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Beaulieu 5008S unsharp


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#1 Thomas Thomas

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Posted 14 October 2016 - 09:14 AM

Hi,

 

my Beaulieu 5008S is sligthly out of focus. I had to turn the focus greater than infinity. I noticed it at the beginning of the film.

The film seems to move up and down, and one frame is in focus! So can see its not the lens, not the film (50D).
I know it must be greater infinity because other way round some nearer objects should have been in focus.
 

My film is not in the focus plan.

I removed the plastic 85B filter and its clear dummy.
I suspect that my out of focus problem lies here.

Can it be? I thought the plastic was quite thin witout optical effect. Does anyone know if I can replace it with a thin glass plate? How think?
It should have not much influce how this plate was mounted.

 

Thomas
 


Edited by Thomas Thomas, 14 October 2016 - 09:15 AM.

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#2 Perry Paolantonio

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Posted 14 October 2016 - 10:50 AM

My first guess would be to make sure you've got the viewfinder diopter set correctly. If that's off, your focus will be totally off. 


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#3 Thomas Thomas

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Posted 14 October 2016 - 11:01 AM

Thats not the reason. I filmed most of the time @6mm around f/4 - f/5.6 and totals of the city. The lens was at infinity.
And some shoots at longer focus length are sharper. 
That would match the theorie, that the filter is missing.
Btw. but viewfinder was correct. I used the matte screen.


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#4 Perry Paolantonio

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Posted 14 October 2016 - 12:29 PM

I don't really know that model (I've got a 4008, but it's got a totally different lens). I do know someone who has a 5008 that was dropped once, and has never been the same, focus-wise, ever since. Is it possible something like this happened and knocked the lens out of whack internally? 

 

I can't see how the filter would affect focus (I mean, beyond a slight softening because you've introduced *something* between the back lens element and the gate. It may affect the image in some ways, but I don't think it would alter the focus. 


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#5 Thomas Thomas

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Posted 14 October 2016 - 12:37 PM

On the viewfinder screen its sharp. But that the cam was damaged is possible. 

 

They write something about removed filter:

http://www.pro8mm.co...de=Beaulieu4008

"• Lens re-collimation (Because this is a reflex system, when you remove this filter system you must recollimate the camera body to standard specifications or your resulting images, particularly in wide angle, will be slightly soft.)"
 


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#6 Dom Jaeger

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Posted 14 October 2016 - 05:58 PM

Yes, behind-the-lens filters cause a lens to focus about 1/3 of the filter thickness further back, in the case of the Beaulieu in-built filters I think that's around 0.04 mm, so the Beaulieu flange depth was mechanically set that much deeper than the nominal 17.52 mm C mount standard to compensate. It's the same principle at work with the reflex Bolex flange depth, which is set physically longer to compensate for the prism (only there it's a 9mm thick piece of glass rather than a wafer thin filter, so the light rays coming out the back of the lens are extended much further back).

If you remove the Beaulieu filters, the flange depth is now a little long, and can throw the focus off. On a zoom the wide end will be a bit soft, and with primes the shorter the focal length the more the focus scale will be out. You need to either recollimate the lens or what I've done on 4008s is sand down the back of the camera mount so any C mount lens can be fitted and will focus properly. The groundglass also needs a slight adjustment, otherwise what you see in the viewfinder will not perfectly match what's on the film. It helps to have a collimator for this job.

I suspect a lot of people remove the filters and don't even notice the slight softening of their wider shots.
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#7 Thomas Thomas

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Posted 15 October 2016 - 09:10 AM

What about a little glass in the filter holder instead of the filters with same optical "thickness"?


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#8 Michael Lehnert

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Posted 15 October 2016 - 12:28 PM

I think you will struggle to find a glass filter replacement with the same optical thickness of the gelatine filters that Beaulieu used, both Wratten 85 and clear. Having to cut glass down to the miniature size you need for fitting it into the filter frame holder adjacent to the guillotine shutter mechanism may simply be quite uneconomical (too expensive) over just doing a re-collimation.

Ritter Film + Videotechnik in Mannheim, the former Generalvertretung of Beaulieu in Germany in the pre-Wittner days, routinely removed the gelatine filters during regular TLC jobs from the 2/4008- and 3/5008-series from the late 1980s onwards, and replaced them with screw-in front filter lenses. Re-collimation was part of that job. Higher optical quality and lower threats of gelatine degradation through aging were stated as reasons for that, but that was a bit of an exaggeration. You never got rid of the suspicion they wanted to sell you those B+W filters after the fact of removing the gels ("had to be done, monsieur").

At this stage, re-collimation or re-inserting gelatines (which are readily available in reasonable sizes to cut down yourself - have done it myself) may be the best way forward.
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#9 Thomas Thomas

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Posted 15 October 2016 - 01:19 PM

Where do I find clear gelantine filter?
 

In the 1980s when I hade a dark room and developed color prints I used a set of 33 cheap gelantine filters (I was a school kid at this time with less money). They said they are for use above the film in the filter mount due to its bad optical properties. Although I used it for color Dogde. Are gelantine filters really good to be behind the lens?

Actually you dont need 85 filters when filming wih negativs. I tried it. The 3200K<->5500K filters are round about one stop in the red or the blue channel. That can be fixed by grading.


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#10 Michael Lehnert

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Posted 15 October 2016 - 04:37 PM

I havn't a clue. Dedo Weigert in Munich sold them, like in 1995, I remember. Tiffen and Lee (#130) offered them, in 50cm x 50 cm sheets. The last set I bought was from a Chinese optical company on eBay, but that too is over a decade ago. Occassionally, Paillard slot-in filter gels show up on eBay in a complete set, which includes a Clear, but it's a bit of a sacrilege to break them up.

Behind-lens gels on the Beaulieu are better than their bad reputation, and with the resolving power and aesthetic immanent to Super 8, even with a 2K scan, it's not something to get too hung up with I Think. One of my 4008 bodies, a B body, still has them. I won't replace them there. I use that body when it's the best tool at hand for what I want to ahoot, But I admit all the other bodies have had them removed and supplanted by front filters, during Ritter or Björn or Dresel TLC jobs.

And I agree with you, with color grading in post, you really can do without corrective filters likemthe Wratten 80 or 85.
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#11 Thomas Thomas

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Posted 15 October 2016 - 05:07 PM

Here an example. scaled to 1024

Attached Images

  • alterbrunnen_s8.jpg

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#12 Andries Molenaar

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Posted 21 October 2016 - 05:36 AM

There is nothing wrong with the image. It comes from 4x5 mm!

Mind the wires high across the street.

 

This filter nonsens theoretically only comes into play when shooting from tripod at max wide aperture. Don't bother with it it is only theory. Most people shoot super-8 handheld and modern film is always way too sensitive, aperture is more likely F11 rather than F1.4  Don't bother with collimating your lens or having a hair of thickness removed from you C-mount.

 

Should you persist, refitting gel filters is the cheapest,  gel filters for UV or 85 are easy to find. You would need at best some 6x5mm of it.


Edited by Andries Molenaar, 21 October 2016 - 05:43 AM.

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#13 Thomas Thomas

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Posted 21 October 2016 - 06:54 AM

There are much sharper super8 videos on youtube filmed with Kodak 50D. (though, there's also a lot of crap)

But more importantly:
At the beginning of the film and at the end the film moves up and down. And there are 2 sharper frames!

Here the test footage:



At 1:27 theres one of the sharper frames. Look at the orange LED writing over the tram's front window. Just as it is exactly below the round ceiling window the writing is sharper in one frame!


Btw. here the comparison:


 


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#14 Michael Lehnert

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Posted 21 October 2016 - 11:35 AM

Thank you for this! Excellent movies. Clearly lots of effort went into their making. Also great composition to make the comparative shots technically meaningful, in terms of motif, color palette, contrast, mix of still and moving objects etc.

 

I agree that - viewing the YouTube sample at 720p – the image is softer than it should be. You can get visibly better resolving power with Kodak 7203 through your Schneider Beaulieu-Optivaron 1:1,4 / 6-70mm (C-Mount) with Beaulieu Reglomatic. I can also see the much sharper frames at the beginning and ending, as if the film would briefly loop out or pop into the right planar position in the camera's transport mechanism. I suppose you used different cartridges, so pressure plate issues in that one cartridge can be eliminated. It may be that this relates to the Wratten/Clear removal, but this is too soft to be caused by this only, I think, based on my experience with non-gel'd 4008 bodies.

 

Frame stability is also not great overall with your 5008 S. The transport mechanism is in need of some TLC, as you can achieve much more stable frames (and I hope you forgive me saying that you need to be a bit more careful loading the cartridge into the camera B)  ). So it may be that a variety of factors around collimation and transportation come into play that cause the images to be sub-par to what can be achieved with your set-up.

 

Before people flood in and start saying stuff like "It's only Super 8, whatdayawant, ditch precision, embrace being slovenly" – an approach that I don't subscribe to – can I ask where you did the digital transfer and on what machinery? Just to eliminate any cause on that side? The softness is also persistent independent of codecs or scaling to different sizes?


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#15 Thomas Thomas

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Posted 28 October 2016 - 10:06 AM

Hi,

Scanning was done at Berola as 16bit uncompressed TIFF. The grain structure and the perfo hole are sharp. So I doubts its the scanning.

I think I use the auttum here and shoot another cardridge, while changing focus and focus length. If it is wrong collimation or film alignment, something must be sharp. Either far objects when focusing near object or vice versa.

 

What does TLC mean?

 

Would it be an option to get a C-Mount -> MFT-Adapter and check the Schneider-Kreuznach at the blackmagic or panasonic?

 

But theres another completely different problem:

Its visible best at 3:00 at the stone of the fountain just in the middle and at 3:50 at the gates.
Some stones get a green color cast. The 50D shot the stones around the gate goes into the green. Where as the stones in the blackmagic shot goes into orange.

Even the shot at 2:14 where the orange tram moves by.
The shadows at the left have a magenta cast and the houses at the right have still a greenish cast.
I dont know if something during development went wrong (by Andec).

It did only "global" color corrections. (primary wheels and YRGB-curves in resolve). No power windows, no selective color correction, no sharpening, no stabilizsation.
 

The blackmagic have a different red reproduction since it seems to beo optimized for skin color. (skins perfect, red roofs too orange)
But I used my panasonic G3 as light meter and have stills of every scene. Even there the stones are not greenish, but orange.

Its strange because it you look at the color circle, some orange tones will get a greenish cast and some slightly different ones a magenta cast. I cannot imagine any scientific explanation.









P.S did someone understand the gag with the four additional accus for the BMPCC?
P.P.S it was not a gag. Is really needed them ...



 


Edited by Thomas Thomas, 28 October 2016 - 10:18 AM.

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