Machine Vision cameras/ Mirrorless DSLR for 4K

#1

First Post of mine coming up!

Glad to be apart of the community, as there is a lot of great discussion happening.

I am gearing up to get my feet wet in my first Kinograph build and want to hammer out some finer details before proceeding.
I have a lot of experience with machine vision cameras in combination with The Retro Scan Universal system. I know that machine vision cameras are highly recommended for this application and I understand why, they are compact, task dedicated, and offer a wide spectrum of affordability with quality. However, as 2K will age I want to implement a 4K system from the beginning and I am curious if some one can chime in if I have this wrong. I would assume that using a full frame mirror-less camera for image capture would be the best. I have been looking at buying a Sony A7R II for use with this as it would be slightly cheaper than a PGR Grasshopper, and could use it for other things.

So my question is:

Is a full frame mirror-less system over kill or too much hassle for what it is worth? or perhaps not adequate in terms of quality? ( My intuition tells me the latter is highly unlikely)

Thank you for your input!

#2

@Owlinsky One important point on the discussion is what is the size of the film? that would give some context to the options. I used a DSLR, and one of the issues with DSLR and mirror-less camera is that the shutter has a finite life. I was willing to take the cost of the camera as part of the project, but it is a consideration. Having said that, I am very pleased with the results. See for your self, with an 8mm film, @4K. https://www.youtube.com/watch?v=g1ywW8EKa3k&t=70s

Hope the info is helpful.

#3

@Owlinsky It’s also good to weigh whether or not the particular sensor you’re using has any issues with being in use for the duration of time you’d need to scan a film. The system would have to be “on” for hours at a time, rather than the relatively short duration it’d normally be on for taking a few still images. The quality would likely be very good, but I’d be concerned about the light loss and depth of focus on a MUCH larger sensor.

#4

This is not mine, cite as an example.

Sony a6300 + Sigma 105/2.8 macro.
The distance from the film to the matrix is about 35 cm. Frame by frame 4K 6000*4000px
http://uploads.ru/4oxBw.jpg


It is too Sony a6300 - https://www.youtube.com/watch?v=PE1esXyPd-o

#5

Welcome, @Owlinsky! First thing to check is if the sensor is global or rolling. If it’s a rolling shutter, you will be limited in the speed at which you can scan.

Also, even though mirrorless cameras have less moving parts, most (all?) still have mechanical elements that move every time you take a photo. An example is a shutter on the sensor itself that clears the pixels. I’m not totally up-to-date on this so hopefully someone else can chime in and tell me I’m wrong or validate.

#6

Thank you for the great info!
Yes I @PM490 I should specify, that I would be scanning all formats ( if S8 is up and running reliably). Yes @dan74, I have looked into those as well, and that might be my best option if I decide to risk it with the mirror-less, that example you linked is quite nice.
@johnarthurkelly, and @matthewepler, yes, device stamina would be lower than a PGR camera, and echoing what most stated that mirror-less is misleading in that they do have components that are susceptible to wearing out just like a traditional shutter, but exact life is still unknown? and the Sony A6300 are global shutters. Also I didn’t think of the loss of light but that totally makes sense.

Thank you all again, I will see you on the forums!

#7

@dan74 is this a kinograph project or some other type of scanner that uses a a6300? I am quite attracted to the quality. I understand it is 35mm. but I am hoping this is a Kinogrpah project because I would like to replicate this quality. It also looks stabilized some how, do you know what it was processed with? I speaking about the youtube of the b/w film.

Thank you.

#8

Owlinsky
This is not a project kinograph. It is based on a film projector, frame by frame.
Start here - nick Huan-Carlos http://kinoperedvizhka.mybb.ru/viewtopic.php?id=98&p=9
author’s channel - https://www.youtube.com/user/HuanCarlosLJ/videos

#9

Have to add: this is Fomapan, so good amount of grain :wink:

#10

Hi there!

This is my first post, actually i just found this forum accidentally.
Just today i published first notes on my Telecine for 8mm based on a film projector and working with the A6300. The first examples have a lot of issues due to bathtube development, long lenses, so shaky image etc., but i really like the results, they look better then projected i would say.

Here is the post in a german forum:

And here is the first example, the quality is little shaby due to Vimeo i guess, it looks totally different from what i see on my computer.

The images produced by the Telecine are almost 6K, the 8mm fills the APS-C sensor.
I reduce it to 4K, the example you see on Vimeo is 2K.

If someone is interested in sharing ideas, i could post the description of my machine in English…

#11

Was he using a normal projector running at 24 fps. I found this interesting video, where the poster was recording the projected screen with an iphone, and (according to him @ 30fps where the flicker disappears).

#12

A few different thoughts to share with folks in this thread.

First, while I don’t recommend using a DSLR with a physical shutter I do want to point out that a few years back I came across a website where end-users were able to log the shutter accusations they had for their cameras. At the time, I was likely looking at models like the Canon 7D and 5D. Actuations are usually rated in the 100K to 200K range. Turns out those numbers are VERY conservative. 80% or users listed cameras as still being functional way past those metrics (500K+ if memory serves correct).

I’ll stress again that those users would not have their cameras always on or shooting the way a user here would want to.

Second, according to the famous Ken Rockwell we still have a bit of a way to go before we can really capture all the detail that’s there in 35mm film. You can read through his assessment here:
https://www.kenrockwell.com/tech/film-resolution.htm

In short, 75MP-175MP might be required to truly match what our old film emulsions are capable of capturing. (So you may want to hold onto those films for future scanning).

Slightly off topic…
Last year the footage form the Apollo moon landing was digitized once again and yielded some pretty cool footage never seen before…
Historian Finds Never Before Seen Footage of Apollo 11 Moon Landing

#13

It’s an interesting approach to analyze it, but there are some key oversimplifications he makes:

First, he states that all digital cameras use Bayer matrices and that there’s always a “lie factor”. However, if you use a monochrome camera and shoot three separate images with RGB backlights, you capture the true resolution of that sensor and thus you have no “lie factor”.

He also chooses only one film stock to calculate the overall film resolution. But the film stock he chose is on the higher end of photographic film stocks. Different film stocks are going to have more or less film resolution by a wide margin. The displacement of grains in the film itself also play a role. (If you have copies of copies of film prints, the true resolution will be significantly less.)

And there’s also dynamic range. Film cameras can have more dynamic range than some digital cameras, but by scanning the film at three different brightnesses and merging them via a tonemapping algorithm, one can get past this issue.

I recommended you take a look at this analysis; this person tests different film stocks and presents how different film stocks measure against digital cameras in both spatial resolution and dynamic range.
https://clarkvision.com/articles/film.vs.digital.summary1/index.html

EDIT: I should also state that regardless, I do agree with you in that we should always keep our films for as long as possible. Mainly because they can sometimes last longer than their digital counterparts, and are useful for those continually upgrading their film scanners.

#14

Excellent points. I’m glad someone with more knowledge than I could weigh in here.

I’m not sure how the kinograph is currently set up but I think that you’re suggesting capturing 3 monochrome images per frame which would significantly slow down the digital capture process. I’m also curious about the cameras people choose to use for this task. My guess is that we’re still well below Ken’s 75MP low watermark.

I’m in agreement about degraded film stock and poor initial quality material you mention.

I’m going to guess that within the next few years someone may well develop and OpenCV app that finds its favorite of the 24 frames and generates a composite image it likes. It may already be usable to remove spots and other artifacts during the digitization process. I’ve only fiddled with OpenCV briefly but I’ve already been impressed with what it is capable of for converting B+W images to color.

With regards to lost digital content…
I’ve lost no shortage of hard disks in my time, so I certainly feel the pain there. I’ve also had drives that somehow crush raw cr2 files. Presently I try to back everything up in at least two locations.

#15

Yes you’d certainly be right about that, and one can compensate for this by using a higher frame rate camera, or just making the digitization process a bit longer.

I don’t think we’ll see 75MP cameras within our reach anytime soon (it’s almost twice as many pixels as widescreen 8K). Besides, the analysis that I posted estimates that the Velvia 50 stock (which Rockwell claims is 75MP) is more like 16MP in practice, which is very much within our reach. Up to a certain point, all we’d be capturing is more distorted grain and not necessarily more image detail. The only reason I’d see scanning something in 75MP is if I were scanning 70mm prints.

I highly recommend you read this thread if you haven’t yet.

Some slightly off-topic stuff here:

If you’re talking about using OpenCV to automate film dirt removal, there’s a guy who used AviSynth to automate his dirt cleaning process as well as apply a bunch of other enhancement filters.
https://vimeo.com/2823934

I also have written a fully-automated experimental film dirt removal algorithm based on neural networks.

#16

Thanks for the thorough and quality response, @ImgKD!

@WirelessGuy_NY Kinograph 2.0 (work in progress) is only capturing a single color image per frame. The camera I bought is this one: https://www.flir.com/products/blackfly-s-usb3/?model=BFS-U3-32S4C-C

Note that the camera can be switched out, however, and you could use whatever camera you wanted as long as it’s capable of being triggered by an external source (via GPIO pins).