Replacing Beaulieu 4008 filters

[jessh]

I have a beaulieu with filters that are in really bad shape. Does anyone know where I can get a replacement filter tray with clean filters for a reasonable price? Or does anyone know how to go about replacing the filters?

I wish there was a way to remove the filters without taking the lens to film distance out of spec.

~Jess

[Steve P.]

I know that it’s argued here that the internal filters are important, but that importance has yet to be conclusively proven to me. Yes, that thickness should make a difference in theory, but I don’t see a difference in my practice. My point is really this: If your filters are in rough shape and have to be removed anyway, you could remove them and shoot some test footage. Shoot some test footage with and then without. See what happens. Compare.

If you decide to replace the filters, and you want to try a DIY, I think it’s been suggested before that you can try cutting down gelatine filters, like the Lee or Cokin brands. You wouldn’t have to do a two-panel, joined UV-85 combo -- just UV for the whole thing, and then a lens-mounted 85 when you need it.

[aj]

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Or does anyone know how to go about replacing the filters?

I wish there was a way to remove the filters without taking the lens to film distance out of spec.

~Jess

The filters are optically neutral and can be pushed out like instructed by Baumgarten (I believe).

But, you can indeed replace them with fresh gelatine filters. You need access to the brass filterholder behind the guillotineshutter which swings in from the side. That would mean taking the mechanical core from the housing... Left and right (the hard one). When you are there things aren't that difficult anymore. The brass holder swings out sufficiently to glue in the new filters. No further disassembly is needed.

[Sparky]

Seeing as we don't have any type A stocks anymore, you could replace with a piece of 85b and not have to bother with external filters anymore- think I'll do that with my Leicina as I can't find a series 5.5 85b for the cinegon anywhere.

Mark

[leadlike]

The filters can be very easily popped out. Replacing them can be an extreme pain as it is simply and 85 filter sitting next to a UV filter in the tray-nothing to separate them, so one normally has a heck of a time lining them up right so they don't overlap, ect. I just simply replaced both filters with a single UV, and shoot with my choice of an 85 or 85b threaded onto the lens.

[mathis]

The filters are optically neutral

On my camera service Bjorn Andersson strongly advised me to renew the filters (also the blank one) instead of getting rid of them. Because of some optical reasons.

[aj]

The filters are optically neutral

On my camera service Bjorn Andersson strongly advised me to renew the filters (also the blank one) instead of getting rid of them. Because of some optical reasons.

Mystic properties. The cornerstone of unneeded work.

Make sure you get your lens regularly collimated too even though there is nothing wrong with it.

How is that with filters in front of the lens. Still or cine.
You don't get a neutral filter with the lens which you swap when you want
to use color, polarizer or anything else.

[ccortez]

Seeing as we don't have any type A stocks anymore, you could replace with a piece of 85b and not have to bother with external filters anymore- think I'll do that with my Leicina as I can't find a series 5.5 85b for the cinegon anywhere.

Mark

Can I ask again why we aren't all replacing the 85 material in our S8 cams w/85b for the new color rev? Is that process going to be wildly different from manufacturer to manufacturer? I think I'll try with the dead compact Nizo on my workbench and report back...

Can I get 85b in a wratten gel sheet?

Maybe somebody should offer a service: adjusting S8 cams for 64T, including adjustment and calibration of the light meter and changing out the filter to 85b.

[Sparky]

Can I get 85b in a wratten gel sheet?

Yep- check ebay- I think there are a few there now in the US.

Mark

[jessh]

Thanks for the advice. I am currently thinking that I will try to remove the old filters and glue new ones in place. either just UV or UV and 85b. My only real concern is with the thickness of the filter. Will all wratten filters have the same thickness as the origional one?

~Jess

[Nigel]

My advice is rip them out and just leave them out. Use screw on filters. I had mine pulled long long ago and it was the best thing I did for my 4008. I have heard that you need to make some lens adjustments but perhaps Bjorn could confirm that.

Good Luck

[jessh]

I would love to be able to remove the filters but unfortunately the camera wasn't really designed to work that way. When you remove the filters it changes the optical distance between the lens and film plane but not the distance between the lens and the ground glass. In order to fix this you have to colimate the lens and adjust the ground glass. This wouldn't be that big of a deal to me except then most lenses that you use with it will be need to be colimated to the body since it will now have a non standard lens to film plane distance. This is a problem for me because I want to be able to switch lenses between this and other cameras (mainly my filmo and my friends eclair). If there was a way to move the lens mount closer to the film plane and return the mount to spec that is what I would prefer to do, but unfortunately there does not seem to be a good way of doing this.

Some people simply remove the filters and are happy with the results. This results in focus that is not as sharp as it could be which is a problem for me especially because I hope to use this camera for professional work.

~Jess

[Bjorn Andersson]

jess.
You are exact right on the point.
The filter between last lens and film, affect the OPTICAL distance and are one important PART of the total optical system in your camera.
If remowing this filter, the camera-body have to be adjusted! Otherwise you don´t have the crisp and exact sharpness on exposed film. This is more critical on shorter focals, 6mm, and fully open than 66mm and f22.
Is there somebody out there, who think Beaulieu tech didn´t understand this optical nature law, when they constructed their cameras?!? Or do you think they did it because they wanted to make the construction more complicated than needed.

[Steve P.]

I would love to be able to remove the filters but unfortunately the camera wasn't really designed to work that way

I don’t see a difference in my practice. If your filters are in rough shape and have to be removed anyway, you could remove them and shoot some test footage. Shoot some test footage with and then without. See what happens.

If you’re not satisfied, re-fit an internal filter.

I hope to use this camera for professional work.

Then you probably want the versatility of external CC/filters anyway.

This is more critical on shorter focals, 6mm, and fully open than 66mm and f22.

I would have thought it was opposite that: more critical on longer focal lengths, open apertures and short working distances.

[aj]

I would love to be able to remove the filters but unfortunately the camera wasn't really designed to work that way. When you remove the filters it changes the optical distance between the lens and film plane but not the distance between the lens and the ground glass. In order to fix this you have to colimate the lens and adjust the ground glass. This wouldn't be that big of a deal to me except then most lenses that you use with it will be need to be colimated to the body since it will now have a non standard lens to film plane distance. This is a problem for me because I want to be able to switch lenses between this and other cameras (mainly my filmo and my friends eclair). If there was a way to move the lens mount closer to the film plane and return the mount to spec that is what I would prefer to do, but unfortunately there does not seem to be a good way of doing this.

Some people simply remove the filters and are happy with the results. This results in focus that is not as sharp as it could be which is a problem for me especially because I hope to use this camera for professional work.

~Jess

According to two different encyclopedia gelatine filters are the material of choice when no optical influence is permissable. They are NEUTRAL except for their colouring.

A disadvantage of these gel filters is that they are not coated and when used in front they give mirror images when doing solar photography. I suppose the mirroring is always there but goes unnoticed in normal usage.

There are plenty lenses with a filter between elements or at the rear. Where the manufacturer doesn't require a filter just for the sake of the optical distance/path

BTW (old discussion) according to the collimate-adepts you cannot switch lenses between cameras. They are collimated to a specific camera! Supposedly Beaulieu engineers had difficulty designing (and having manufactured? even at 10.000's) cameras with uniform distance between film and C-mount front.