Diopter Magnification Query

I am trying to figure out magnification strength of stacking two lenses

a) Inon UCL-165, which is +6 diopter.

b) Inon UCL-67, which is +15 diopter.

How many times magnification does stacking the UCL-67 onto the UCL-165 result in?

Thanks

Apparently you just add the diopter powers together so that combo would be a +18 diopter. 

Edit it's a +21 diopter

1 hour ago, ChrisRoss said:

Apparently you just add the diopter powers together so that combo would be a +18 diopter

Thanks. I found the answer somewhere on the web.

Formula

Diopter focal length x diopter power = 1,000 (1,000mm or 1 meter)

Therefore 1,000/diopter focal length = diopter power.

And 1,000/diopter power = diopter focal length.

As an example, the Inon UCL-165 (165mm), which has a power of +6. 165mm x +6 = 990 (plus rounding error).

Another example is the Inon UCL-67 (67mm), which has a power of +15. 67mm x +15 = 1,005 (minus rounding error)

When stacking diopters, just add the diopter powers together. Therefore +6 added to +15 = +21. And 1,000 / +21 = 48mm combined focal length.

Lastly, calculation of magnification is dependent on camera lens and given by the formula camera lens focal length/diopter focal length. Based on my camera's (equivalent) focal length of 135, we have 135/48 = 2,83x. The image from the stacked UCL-165 and UCL-67 will be magnified 2,83x.

The above is based on google power, Corrections anyone?

Yes the diopter calcs are available on the web, and what you have set out sounds about right.  What it doesn't tell you is working distance which will be getting very low - but as you already have the diopters you can try it out and see if it is practical.

22 hours ago, ChrisRoss said:

Yes the diopter calcs are available on the web, and what you have set out sounds about right.  What it doesn't tell you is working distance which will be getting very low - but as you already have the diopters you can try it out and see if it is practical.

Working distances seem fine on land. I'll test it underwater later in the month.

On 6/30/2023 at 10:06 AM, WK's Gone Diving said:

Thanks. I found the answer somewhere on the web.

 

Formula

Diopter focal length x diopter power = 1,000 (1,000mm or 1 meter)

Therefore 1,000/diopter focal length = diopter power.

And 1,000/diopter power = diopter focal length.

 

As an example, the Inon UCL-165 (165mm), which has a power of +6. 165mm x +6 = 990 (plus rounding error).

Another example is the Inon UCL-67 (67mm), which has a power of +15. 67mm x +15 = 1,005 (minus rounding error)

 

When stacking diopters, just add the diopter powers together. Therefore +6 added to +15 = +21. And 1,000 / +21 = 48mm combined focal length.

 

Lastly, calculation of magnification is dependent on camera lens and given by the formula camera lens focal length/diopter focal length. Based on my camera's (equivalent) focal length of 135, we have 135/48 = 2,83x. The image from the stacked UCL-165 and UCL-67 will be magnified 2,83x.

 

The above is based on google power, Corrections anyone?

 

 

If the magnification formula only depends on lens focal length then I assume it is for that lens set at infinity (otherwise the formula should also include the focus distance). If so, true magnification may be higher if focusing the lens to its closest distance.