DIY Video Tap

[Aapo Lettinen]

10 minutes ago, Heikki Repo said:

Aapo, are you suggesting a bracket around here?

yes, it seems it might be possible to make a bracket which mounts there. It would be ideal if there would be another bracket which would attach the bottom of the camera to another point on the ACL so that those combined with the machined lens tube would total 3 mounting points which should make the system stable enough to reduce the vibrations to minimum. 

If a double threaded lens adapter tube would not be possible, then it could be possible to just machine a tube which mounts all the way over the lens so that it rests against the C-mount -->MFT adapter of the BMPCC. One could leave a small slot on the side of the tube if the iris of the lens needs to be adjusted regularly. That would be even more secure system than attaching the lens to the ACL by the filter threads. And it would be a little bit easier to adjust by adding shims.

[Aapo Lettinen]

1 minute ago, aapo lettinen said:

And it would be a little bit easier to adjust by adding shims.

or tape.

It would be a good idea to ask the HPC guys about the machining job. They could make a nice quality custom bracket as well

[Heikki Repo]

Just contacted them, I'll visit them next week ?

[Toto Vivian]

On 5/5/2020 at 11:47 PM, D John Carroll said:

Do it!

 

the board cameras are only about $20 so it’s very reasonable to give it a shot!

hi guys, super interesting thread.

wondering what would be some cheap & relevant board cameras to look at atm? 

[D John Carroll]

I’ve updated this to 1080p hd-sdi

 

ill release a how-to soon 

[Levi Porter]

On 9/4/2021 at 3:51 PM, D John Carroll said:

I’ve updated this to 1080p hd-sdi

 

ill release a how-to soon 

Hey John, very interested in this update. I’m especially wondering what camera you’re using for the tap now to get 1080p sdi ?

[Raymond Zrike]

On 9/4/2021 at 4:51 PM, D John Carroll said:

I’ve updated this to 1080p hd-sdi

 

ill release a how-to soon 

I’d very much like to hear your results too!

[Raymond Zrike]

I’m soon going to attempt making a video tap out of a Sigma fp with my ACL. Very similar to y’all’s BMPCC solution, but I thought I’d go for an fp since it’s almost half the weight and a bit smaller. Plus it’s got the director’s viewfinder feature built in that could increase its functionality a bit.

This might be a dumb question, but do I need a lens that focuses very close in order for it to work as a video tap? 

[Heikki Repo]

9 minutes ago, Raymond Zrike said:

I’m soon going to attempt making a video tap out of a Sigma fp with my ACL. Very similar to y’all’s BMPCC solution, but I thought I’d go for an fp since it’s almost half the weight and a bit smaller. Plus it’s got the director’s viewfinder feature built in that could increase its functionality a bit.

This might be a dumb question, but do I need a lens that focuses very close in order for it to work as a video tap? 

That was the tricky part with BMPCC and ACL: finding the lens of correct focal length and then solving the close focus issue. I used c-mount lenses and spacers to get it working.

My near future plan is to explore the board cameras (CCTV) again due to the smaller size and because new such CCTV cameras have wide dynamic range setting, which might solve some of the issues I previously faced.

[Raymond Zrike]

So maybe I should try a macro lens? I was able to get it working with my iPhone camera which has a minimum focusing distance of about 4”, so maybe I need to aim for that. Although I attached the iPhone to the viewfinder rather than mounting it directly to the camera body.

What focal length did you settle on with the BMPCC?

[Heikki Repo]

I tried 50mm, 35mm and 25mm. If I remember correctly, the 35mm was the sweet spot, although 25mm worked as well.

[Raymond Zrike]

5 minutes ago, Heikki Repo said:

I tried 50mm, 35mm and 25mm. If I remember correctly, the 35mm was the sweet spot, although 25mm worked as well.

Which BMPCC did you use, the 4K one with M4/3 mount? So that would mean I'd need around 50-70mm full frame (plus the Sigma fp doesn't lose any resolution at super-35). I could probably do that. Also thinking I could just use a couple close-up filters to fix the close focus issue.

[Heikki Repo]

7 minutes ago, Raymond Zrike said:

Which BMPCC did you use, the 4K one with M4/3 mount?

No, the original BMPCC with S16 sized sensor.

Here's the latest setup I had in 2020:

https://www.instagram.com/p/CDE7S1ZluVf/?utm_medium=copy_link

 

[Raymond Zrike]

Oh the original BMPCC, wow that’s like 2.8x (owned one myself at one point). So the full frame equivalent would be like 70-100mm? Way more telephoto than I was expecting. There are definitely some macro lenses in that range though. 

[Heikki Repo]

8 minutes ago, Raymond Zrike said:

Oh the original BMPCC, wow that’s like 2.8x (owned one myself at one point). So the full frame equivalent would be like 70-100mm? Way more telephoto than I was expecting. There are definitely some macro lenses in that range though. 

Yeah, I think that's why those board cameras tend to be the best option - even if cameras like BMPCC or Sigma FP are small, the bigger lenses and distances make the setup bulkier.

Some people have been experimenting with Raspberry Pi 4 too:

https://www.instagram.com/p/CXrV-XMOStA/?utm_medium=copy_link

[Raymond Zrike]

I looked into a using a pi for a bit, but the issue there is you have to add hdmi/sdi in some way, and you have to interface with the pay some way too, so then you end up with the same amount of bulk. Also the loose cabling freaks me out.

I’m hoping to use the video tap for not just framing but also for focus, so I’m okay with some extra bulk if I can punch in on the image and keep a good amount of resolution. There are some tiny all in one 4K cameras that are probably of decent quality, but then your price starts to go up again, and then by that point the price isn’t too different from the fp (which just had its price lowered). It’s probably less of a permanent solution though, I agree. 

I also can limit the size of the lens if I just go for an apsc lens and change the fp to apsc mode—it stays at 4K in that mode. Something like this: https://www.bhphotovideo.com/c/product/1611819-REG

Also wondering, does the speed of the lens that you’re using in the video tap matter?

[Raymond Zrike]

Also just noticed you had the BMPCC mounted at a 90 degree angle—is the image sideways before it goes through the viewfinder? Had no idea.

[Heikki Repo]

4 minutes ago, Raymond Zrike said:

Also just noticed you had the BMPCC mounted at a 90 degree angle—is the image sideways before it goes through the viewfinder? Had no idea.

My experience with BMPCC as the videotap was that it was quite possible to focus using the built-in focus assist feature. Now then, many of those board cameras I have mentioned have HD-SDI output. Get one of those (one with m12 lens mount), put it in a black box that you can easily setup in the place of viewfinder and make sure it is 90 degrees rotated. Take the signal out to a LCD panel with the focus assist feature. No need for 4K in the videotap, the ground glass is going to pull the resolution down in any case.

Well, that's at least the plan I'm going to go forward with the other, viewfinderless ACL I have.

[Raymond Zrike]

1 hour ago, Heikki Repo said:

Well, that's at least the plan I'm going to go forward with the other, viewfinderless ACL I have.

What board camera are you planning on trying next? 

[marc swadel]

Hi Guys - I have been enjoying this thread! I have an ACL 1.5 that I recently got super 16'd by Les Bosher. Dead keen on a video tap! Any update on the experimenting?

[Heikki Repo]

5 hours ago, marc swadel said:

Hi Guys - I have been enjoying this thread! I have an ACL 1.5 that I recently got super 16'd by Les Bosher. Dead keen on a video tap! Any update on the experimenting?

Actually, yes - I bought a SDI HD board camera, a suitable lens and an enclosure. This is intended to be used in place of the viewfinder. It's still work in progress.

However, I'm still planning to buy a tap that goes between the VF and the camera and allows using the optical viewfinder as well. 

[Diego Collado]

On 6/28/2023 at 1:23 PM, marc swadel said:

Hi Guys - I have been enjoying this thread! I have an ACL 1.5 that I recently got super 16'd by Les Bosher. Dead keen on a video tap! Any update on the experimenting?

I'm currently experimenting with a Sony sensor I bought on Aliexpress, which outputs to HD-SDI. I'm waiting for the final parts to arrive before I can start properly testing it with a 16SR, but hopefully I'll be able to get a semi-decent feed out of the light sensor hole. Will post some pictures once I've got everything together and running!

[Geffen Avraham]

On 6/28/2023 at 10:45 AM, Heikki Repo said:

Actually, yes - I bought a SDI HD board camera, a suitable lens and an enclosure. This is intended to be used in place of the viewfinder. It's still work in progress.

However, I'm still planning to buy a tap that goes between the VF and the camera and allows using the optical viewfinder as well. 

Hey, I'm curious to know more about this. For the types that fit between VF and camera, how do they get a beam splitter and sensor in so thin? And wouldn't you need a rather high ISO?

I'm thinking of using an Aida 4K hdmi camera from B and H, but maybe you've found a better option.

[Heikki Repo]

On 12/12/2023 at 1:01 AM, Geffen Avraham said:

For the types that fit between VF and camera, how do they get a beam splitter and sensor in so thin?

Unfortunately I'm not knowledgeable enough to answer those questions!

My project hasn't really progressed that much as making the parts necessary for attaching the sensor to the camera would pretty much require a 3D printer... ?

[David Sekanina]

I can print them for you Heikki