Target size relationship

[!!!]

My first question on here so be gentle.

I am sure there is a mathematical way of working this out but it’s a long time since I was at school.
What I would like to find out, is what is the size relationship of a round target as its moved back 10 yards?

If you are shooting at say 20yards using a certain size round target and then move the target back to 30 yards. How much smaller with the target actually look from the shooting line.

If you were hitting red’s and gold’s at 20 yards with the same groupings would you be missing the target all together when moved back 10 yards further or would they all hit but be in the black and white?

If you move it back to 40, or 50 yards again how much smaller would the target actually appear to be?
Hope this makes sense.

[jaarus]

I too would like to know this.

I know there are many variables in the fact that groupings wont be the same due to the fact that inconsistencies would be greatly pronounced over a long distance compared to a short distance - not to mention the psychology of shotting at something further away (it does always feel heavier shooting at 100 yards compared to 20 yards doesnt it!?)

But just to know as you ask - how big is a 122cm target for example relatively at the different distances.

I will watch this thread with great interest.

[LineCutter]

You could always ask Grant to continue his work. Or I guess you could use his equation & a calculator. Or maybe just your thumb.

You should note that at point blank range the linecutters start to score differently (your arrows don't get smaller) & that at longer distances your technique issues become more apparent so extrapolation becomes progressively more dodgy.

The target scaling software for shooting at point blank range is here.

Oh, there is a sightmark estimator & the truly wonderful FullMonte on my website (haven't mentioned that in ages ).

[geoffretired]

I know this can be calculated using angles, but the angles involved are so small that a simpler formula can be used, which gives similar results.
When a target at 100y is moved to 50y, the distance has been halved so the width and height appear doulbled. The area is four times bigger, to look at.
In the case of moving 20y to 30y, the new distance is one and a half times longer( 3/2) so the width and height appear to be two thirds the original(2/3)
Roughly, if you shot your arrows into the 2inner rings at 20y you could expect the group to fill the three inner rings at 30y
This is not the same as moving 10y back from 50y.
The new distance will be 6/5 of the original and the width/height will appear to be 5/6 the original. Scoring on ten zone target(metric) if the groups were in the inner five rings at 50y you could expect the groups the use the six inner rings at 60y.

[martin]

70m on a 122cm face is the equivalent size to 50m on an 80cm I think.

[ben tarrow]

Surely we are just dealing with what goemetrists call "similar" triangles here, so
if we halve the size of the face, we are halving the distance.


122cm at 60yds is approx same as 60cm at 30yds or 40cm at 20yds
122cm at 100yds is apprx same as 60cm at 50yds or 40cm at 30yds

[Russ]

Since we're discussing this, would someone who knows kindly give me an idea of FITA's regulation target sizes at the standard distances?

I know for example 18m = 40 cm target face, but I've not shot 30m, 50/60m, nor 70/90m so I don't know what size targets to expect.

It would actually help me put some of the comments on this thread in perspective. Is the whole point of increasing target size relative to distance supposed to be that the target always appears (more or less) the same size from the shooting line?

[OpaNL]

You can find an answer for FITA targets here:

http://www.koniaris.com/archery/targets/

BTW: Nice bug, what do you have on the other end of the lines?

Opa

[OpaNL]

18 m = 40 cm face
30 / 50 m = 80 cm face
70 / 90 m = 122 cm face

Opa

[tel]

Originally Posted by OpaNL

18 m = 40 cm face
30 / 50 m = 80 cm face
70 / 90 m = 122 cm face

Opa

So 'NO' then - unless something looks the same across a 20m range of distance...