Camera lens microfocuser

[tooth_dr]

Does anyone have any alternative suggestions to the design that doesn’t involve opposing screws to move the bar? I’d like one that just requires a single knob to move that bar in and out.

 

 

[Dr_Ju_ju]

What bar ??  Consider fitting a Vernier control, which should give much finer control.

[tooth_dr]

7 minutes ago, Dr_Ju_ju said:

What bar ??  Consider fitting a Vernier control, which should give much finer control.

Picture would help!

[Gina]

I wondered what bar too.  All the camera lenses I know of have knurled rings for focussing.  I design and make 3D printed gears for lens focussing.  A large one has a clamp arrangement to hold it on the focus ring and a small one to go on a stepper motor.

[tooth_dr]

Apologies myinitial post was poorly worded. Can you see what I mean now, the connecting bar between the two rings. 

[tooth_dr]

It needs to be manual too. 

[Gina]

[Thalestris24]

11 minutes ago, tooth_dr said:

Picture would help!

I have one of those! I find it ok but only for some lenses. Usually, once focus is achieved it holds very well. I imagine one could knock up something better with the aid of a 3d printer as Gina has done. Maybe a manual version of Gina's and maybe a friction 'drive' rather than a geared one? Obviously you only need to make very small and limited movements of the lens mechanism, If I had a 3D printer I'd have a go! Have been thinking about getting one for a while now and they aren't expensive - certainly aren't when compared to the cost of most astro-related stuff!

Louise

[Gina]

You might get away with a timing belt depending on how stiff the focus rig is.  I have used that method but many lenses are far too stiff.

[Alien 13]

Never had an issue with camera lens focusing but you could try an app that lets you microfocus in steps, but dont know whats available with Nikon cameras.

Alan

[tooth_dr]

Thanks guys. I do plan on 3d printing this.

Gina your suggestions and photos are very useful.  Is there much backlash in your geared systems?

[tooth_dr]

7 hours ago, Alien 13 said:

Never had an issue with camera lens focusing but you could try an app that lets you microfocus in steps, but dont know whats available with Nikon cameras.

Alan

How does that work for Canon Alan, sounds very helpful.

[cjdawson]

Erm, silly question but.... for a Canon camera, why not simply use the focuser built into the lens itself?  Software like backyard EOS will let you drive the focusser through software.

[Gina]

I'm not using Canon lenses or DSLR but vintage SLR lenses by Asahi of Japan as were fitted to Pentax cameras and ZWO astro camera.  These are high quality glass and not plastic.

[tooth_dr]

1 hour ago, cjdawson said:

Erm, silly question but.... for a Canon camera, why not simply use the focuser built into the lens itself?  Software like backyard EOS will let you drive the focusser through software.

I guess cos one might not always be tethered to a PC or laptop. 

[Adreneline]

Hi Adam

I too got frustrated with the manual "loosen/tighten repeat" system on my Samyang lens so in the end I went for a very basic Arduino based system. I should say at the outset that I am of the Fortran vintage and no longer have the time or the inclination to learn a new programming language so this had to be a simple 'bolt it together' manual system. I am quite happy to pop outside to spend a few moments focusing my Samyang 135mm; nice though it may be I don't need a usb remote system. In the last year I have never known my Samyang go out of focus during an imaging session.

So I bought an Uno, a stepper motor, a stepper motor interface (this is an amazing piece of kit), a rotary encoder and a voltage converter module (to power the Uno) and programmmed with the code found here using the readily downloadable Arduino software. I assembled all of the above into a suitable IP65 weather resistant box (over-kill) and connected the driver unit to the motor with a length of old network cable and a couple of 4-pin din plugs and powered it all from my 13.8V psu. I bought a suitable belt and pulley from MotionCo and mounted the motor on my lens rings.

A little experimentation is required to get the belt tension correct and select a suitable step-size (easily achieved with the dip switches on the motor interface, but once sorted it works a treat. With power supplied to the stepper it cannot accidentally be moved. It takes me less than a minute to focus the lens and I typically expect to achieve FWHM <<  2.0 - seeing permitting.

It's not pretty (the hole in the box is so I can see the led on the Uno and I know it's powered up) - it's not elegant (neither am I) - but it works every time.

Food for thought maybe? - if not for you then maybe for someone else reading this post.

Adrian

 

[bottletopburly]

Deepskydad does a widefield carriage  for using with camera lenses 

 

https://deepskydad.com/wffs

[tooth_dr]

Thanks guys. I’m just after a very simple manual focuser! I’ve had an idea to just use a single threaded shaft and have a nut in the middle. I’ll report back his it works out. 

[Thalestris24]

Just now, tooth_dr said:

Thanks guys. I’m just after a very simple manual focuser! I’ve had an idea to just use a single threaded shaft and have a nut in the middle. I’ll report back his it works out. 

I reckon you could substitute a suitable bracket, gear and knob in place of the stepper motor driven belt above  Just requires a little imagination  

Louise 

[bottletopburly]

A micro focuser in the mix  like you get on a scope would give you a fine focus 

[tooth_dr]

2 minutes ago, Thalestris24 said:

I reckon you could substitute a suitable bracket, gear and knob in place of the stepper motor driven belt above  Just requires a little imagination  

Louise 

I’m not sure a tooth gear is the right way?

[Thalestris24]

1 minute ago, tooth_dr said:

I’m not sure a tooth gear is the right way?

Depends on whether you need a toothed belt or not. If not, then you'd get away with a smooth one - probably.

Louise

[cjdawson]

1 hour ago, tooth_dr said:

I guess cos one might not always be tethered to a PC or laptop. 

Fair point.

In that case, I'd suggest maybe trying a project like the focusser that I'm building.

This can run stand alone, so there's no need for a computer.

 

Though to be really blunt, without a big screen, how can you be sure that the focus is spot on?

[tooth_dr]

1 minute ago, cjdawson said:

 

Though to be really blunt, without a big screen, how can you be sure that the focus is spot on?

 

Not blunt, it’s a valid q. Bhatinov mask and liveview and zoom on a bright star. 

As I said I want a fully manual focuser

[tooth_dr]

5 minutes ago, Thalestris24 said:

Depends on whether you need a toothed belt or not. If not, then you'd get away with a smooth one - probably.

Louise

Does this need fixed to a base plate or could it be entirely mounted on the lens?