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Chrony Chronographs...

 
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  #8  
Old 05-16-2005, 07:05 PM
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Re: Chrony Chronographs...

[ QUOTE ]
I bought one to determine load consistency for my varmit rifles...

[/ QUOTE ]

I bought my shooting chrony for the same reason. The intent of the thread I posted was to show not that the chrony will consistantly show a velocity of up to 50fps faster or slower than actual velocity, but that it does not have enough resoultion to see differances accurately that are smaller than 50fps. This makes it mechanically incapable of giving accurate es and SD data. That being said, with good conditions, the window of accurate velocity resoultion is a good bit smaller than 50fps... at least in my opinion. But it does mean that there is a limit to the resolution, and that this chrony cannot give accurate es or sd figures down to the single digits like the Oehlers will with the longer skyscreen spacings.
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  #9  
Old 05-16-2005, 09:42 PM
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Posts: 302
Re: Chrony Chronographs...

The very first chronograph that I ever bought was a shooters chrony, it was interesting at first to have a new toy, but after a while it was very apparent that it was just that (a toy) after shooting it 2or 300 times just to make sure it was dead I bought an Oehler 35 and have lived happily ever after owning a tool not a toy.
B
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  #10  
Old 05-19-2005, 11:23 PM
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Re: Chrony Chronographs...

I agree that the absolute velocity that you measure will be more accurate if the skyscreens are spaced farther apart. Relative velocities between shots are different story. If I am reading your comments correctly, you seem to be assuming that there is going to be a 0.2" variation in the skyscreen spacing shot to shot, but that clearly isn't the case. Once you are set up, the screen spacing is fixed, the position of the chrongraph relative to the rifle is fixed, and as long as the lighting conditions aren't changing, the only real source of variablity is in the timing circuitry, and that's a pretty simple gizmo. One of the reasons the Oehler is the better instrument is that the timing is measured twice and compared for each shot, and even here the Oehler is going to give you an odd reading every now and then.
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  #11  
Old 05-28-2005, 10:15 PM
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Re: Chrony Chronographs...

I believe that it is the shot to shot variation that is minimized by the extended screen spacing. I do not believe the timing circuitry is the cause of this type of error but rather the threshold trip point of detecting the bullet in flight. Although the spacing is fixed the detected signal may not be. A .5 inch in variation could be very real if the first light sensor detected the very front, and the second detected the middle of a 1.6 inch 30cal Matchking. Then the next shot had a slightly tarnished bullet or whatever and detected the front on both sensors. By increasing the screen spacing the variation would be lessened because the measuring surface of the bullet is less of an issue. Say 10 feet .5 inch bullet detection error vs 1 foot .5 inch bullet detection error. Which is why as you say even an Oehler will give an odd reading every now and then. Now stretch a "junk" Chrony to 10 feet and......Well I'll let you know how I make out.
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  #12  
Old 11-13-2005, 12:05 PM
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Re: Chrony Chronographs...

Appreciate the thrust of this thread - but a question to follow the last post.

If you JUST change the spacing of the screens on the 'junk' chrony - am I right in assuming this change in distance needs to be programmed into the software operating the unit - or all mathematical calculations would be meaningless?

Rgds Ian
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  #13  
Old 11-13-2005, 02:35 PM
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Re: Chrony Chronographs...

ian

if you doubled the distance say, then the output speed you'd be getting would be half of what the true reading was etc. etc. then again it would be roughly half the true speed as chrony's are pretty poor in accuracy terms. just mho. i have a beta master if you want one? i am saving for the ohler [img]/ubbthreads/images/graemlins/grin.gif[/img]
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  #14  
Old 11-15-2005, 01:47 PM
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Re: Chrony Chronographs...

Nowler.

Many thanks - reading your post was accompanied by cries of 'Doh!' and much forehead slapping. [img]/ubbthreads/images/graemlins/smile.gif[/img] Makes perfect sense - but keep saving! [img]/ubbthreads/images/graemlins/wink.gif[/img]

Ian
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