Focus throw pairings for a single focus solution

[elwsch]

Hello, I'm new to the world of anamorphic lenses but I've been wondering about the possibility of one sort of solution to the double focussing problem: pairing anamorphic lenses with their taking lenses by the distance of their focus throws. The idea would be to measure in degrees the total throw of the anamorphic, and see whether any possible taking lens possessed that same throw measurement between infinity and the minimum focussing distance of the anamorphic as measured on the taking lens.

Given the very great variety of taking lenses, and the vast number of variations even of particular models, I wonder whether any combinations of taking lenses and anamorphic lenses might, by luck, exhibit this feature. I expect even then it's probably unlikely, with anamorphic lenses often having longer throws than usual, and the throw distance of the taking lens having the start at the minimum focussing distance of the anamorphic, thus some way round already. But perhaps if there are any possible taking lenses with especially long throws, then perhaps we get our hopes up.

I would imagine that if such a thing were found, it would mean that if one calibrated the two lenses and connected them via something like a rod, one might have a single focus solution without having to introduce any more glass. Unless I have overlooked that the focal distance of the two lenses could diminish at different rates as their respective rings turned (I don't know if this is possible, but somebody with better knowledge of physics will put me right if I am wrong, I am sure).

Anyway, just an idle idea I had. I would be most interested to know if and why it was a bad one. Or whether anybody had tried this before and what he or she had found.

[elwsch]

I should mention of course that you'd also have to account for the difference in distance from the subject of the two lenses, so their focal 'starting positions' will be slightly different to take in the fact that the taking lens is further away from the subject than the anamorphic lens - thankfully it's always the same distance further away, if you assume the barrel does not extend in focussing. But this does mean that a certain degree of trial and error would be necessary.

[au8ust]

Synchro focus has been utilized in both basic DIY, advanced DIY, and even at pro levels (Lomo Squarefront, Kowa Cine Prominar anamorphic, Nipponscope Series I, Dyaliscope, etc) for a long time.

Here are a few DIYs

 

 

 

 

 

 

[Tons_o_Glass]

On 3/8/2022 at 6:55 PM, elwsch said:

Hello, I'm new to the world of anamorphic lenses but I've been wondering about the possibility of one sort of solution to the double focussing problem: pairing anamorphic lenses with their taking lenses by the distance of their focus throws. The idea would be to measure in degrees the total throw of the anamorphic, and see whether any possible taking lens possessed that same throw measurement between infinity and the minimum focussing distance of the anamorphic as measured on the taking lens.

Given the very great variety of taking lenses, and the vast number of variations even of particular models, I wonder whether any combinations of taking lenses and anamorphic lenses might, by luck, exhibit this feature. I expect even then it's probably unlikely, with anamorphic lenses often having longer throws than usual, and the throw distance of the taking lens having the start at the minimum focussing distance of the anamorphic, thus some way round already. But perhaps if there are any possible taking lenses with especially long throws, then perhaps we get our hopes up.

I would imagine that if such a thing were found, it would mean that if one calibrated the two lenses and connected them via something like a rod, one might have a single focus solution without having to introduce any more glass. Unless I have overlooked that the focal distance of the two lenses could diminish at different rates as their respective rings turned (I don't know if this is possible, but somebody with better knowledge of physics will put me right if I am wrong, I am sure).

Anyway, just an idle idea I had. I would be most interested to know if and why it was a bad one. Or whether anybody had tried this before and what he or she had found.

Hey! I had some similar thoughts and I tried them out!  You're on to something.  As au8ust mentioned, we're thinking of Synchro Focus.  It's been done and it's just a matter of figuring out gear ratios generally.  I went a route that is simpler in a way.  With some measurements and an online calculator I found a perfect lens pairing for my Kowa Vidoscope Super-16mm 2X attachment for an instant Synchro Focus setup (I didn't need to synchronize anything - just had to connect them together in the right way hehe). 

https://www.dpreview.com/forums/thread/4640463#forum-post-66072400