit for you which can do shorter exposure times. The Hardware is Capeable of doing so.
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 Hope this Helps
« Last Edit: April 25, 2020, 08:20:05 PM by Nikon1 »

Nikon1

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Re: Extracting still images
« Reply #2 on: April 25, 2020, 08:37:35 PM »
ok, i just looked up that "Vela One flash" and it seems, this is not an camera but a Flash unit.
So, the Chronos Cameras and an High-Speed Flash will give you VERY different fields of application.
I am still not too sure what you try to do with any of both options, but if you consider to use something like a Flash, i am not sure if the Resolution of todays High-Speed Cameras will do the job for you. (I am thinking of very High-Resolution Fine-Art High-Speed-Photography and such...). .
 If you want to do Large-Scale Prints or anything like this, i doubt, that an High-Speed Video-Camera will do the Job. If that is the case, you should propably look more into getting an very high-Resolution Full-Frame DSLR/ DSLM-Camera or even an Medium-Format Camera. Those will give you Resolutions of 50 to 100 Megapixel and sometimes even more. In Combination with a Flash and an otherwise completly dark Room, this will also allow for very short exposures! Difference to an Real High-Speed-Camera like the Chronos Cameras is, that such Photography Cameras are not able to do a lot of Images Per Second. For most time Very High Resolution Cameras wont allow for more than a few images per Second (if even that...), while an actual High-Speed-Video-Camera can do multiple Thousand Images Per Second without a Problem.
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 So for now, i cant really say more about this, since i am just guessing at this point. for anything beyond guesswork it would be very good to know what kind of results you are trying to get with this. Thanks.
« Last Edit: April 25, 2020, 08:40:20 PM by Nikon1 »

rdemyan

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Re: Extracting still images
« Reply #3 on: April 26, 2020, 06:48:35 AM »
Nikon1:

Thank you for your reply.  Yes, the Vela One is a flash unit that will flash as short as 0.5 microseconds and my plan is to take pictures in darkness using the flash and a DSLR Camera.  However, I'm thinking that, down the line, I might want to have high-speed video as well, so I'm investigating whether or not I can kill two birds with one stone by purchasing a Chronos camera.  The company that produces the Vela One is currently not manufacturing due to the pandemic and is completely sold out of the flash unit.

I have been taking pictures of a special type of water spray with a DSLR capable of 25 megapixel resolution and a Nikon SB-800 flash capable of a flash as short as 24 microseconds. I have been getting some high quality still images, but need shorter "exposure" times since the water travels at least 120 microns during the 24 microsecond exposure.

Do you know if there is anyway to compare the "resolution" of a still image extracted from video taken with a Chronos camera with the resolution of a DSLR camera?  So 25 or 50 megapixels for the DSLR for a still image versus ??? for a Chronos camera.

Regards.

Nikon1

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Re: Extracting still images
« Reply #4 on: April 26, 2020, 08:36:47 AM »
As far as the Whole situation now goes, Krontech also cant Produce Cameras right now, and especialy the 2.1 is sold out since a while, take a look on the Website. They however plan to start shipping Cameras Again soon.
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 I dont know if this would help you (Also not knowing the Brand or exact model of DSLR you are using?...), but i assume your DSLR would be able to shoot Video with 1920x1080px Resolution as well? If so, you could just take a Still image and Video of something (Has to be as Sharp as Possible and an non-Moving Object, and shot from an Tripod, otherwise Compression will destroy the Quality of the video for a propper comparison), and Compare the Detail in both, that will give you an Idea of what the Chronos 2.1 should be able to do.
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 The Monochrome version is basically just limited by the 1920x1080 Resolution. Images are as sharp as this resolution allows. color versions will be a bit less sharp, look up bayer sensors and anything related to learn more about this:
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 https://en.wikipedia.org/wiki/Bayer_filter
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 It is however not an extreme Loss in Shapness compared to Monochrome, but it is there. Monochrome Also allows for brighter images, requiring less light for such short exposure stuff you are doing.
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 Most limiting Factor to The real world Resolution for those sensors is most of the time the Lens and Light situation (Sometimes also the User itself because of bad focus/ bad Settings), so you will need an Propper Lens to go with your camera if you want to get the most out of it.
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 As far as actual still frames from the 2.1 Chronos go, i cant do anything for you right now, since i dont have my 2.1 yet. You can take a look at the other Thread here on the Forum, where you will find quite some Videos from People with a 2.1 Chronos. From what i have seen, the Footage from the 2.1 can get pretty close to the Maximum Image Quality, which 1920x1080 would be able to deliver, if used right.
« Last Edit: April 26, 2020, 08:45:59 AM by Nikon1 »

rdemyan

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Re: Extracting still images
« Reply #5 on: April 26, 2020, 08:19:26 PM »
After doing a little research, it seems to me that if I want to compare my still photos at 25 megapixels with the Chronos 1.4 all I have to do is multiply the Chronos resolution to get megapixels.

So, the best resolution for a Chronos 1.4 is 1280 x 1024 at 1057 FPS.  So the megapixels is 1.3 MP, isn't it?

Also, I've been looking on ebay for the Computar lens that Kron has listed as an extra.  On eBay a Computar TV Zoom Lens like the kind recommended can easily be found for under $100.  One ad even lists it as a "Chronos 1.4 Computar 12.5-75MM f1.2 Lens" for $81.

I admit to knowing nothing about video and what to expect for resolution.  However, with such cheap lenses, it seems to me that the quality of an extracted still frame would be sorely lacking compared with a DSLR at 25 or 50 Megapixels when the picture is taken with a 1 microsecond flash.  I'm not trying to be critical, just trying to understand so that my expectations are inline with reality.  Is my analysis correct, or am I missing something?

Thanks.

Nikon1

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Re: Extracting still images
« Reply #6 on: April 26, 2020, 08:56:20 PM »
Resolution of the 1.4 Chronos is around 1.3 MP, that is correct!
 You could also just lower the Resolution in your Image Editing software (Using an Sharp [whatever ...HIGH] Megapixel Source Image from DSLR) to the ~1.3MP resolution of the 1.4 Chronos. This could also give you an Quick idea of what to expect from that kind of Sensor Resolution.
 The New Chronos 2.1 HD will give you higher resolution of a little over 2 Megapixels, but it does cost quite a bit more. The 2.1 is also the way to go if you want best image Quality, since the Sensor itself is much bigger.
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As Far as Lenses go, the 12-75mm Lens Krontech is selling ist surprisingly good for a Multi-Purpose Lens, tested it myself a while ago and was quite impressed by the Sharpness. This Lens has some problems, such as that it is not 100% sharp on the Corners and has some vignetting, but in terms of Price-Performance a very solid lens that could produce Serios Results.
 However, big Warning about most 12-75mm Lenses on Ebay, especialy old ones. This one Krontech is selling is a very new Version of this Lens, the Older ones, old TV-Lenses mostly are pretty bad in image Quality indeed. Also, this lens will only work with the 1.4 Chronos. It will not work with the 2.1 HD! (Well, you can use it on the 2.1, but only on low Resolution Settings.)
If you want to buy this lens from ebay used, make sure that it is the exact same version of the Lens, which krontech sells on the Website, otherwise you may get a bad surprise in the Image Qualtiy.
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 Would i Reccomend the 12-75mm 1.2 for your application? Propably not. Unless you need a Zoom, i think a good Prime Lens would maybe do better for your application (Dont know what kind of magnification you are dealing with on your Spray-Images? For More serious Macro, Primes or dedicated Macro-Lenses generaly do a lot better). If you are Serious about your Image Quality, put some Money into your Lens(es). Its still the Lens that makes the Image, the Camera does only record it...  Big Mistake some People make, is, to buy an expensive Camera, but stupid Cheap glass, and then Blame the Camera because the Results are bad....
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 For the 2.1 Chronos you can mostly get away with using your DSLR Lenses, since the Sensor is so big. But that i would only reccomend, if you own rather Sharp lenses. Very old lenses Made for Analog SLR Cameras tend to be not sharp enough (very high end ones are, but those are Mostly rare and pretty expensive) mostly.
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 For the 1.4 Chronos you can also try using DSLR Lenses, and for your application it might even work. The Sensor on the 1.4 is Way smaller, making your DSLR Wide-Angle Lens into an Tele-Lens. Everything is even More Zoomed in than on the 2.1! Again, for Close-Up-Stuff like you apparently do, it should be fine (I dont think you would need very wide-Angle Lenses for that, right?). But for the 1.4 make sure, that you have really sharp DSLR-Lenses, otherwise you might not get the most out of the Camera resolution-Wise.If you really need wide-Angle Lenses for the 1.4, the 12-75mm 1.2 from Krontech is actually one of the better options to get.
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 If you need more specific Reccomendation on whatever lens to get, let me know. For that it would be very helpfull, to know more about what you use now (Sensor Size of Camera, Focal Lengh of Lens, Apperture of Lens (Maximum/ Used apperture), Magnification/ Distance and Maybe Camera Mount (Because lot of Lenses can be used on Chronos Cameras via adapter))
« Last Edit: April 26, 2020, 09:01:57 PM by Nikon1 »

rdemyan

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Re: Extracting still images
« Reply #7 on: April 27, 2020, 08:16:37 AM »
Once again thanks for taking the time to help me understand in my own mind what it is I really need.  I'm beginning to realize that what I really need is sharpness.  Resolution is a part of that but so is acutance.  Acutance is most likely a bigger issue for me since focusing on the region of spray interest is difficult. So, it's quite possible that a 1.3 MP image with an exposure time of 1 microsecond might be perfectly acceptable compared with my 25 MP still photographs with an exposure time of 24 microseconds (using the Nikon flash). If you don't mind, I would like to continue our discussion privately where i can include some photos that I currently have.

Again thanks for your help.

Nikon1

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Re: Extracting still images
« Reply #8 on: April 27, 2020, 08:23:28 AM »
yeah, no problem, we can continue the Conversation via Personal Message.

Photopage

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Re: Extracting still images
« Reply #9 on: April 29, 2020, 07:37:50 AM »
Hi, interesting discussion.  The 2.1 can shoot with exposures down to a micro second.  I just tested it.
You’ll need a lot of light, so using a flash as your light source is a good idea.
In my quick test, I used the highest standard setting, around 24000 frames per second and an 8 degree shutter to get the 1 microsecond exposure.  The camera crops the sensor to achieve very high shutter speeds, so resolution is greatly reduced.  At that speed I get a number of we’ll exposed frames from a single flash.
I also tried at full resolution, but had no luck.  That’s probably because I had no way of triggering the camera to the flash, and at full res the camera only grabs 1000 frames per second, and my little flash was most likely firing at around 1/4000th of a sec.  I’m sure you would get exposures if you tried for more than 5 minutes, or worked out a trigger / delay or used a longer duration flash.
You won’t get a million frames per second video by selecting an exposure of 1 us, but you will get a good 2meg still frame if you can figure out the light source or trigger, and a thousandth of a second later you’ll get another still frame.
Sounds like fun

Nikon1

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Re: Extracting still images
« Reply #10 on: April 29, 2020, 07:41:28 AM »
We talked a bit via PM and had an quite in detail discussion about the topic.He tries to get something rather small in focus, and because depth of field is pretty important for this, will use a very small apperture. Talking f/11 to f/33. That will need tons of light...!

rdemyan

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Re: Extracting still images
« Reply #11 on: May 01, 2020, 10:13:54 AM »
"The 2.1 can shoot with exposures down to a micro second.  I just tested it."

I've pretty much decided that I am going to buy one of the cameras.  The datasheet for the 2.1 says that the minimum exposure time is 10 microseconds and not 1 microsecond.  Would you please confirm that you were able to get 1 microsecond?

Also, is the fps really limited to 24,046 per the datasheet?  It seems odd for a higher resolution camera and given that the initial announcements for the 2.1 said the camera would be able to shoot 100K fps.

Thanks.

Nikon1

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Re: Extracting still images
« Reply #12 on: May 01, 2020, 01:02:40 PM »

Also, is the fps really limited to 24,046 per the datasheet?  It seems odd for a higher resolution camera and given that the initial announcements for the 2.1 said the camera would be able to shoot 100K fps.

Thanks.
I dont know the current Max. Framerate, but it for sure is possible that the 2.1 Is currently limited to less than 100kfps. Just because the Hardware is Capeable of doing it, does not nesercarily mean, that it is implemented and tested yet. When the First few 2.1 Chonos Cameras Shipped, the Max Framerate was around 5000fps if i am Not mistaken, because the First firmware hasnt implemented higher framerates Yet. The Update, that came Soon after Shipping of the First units increased Max Fps by quite a bit.
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 Also, its actually the other way around. Higher Resolution/ Bigger sensors usualy are slower, not faster than Small Resolution Sensors. Just look at DSLR Sensors, those are Much higher resolution, and WAY slower than "low-Resolution" Highspeed-Camera Sensors. For DSLRs a Maximum Framerate of 180fps on those Large, High Resolution Sensors is considered Extremely high (panasonic GH5).

Photopage

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Re: Extracting still images
« Reply #13 on: May 01, 2020, 04:14:23 PM »
Anyone got any ideas about how to measure if the camera is doing what it says?  I think the maths is right, (1/24000)/360 x 8 for an approximate microsecond with an 8 degree shutter at 24000 FPS, but how do you test if that is actually what the camera is doing?
Happy to do the test if anyone has a method that can be with household items.

Exposure seems like the easiest option, but does the sensor have any reciprocity failure at very small exposure times?

Nikon1

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Re: Extracting still images
« Reply #14 on: May 01, 2020, 04:32:01 PM »
Well, one option would be to record some Footage of something that moves very fast at a known speed and look at the distance it traveled/ The Motion blur, that is visible. But since this is Really Fast Exposure time, its kinda hard to get something that moves that Fast and could be Measured that precise to be sure.
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 An idea would be for example some Kind of spinning Disk with a lot of marks/ Lines filmed very up close on the Edge, and Measuring the Rotations per minute Of the Disk very percise, for example with some kind of Photo-Diode and an Osziloscope or an Percision Thing To measure RPM (No idea what this kind of Measuring Device is called in english, for German its "Präzisions-Drehzahlmessgeät"). If you can for example spin up a Disk of 500mm at 1000 or more Revolutions per Minute and Had a lot of small markings on the outside, doing an Macro shot of that, and Knowing percisely the distance between markings, exact diameter of the Disk and the Exact rotation speed, you would be able to do some math and had a rather simple and very Reliable and Percise Way of figuring out the Exact time Between Frames and the Exposure time, based on motion blur (Depending on Framerate you may need to add numbers to the Markings or do some other thing do differeciate between individual markings, to know where you at on the disk).
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 I dont know if that is what you meant by "easy", but for that kind of really fast Exposure times, i think its about as easy as it gets while still beeing as percise as you can get. 1µs is actually really fast. For longer Exposures and lower fps, you would for sure get away with simpler measuring setup, but since the FPS is so high, i dont think, you can get much simpler than that, while also beeing able to get an Exposure Time Measurement or Framerate Measurement as accurate, to actually say something about the percision of the Camera itself.An other way would be something Smaller (also some Kind of Marked disk maybe?) but spinning way faster, like a few dozen kRPM, but i dont know if that can be measured as Percisely as Low RPM?
« Last Edit: May 01, 2020, 04:34:14 PM by Nikon1 »