I have both on various rifles, but the more I think about it, reticle illumination is only really necessary in mixed light. Meaning, the transition from light to dark or vice versa. So for straight day or night use, a regular, unilluminated reticle will probably work just fine.

I guess what I'm asking is, is a tactical rifle scope useless if it has no illumination?

I can only speak from my own operational experiences... as a LE marksman, I've been on many night time and low light call outs. The max range has been about 200 yards whereas the closest has been perhaps 50 yards... while I have a scope with an illuminated reticle, I've never needed it or used it. There was always a backdrop of some kind that made discerning the reticle easy. Granted, this always involved a vehicle or some type structure.

All my years of deer hunting I've never used illuminated reticles despite having them.

I would not call a scope w/o illumination useless... but it's like all other things... better to have it and not need than need it and not have it.

My first illuminated scope was one I picked up for a recce type build that I planned on carrying for hunting. I won't buy anything else now, without the illumination the crosshairs would be lost at dusk when transitioning from light to shadow.

With the price in NV dropping, I might jump one day which would somewhat negate my last comment.

Yes... w/o a contrasting background of some type, reticles are near impossible to see... if not impossible. NV on a scoped rifle is great shit...

A) I have never needed reticle illumination to make a makable shot.

B) An illuminated reticle can be seen by a person who has a scope pointed in your direction out the front of your scope.

I'm hunting coyotes at night, not people.

Your post kind of confirms my thinking, thanks.

I want and like options, so when possible I will get illuminated reticles jn my scopes, but they are kind of optional.

I have and have needed (hog hunting)

Under what conditions...?

I've lost the center of my reticle on a black pig at dusk. Had I had an illuminated reticle, I would have confidently taken the shot. As it was, I hesitated and let one of the filthy creatures walk. Damn my ethical sense of hunting!

So timely and relevant a post, ARF decided it needed to be said twice!

Even in good light if the target and its background are dark, a black reticle can get lost and crosshair juncture not visible.  Being able to turn on an illuminated center dot can be very helpful under those circumstances.

I use an illuminated reticle for 3gun. Would not have a scope without at least and illumunated center dot. When trying to find targets at distance, in the shadows, the reticle can disappear.

Hog hunting is another one were it really helps, as the other poster mentioned. On a large black furred pig, that retcle can be nearly impossible to see.

When I was looking at glass a few years ago, the scope i decided to buy was available with or without an illuminated reticle.  I decided on the non-illum.  In the few years since then, there has not been one instance shooting where I wish I had it.  If it's too dark for me to see the crosshairs, it's too dark for me to clearly see the target.  see: Jeff Cooper Rule 4

Super handy when shooting at night.

Aimpoint on the AR; TR-24 on the Beowulf; and an illuminated Leupold VX-3L on the Rem 700.

My AR is pretty much a fun gun only. I tell myself that I have it for SD too, but I'd probably reach for something else first in that situation.

I deer hunt with either the Beowulf or the 700. The TR-24 is illuminated by Tritium so it's always on. The Leupold has to be turned on manually. The battery life doesn't compare to an aimpoint and I have never taken the time to turn it on if a shot presented itself. It's a cool/supercool feature if you're at the range or gravel pit, but overrated/unnecessary if you're hunting.

A non-illuminated scope is far from useless. My 0.02.

In my experience, absolutely not. If its too dark to see the reticle against the background, then most likely its too dark to see the target.
If you have the option to configure the optic to not install illuminate reticles and save some money, Id go that route and spend the money elsewhere. But, it may be better to have it and not need it vs not have it and need it.
Every time I tried to use an illuminated reticle in low light, I ended up turning it off because it was making the reticle fuzzy and hard to focus on.

if your cool with not being able to aim for 12 hours a day then no.

They have limited use, but fill the time when you can shoot at sun rise and sun set, times when you cross hairs seam to wash out.  From the LE perspective, you can't shoot what you can't identify, so near darkness is a no go.  As far as night vision goes, they have limited use also, since in most cases facial identifiers are non existent to the shooter.

Why by equipment that has limited use.  Buy once cry once.

LGS owner tells me any optic with a battery is illegal to hunt with in Colorado.

Hmmm.  I did not know that.

I'd double check that with your state's hunting rule book.  

I use my lit reticle when coyote hunting and it is still too light for my night vision.  Or prior to NV, you will lose a black reticle on black pigs even under flashlights, so I used it there as well.

Dark backgrounds (think in the woods), even during legal hunting hours (deer), are much easier to shoot at with a lit reticle.  I typically see more game on those rainy dark days than days when I get sunburn.  When trees are soaked and it is cloudy and overcast, everything is darker than when it is dry with the same cloudy and overcast sky.  This of course is not based on my observations, but on the physics of light refraction itself.

Ever see an aimpoint or eotech with a black dot?  I wonder why.

There are plenty of opinions here but no real substance to back up those opinions, which is unfortunately fairly common as people often make equipment choices based on recommendations or based on what other people have with no real understanding of the factors involved or how their individual requirements may differ.

In truth, the need for an illuminated reticle depends to a large degree on the reticle and the design of the scope, as well as what you intend to do with it.  

1.  First versus second focal plan scopes

First focal plane scopes are popular with the tactical crowd.  However the width of the lines in the reticle shrink as the magnification is reduced to ensure the reticle elements subtend the same angular distance.   That means that in low light, where you'll want to use lower magnification on a variable scope to both increase the size of the exit pupil and increase the image brightness, the reticle will be at it's hardest to see as the lines will be very thin.(They need to be thin at low magnification so that they are not overly thick and obscure the target at high magnification.   For a FFP scope then the answer is generally "Yes, you want an illuminated reticle" to overcome one of the inherent limitations in the design of the scope.

With a second focal plane scope this is much less of an issue as the size of the reticle and the width of the lines in the reticle are constant. The lines in the reticle can be made large enough to in low light, without being so large as to obstruct a long range target at high magnification.

In addition, for a given dollar amount spent on the scope, a SFP scope will have better optics than the generally more expensive FFP scope and at the same price point the SFP scope will probably benefit from greater light throughput through either a larger objective lens or better quality optics with better lens coatings, and consequently have better low light capability with a brighter image and higher contrast, making the reticle easier to see.  

Reading between the lines here, the sharper students in the class will have figured out that a) there is a sharp downside to a FFP scope, and b) unless you are using a Mil-dot or MOA reticle to range the target and/or establish holdovers and windage corrections  at anything other than maximum magnification, you don't really need or want a FFP scope.   Balance your individual needs accordingly and don't base your selection on what a military sniper might be issued based on an entirely different set of tactical needs and priorities.

2. Variable scopes pose greater low light challenges

Variable scopes incorporate a few more lens elements than fixed power scopes and the throughput of the fixed magnification scope will generally be higher at a comparable magnification. Similar to the SFP versus FFP issue,  a fixed power scope can be made to a higher quality standard at a give price point so the objective lens size and quality can be better, improving brightness and contrast.

3.  Objective lens size, quality, and magnification matter.

Larger diameter objectives (assuming equal quality to smaller diameter objectives) greatly increase light gathering ability and allow for higher usable magnification, however, excessive magnification has a significant impact on low light performance and the ability to have enough brightness and contrast  to see the reticle.  

In other words, at the same level of quality and with the same objective lens diameter, more magnification means a smaller exit pupil and beyond certain limits a dimmer image.  In simple terms a 4-14x56mm variable on 4x will produce a larger exit pupil than a 5-20x56mm variable on 5x.  Where it gets harder to quantify is how a 3-10x42mm variable might compare to the higher magnification 56mm scopes.   In this case, you divide the objective lens diameter by the magnification being used to find the exit pupil and match that to the size of your pupil in twilight and dark conditions.

For the 4-15x56 the exit pupil will vary between 14mm at 4x and 3.7mm at 15x, the 5-20x56 will have an exit pupil that varies from 11.2 mm to 2.8mm  at 5x and 20x respectively, and the 3-10x42 will have an exit pupil varying between 14mm at 3x and 4.2mm at 10x.  Overall, the 3-10x42mm scope has the largest exit pupil at maximum magnification and it will be usable at 10x under anything short of deep twilight and dark conditions, while you'd have to back the magnification off on the larger, higher magnification scopes well before sunset.

Beyond that however, given that a dark adapted pupil in twilight conditions will be around 5mm in diameter, and it will be around 6-7mm in diameter (depending on age) in in dark conditions, those values determine the maximum useful magnification before the image starts getting dimmer than it needs to be.   You want to fully utilize the pupil diameter of your eye, but larger exit pupils will waste the light on the iris outside the pupil (although larger exit pupils offer the advantage of the eye not having to be exactly centered in the optic).  

In that regard if we assume a 6mm pupil size, the maximum usable magnification with the 56mm scopes is 9x and the maximum usable magnification with the 42mm scope is 7x.   Using the 56mm scope at 7x however would give you a larger 8mm pupil and make alignment with the optical center of the scope a little less critical, so the larger objective lens adds significant benefit at comparable magnification.

There is no free lunch however, as a larger objective lens is more expensive to produce and at the same price point the lower quality of the larger objective lens may more than offset the advantage of the larger diameter if the lens won't produce the same level of image sharpness and contrast as a smaller, higher quality objective lens.

4. Finally, the reticle used makes a difference regardless of the scope design.  

The Duplex / Multi-plex / Dual X reticle has design has been around for nearly 50 years and it's based on the concept of having wide posts in the outer portion of the reticle that reduce down to fine crosshair in the center.  The idea behind this is that even if you can't see the fine wire portion of the reticle, you can still see the wider pickets that are all pointing at the center of the reticle and can be used to identify the aim point.   You'll also find thicker duplex reticles where the reticle elements are thicker, and this is done to promote low light capability,, usually on lower magnification scopes..   Similarly, you'll find narrow duplex reticles where there is comparatively less space between the pickets and the center of the reticle, usually 4 MOA rather than 8 MOA, and this again can help determine the center of the reticle in low light.  

Center post reticles are not as common but have bene used in the past for low light purposes.  In this case, there is a single wide picket (significantly wider than in a duplex reticle)  that tapers quickly to a point at the reticle center. In low light, you'll still see all but the narrow tip of the picket and be able to establish an aim point in the scope.   Some of these have pickets that come down from the top to avoid obscuring the target when holding over the target.

Ever lost the crosshairs on a deer in the shadows during the magic hours of dawn and dusk? I sure have.

He is mistaken.