Quoted: How does one switch between 1x and 4x?

If you look closely at the left side of the optic, you will see a single lever (green) just above the two ARMS mount levers (black).  I don't remember which position is which.  I think to the rear was 1X and forward was 4X.  The lever rotates roughly 120degrees.  It's pretty small and may be difficult to manipulate with golves.  But the process to switch magnifications is very fast.

Quoted: I did get a call from ELCAN and they told me it would be about another 4 weeks.

Don't sweat it Mike.  I couldn't get my doctor to remove one of my kidneys until after April 1st anyway.

Interesting... as is the integrated BUIS system on the top end.

Is this correct?

FOV at 100 yards:

1x = 115.2 feet
4x =  31.2 feet

elcan.phpinternet.com/specter_DR/SpecterDR1.pdf

elcan.phpinternet.com/specter_DR/DFOVDemo.html

www.armament.com/SpecterDR_Dual_Role_Optical_Sight.PDF

I did a google search and found some links to more visual info.....  I want one of these!  How much?

$1449.00 each?  I will take two!  

Very cool sight though.  I am going to buy an ACOG and wait for the price to go down a bit on this cool new toy.

Quoted: www.armament.com/SpecterDR_Dual_Role_Optical_Sight.PDF

That's funny!  146.3 feet at 100 yards!!!!!!!

I think NASA did their FOV math  

Yes, I see the error in our distributor's datasheet.  Thanks for the heads up.


I always like to use FOV in degrees.

FOV at 1X is 24 degrees minimum, 26 degree nominal, and about 28 degrees max.
This yields a FOV in yards of  2 x tan (half angle) = 42.5 yds = 127.5 ft (minimum);  138.5 ft (nominal);  and 149.6 ft (max)      

Nominal FOV at 4X is 6.5 degrees which yeilds a nominal FOV at 100 yds of 34.1 ft.  

The SpecterDR provides sharp imaging out to the edge of the scene without requiring accomodation from your eye, so this FOV is real for even 40+ year old eyes.

Quoted: $1449.00 each?  I will take two!   Very cool sight though.  I am going to buy an ACOG and wait for the price to go down a bit on this cool new toy.

Go down?  If its like the ACOG the price will only continue to climb on the optic.  Is $1449 the MAP?

Quoted: Yes, I see the error in our distributor's datasheet.  Thanks for the heads up. I always like to use FOV in degrees. FOV at 1X is 24 degrees minimum, 26 degree nominal, and about 28 degrees max. This yields a FOV in yards of  2 x tan (half angle) = 42.5 yds = 127.5 ft (minimum);  138.5 ft (nominal);  and 149.6 ft (max)       Nominal FOV at 4X is 6.5 degrees which yeilds a nominal FOV at 100 yds of 34.1 ft.

So it's 5.3 feet FOV at 100 yards per degree?

I've been using 4.8 feet so now I'm confused where I went wrong.

So this optic on the 1X setting only has 2.75 inches of eye relief??? A 3.5X ACOG has around 2.4 inches of eye relief. Am I the only one that thinks this WAY to low of eye relief for a "TRUE 1X" optic???

1)  Scene width is equal to the tangent of the half angle of the FOV times the twice the distance under consideration.  If you are looking at 100 yards using a sight with a 12 degree FOV, then the scene width at 100 yards = 2 X 100 yds x tan ( 12 / 2) = 63 ft.   [Make sure your calculator is set to use degrees when plugging the numbers used into the TAN function.  Otherwise you need to convert the 12 degress into radians ( 3.14159 X angle in degrees / 180 degrees ) before using the TAN function.]   Since the TANGENT function is a non-linear function, there is no fixed ratio you can use like 4.6 ft per degree at 100 yards.  Such a ratio will only be exactly accurate at the one FOV angle which arrived at that number.   If your considering small angles however, such a ratio, if determined from a small angle initially, will be a good approximation.  At larger FOVs this approximation will exhibit increasingly large errors.  

2)  The ACOG is 3.8X and has 38 mm of eye relief which equals 1.5 inches.  The ELCAN SpecterDR is 4.0X with an eye relief of 71 mm, (we tyipcally just list 70mm) which equals 2.76 inches.    Your eye will be further back from the end of the SpecterDR than it will from the ACOG.  (Provided you are using both sights at their design distance. )
   
     When the ACOG is mounted on an M4 (all the way back and overhanging the rail mounted BUIS), the proper eye relief puts your nose almost touching the charging handle.   Since the M4  doesn't kick anyway, this isn't an issue and its easy to adjust the stock length to put your cheek weld at this correct distance.  

     With the SpecterDR, your eye will sit 1.25 inches further back and its easy to adjust the stock length to be a bit longer to obtain the correct cheek weld.     This longer eye relief lets you more easily shoot with goggles or glasses or NBC gear.    Also, when shooting a weapon with large recoil, you have an a added 1.25 inches of travel before you become aquainted with scope eye.     Finally, when are using an M249SAW, the longer eye relief of the ELCAN M145 and SpecterDR become really important since the stock length cannot be shortened and the proper bi-pod firing position doesn't let you crawl up the stock very comfortably.  

     Now - "TRUE 1X" optic may mean a couple of things.  If it means 1.0X magnification, then yes the SpecterDR has true 1.0X magnification.     If its intended to mean a 1.0X reflex optic with infinite eye relief, then NO the SpecterDR is a telescopic sight and not a reflex sight.   The question then is do you train into a fixed cheek weld or does your cheek weld regularly slide forward and backward during CQB.    If you slide forward and backward you definitely want a reflex, but if you also participate in urban combat, you might want to consider the SpecterDR approach.

Our expectation is that most shooters train into a fixed cheek weld (or can).  In addition, SOCOM and Army requirements indicate that urban combat enviornments involve rapid changes in engagement range (inside a building you'll want 1X, but upon exiting and taking fire from a rooftop at the end of the street, you'll want 4X and you'll be much happier with flipping a lever and returing precision fire than with fishing for and attaching your 4X while taking fire and hoping that the boresight was retained from when you last put it on the rifle.)  

   If you are a strict CQB with no chance of dynamic engagement ranges, or a strict designated marksman with no chance of close range combat, then you'll be very well served by dedicated 1X reflex and single field of view 4X optics (respectively).      

Quoted: So this optic on the 1X setting only has 2.75 inches of eye relief??? A 3.5X ACOG has around 2.4 inches of eye relief. Am I the only one that thinks this WAY to low of eye relief for a "TRUE 1X" optic???

Eye relief and magnification do not equate the way your are thinking.  The shorter the eye relief the wider the FOV and the longer the eye relief the narrower the FOV for a given optic and magnification.  If the 1X setting had more eyerelief it would have a narrower FOV.

JRS Thanks for the posts about the elcan, looks like an awsome optic. Can you give any info on when i can purchase one and where? map? Thanks looking forward to getting one.

Holy-Tag!  

I will have one...donating marrow tomorrow.  

DevL -  I agree with your first sentence except when it comes to telescopic sights.    As regards your second sentence, "It depends"  I hope the below explaination helps.

Eye relief and FOV are first tied to the diameter of the optic you are looking at.   For a fixed diameter flat piece of glass, DevL is exactly correct,  Get closer, and you'll get a wider FOV, move back and you get a smaller FOV.    Traditional Red Dot sights (Aimpoint, EO Tech, Dr. Optic, etceras, all behave this way, and, since their "windows" have zero optical power, you can move your eye closer or further away and still get a clear view through the sight.

When we are looking through an eye piece on a telescope, however, there is the additional constraint in that the eye piece only focuses the telescope image at a certain distance - the eye relief distance of that eye piece.   Get too close or too far from this and you'll exit the "eye box", i.e. the volume where your eye should be to get a clear focused image.  

Lets put our eye at some desired distance and design an eye piece to focus at that distance.  Once done, our FOV is now limited by the diameter of the eye piece.  If the eye piece has a small diameter, then you will have a small FOV no matter what the rest of the telescope is does.   If the eye piece has a large diameter, then the FOV can be large (if the rest of the telescope doesn't interfere).  

The angle between the diameter of the eye piece and the focus distance of the eye piece defines the FOV just like we saw with the flat circular window.   However, with a telescope, there are multiple windows to go through and each one has to not interfere with the FOV of the eye piece.  Note that once the eye piece is built, you can't get closer and make the FOV bigger.  You have to stay in the "eye box" which is centered on the "eye relief" distance in order to see clearly through the telescope.

So, if we briefly compare the ACOG and the ELCAN, you should notice that the eye piece diameters are quite different.   Since the ELCAN eye piece has a much larger diameter, it can support a much larger "eye relief" while maintaining an wide FOV.   (There are many finer points to eye piece design and human perception that are beyond the scope of this forum).  

The ELCAN eye piece has a 34 mm diameter and a 71 mm eye relief.  This equates to an eye piece FOV =  2 x ATAN ( 34/(2 x 71)) =   26.9 degrees.   Now when the SpecterDR is set to its 1X magnification, the rest of the optics don't limit the eye piece FOV so that the entire telescope can transmit this 26 degree nominal FOV from the scene to the eye piece and subsequently to your eye.  

Now, when we switch the SpecterDR to 4X, the erector prism and the front lens limit the FOV to 6.5 degrees nominal.   If we make them much much larger, then just like making a window larger, the FOV of these optics could also be increased up to the 26 degree FOV of the eye piece.   The resulting telescope however would be huge and very heavy.  


Now to address the second sentence....my answer is "It depends".

If we take the 1X SpecterDR optics and redesign the eye piece to have a 4 inch eye relief all we have to do is also increase the diameter of the new eye piece so that the new eye piece still has 26.9 degrees FOV,   The new sight will then have longer eye relief and still have 26 degree (nominal) FOV.      HOWEVER, if we increase the eye relief and don't increase the eye piece diameter, then the FOV of the eye piece will be lower and so the new sight would have a lower overall FOV.

Now lets consider the 4X SpecterDR optics and again redesign the eye piece to have a 4" eye relief AND lets not increase the eye piece diameter.   We will end up with an eye piece with a FOV = 2 x ATAN (34/(2 x 102)) = 18.9 degrees.    We might think that 18.9 degrees is still bigger than the 6.5 degrees of the 4X optics so that the system FOV should still be 6.5 degrees but this would be wrong.   When you change the "eye relief" of the eye piece without changing the diameter, you also begin to shrink the diameter of the imaging area that the eye piece will relay from the image plane to your eye.   Since the front optics have already established an image of a certain diameter, shrinking the amount of this image that gets relayed to your eye shrinks the FOV of the system.  The overall result at 4X would be a sight with a smaller overall FOV.   If we redesign the eye piece and let the diameter increase accordingly, then the resultant 4X system would retain its 6.5 degree FOV.

There are a significant number of coupled considerations that go into balancing between optics diameters, eye relief, FOV, magnification and optical length, errector prism type, errector prism size, aberation correction, human perception, mechanical ergonimics and suitability for intended use.   Mastery of these issues and insight into what choices improve survival and lethality is what careers and companies are made of.    
   

Specter is for sale. IM if interested.

Quoted: Specter is for sale. IM if interested.

Decide you didn't like it or need the cash for another project?

Quoted: Quoted: Specter is for sale. IM if interested. Decide you didn't like it or need the cash for another project?

STRICTLY need the cash. I'm very impressed with the Specter...but I'd much prefer some long range glass for my M1A. Fact is I'm very used to my TA01NSN and Doctor piggyback that were mounted on the pictured rifle.

Quoted: DevL -  I agree with your first sentence except when it comes to telescopic sights.    As regards your second sentence, "It depends"  I hope the below explaination helps....

Yes I should have prefaced with "all else being equal" thanks for the more detailed explanation.