Rifle Scopes Side focus and AO question
- Thread starter holy cow
- Start date
Re: Side focus and AO question
On a "budget" scope, probably.
On an IOR, nightforce and higher, not so much.
On a "budget" scope, probably.
On an IOR, nightforce and higher, not so much.
Re: Side focus and AO question
Parallax adjustment works by focusing your objective so that the target image is in the same focal plane as the reticle, so both are sharp at the same time. At the same time, parallax will be eliminated for a certain distance.
This focusing adjustment can either be done by moving the lens (or the group of lenses) that forms the objective (AO) or by moving an internal lens (side focus).
Neither of these systems is inherently better or worse optically, it is a matter of a different optical layout of the objective system. Chances are that a sophisticated design for a variable scope objective will have the lens that is being moved in a side focus parallax adjustment setup anyway, so there isn't necessarily an "additional" lens that is being put there just to allow side focus.
The seemingly common assumption that "more lenses" in an optical design equals "less clarity" is a grave misconception. In order to correct certain optical abberations (for example to achieve good edge sharpness or get rid of color fringing), it is necessary to use an optical design more sophisticated than what is necessary to create a recognizable but low-quality image of the target. While of course every lens causes a minor light loss, this loss is far outweighed by a design that delivers a well-corrected image by maybe using an additional element in the optical layout, because there is no point in transmitting lots of light if that light isn't ending up in the right places to form a sharp and contrasty image.
Parallax adjustment works by focusing your objective so that the target image is in the same focal plane as the reticle, so both are sharp at the same time. At the same time, parallax will be eliminated for a certain distance.
This focusing adjustment can either be done by moving the lens (or the group of lenses) that forms the objective (AO) or by moving an internal lens (side focus).
Neither of these systems is inherently better or worse optically, it is a matter of a different optical layout of the objective system. Chances are that a sophisticated design for a variable scope objective will have the lens that is being moved in a side focus parallax adjustment setup anyway, so there isn't necessarily an "additional" lens that is being put there just to allow side focus.
The seemingly common assumption that "more lenses" in an optical design equals "less clarity" is a grave misconception. In order to correct certain optical abberations (for example to achieve good edge sharpness or get rid of color fringing), it is necessary to use an optical design more sophisticated than what is necessary to create a recognizable but low-quality image of the target. While of course every lens causes a minor light loss, this loss is far outweighed by a design that delivers a well-corrected image by maybe using an additional element in the optical layout, because there is no point in transmitting lots of light if that light isn't ending up in the right places to form a sharp and contrasty image.
Re: Side focus and AO question
David S.:
Know-it-all!!!!
Seriously, thanks for explaining all that. Well stated and appropriately "clear", every pun intended. If you're not a native US-English speaker, your sure write like one.
David S.:
Know-it-all!!!!
Seriously, thanks for explaining all that. Well stated and appropriately "clear", every pun intended. If you're not a native US-English speaker, your sure write like one.
Similar threads
