Manual or Electronic Slider for Vertical Use w/ Heavy DSLR?

Jesse3Names · Post by **Jesse3Names** » Thu Aug 21, 2014 12:24 am

Hi everyone. I'm brand new here and I have a bit of a DIY project I would love your opinions on. I'm attempting to build a rig to scan film negatives using a DSLR (Canon 6D) and a macro lens (Canon 65mm f/2.8 MP-E 1-5x). I could go into detail about why I chose that lens and what other aspects of the rig I'm carefully controlling, but that's not absolutely necessary at the moment. If you'd like to know specifics about the rig, please message me and I'll be happy to inform you.

On the base will be two sets of linear guide rails to allow movement in only the x and y (horizontal) directions, but no rotation or z-direction (vertical) movement. Along these guides will be moving a light box where the negative will rest atop. The camera will be fixed and centered over the lower stage so I can move the negative relative to the camera. The camera shall only move vertically. My problem rests here.

I need a way to smoothly and reliably move the camera up and down at the necessary increments to allow for shooting up to 5:1. If it's too coarse of a movement, I will miss focus! So it needs to be capable of very fine adjustment. I do not know what the requirement is to be manage focusing with 5:1 magnification, so if someone does, please say so! Here are the two obvious approaches:

Manual Solution - LINK 1 or LINK 2 - The first link appears to be one of the simplest solutions. The second link shows a bit more complex way of going about it, but essentially the same idea. My concern with going manual is adjustment. How could I make it finer - a bigger turning wheel + a finer metric threaded bolt? I think that'd let me use mechanical advantage to my, um, advantage.

Electronic Solution - LINK - Something like this, but not necessarily the same. I would need a little controller module not operated by the turn of a dial, but instead by two pairs of buttons that would allow for coarse and fine adjustment, respectively. My concerns here are weight. The motor would need to be capable of supporting the vertical-only static load of the camera and lens as well as the platform they're mounted to. My estimate is around 10 pounds to be on the very conservative side - I'd rather have an overly powerful motor than one that will crap out/not perform at all, of course.

An obvious concern for both approaches is the vertical static load applied by the camera/lens and the platform the hand crank or motor is moving. It cannot move AT ALL when I let go of the hand crank or back away from the electronic controller. What kind of precautions can I take to reinforce the manual approach and/or what kind of motor power do I need to be able to hold the weight? I'm guessing a vertical static load rating of ~10-15 lbs on the very conservative side would do it, unless someone suggests a higher load rating for some reason. I haven't built it yet so I don't know how much everything weighs besides my camera and the lens (I'd be renting the lens by the way... that thing is expensive!).

lothman · Post by **lothman** » Thu Aug 21, 2014 3:47 am

For a manual solution I would go for a Proxxon KT70 xy-table instead of the DIY-solution you showed. The KT70 should easily handle the weight, spindle pitch is small enough to find focus at 5x.

Jesse3Names · Post by **Jesse3Names** » Thu Aug 21, 2014 8:45 am

lothman wrote:For a manual solution I would go for a Proxxon KT70 xy-table instead of the DIY-solution you showed. The KT70 should easily handle the weight, spindle pitch is small enough to find focus at 5x.

And for basically $100? I'm sold. That's simple and exactly what I was looking for! The thing only weighs just under 2 lbs. I can't believe it.

Is there a fitting I could slide into the tracks to allow me to mount an Arca-style quick-release clamp? My camera is on an Arca L-bracket and I'd love to be able to pop it in and out without hassle.

lothman · Post by **lothman** » Thu Aug 21, 2014 12:32 pm

Jesse3Names wrote:Is there a fitting I could slide into the tracks to allow me to mount an Arca-style quick-release clamp? My camera is on an Arca L-bracket and I'd love to be able to pop it in and out without hassle.

You could get some T-nuts, drill holes and countersinks in an arcaclamp and screw it to the Proxxon table.

Jesse3Names · Post by **Jesse3Names** » Thu Aug 21, 2014 2:41 pm

lothman wrote:You could get some T-nuts, drill holes and countersinks in an arcaclamp and screw it to the Proxxon table.

Brilliant. I've been doing some more thinking about the base. I think it'd be smart to make the x and y directional movement of the light box under the camera be lead screw-driven. If I try to move it by hand on linear guides with the camera at 5:1 I think I'll get so frustrated not being able to do it repeatably. Is there a simple tutorial I'm missing to build a wooden frame linear stage driven by a mechanical lead screw with a big knob on the end of it? The two links I posted initially are basically what I want, but I'd rather not machine anything. I'd love to build it from off-the-shelf parts. Any help to be had here?

lothman · Post by **lothman** » Thu Aug 21, 2014 3:32 pm

Jesse3Names wrote: I'd love to build it from off-the-shelf parts. Any help to be had here?

Something like this?

Jesse3Names · Post by **Jesse3Names** » Thu Aug 21, 2014 3:53 pm

lothman wrote:
Jesse3Names wrote: I'd love to build it from off-the-shelf parts. Any help to be had here?
Something like this?

Not quite. That's a very small amount of movement. The first reply is what I'm going to use for the vertical component. Now I'm looking for an off-the-shelf way to build the two-axis horizontal component similar to one of the mechanical solution links. I don't want to have to machine anything if I don't have to!

lothman · Post by **lothman** » Fri Aug 22, 2014 12:48 am

Jesse3Names wrote: Not quite. That's a very small amount of movement.

so a stroke of 75mm x 56mm with an accuracy of 0,1mm is very small? So what size of film do you want to photograph at 5x?

Jesse3Names · Post by **Jesse3Names** » Fri Aug 22, 2014 8:25 am

lothman wrote:so a stroke of 75mm x 56mm with an accuracy of 0,1mm is very small? So what size of film do you want to photograph at 5x?

Thing is, I'm planning to scan 4x5 at 1x (giving me ~289 MP), but I want to scan 35mm at a higher magnification. The light box has to have a base that mounts it to the rails, and even if that base is 3x3" (much smaller than the light box) I would need roughly 10" of travel in the x and y directions to reach the edges of a 4x5 negative.

Are there any lenses out there for Canon that allow for 2x and 3x magnification while still providing AF and the ability to correct properly for distortion, CA, and vignetting besides the 65mm MP-E 1-5x lens?

elf · Post by **elf** » Fri Aug 22, 2014 12:07 pm

I'd recommend reviewing the threads listed in the following:

http://www.largeformatphotography.info/ ... ht-Sources

If this is too much machining for you, then a small CNC router for around $500 could easily be modified to make a complete scanning system.

Peter De Smidt · Post by **Peter De Smidt** » Fri Aug 22, 2014 4:23 pm

Here's a video of an early version of my scanner in action:
https://www.youtube.com/watch?v=gmRHTausFls

Currently, I use a D600 and a Rodagon D 75mm F4 lens at 1:1.
For vertical positioning of the camera, I use a Velmex 4000 series slide along with an Arca style clamp.

You can see Daniel Moore's rig, based on the same arduino control system, in action at: https://www.youtube.com/watch?v=PXy7RJwIBAo