iris Foresight

[conradin]

What is the difference between an iris foresight and a normal front sight using aperture inserts? I shoot at a reduced target and it is hard to find anything less than 3.0 for inserts.

[Tim S]

There isn't really any difference, except that an iris aperture allows you to alter the size much more quickly than swapping out an insert. In practise, some irises have a thicker ring than inserts (especially Perspex). Also some irises only adjust the inner diameter, so the ring becomes thicker as the aperture size decreases, and vice versa, whereas others maintain a constant thickness, and others allow the ring thickness to be varied too.

As for reduced targets, the target diameter has to be proportionate to the distance. If the target is reduced correctly you should not need a smaller aperture. Unless you mean that you are using a disproportionally small target.

[Andre]

My Centra "Ring-Adjust" foresight goes from 2.8 - 4.8mm. You won't find much smaller out there, if you need it smaller get one of those sight extension flat bars. You can't use one in competition, but then again you don't shoot reduced targets in matches either.

Also can magnify your shake, and give you feedback on what certain changes are doing to your hold and pattern.

[patriot]

What is the difference between an iris foresight and a normal front sight using aperture inserts? I shoot at a reduced target and it is hard to find anything less than 3.0 for inserts.

Around $200 :-)

[conradin]

So on a Iris Foresight the "ring" actually changes its radius? How is it possible...?

[Tim S]

Vince,

I think they have two sets of leaves, one for the inner edge and one for the outer.

My old Gehmann iris had one set of leaves, so only the inner edge of the ring could be adjusted. My new Centra iris has two I think (I haven't looked closely at it yet); both turn together to keep a constant thickness. The leaves on Andre's Vario iris will turn independently so both ring thickness and aperture diameter can be changed.

[spektr]

Hi Vince.
I replaced both the front and rear on my Savage. My front go's from like 2.4 to 4.8. I shoot 25 yards and 50 foot targets. I have the flexability to actually see them with these tired old eyes. Splurge a bit, this isnt a test drive for the next life....

[Andre]

The ring you look through is a tube, and it is split in several places and bent outwards. There is a larger ring slipped over the tube, that when you twist the size collar moves back and fourth. When it moves toward you, it closes that split tube and you get a smaller diameter to look through. (the split section of the tube is facing you)

Works just like a collet in a dremel tool or milling machine.

[gwsb]

Anschutz makes a front sight with inside and outside independently variable. That way you can change the thickness of the ring.

[conradin]

I have just ordered a centra 1.8-4.3 clear front iris. I wish they would have a pink front iris, but I guess I can use my diopter's red filter. It is not ideal, but I think this will do. With a 1.8-4.3 I can switch between air rifle (10m or 10 yards) and smallbore (50 ft, 25 yards, 50 yards and 50 ft). Let see if it works.