zevobh

zevobh

Has a website at www.zev.tv
Joined on May 22, 2011

Comments

Total: 68, showing: 1 – 20
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On article How I built a large-format (8x10) video camera (221 comments in total)
In reply to:

ProfHankD: What you've built is a large-format camera obscura. The use of shifted secondary optic is a bit unusual, but obscuras are fairly common. For example, https://www.dpreview.com/forums/thread/3996328 discusses a transmissive digital pinhole obscura I made; http://aggregate.org/DIT/FourSee/ is a reflected light multi-camera obscura using a 4x5 format primary lens. Aside from grain/specular reflections, photographing an obscura image works well. However, the image isn't just darker, but actually has a smaller dynamic range than the original scene... which can be good or bad.

hmm I am still not quite convinced. ray bumping? I have no reason to believe the white plane I am using does not have linear response (if we ignore the possibility of fluorescence which I certainly have not noticed and would mostly be removed by the UV blocking glass anyway).

Link | Posted on Feb 7, 2018 at 20:28 UTC
On article How I built a large-format (8x10) video camera (221 comments in total)
In reply to:

migus: Kudos for this camera with folded optical path!
Would be useful to post a few diagrams and drawings of the optical path and overall system.

However, one could argue that an LF camera intrinsically requires an 8x10" sensor - which could also be a (modified) liniar scanner ($50) from a flatbed. Slow and not for video, yet VERY high resolution for static subjects.

have you posted the results somewhere? both of those products sound amazing.

also, you have gotten started with hacking into the scanner? the furthest I got was ripping out the internal lenslet array and running them with SANE scanimage to scan without the light and with some manual control. it just wasn't enough. calibration got messed up without the light guide and it was always just super hit or miss. got a few decent images, but never reliably. if you have any progress please share it somewhere publicly, it would be awesome to sort of open source this project and get scanning cameras into the diy consciousness.

anyway, here was the best image I ever got from one of my scanners, this is after a bunch of processing to get rid of lines including dark and light frame subtractions. the original is something like 150mp: https://imgur.com/a/er7pZ

Link | Posted on Feb 7, 2018 at 20:10 UTC
On article How I built a large-format (8x10) video camera (221 comments in total)
In reply to:

Mike Fried: Very well done. I love the imagination to use a second camera with lens shift to correct for the off-axis skew. Obviously, you don't collect as much light as if there was a large format sensor, but you get the feeling of using the large format projection lens and can capture high resolution video directly.

Any issues with focusing the digital camera at the projection plane during video? Can focus of the primary lens and focus of the digital camera ever combine to fix slight mis-focusing, or do you just lock it to manual focus?

secondary camera should always be locked at the same distance, which it is thanks to MF and the physical focus lock on the Irix.

Link | Posted on Feb 7, 2018 at 20:00 UTC
On article How I built a large-format (8x10) video camera (221 comments in total)
In reply to:

NCB: Wonderful! The MGB GT I mean. I had one, wish I still did...

But impressive pics as well.

for sale! im not joking, hmu.

Link | Posted on Feb 7, 2018 at 19:57 UTC
On article How I built a large-format (8x10) video camera (221 comments in total)
In reply to:

SimenO1: At 18 I filmed projection screens at my local cinema. Some differences in equipment, but in principle the same. If the bar for beeing called genious is this low, well ..

well, in an odd way and most likely not in the way you mean, but I would say that actually is a huge format camera. not a camera imaging whatever scene is in the movie, but one capturing a super macro image of a reel of film. think, if you replaced the film with a leaf or your thumb, what would be projected on the movie screen would be a ridiculously macro silhouette image of that object.

now I want to try that.

Link | Posted on Feb 7, 2018 at 08:13 UTC
On article How I built a large-format (8x10) video camera (221 comments in total)
In reply to:

BostonC: Can you put it on a Gimbal? :)

on a well balanced glidecam even with a normal camera it becomes an issue at running speeds.

Link | Posted on Feb 7, 2018 at 08:07 UTC
On article How I built a large-format (8x10) video camera (221 comments in total)
In reply to:

Ellis Vener: Just to be accurate, he is using a 4x5 camera, not an 8x10.

righto, they definitely are 4x5 bellows. I am not experiencing any obstruction with a 300mm since the base of the bellows is so much further from the image plane than on a normal camera.

Link | Posted on Feb 7, 2018 at 02:34 UTC
On article How I built a large-format (8x10) video camera (221 comments in total)
In reply to:

ProfHankD: What you've built is a large-format camera obscura. The use of shifted secondary optic is a bit unusual, but obscuras are fairly common. For example, https://www.dpreview.com/forums/thread/3996328 discusses a transmissive digital pinhole obscura I made; http://aggregate.org/DIT/FourSee/ is a reflected light multi-camera obscura using a 4x5 format primary lens. Aside from grain/specular reflections, photographing an obscura image works well. However, the image isn't just darker, but actually has a smaller dynamic range than the original scene... which can be good or bad.

thanks for the link on that FourSee camara, crazy design! do you know if there is any sample data available? quick search didn't find anything.

can you explain why an obscura image has lower dynamic range? that has not been my experience and I don't see why it would be the case theoretically.

Link | Posted on Feb 6, 2018 at 20:12 UTC
On article How I built a large-format (8x10) video camera (221 comments in total)
In reply to:

migus: Kudos for this camera with folded optical path!
Would be useful to post a few diagrams and drawings of the optical path and overall system.

However, one could argue that an LF camera intrinsically requires an 8x10" sensor - which could also be a (modified) liniar scanner ($50) from a flatbed. Slow and not for video, yet VERY high resolution for static subjects.

oh believe me, I have a pile of gutted LIDE scanners from various attempts at using them as sensors. they work, but sadly have really awful dynamic range and to do it properly I would really have to write new software to manually control the scanner functions. one day!

Link | Posted on Feb 6, 2018 at 20:08 UTC
On article How I built a large-format (8x10) video camera (221 comments in total)
In reply to:

Ellis Vener: Sinar did this decades ago but very few people bought it.

got a link?

Link | Posted on Feb 6, 2018 at 20:05 UTC
On article How I built a large-format (8x10) video camera (221 comments in total)
In reply to:

Ellis Vener: Just to be accurate, he is using a 4x5 camera, not an 8x10.

oh, yeah, my bad. I could be wrong, but isnt the front standard the same for 4x5 or 8x10?

either way it is definitely 4x5 bellows so you are correct.

Link | Posted on Feb 6, 2018 at 20:04 UTC
On article How I built a large-format (8x10) video camera (221 comments in total)
In reply to:

BostonC: Can you put it on a Gimbal? :)

my original goal was to make it small enough to put it on a glidecam. it is probably possible, but wind resistance might be an issue for a camera of this size.

idk of any commercial gimbels it would fit on, but you could certainly build one.

Link | Posted on Feb 6, 2018 at 20:02 UTC
On article How I built a large-format (8x10) video camera (221 comments in total)
In reply to:

biggercountry: Coolest thing I've seen on DPR this year. I love it when people hobble things together and get such usable results.

thanks! just wait till you see v2 :)

Link | Posted on Feb 6, 2018 at 20:00 UTC
On article How I built a large-format (8x10) video camera (221 comments in total)
In reply to:

Scottelly: The last scene in the video looks amazing, as if you were using some lighting to get the exposure like that (very HDR). Did you use lights to make that possible, or is this a result of using the 8x10 set-up? I didn't notice scenes where it looked like you had tilted the lens to change the focal plane to match the surface of the ice or to get two people in focus even though they would be different distances from the lens, but I didn't watch in slow motion either. Do you find that tilting the lens works well with this set-up?

thanks! that last scene just had really nice light; it was just sunset which gave that orange glow and the white snow all around was acting like a reflector bouncing light up into the shadows. no HDR and not really anything to do with my camera, just a pretty moment.

tilting and shifting work great, but I didn't really do any for the video. it was 90% handheld, and operating focus was tricky enough let alone messing with tilt. I did tilt for some stills though, in the wide shot of the MG above you can see that the focus plane is shifted to keep the whole side of the car sharp.

Link | Posted on Feb 6, 2018 at 19:57 UTC
On article How I built a large-format (8x10) video camera (221 comments in total)
In reply to:

Vassilis Skopelitis: Well done my son , you are the future , just don't give your work for free on Unsplash.
One silly question though , does the Irix 15/2.4 has an image circle large enough that can allow the Kipon adapter to shift 12mm without vignetting ?
Thank you

Vassilis, it has just enough, if you only care about an APS-C sized area as I do.

cheers Kurt.

Link | Posted on Feb 6, 2018 at 19:53 UTC
In reply to:

D1N0: We were hoping for a 50 1.2 Samyang!

me want quarter stop.

Link | Posted on Sep 8, 2014 at 04:42 UTC
On article Hasselblad unveils pixel-shifting 200MP H5D-200c MS (218 comments in total)
In reply to:

johnbandry: At what point would the resolution of the captured image outdo the (current technology) limits of ability of printers to print it? In other words, what is the maximum number of pixels a high-end printer (of any technology) can output onto a single sheet of paper?

That's in one go, without chopping the image into pieces to be printed separately and then reassembled, as in a billboard.

never. high end printer can print at least at 2880 x 1440 dpi. the epson 11880 can, and at 64in x however long your roll is. lets say you print square, that is still a 16,986,931,200 pixel print, or 17 gigapixle.

Link | Posted on Aug 22, 2014 at 18:12 UTC
In reply to:

lem12: This x100s is probably one of the nicest looking rangefinder camera out there.

other then the small fact that it isn't a range finder

Link | Posted on May 3, 2014 at 00:42 UTC
On article SmugMug Films: Master of illusions (40 comments in total)
In reply to:

stratplaya: I'd like to take Photoshop lessons from Grimes.

actually, I am wrong. they seemed to choose literally his worst work for this article though...

Link | Posted on Apr 25, 2014 at 05:19 UTC
On article SmugMug Films: Master of illusions (40 comments in total)
In reply to:

stratplaya: I'd like to take Photoshop lessons from Grimes.

really? those sun beams are ghastly, and the shadow on the runner is almost worse.

Link | Posted on Apr 25, 2014 at 05:17 UTC
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