Sight mark vs sight extension bar

I have sight marks for up to 70m with the sight fully out.

I want to calculate a rough sight mark for 90m, and I am going to have to push the sight in one or two extension positions.

Is there a formula for working out how much sight mark you get for pushing the extension bar in (without buying software to do it like Archers Advantage).

For example, for arguments sake, if I move the sight mark extension in by one bolt hole, I get an equivalent of 1 cm on the sight mark.

[LineCutter]

No formula that I know of, but there must be one. Try something like "Accurate sights". These programs have an eye to sight / peep to sight distance included, so if you know the change you're proposing you could test out the likely impact.

Failing that, extrapolate your 30 & 70m sightmarks to 90m. Then bring the sight inwards, but leave the 70m mark set on the sight. Shoot 70m & see what the difference is worth, then fudge that into a new estimate for 90m. Then go shoot it!

[Shirt]

If you weren't moving your sight in towards the bow, it would be simple. However, doing so makes it tricky and you get the introduction of lots of variables like length of face and so on... too many variables to guess.

[Mad Archer]

Originally Posted by Shirt

If you weren't moving your sight in towards the bow, it would be simple. However, doing so makes it tricky and you get the introduction of lots of variables like length of face and so on... too many variables to guess.

Unfortunately the best way is trial and error. I'd recommend setting your sight block low on the track, allowing enough space for arrow clearance and for shooting on a windy day with the wind in your face (typically you would have to move your sight down in these conditions). Then move your sight progressively in towards the bow until the arrow reaches the target.

[geoffretired]

The sight at full extension is, say 36" away from your eye. Move it in one hole and it will be 35" away. That's about 3% closer(roughly,I know)
With such small angles I would expect the sight marks to match that quite well so they would be 3% closer on the scale.
Let's say your 20y sight mark and your 80y sight mark are 5" apart, now. With one hole closer they would be 3% closer. 4.85" apart. The sight will be raised by 1 1/2 tenths.
Do that on a metric sight scale. Same space between 20y and 80y would be about 12c.m. 3% closer would be almost 4mm.closer.
So 3 holes closer might be worth 1c.m. rise in sight mark. The 90m or 100y would be roughly 25mm below the current 80y mark.

[wingate_52]

Everybody shoots differently with different equipment. Calculations are a guide, bring in your sight keep the recticule on the 70m mark and adjust from there.Trial and error.Make a note of the temperature, arrows rise on a hot day. Wind direction.A higher sight mark if the wind is blowing from behind you.

[Hidden Hippo]

I'd probably just leave it in the same place and then move it in a hole or two. You can just fine tune from there in my opinion.

[andrew.paterson]

Originally Posted by beowulf

I want to calculate a rough sight mark for 90m, and I am going to have to push the sight in one or two extension positions.

This is all part of the 'fun' of learning about your equipment. Experimentation means that when you get to a competition and something starts to go wrong you have knowledge about how to try and rectify it because you know what adjustments will do.

Here is a test I like to carry out.

If you are shooting at 60yds, and have the arrows at gold high consistantly, it is a good time to work out how many clicks of the sight will put an arrow in the blue. When you are at a tournament and the weather is different to when you got your sightmarks you can then adjust your sightmarks with confidence, not just guessing. e.g. if to move up the target from gold to blue took you 8 clicks, and in your first 3 sighters were high in the red, then you know that a good adjustment would be 4 clicks.

[dino1300]

Asuming your sight is a shibuya or arten or the like, i recon on about 2/10 inch height per hole brought in.

The holes on the sight bar are about 1 1/2 " apart i think.

For me, from 70 - 90 is about 1 2/10 drop in sight. So if you can only go 1" lower from 70m mark, then do that and bring in one hole.

Thanks all for the advice. As it turned out I got a sight mark after 1 doz arrows so not so bad