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7/28/2013 12:36:33 AM EDT
I just picked up a D 300 Milspec unit about 5 days ago and I like it so far; however, I noticed that every now and then when I'd put it down and then look back into it the image would be out of focus, when it was just in focus a while ago. I noticed that there is a little slack in the focus ring. There doesn't appear to he anything missing as far as screws, so is this normal, is there a way to fix this myself, or do I have to send it in to be fixed? I only ask because it would seem that running or jumping off of things while out and about at night with it mounted to my PASGT helmet might make this problem more appearent. I can post pics or a vid tomorrow; but for now I'm turning in...

ETA: pic of the unit.

7/28/2013 3:18:37 PM EDT
[#1]


I'm not familiar with the insides of a D300, but from your description, it sounds like the tube can slide back and forth a little inside the housing.




If you got it new, contact the seller and they can probably either fix it quickly or supply instructions. Otherwise, if it's secondhand, just remove the ocular and you should be able to see the lock-ring, assuming that's the fault. Just push the tube forward with a clean glass-cleaning cloth ( to avoid putting prints on the tube,  which will affect image quality ) and then tighten the lockring to hold it in place -




REgards

David
7/28/2013 3:52:40 PM EDT
[#2]
Quote History
Quoted:
I'm not familiar with the insides of a D300, but from your description, it sounds like the tube can slide back and forth a little inside the housing.

If you got it new, contact the seller and they can probably either fix it quickly or supply instructions. Otherwise, if it's secondhand, just remove the ocular and you should be able to see the lock-ring, assuming that's the fault. Just push the tube forward with a clean glass-cleaning cloth ( to avoid putting prints on the tube,  which will affect image quality ) and then tighten the lockring to hold it in place -

REgards
David
View Quote


Yes, it is second-hand. About 3 years old, just a year out of reach from the manufactures warranty.

Is the ocular the 1x piece that you look through? I noticed that it has a ring just aft of the housing that is supposed to remove the ass-end of it to be able to replace it with a 3x or 5x system for weapons mounted fun.

Sorry, I'm new to NV.

ETA: There are 3 tiny flat head screws just aft of the knurled focus ring and forward of the main housing (You can see one in the pic, tiny black hole). Could those being loose cause this?
7/30/2013 12:11:18 AM EDT
[#3]
Rusty provided the following information;















The ocular is held in place by a threaded locking ring , to remove loosen the locking ring it is knurled no tools needed and then unscrew the ocular.


The locking ring for the tube is clearly visible as the next ring once the ocular is removed from memory it has two small holes in it, I think I used a couple of small screwdrivers to get it off.


For his to be a gen3 i suspect he would have an adapter to fit a mx10160 tube in to the housing there may be movement in the adapter to tube fitting, mine has a 44mm tube squeezed into the housing and the locking ring tightens onto the back of the tube.


I am sure Ive had a similar issue where the monoc is focused and if you lift it up to look at stars etc and them back to horizontal you have to refocus.


I will test it on the weekend and let him know what I find. If he takes the ocular out and the objective lense off he will be able to see if there is movement in the tube easy enough. Which is what I have been meaning to do with mine.










So that may help - He will possibly post the rest himself when he has time.







David























 
7/30/2013 1:42:04 AM EDT
[#4]
Great! Good info so far. I'll take a look in a few hours after I get some sleep. Oh, and it's a Gen 2+ unit.

ETA: does not seem to be the problem, there's no apparent movement in the tube when I took the ocular off.
7/30/2013 3:27:33 PM EDT
[#5]


Can you take a photo of the objective lens?




There's a few for the D300.




THanks

David
7/31/2013 12:45:02 AM EDT
[#6]
Quote History
Quoted:
Can you take a photo of the objective lens?

There's a few for the D300.

THanks
David
View Quote


Gladly, and it's what turned out to be the problem. There's 2 set screws that ride in the spiral geometry of the focus knob. It seems that they don't fit too well and thus had a lot of slack. I just screwed them out a little ways and then threaded the ring back on.

No more slack as far as I can feel. I then took the ring out and backed it out a tiny bit more just to let it have some more bite.

I even managed to clear most of the 'blemishes' off of the front and back of the tube that turned out to be little bits of dust. Now the image is even more clear and stays in focus now.

Special thanks to cj7hawk and his friend Rusty for providing info on this unit.

Pics:





Here she is all mounted up.


8/1/2013 3:47:14 PM EDT
[#7]
Nice work ! :)



Thank you for sharing the final solution here also -




David
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