Comment pourrais-je ne pas répondre a l'invitation de mon ami Pato?
Il existe 3 types d'instruments a prix abordable pour mesurer la vitesse d'un projectile. Ces instruments peuvent mesurer les ondes optiques, magnétiques ou sonores.
Les instruments sonores doivent etre placés a différentes distances pour mesurer l'espace de temps entre la mise a feu et ces différentes distances. Ces instruments sont préconisés par les balisticiens, comme Bryan Litz de Berger bullets, mais ne sont pas très pratique pour les tireurs moyens.
Pour le moment, il n'existe qu'un seul instrument a prix abordable, conçu pour capter les ondes magnétiques. Il s'agit du Magnetospeed disponible seulement aux E.-U.. J'en ai un mais je n'ai pas encore eu l'occasion de l'essayer.
Enfin il existe 2 types d'instruments pour capter les ondes optiques, soit ceux qui se basent sur la luminosité ambiante et ceux qui utilisent les rayons infra-rouge (IR). Règle générale, ces derniers sont beaucoup plus fiables. Voiçi une évaluation (en anglais) des différents produits disponibles dans la catégorie des capteurs optiques, publiée sur le site 6mmBr:
Citer :
We tested all the major brands.
1. Shooting Chrony -- Narrow sweet spot. Controls are confusing -- multiple pushes of same button required. Some units are very fussy as to light conditions. No IR option. Good Battery life.
2. PACT -- IR option doesn't work very well. Too many buttons on keypad. Thermo printer burns batteries quickly. We had to send one unit back. Having printer is nice, but overall, battery life is big issue.
3. Oehler 35P. Big, heavy with proof channel. Base unit very simple to use and very reliable. Sensors have proper lenses so the beam is focused, giving bigger sweet spot. Paper is very hard to feed when you run out. Battery life is pretty good considering it has a printer.
4. CED -- Small, light keypad. Nice big display. Keypad is pretty intuitive. Hinged sensor mounting bar is clever, compact when stored, but you have to be careful to slip the sensor bases on securely. IR option works good, IF you have the plugs seated tightly.
5. PVM-21 -- Once assembled (like a box kite), it is very fast, easy to set up. IR emitters work fantastic -- it will register lead pellets in complete darkness. AC adapter is funky. Unit works better with 12V battery but that has to be carried separately. Very reliable unit if you just use the white receiver box, but then you have to write down the results. Software is cranky to install and Not at all intuitive. Most guys using PVMs have given up on using with a lap-top. Unit desperately needs a better (less buggy and simpler) software interface, and it should be converted to run 5.5 volts so you could power from your laptop.
What would I buy? CED for entry level. Oehler if you have the money. PVM-21 if you shoot in low-light. PVM is excellent, but the computer interface is "not ready for prime time" and far too complex for most users. We had issues just installing the software on laptops -- you have to fiddle around to get the drivers to "take". If PVM would plug directly into USB port (like a printer) with clean software, it would be my choice for field assignments.
1. Shooting Chrony -- Narrow sweet spot. Controls are confusing -- multiple pushes of same button required. Some units are very fussy as to light conditions. No IR option. Good Battery life.
2. PACT -- IR option doesn't work very well. Too many buttons on keypad. Thermo printer burns batteries quickly. We had to send one unit back. Having printer is nice, but overall, battery life is big issue.
3. Oehler 35P. Big, heavy with proof channel. Base unit very simple to use and very reliable. Sensors have proper lenses so the beam is focused, giving bigger sweet spot. Paper is very hard to feed when you run out. Battery life is pretty good considering it has a printer.
4. CED -- Small, light keypad. Nice big display. Keypad is pretty intuitive. Hinged sensor mounting bar is clever, compact when stored, but you have to be careful to slip the sensor bases on securely. IR option works good, IF you have the plugs seated tightly.
5. PVM-21 -- Once assembled (like a box kite), it is very fast, easy to set up. IR emitters work fantastic -- it will register lead pellets in complete darkness. AC adapter is funky. Unit works better with 12V battery but that has to be carried separately. Very reliable unit if you just use the white receiver box, but then you have to write down the results. Software is cranky to install and Not at all intuitive. Most guys using PVMs have given up on using with a lap-top. Unit desperately needs a better (less buggy and simpler) software interface, and it should be converted to run 5.5 volts so you could power from your laptop.
What would I buy? CED for entry level. Oehler if you have the money. PVM-21 if you shoot in low-light. PVM is excellent, but the computer interface is "not ready for prime time" and far too complex for most users. We had issues just installing the software on laptops -- you have to fiddle around to get the drivers to "take". If PVM would plug directly into USB port (like a printer) with clean software, it would be my choice for field assignments.
Personelement j'utilise le CED Millenium II avec option IR et je suis très satisfait. J'ai un copain de tir qui utilise le Oehler 35P et on obtient sensiblement les memes résultats. Mon copain possède aussi un chony et il n'est tout simplement pas fiable comparativement au CED IR et au Oehler 35P.
Le CED Millenium II coute environ $200 et un peu moins de $300 avec l'option IR (que je recommande fortement). Le Oehler coute plus de $500 et le PVM plus de $750. Le Magnetospeed me revient a environ $300 avec les taxes et les évaluations sur Internet sont très positives. J'ai bien hate de le comparer au CED IR et au Oehler 35P dès que la température sera favorable.
Enfin, il est très important de placer le chronographe optique de façon constante pour obtenir des lectures fiables d'une scéance a l'autre. Mais il s'agit la d'un autre sujet.
En espérant que ces renseignements seront utiles a ceux qui contemplent l'achat d'un chronographe.