I think GuitarGuy chose the setting he did to approximate where you would want it for normal daytime shooting.  Sounded good to me, so I just followed along.

Thats exactly why i chose the setting that i did.  However, I am open to trying sevral settings for a benchmark.  Keep in mind, we are not testing these for deployment, because none of us will deploy with a Kobra.  This is purely for our own interests and perhaps SHTF use.  I am sure that there are other optics out there that will last longer, but we are simply trying to clarify the stats for our chosen optic, as well as help any other shooters that may be attempting to make a decision on a particular optic.  Thank you for the suggestion.

Glad that the battery life is so good....

I have had two Kobras (AA versions) for a few years.  I personally don't find them bright enough for use in the FL sun.

i have no problems with EOTechs or Aimpoints.  Anyone else have a similar problem?

No actually, i have found my Kobra to be perfectly bright, often too bright outside.  In fact about the only time its not easily used is when looking at glare, other than that, its excellent for direct sunlight.  Then again, i do use the sunshade.


EDIT:
- On a side note, on a previous discussion someone had inquired about weather or not the batteries in the optic (particularly the male ends) had suffered damage that rendered the optic unusable.  Well the answer is two fold, yes there was some deformation however it was on the female side of the batteries, the male ends caused dimples on the female ends.  This however had no effect on the operation of the optic.  

Conclusion:  Yes the recoil from the 7.62 is enough to deform the batteries inside the compartment durring use, however the deformation does not cause the optic to fail.

Originally Posted By RS39: Originally Posted By criley: Glad that the battery life is so good.... I have had two Kobras (AA versions) for a few years.  I personally don't find them bright enough for use in the FL sun. i have no problems with EOTechs or Aimpoints.  Anyone else have a similar problem? Sunshade model Kobra?

Yes, sunshade installed.

Maybe it is because I like to use the single dot and it is so small.....

Originally Posted By criley: Originally Posted By RS39: Originally Posted By criley: Glad that the battery life is so good.... I have had two Kobras (AA versions) for a few years.  I personally don't find them bright enough for use in the FL sun. i have no problems with EOTechs or Aimpoints.  Anyone else have a similar problem? Sunshade model Kobra? Yes, sunshade installed. Maybe it is because I like to use the single dot and it is so small.....

I am not so sure that the "sunshade" is there to make the reticule stand out insamuch as it acts as a "killflash", i.e. it conceals the glint of sunlight off of the front of the lens so that a potential adversary would have a harder time seeing it.

Originally Posted By criley: Originally Posted By RS39: Originally Posted By criley: Glad that the battery life is so good.... I have had two Kobras (AA versions) for a few years.  I personally don't find them bright enough for use in the FL sun. i have no problems with EOTechs or Aimpoints.  Anyone else have a similar problem? Sunshade model Kobra? Yes, sunshade installed. Maybe it is because I like to use the single dot and it is so small.....

Well, sunshade or no sunshade, is it the 03m of the very early model? Both had sunshades, but I'm pretty sure the early models arent as bright as the 03m. I have both kinds, and that is the case with mine. The older one isnt as bright.

I belive the sunshade is present to accomplish one thing.  This is to limit the angles at wich light can enter the optic from the front.  This has two results.  First, it reduces the potential for off angle glint, in this respect it does work like a killflash.  Second, because light can only enter the optic from a very narrow selection of angles, it has the overall effect of dimming the area where the reticle is observed because fewer light rays strike the lens, much as is the case with the diameter of the objective lenses of rifle scopes.  

(HINT: Try pricking a hole with a pin thru a sheet of paper, hold this up to your eye and close the other.  You will see that the image you see thru the hole will be significantly dimmer than the image you see without the paper.  This is because fewer light rays make it to your eye with the pinhole in place.)

Simple answer:  The sunshade blocks off angle rays from entering the optic, dimming the image (if only slightly) and preventing most lens glint.

This works in tandem with the tinted and coated lens.  If you'll notice, the tint of the lens is a greenish blue.  It just so happens that the human eye is most sensitive in the green part of the spectrum (likely because moste edible vegitation is green and its pretty handy to be adapted to locate food) so this tint allows only wavelengths of light that fall in the blue green range of the spectrum to pass thru the lens.  This aids in distinguishing a target from its background.  SECOND:  since we are dealing with light here, we must think in terms of additive color mixing (this is how the human eye determines color).  The additive compliment of Red is Green, therefore the GREEN tint in the lens of the Kobra helps our eyes to contrast the RED reticle.  

An interesting side note.  1 in 5 males is a type 1 dichromat.  This is the medical term for Red-Green color blindness.  This means that 1 fifth of all males cannot see red next to or superimposed on green.  Perhaps the designers of the Kobra should have considered this when they designed the lens tint.  Or perhaps that is why the tint is slightly blue, to prevent the total inability to use the optic.

Im really glad i had to take that physics of light and optics class for my satellite imagery work.  It has proved damn helpful with my rifle hobby hehe.

I know you have stated your optics specs somewhere here beofre, but just for the record could you give us the model, battery type, and anything else you think necessary.

Thanks for backing up the test.  The more results the better.

My AA kobra with Ni-MH rechargeables has just passed 144 hours, no signs of the reticle dimming.

Game on.  

Excellent guys, im really happy with the results.  I am very curious about the coin cells.  Anybody have any other evaluations to conduct?

What is your hour count, and might i suggest keeping notes of brightness level with hour count.
Anyone else willing to drain an optic?

Originally Posted By pmbiker: My AA kobra with Ni-MH rechargeables has just passed 144 hours, no signs of the reticle dimming. Game on.

What is the rating on those rechargeables?

2300mAH

Tonight at @11pm will be 240 hours and 2 range trips with still no signs of dimming.  

The possibility of the contacts being crushed has been discussed.  It seems that on my Ni-MH rechargeables the contacts are solid and sturdy and I've not noticed any crushing or major dents on the +/- contact points with about 400 rounds of 7.62x39 downrange.  

It seems this thread is dead.  This will be my last battery life update unless there's more interest.

288 hours on a set of 2300mAH Ni-MH rechargeables with no signs of dimming.

Originally Posted By pmbiker: 288 hours on a set of 2300mAH Ni-MH rechargeables with no signs of dimming.

When the batteirs get weak they go dead REALLY quick, they have a voltage curve similar to Lithiums (very flat - then they just 'go dead').  I wouldn't expect to see much (if any) dimming.

Well, she's finally dead.  My AA Kobra with Ni-MH rechargeables rated at 2300mAH has given up somewhere between 816 and 840 hours.  So I can expect at least 800hrs when running these batteries, not bad.  As mentioned earlier, the Ni-MH batteries gave no warning before they died.  Thursday night it was fine bright and by Friday night totally dead.

Thanks!  I was really curous about the cobra and now I know a great deal more.  This has been very informative.

Originally Posted By Forest: Originally Posted By GuitarGuy: Haha, thanks for all the responses guys.  Lets make this into a comprehensive test, anyone willing to drain a coin cell model for grins?  Im curious about those Ni-Mh rechargeables, ill bet anything that they dont last as long, but the rechargeable factor is cool.  .. I think you'd be surprised at how long the NiMH batteries will last, especially the newer 2500mAH models.  No they won't last as long as the Alkalines, but they did very well in my tests with an EOTech.

The high capacity NiMH batteries have a less stable chemistry than the lower capacity NiMH batteries, according to a few sources on the int3rw3b.

Originally Posted By pmbiker: .. As mentioned earlier, the Ni-MH batteries gave no warning before they died.  Thursday night it was fine bright and by Friday night totally dead.

Yep both Lithium and NiMH have similar voltage curves.  They are relatively stable, but when they die - it's quick, no lingering like the alkalines.

Just for those who want them , I found a site that sells 4 pack Energizer Lithium AA batteries for $8.99 a pack shipped. Check out www.batteryspecialists.com

These are the ones that get you max hours in EoTechs and small digital cameras. I am sure the EKP-1 will ove the heck out of them....

I have the Coin battery one, but found a place that had batteries for $1 each, so I bought a sack of them. Notice that the camo carrier for the Kobra has little pockets for spare batteries in the cover flap. Useful....  :)

-Cabby

,,  

Answered alot of questions for me. Thanks alot for going through all the hard work.

Recently picked up a Kobra sight (thanks again, Thekatar!) and found this thread very informative.  Thanks guys, for running the tests.

Well I just purchased a kobra sight at freedom optics. We shall see how it will hold up in the tropics (Puerto Rico.)

I'm in Monty County.  It feels like France, but without all the beautiful buildings, great food, poodles and hot french chicks.  

Just another failed attempt at the socialist utopia.  You would think that in such a "progressive" place, where it is supposed to be all about the working man/woman, that my living expenses would have gone DOWN, not up at least 30%.  Isn't it weird how in liberal/progressive areas, a working man can't afford to squat?  The required no trans fat and smoking ban signs on all of the restaurants and bars is a nice touch.  They're about to become even more cosmopolitan by banning foie gras'.  My neighbor asked me, "What, you want to eat foie gras?"  I said, "No, I want to right to decide for myself NOT to eat foie gras."  I don't think she understood.

Now the important question, where do we get Kobra sights?  

Hi All,

Love this thread.  I just picked up a Kobra for $220.  The directions tell me to use lithium CR2325 batteries, but they are button sized batteries, whereas the compartment on this scope looks to fit AAs.  So do I take a chance and put some AAs in there?  I also have no idea how to properly adjust the acope for windage and elevation, so any advice is greatly appreciated.

Roy

Not sure if its reputable, but Im a click away from ordering for $199.

http://www.binocularsmart.com/scopes/kobra-cobra-red-dot-rifle-scope-sight-ak-akm-svd-sks-tigr-saiga.shtml

Good luck.  I don't think they're in business anymore.  I ordered through them a year ago, fortunately used PayPal.  Nothing every arrived, no communication, etc.

The current price on eBay is over $400 for the AA battery version.

Does any one know of anyone who works on a Kobra Sight?

I have a kobra with a battery EKP 1C-03 with a battery of CR2 of 3V, have you an idea of the life expectancy (cycle), it is as with piles AA?

Wow old thread..

 

I have a kobra that uses coin type battery and it lasts longer than the N type batteries in my eotech

Mine ate batteries like they were M&M's.