Sled Internal SDI only works with interlaced

[Yngve Bugge Drangsholt]

Good day!

Just got my first sled, and i'm super happy with it! I do however have a bit of an odd problem (or maybe it isn't and i'm just a newbie ((most likely))

The guy i purchased it from has an older Canon C300, which i have used as a practice camera for a while. I wanted to put my own camera on the sled, but this is where my problems began. My camera is an A7IV, which i've weighed down with a v-mount battery and a practice cage. To get signal down to my monitor, i'm having to use a blackmagic micro 3G HDMI-SDI converter. Now if i connect directly to my monitor from the converter, the signal is fine nomatter the output resolution of the camera. However, when i try to go via the internal SDI in my sled, the signal will only work with 1080 interlaced, and even then, the signal is quite glitchy. The sled has three HD-SDI connectors, which to my knowledge should be able to output 1080 25P? 

I have tried to configure the blackmagic converter, but my choices are only Level A or Level B, none of which work. 

The sled is a Glidecam X-45 (it has been upgraded in several ways, but the internal wiring is still the same). The monitor is a 702 Touch. 

 

TLDR; My sleds internal SDI cables will only output a glitchy interlaced signal, despite being capable of progressive(?)

[Alex Postowoi]

I don't know what weight you are planning to fly, but here's an approach. You'll  need a machinist to build and source the mild steel for this.  Let's say like me, 28 pounds on the sled is/was a normative comfortable weight to fly around the neighbourhood to build ones flight skills. For me that weight consisted of 2 one inch steel plates, about 12x5 inches, duct taped together over a piece of steel tapped for a 3/8-16 accepting insert to mount the thing to the sled's base plate adapter. Get holes drilled out up top to accept a GoPro (or whatever you're going to mount). And the with "GoPro" and lens converter of your focal lengthening  choice - go run up some stairs.  Just kidding about the running part.  Directors will torture you with endless takes of something far heavier and worse than that. 😉 Also be sure to consider the actual motion picture camera lens height heights and positions.

[J. Zachary MacDonald]

Suspect that your sled wiring is HD-SDI - not 3G SDI - so it cannot understand the higher bitrate signal that is being passed through it from your blackmagic convertor. Though it's odd that it cannot completely understand the 1080i output.. It may have something to do with the convertor assuming a 3g bitrate in its conversion process so it outputs more than the 1.5g that the signal would require.

 

below copied from internet. may be important to note that date of introduction would be far earlier than date of general adoption in industry.

SD-SDI, with a bit rate of 270Mbit/s, was introduced in 1989. It can transmit a video format of 480i and 576i.

HD-SDI, with a bit rate of 1.485Gbit/s, was introduced in 1998. It can transmit a video format of 720P/1080i.

3G-SDI with a bit rate of 2.970Gbit/s introduced in 2006. It can transfer a video format of 1080P 60F/s.

[Yngve Bugge Drangsholt]

8 hours ago, J. Zachary MacDonald said:

Suspect that your sled wiring is HD-SDI - not 3G SDI - so it cannot understand the higher bitrate signal that is being passed through it from your blackmagic convertor.

You are right indeed! The wiring is HD-SDI. I knew this beforehand, but only just figured out that the converter probably forces a 3G signal whenever it gets the chance, i.e the 1080p signal got too powerful. It is odd that 1080i was glitching as well, but as you say, i'm guessing the converter just forced a signal that was right at the edge of what the internal wiring could handle. 

My solution was to go via my newly acquired low-mode monitor, which can cross-convert HDMI to a manageable SDI signal. Little jank, but it works well for practice.

Thank you for the input! :)