Changing aspect ratio

I have a square fractal, say 600x600 in the UF6 window. If I change it to 900x600 in the Image tab, the apparent magnification changes. I want to make it wider without changing the center or the apparent magnification. Is there a formula for changing Magnification in the Location tab that will do this?

Hello,

I have noticed the same thing. I tried it with your exact dimensions on one of my fractals. By adjusting the corners to the exact same y-coordinates in both images and keeping the center of the image the same, I allowed UF to adjust the zoom factor. It seems that going from 600x600 to 900x600 requires you to reduce the zoom by a factor of exactly 3/4. Not sure how this number is calculated, it would need further testing.

Old zoom: 29925.684
New zoom: 22444.263
Same center

Result 600x600:

Result 900x600

I hope this helps!

Best regards,
Phillip

//edit: for those who wonder :

CopyOfDivineKnot {
fractal:
  title="Copy of divine knot" width=600 height=600 layers=1
  credits="Phillip;9/25/2020" antialiasing=yes
layer:
  caption="Background" opacity=100
mapping:
  center=-0.750037549364005/-0.00714189801442985 magn=29925.684
formula:
  maxiter=349440 filename="phs.ufm" entry="coupling_loops"
  p_dkmax=43.3839 p_test=mod p_bailout=444 p_c=0.00509951/0.00543232
  p_exp1=2/0 p_exp2=-1/0
inside:
  transfer=none
outside:
  density=0.000768399 transfer=linear repeat=no
gradient:
  smooth=yes rotation=116 index=416 color=15200767 index=520
  color=4597306 index=178 color=512 index=269 color=2368658 index=321
  color=3251169
opacity:
  smooth=no index=0 opacity=255
}

Yes, that's just what I find.

Deep within UF is a special aspect ratio, 4:3, width:height. You can see this, as an example, in class FractalCoordinate in common.ulb.

        if (#width*3 <= #height*4)
            m_Distance = 4 / (#width*#magn)
        else
            m_Distance = 3 / (#height*#magn)
        endif

Going from 600x600, ratio 1:1, to 800x600, ratio 4:3, the Magnification has to be reduced by a factor of 3/4, to keep the apparent magnification constant. Going beyond 4:3, as in 1200x600, the reduction factor remains 3/4.

Going from ratio 1:1 the other way, as in 600x1200, the needed Magnification is unchanged.