Here's an evaluation I recently conducted and reported for a LRH Forum member.
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"Today I compared the SIII 6-24x50mm to a new IOR 3-18x42mm MP-8 and my Zeiss Conquest 4.5-14x44mm Mil-Dot scopes. I conducted an elevation turret test on all three scopes at 100 yds. Then I compared all three scopes for resolution and light transmission at 300 yds in the evening (fading) light. The SIII is hitting on all cylinders and I would rate it the best scope of the three - without regard to cost - provided you're content with that 6-24 power range. Based on cost it's obviously the best buy. Here's how I rated these three scopes. I own all three so there's no pride-of-ownership compromises involved in my evaluation.
Resolution.
1) IOR and SIII equally good at 18X. Then I turned the SIII up to 24X and it maintained excellent resolution and improved my ability to resolve details at 300 yds that I was unable to see at 18X through either the IOR or the SIII. In other words, I felt like I obtained the full benefit of the higher powers available in the SIII. Razor sharp.
2) Zeiss provided less resolution with all three scopes tuned to 14X at 300 yds. Still good, but not as sharp as the IOR and SIII.
Light transmission.
1) SIII - best
2) Zeiss - about midway between the SIII and the IOR.
3) IOR – I believe the IOR has some extra lenses in it to provide the 6X power range magnification, and every additional lens will reduce light transmission.
Weight.
1) Zeiss - 17.5 oz - 1" tube
2) SIII - 21.9 oz - 30mm tube
3) IOR - 28 oz - 35mm tube
Parallax Adjustment.
1) SIII - easiest to adjust, however the adjustment operates at a pretty fast rate.
2) IOR - just about as good as the SIII - operates at a slower rate than the SIII.
3) Zeiss - I've never really cared for the parallax adjustment on my Zeiss. It's OK but sometimes a struggle to know if it's set properly.
Crosshair/Reticle.
1) IOR - Best, I really like the IOR MP-8 reticle.
2) SIII and Zeiss - both standard military Mil-Dot.
Cost.
1) SIII ~$800
2) Zeiss~$850 w/o or $950 with target turrets
3) IOR ~$1565 w/illuminated reticle
Elevation Turret Test Results.
SIII: 0.273"/click/100yds in both the UP direction & DOWN direction over a distance of 26" at 100 yards. Same value/click/100yds in both the UP and DOWN directions, however different than the advertised 0.25"/click/100yds. This is why an elevation turret test is mandatory prior to putting any scope into action. Now that I know the IPHY click value, I'll be all set.
Zeiss: 0.243"/click/100yds in the UP direction over a distance of 26" and 36" at 100 yards. No DOWN test completed with Zeiss.
IOR: 0.260"/click/100yds in the DOWN direction over a distance of 26" at 100 yards.
0.250"/click/100yds in the UP direction over a distance of 26" at 100 yards.
The IOR yielded a different value per click per 100 yards in the UP direction versus the DOWN direction. My other IOR is dead nuts on - yielding 0.249"/click/100yds in both directions. This was a brand new IOR scope so I will have to conduct the elevation turret test again and make sure I didn't make a mistake with my calculations and determination.
[IN ORDER TO CLARIFY MY ELEVATION TURRET TESTS: All three scope's elevation turrets returned to zero properly. From a set Zero, I turned the turret in the UP direction and then returned back to zero. Then I turned the elevation turret in the DOWN direction followed by a return to zero. The IOR yielded a slightly different click value when turned in the DOWN direction than in the UP direction, however it and both of the other two scopes returned back to their zero setting correctly.]
I haven't shot the SIII yet but others have already confirmed the turrets are repeatable and that the scope is durable. The SIII has as good, or better, of a replacement warranty as the Zeiss or the IOR. If I were to buy another scope today, it would be another SIII 6-24x50mm Mil-Dot. Sightron is supposed to be adding some additional offerings to their SIII line. Whether there will be additional reticle options or power options, we'll have to wait and see.
Hope this helps you spend your money wisely. For the money, the SIII is a best buy in my book." lightbulb
One year earlier I compared my Zeiss Conquest to my Leupold VX-3. The Zeiss Conquest smoked the Leupy in resolution and light transmission. It wasn't really even close. And I'm now telling you that the Sightron SIII bested the Zeiss Conquest in both categories in my recent side-by-side field comparison. The Sightron SIII is Sightron's top of the line scope. Comparing it to the SIs or SIIs is like comparing a Leupold Mark 4 to a Leupold VXII. The current limitations in the SIII series (my opinion) are the power range and the reticle options currently available. I'm led to believe some additional SIII options may become available later this year.