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The Digital Bolex mount. Will it be robust?
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April 25, 2012
11:59 am
avisual
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I'm not sure what sort of 'universal' mount is in the works for the Digital Bolex (perhaps it is similar to the Ikonskop universal mount?). Anyhow, I use to own a Eclair ACL 16mm camera, and that camera actually had one of the best universal mounts I had seen.

Basically, if you can imagine instead of your typical c-mount on the front plate of a camera that is just a threaded hole into the face plate, the Eclair ACL body and front c-mount had … how can I describe this? … it was a bit like a threaded donut of a plate. If you can imagine that the donut hole in the center of the plate contained the threaded c-mount (inner threads), and the very generous 'body' of the donut was threaded (large outer threads) to accept other mounts on top of it. So, when you 'screwed' an adapter (like a PL mount, Arri b-mount, Nikon mount, or Aaton mount) on to the outer threads, it made for a very robust connection (as the adapter wasn't just screwing into the small c-mount opening, but the much larger circumference portion of the outer threads -- this larger outer circumference also contained about six screws holding the plate onto the body of the ACL -- again, making it very secure, as well).

Anyhow, if you go to the page of the link below:

http://www.filmcamerakit.com/h…..aptors.htm

… and scroll down to the "Eclair ACL Adaptor" on that page, you will see one of these robust ACL adaptors that screws onto the c-mount face plate I am describing above. If you look at the image, you will notice a very robust back ring, that is basically threaded in the inside, and that turns and secures onto the threaded 'body' of the ACL c-mount face plate, again, as being describing above. Also, on that same page, right above the Eclair ACL Adaptor image, you will see a C-Mount Bolex Bayonet adaptor. Looking at the two pictures, you can see how fragile and un-robust the C-Mount Bolex Bayonet adaptor is compared to the Eclair ACL Adaptor. This is because it just consists of a tapered funnel like design, which in the end, just gives you a very small set of threads just the size of the c-mount hole. And this clearly will not support a heavy pl-mount or b-mount lens.

Two other cool things about the above ACL design:

1) you don't have to use any screws to mount the additional mounts you have on top of the c-mount (there is a set pin, and you just screw them on) … flange focal depth in sound, as well.

2) If you want to use the original c-mount, you quickly just unscrew the outer mount to reveal the original c-mount. Again, no removing a additional face plate and re-screwing another face plate in, etc. The same holds true for going from a Pl-Mount adaptor or a B-mount adaptor: just unscrew the outer mount, and screw in a new mount … takes a few seconds and no shimming required.

Anyhow, if the face plate and mount for the Digital Bolex are still in the planning stage, you may want to look at the above configuration. Again, it is very simple, strong and sound solution.

-T

p.s: if the above description seems a bit confusing, let me know, and I will try to track down some more pictures of the design.

May 3, 2012
1:33 am
joerubinstein

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Hi Avisual,

This sounds really interesting, I will send your post to our engineering team and see what they say.

We are planning on having a large front section of the camera on a tight rail system with two locking screws, one at the top of the camera, and one at the bottom, so you can replace the entire front end of the camera.

This also allows for really being able to get in there to clean the sensor.

I will pass it on though.

Thanks for your suggestions, Joe

May 3, 2012
11:39 am
Razz16mm
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What provisions if any will there be for back focus adjustment?

May 6, 2012
4:07 am
joerubinstein

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Razz16mm said

What provisions if any will there be for back focus adjustment?

Hey Razz,

We are planning on having a technician level adjustment bracket for the sensor, and check each one before it goes out.

Do you think it's necessary to have a user level adjustment? I am worried people will mess with it too much.

Since this isn't an S35mm camera the depth of field isn't as critical, do you think it will be a big deal if it isn't adjustable by the user?

What percentage of users do you think would use this?

How often would they use this?

Thanks for your input! Joe

May 6, 2012
8:49 am
Razz16mm
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Back focus is extremely critical for very short focal length lenses. For many of us using vintage lenses, if there is no user adjustment we will have to take the camera and our lenses to an optical shop and have the lenses collimated to the camera. An example from my own collection is a 3.5mm Century fish-eye for 16mm which will convert to PL mount. With PL mount film cameras back focus is often deliberately set a few thousandths short to insure that all lenses will focus to infinity and optical shops shim the lenses to match spec and align the distance marks correctly.
Actual back focus depth for new industrial c-mount lenses that many people will want to use varies significantly. Industrial and security cameras all have some form of adjustable back focus.

May 7, 2012
8:03 pm
avisual
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Hey Joe,

So, your idea is that the additional mounts you will be manufacturing would consist of this large front end section of the camera. So basically, the alternate mount would just require swapping this whole piece (face plate and new mount) for each additional mount you wanted to use (PL, Aaton, Arri B-mount, etc)? That seems like it could work and be very sound, too.

Let me know what the engineering team thinks and comes up with.

Thanks,

-T

May 10, 2012
3:46 pm
analoggab

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Razz16mm said

Back focus is extremely critical for very short focal length lenses. For many of us using vintage lenses, if there is no user adjustment we will have to take the camera and our lenses to an optical shop and have the lenses collimated to the camera.

Yes agreed. And vintage lenses are gonna be popular with this cam I think.

Joe: I too think it's a big deal.

I don't see people messing with it since a part of owners won't necessarily know what back focus is. People who know what back focus is will hopefully know what they're doing. And we'll be happy to have that option.

I think you're trying to put out there a pro camera and if people *want* they'll always find ways to mess with something so this is the part where you "let go"… ;)

This is a delicate equipment and they should know it's their responsibility if they mess with the insides.

May 10, 2012
4:56 pm
mrbrianmorgan

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analoggab said

Razz16mm said

Back focus is extremely critical for very short focal length lenses. For many of us using vintage lenses, if there is no user adjustment we will have to take the camera and our lenses to an optical shop and have the lenses collimated to the camera.

Yes agreed. And vintage lenses are gonna be popular with this cam I think.

Joe: I too think it's a big deal.

I don't see people messing with it since a part of owners won't necessarily know what back focus is. People who know what back focus is will hopefully know what they're doing. And we'll be happy to have that option.

I think you're trying to put out there a pro camera and if people *want* they'll always find ways to mess with something so this is the part where you "let go"… ;)

This is a delicate equipment and they should know it's their responsibility if they mess with the insides.

I agree… I know some of the angenieux retrofocus lenses are back focus. The demand is small but it is there.

May 10, 2012
5:07 pm
joerubinstein

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I will talk to my design team about this and get back to you guys soon!

May 11, 2012
12:38 pm
joerubinstein

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OK I talked to the design team.

I think we are going to have a sealed door over the back focus adjustment so if you break the seal you void your warranty.

I know this is probably not what you guys want ideally, but I think this is a good compromise, you can get in there if you really want to, but protects us against people going in and messing with it then returning their "broken" camera if you know what I mean.

I am interested in your comments though. Better solutions to this problem?

Thanks, Joe

May 11, 2012
3:07 pm
Razz16mm
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joerubinstein said

OK I talked to the design team.

I think we are going to have a sealed door over the back focus adjustment so if you break the seal you void your warranty.

I know this is probably not what you guys want ideally, but I think this is a good compromise, you can get in there if you really want to, but protects us against people going in and messing with it then returning their "broken" camera if you know what I mean.

I am interested in your comments though. Better solutions to this problem?

Thanks, Joe

Probably the best compromise for now since many using this camera may not have the necessary gear and training to mess with it anyway.

May make using some of the industrial C-mount lenses a bit risky as they don't always conform to the C-mount film standard.

May 13, 2012
5:13 pm
joerubinstein

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Razz16mm said

May make using some of the industrial C-mount lenses a bit risky as they don't always conform to the C-mount film standard.

We are going to make C-mount lenses for you guys that I hope you will love both the look of and the price points!

May 14, 2012
11:41 am
hieber

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Hey joe, could you tell us more about the lenses that you plan to make? Primes? Or zooms?

What coverage will they have?

And what coatings will they have?

May 14, 2012
5:43 pm
joerubinstein

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hieber said

Hey joe, could you tell us more about the lenses that you plan to make? Primes? Or zooms?

What coverage will they have?

And what coatings will they have?

Hi Hieber,
I can't say too much about them right now, but I'll say a little. They will be primes, at least the first set, they will be C-mount, and cover S16mm, and they will have the sharpness and quality of lenses 4 times their price :)

As soon as I can I will let you guys know more, and I will as always ask for your advice and thoughts.

Thanks! Joe

May 16, 2012
9:48 am
harmonica

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Joe, regarding the lenses in development, do you feel comfortable disclosing your hopeful release date i.e. spring of 2013 or some date range like that? Have you determined what focal lengths you will try to include in the set?

May 16, 2012
1:48 pm
mrbrianmorgan

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Going back to the back focus… I've been playing with a canon cctv zoom and the 10mm angenieux retro focus on a GH2. The zoom lens I can adjust directly from the lens it has an adapter that screws on and off where you can lock it down exactly at the back focus length you want before going to the adapter. The angenieux retro focus… you can get macro/close up shots by loosening the lens from the mount… Certainly not the best option to have the lens loose on the mount but I'd rather that then voiding your warranty.

May 16, 2012
3:45 pm
Razz16mm
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mrbrianmorgan said

Going back to the back focus… I've been playing with a canon cctv zoom and the 10mm angenieux retro focus on a GH2. The zoom lens I can adjust directly from the lens it has an adapter that screws on and off where you can lock it down exactly at the back focus length you want before going to the adapter. The angenieux retro focus… you can get macro/close up shots by loosening the lens from the mount… Certainly not the best option to have the lens loose on the mount but I'd rather that then voiding your warranty.

I am more concerned that lenses focus to infinity, especially extreme wide angle lenses like the Century 3.5mm fisheye. Shorter the focal length the more critical and narrower the back focus depth is. But getting your lenses collimated so that they all focus to infinity at the correct reference depth is better anyway.

May 16, 2012
3:45 pm
Razz16mm
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mrbrianmorgan said

Going back to the back focus… I've been playing with a canon cctv zoom and the 10mm angenieux retro focus on a GH2. The zoom lens I can adjust directly from the lens it has an adapter that screws on and off where you can lock it down exactly at the back focus length you want before going to the adapter. The angenieux retro focus… you can get macro/close up shots by loosening the lens from the mount… Certainly not the best option to have the lens loose on the mount but I'd rather that then voiding your warranty.

I am more concerned that lenses focus to infinity, especially extreme wide angle lenses like the Century 3.5mm fisheye. Shorter the focal length the more critical and narrower the back focus depth is. But getting your lenses collimated so that they all focus to infinity at the correct reference depth is better anyway.

May 16, 2012
5:15 pm
mrbrianmorgan

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Razz16mm said

mrbrianmorgan said

Going back to the back focus… I've been playing with a canon cctv zoom and the 10mm angenieux retro focus on a GH2. The zoom lens I can adjust directly from the lens it has an adapter that screws on and off where you can lock it down exactly at the back focus length you want before going to the adapter. The angenieux retro focus… you can get macro/close up shots by loosening the lens from the mount… Certainly not the best option to have the lens loose on the mount but I'd rather that then voiding your warranty.

I am more concerned that lenses focus to infinity, especially extreme wide angle lenses like the Century 3.5mm fisheye. Shorter the focal length the more critical and narrower the back focus depth is. But getting your lenses collimated so that they all focus to infinity at the correct reference depth is better anyway.

Okay, I haven't really gotten into the fisheye photography much. But that probably would be a better option. I wonder how this camera would hold up underwater with a proper casing made.

May 17, 2012
9:48 am
JoeO

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Other cameras manage to have a user adjustable (albeit advanced user) back focus so why should we have to void our warranty to do necessary lens calibration? I'm sure most "cine" lenses will not require adjustment but, as was pointed out earlier, part of the allure of this camera is being able to mount many different types and vintages of lenses. Cine lenses are expensive and many people will be experimenting with all types of "eBay glass." If we have to break a seal and void our warranty to make these lenses focus properly then I feel that is going back on one of the fundamental principals that made this camera so attractive to low/mid budget filmmakers in the first place.

May 17, 2012
10:40 am
mrbrianmorgan

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JoeO said

Other cameras manage to have a user adjustable (albeit advanced user) back focus so why should we have to void our warranty to do necessary lens calibration? I'm sure most "cine" lenses will not require adjustment but, as was pointed out earlier, part of the allure of this camera is being able to mount many different types and vintages of lenses. Cine lenses are expensive and many people will be experimenting with all types of "eBay glass." If we have to break a seal and void our warranty to make these lenses focus properly then I feel that is going back on one of the fundamental principals that made this camera so attractive to low/mid budget filmmakers in the first place.

Yes and no… It's aimed towards students as well. I graduated from Columbia, they first gave us a JVC crap camera for the first shoot. The second shoot was on bolex. I guess they could have a student version of the camera vs indie. But the warranty is only a year… after owning the camera for a year you'll be able to use that feature. Just make sure to have your equipment insured.

May 17, 2012
3:08 pm
joerubinstein

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JoeO said

Other cameras manage to have a user adjustable (albeit advanced user) back focus so why should we have to void our warranty to do necessary lens calibration? I'm sure most "cine" lenses will not require adjustment but, as was pointed out earlier, part of the allure of this camera is being able to mount many different types and vintages of lenses. Cine lenses are expensive and many people will be experimenting with all types of "eBay glass." If we have to break a seal and void our warranty to make these lenses focus properly then I feel that is going back on one of the fundamental principals that made this camera so attractive to low/mid budget filmmakers in the first place.

Hey JoeO,

Adjusting the back focus accurately is definitely an advanced function, most cameras in this price range don't allow that at all. I absolutely have to protect myself against people adjusting this improperly and then returning the camera because it no longer works correctly. If I am going to open up this Pandora's Box, I have to protect myself.

Instead of adjusting your camera which is risky, why not adjust your lenses? Someone needs to start a business adjusting lenses for people :)

Thanks, Joe

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