View Full Version : OK a question that shows my ignorance

Amos De Pasquale
12-01-2013, 7:26 PM
I purchased Laser heads for 38.1mm lens and 50mm lens, and in my thinking, the length of the housing had to be 38.1mm and 50mm respectively,:confused::confused: but they are both 100mm in length???:confused::confused:is this correct?? please educate me in this area. Amos:)276126

Dan Hintz
12-01-2013, 7:30 PM
Those are the focal lengths of the final optic... the tube length is irrelevant.

Dave Sheldrake
12-01-2013, 7:41 PM
The top head unit is for the short focal length and the bottom is for the longer one.

Unscrew the Knurled ring and remove the lens barrel, you don't need (or want) to be changing the entire head each time. The lens barrel will slide up and down inside the main tube to get a basic distance adjustment. Fit the short focal length lens into the shorter cone barrel and the longer focal length into the other one.

The only part that needs to be longer or shorter is the aircone.



Amos De Pasquale
12-01-2013, 8:02 PM
Thanks for that information, had I known this beforehand it would have saved me at least $500, I have been purchasing Laser heads on the basis that I was expecting different physical sizes!!!!, you live and learn, sometimes the hard way! Your teaching greatly appreciated. Amos

Dave Sheldrake
12-01-2013, 10:49 PM
No worries my friend, we all live and learn, I made many many mistakes when I first started out with lasers (more years ago than I want to remember).

For my HX (HPC) machines I keep a set of lens barrels with air cones fitted already set up with stop rings so I can just swap them out as required with no need to refocus. The barrels on their own are pretty cheap and protect the spare lens's quite well when stored.

If you can avoid it, DON'T swap out laser heads, they can take quite a bit of re-aligning to get them working again.If you just swap the barrels they will be pretty much spot on each time.

best wishes


Amos De Pasquale
12-01-2013, 11:16 PM
Thanks Dave, once I read the answers I determined to do what you suggested. Amos