Rifle Scopes ZCO 4-20 Question

nickw

Sergeant
Full Member
Minuteman
Supporter
Mar 15, 2003
881
299
Western MA
Hello and thanks in advance for the help. My question is regarding the ZCO 420 view through the optic. Specifically is there any black from the tube visible around the glass when looking through the optic. I run NF ATACR 7-35s now and have looked through a ZCO 527 and I really like how the glass appears to go right to the edge of the scope tube. Votex Razor 1-6 does this as well. How does the 420 compare? I had a ATACR 4-16 and recently looked at the new 4-20 and don’t like how you see black around the glass.

Considering the 4-20 over the 5-27 as it’s going on a Vudoo and two hunting rifles when needed.

On a side note, what causes the appearance of black around the glass on some optics and not others?

Thanks again,
Nick
 
No their isn't.


@Glassaholic or @koshkin can explain how the field stops work
 
  • Like
Reactions: nickw
No their isn't.


@Glassaholic or @koshkin can explain how the field stops work
Thank you. Thought I'd read every ZCO 420 review. Don't know how I missed this one. Still interested in the sight picture as to why some optics look like the image goes to the edge and others stop at a black ring? Is it because of the FOV stop referenced in the review? Thanks again.
 
Thank you. Thought I'd read every ZCO 420 review. Don't know how I missed this one. Still interested in the sight picture as to why some optics look like the image goes to the edge and others stop at a black ring? Is it because of the FOV stop referenced in the review? Thanks again.
ILya covered this in one of his YouTube "Optical Engineering 101 classes" at least that is what I call them. There is a reason that some scopes have a thinner outer ring vs. others that have the thick outer ring, but I should also mention that putting a flip cap on your scope will also cause this ring to appear thicker. As for the explanation as to why, the below video covers it slightly although may not go into detail regarding eyepiece design and field stops.

What I can say is that the ZCO ZC527 and ZC420 are some of the best I have seen with regard to thin outer ring for a long range scope. However, I like flip caps so it kind of eliminates the benefits here, in an LPVO where I want the 1x to virtually disappear when centered behind the scope, I think that is more important (to me) than having that feature in a long range scope where the lowest power is magnified well beyond 1x.

 
  • Like
Reactions: nickw
Thank you. Thought I'd read every ZCO 420 review. Don't know how I missed this one. Still interested in the sight picture as to why some optics look like the image goes to the edge and others stop at a black ring? Is it because of the FOV stop referenced in the review? Thanks again.

Are you referring to "tunneling" that happens when you turn the mag down and the last little bit the image shrinks? Or just fat, thick eyepieces in general?


All the scopes I've used that tunnel on the low end are only in the last little bit of travel. Not a big deal since the FOV is so much greater here. It did blow me away the first time I looked through a PMII and noticed it.

Thick eyepieces are just something your brain is letting bother you. I don't let it bother me, don't notice it, don't care. This is because I'm focused on the target and the reticle, not anything else.
 
  • Like
Reactions: nickw
ILya covered this in one of his YouTube "Optical Engineering 101 classes" at least that is what I call them. There is a reason that some scopes have a thinner outer ring vs. others that have the thick outer ring, but I should also mention that putting a flip cap on your scope will also cause this ring to appear thicker. As for the explanation as to why, the below video covers it slightly although may not go into detail regarding eyepiece design and field stops.

What I can say is that the ZCO ZC527 and ZC420 are some of the best I have seen with regard to thin outer ring for a long range scope. However, I like flip caps so it kind of eliminates the benefits here, in an LPVO where I want the 1x to virtually disappear when centered behind the scope, I think that is more important (to me) than having that feature in a long range scope where the lowest power is magnified well beyond 1x.


Thank you for your reply and the link. I’ve seen that black ring even at max magnification in the 4-16 and the 4-20 ATACR. The lens in my 7-35 ATACRS appears to go to the outer edge of the scope tube, unlike the lower power ATACRS, if that makes sense. Thanks again.

Edited to add: I watch ILya’s video and his explanation of fov and how the eyepiece design of the optic affects that was very helpful. I’m thinking this is largely what I’m seeing, but there could certainly be other factors that I don’t yet understand.
 
Last edited:
Are you referring to "tunneling" that happens when you turn the mag down and the last little bit the image shrinks? Or just fat, thick eyepieces in general?


All the scopes I've used that tunnel on the low end are only in the last little bit of travel. Not a big deal since the FOV is so much greater here. It did blow me away the first time I looked through a PMII and noticed it.

Thick eyepieces are just something your brain is letting bother you. I don't let it bother me, don't notice it, don't care. This is because I'm focused on the target and the reticle, not anything else.
Thanks. As I mentioned above in my reply to glassaholic, The black ring around the lens appears more prevalent in some optics than others, even at higher magnification. I’m wondering if it’s the field limiter that has been mentioned. I’ve had my ATACR 7–35 side-by-side with a ZCO 5–27 and I saw no black ring around the image / lens in the 15+ mag range in either optic. Since I’m leaning towards the 420 I just wanted to make sure that it was similar to the 527 in this regard. No one around here has one so it’s difficult to buy sight unseen. Thanks again.
 
Last edited: