Cloudy Day Chrono Readings

07 January 2002, 16:27

I have a question, what does a cloudy day versus a sunny day do to a chrono reading? I have an Ohler 35P that I got for Christmas and yesterday I was shooting some 308 Winchester loads over it and got some great extreme spread readings with H380 and the Sierra 168 MK. One load went an exteme of 4 fps and another load went 7 fps for 5 shots with match preped brass. Today I shot in real cloudy dreary conditions and got spreads of 40+ fps with both loads. I used the same powder (H380), brass (Winchester), primer CCI-BR2, rifle (McMillen) as yesterday....WHAT GIVES WITH THIS. It has me baffled. I used new batteries both days. Temperature difference was 9 degrees (41 yesterday 33 today). Does Ohler have a website? Thanking everyone in advance for your advise. Sure hope I don't shoot my Ohler. Sounds like it happens all to often

Shoot Safe, Shoot Straight....RiverRat

07 January 2002, 16:44

D Hunter

Can't say exactly. My Crony will not give readings at all on sunny days. Go figure. "D"

07 January 2002, 18:44

<Hutt>

Mine needs a consistent white backgroud to get consistent readings.Sometime late in the day when the light is fadeing it will throw an error reading.These things are somewhat like cameras where light is the all important ingredient.

08 January 2002, 01:39

<stans>

Chronographs usually need fairly bright, uniform light to operate consistantly. This means bright overcast days are good or sunny days with light diffusers (which give the sensors bright, uniform light). Dark overcast days, dawn, and dusk will provide conditions that are difficult for the chronograph. Shade from trees will also play havoc with chronographs.

08 January 2002, 02:47

old4x4

Same here...I like a cloudy day for shooting over my chrony. Never get an error, but on sunny days, I have to use diffusers or a large semi-transparent piece of plastic (think it's called corrigated plastic). I think the sun reflecting off the bullet or the sun's shining directly into the sensor is what messes it up.

08 January 2002, 07:38

denton

My Chrony definitely gives slower readings when I leave the diffusers in place on a cloudy day.

Photographers have a definition of "cloudy bright" that works for my Chrony, too. If you can see distinct shadows, the light is good. The minute I can't see the shadow of my tripod anymore, my readings start being affected.

If clouds would just be uniform, they would make an ideal diffused light source. The bad news is that they are not. The variation in cloud cover thickness shows up as variation in bullet speed. In my case, it amounts to about 50 fps.

08 January 2002, 08:41

sambubba

If you take a black magic marker and mark the bullet all around it will probably give you a reading every time. It works for me.
Sambubba

08 January 2002, 10:40

waitaminit

http://www.oehler-research.com/

In former days the bullet interrupted an electric circuit (a wire) and nobody had to paint bullets black.

08 January 2002, 12:10

Atkinson

This problem is basically only with Cronys...Your Ohler and the pro-Chrony will not exihibit such problems on cloudy days.

------------------
Ray Atkinson

ray@atkinsonhunting.com
atkinsonhunting.com

08 January 2002, 18:03

RiverRat

Gentlemen, thanks so much for your posts to my question. From what I have read you have to get familiar with you chronograph to understand how it reads. It makes sense that light conditions can and does affect a chronograph. I will continue to work with this one. Just hope I don't shoot it.....LOL

Shoot Safe, Shoot Straight.....RiveRat