Filmwasters

Which Board? => Articles => Topic started by: Ezzie on October 24, 2014, 06:00:52 PM

Title: 5x4 Twin Lens camera build project thread
Post by: Ezzie on October 24, 2014, 06:00:52 PM
As some may know, I have been planning on making a large format TL(R) for some time. Finally got to it a couple of weeks ago. The design will be jotted down in retrospect, as I don't really have one whilst building. I build along the lines of "if at first you don't succeed, try and try again".

What I have in mind is a portrait camera, but can also do whatever is the flavour of the day.

Design criteria:

-Two lenses of course
-150mm focal length
-Focuses down to approx 1m
-No built in reflex viewer, both lenses to project directly onto one Sinar 4x5/5x4 back each
-Add a reflex veiwing device later on, Sinar binocular reflex viewer for instance
-Ideally both backs rotatable, but that means they need to be spaced far apart, making the camera bigger and parallax correction more difficult
-Parallax corrected, by lifting and lowering upper lens board when focusing out and in (respectively)
-Robust, yet lightweightish
-In theory handholdable
-Can be tripod mounted, unsure if can be done in both orientations
-Easily swap viewing for another taking lens for stereos, or bracketing
-Flash capable
-Compact lenses and lens boards, in my case Horseman 8x8cm boards (enables greater degree of parallax correction
-Built using handtools only

Pictured first go at rear and front standard, and rails, and lower (fixed) lens panel.
Title: Re: 5x4 Twin Lens camera build project thread
Post by: ManuelL on October 24, 2014, 10:19:38 PM
Wow, that looks huge to me - probably the perspective of the photo, but my first though was that I could stand inside this camera.  :D
The frame looks good though.
Title: Re: 5x4 Twin Lens camera build project thread
Post by: Ezzie on October 24, 2014, 11:02:23 PM
I am actaully holding it up in the air. Consider two Crown Graphics one on top of the other, and will not be far off.
Title: Re: 5x4 Twin Lens camera build project thread
Post by: Francois on October 24, 2014, 11:14:18 PM
4x5 TLR's are huge by definition. Just look at the size of the Gowlandflex!
Title: Re: 5x4 Twin Lens camera build project thread
Post by: Ezzie on November 01, 2014, 07:48:20 AM
Mine will be a bit bigger even :)

Little progress really, been working on the focusing mechanism. Friction focusing is out. In order to get a good enough grip on the rails the rubberised wheel will apply so much pressure the rail sticks along the other edge. Would have to have rails on wheels or bearings for that to work. So a form of rack and pinion is being tried out. I had some plastic gears lying about somewhere, but they have of course gone AWOL. So I stripped some cable ties of their non serrated edges and worked with that instead. Might very well work.
Title: Re: 5x4 Twin Lens camera build project thread
Post by: Francois on November 01, 2014, 02:19:37 PM
You could always make some sort of cable and pulley system.
A pulley at each end of the traveling bed, cable fixed to the front end.
On the focusing pulley, you select one that's wider and do a few look on it for added friction on the cable. Big knurled knob.
If needed, a spring on the axle of one of the pulleys to act as a tensioner.

That's one way to get fast focus and good precision without the need for an expensive rack & pinion assembly.
Title: Re: 5x4 Twin Lens camera build project thread
Post by: Ezzie on November 13, 2014, 07:00:15 PM
Little progress, but a few more pictures

The upper lens is in the bottom most (parallax corrected) position in pictures. Will be approx 2" higher up at infinity

Focusing will be with home made rack and pinion, one on each leg. Travel will be approx 45-50mm. Enough to focus down to approx 1m.

Title: Re: 5x4 Twin Lens camera build project thread
Post by: Ezzie on November 13, 2014, 07:01:22 PM
A couple more
Title: Re: 5x4 Twin Lens camera build project thread
Post by: Francois on November 13, 2014, 10:28:17 PM
So, did you opt for a geared rack or just friction drive?
Title: Re: 5x4 Twin Lens camera build project thread
Post by: Ezzie on November 14, 2014, 10:28:44 AM
I don't know what you would call it. Something in between. I took some big cable ties and cut off the shouldered edges (non serrated as they are) and used them both for rack, and for pinion. The pinion is a 25mm diameter wooden disc with the cable tie glued around the circumference. It seems to work.
Title: Re: 5x4 Twin Lens camera build project thread
Post by: ColRay on November 14, 2014, 10:41:23 AM
I'm working on a 5x4  camera for the focusing I purchased on eBay a $15  macro focusing rail . and at that low price the quality looks quite good.
Title: Re: 5x4 Twin Lens camera build project thread
Post by: Ezzie on November 14, 2014, 04:13:59 PM
Yes, I have looked at macro rails as well. But I couldn't find a way of adapting one to this particular project. I actually have both gear and rack in nylon, but the gear is just too big. Half a turn and the whole range would be covered. Hopeless for minute changes.
Title: Re: 5x4 Twin Lens camera build project thread
Post by: Francois on November 14, 2014, 10:10:56 PM
I once saw a hand made camera that used a threaded rod and a nut to move the entire carriage.
While this setup is fantastic for its precision, it also means that you have to turn and turn the knob to get your focus point.
But on the other hand, it would be real easy to take a similar setup and add a small motor to the drive rod. A simple momentary-off-momentary switch could serve as a focusing system. This type of system should have no problem driving the weight of the front standard.
Title: Re: 5x4 Twin Lens camera build project thread
Post by: Ezzie on November 15, 2014, 03:38:34 PM
Must say I have considered the threaded rod approach. I have a few yards of M6 rod lying about. But The crank would interfere with the back, and I would prefer to have the focusing controls on the side for handheld use. The electric motor adaptation is however a very good idea. Might try that out on a test rig.
Title: Re: 5x4 Twin Lens camera build project thread
Post by: Francois on November 15, 2014, 03:39:44 PM
The good thing is that you can put it almost anywhere, including the front.
Title: Re: 5x4 Twin Lens camera build project thread
Post by: Ezzie on December 01, 2014, 02:20:55 PM
Not much progress to report. Been a bit under the weather lately. Have tested my parallax correction principle, and found I needed nowhere as much fall to correct for close focus. Hopefully may get some work done this week
Title: Re: 5x4 Twin Lens camera build project thread
Post by: Ezzie on August 18, 2015, 02:55:42 PM
As you may have suspected, progress has been lacking. But I have started thinking about picking up the work again. May involve a major redesign however.
Title: Re: 5x4 Twin Lens camera build project thread
Post by: Francois on August 18, 2015, 10:01:46 PM
Oh well... that's often how things go...
If I had a penny everytime I built something and changed my mind in the middle of the process...
Title: Re: 5x4 Twin Lens camera build project thread
Post by: 6cmsquare on August 22, 2015, 03:35:53 PM
How about a 4x5 SLR?  manual mirror lift?
Title: Re: 5x4 Twin Lens camera build project thread
Post by: Francois on August 22, 2015, 09:25:30 PM
It would actually be somewhat easy to make an instant mirror using a rubber band system.
A hook holds on to the bottom of the mirror to prevent it from flipping up and a pivot with a lever can be used to flip it back down...
Mirror could be an acrylic mirror to make the whole deal break proof.
Title: Re: 5x4 Twin Lens camera build project thread
Post by: Ezzie on August 22, 2015, 10:22:25 PM
Don't get me started ;)
Title: Re: 5x4 Twin Lens camera build project thread
Post by: Francois on August 23, 2015, 02:46:42 PM
 ;D
Title: Re: 5x4 Twin Lens camera build project thread
Post by: jojonas~ on August 25, 2015, 12:08:52 PM
you can get big mirrors on the cheap if you get a polaroid 600/spectra camera to tear up ;)