APO-Telyt-R 180 f/3.4 + APO-Extender-R 2X near INFINITY

[KFo]

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Hello there R people!  I am an M shooter, but I have ventured off the farm for a particular project.  For this project my subjects are 2 -7 km away.  I am using a combination as in the title, with the addition of the Leica R-adapter M.  All this goes to my M10P and sits on a tripod.  It is a lot.  I'm sure you regular long shooters are rolling your eyes now.  For my normal documentary style work 50mm is positively claustrophobic and my norm is in either 28 or 35mm.  This voyage into the 180/360 is a learning experience.

I can only do this project in the winter because the haze of humidity, heat, and air pollution ruins the images so I work now as cooler weather begins.  Running tests from my terrace on a clear day, shooting objects between 1.2 and 3.65km away I dialled in the aperture that looks best with the 360mm combination.

Something I noticed when testing the 360mm combo was that a communication tower 3.65km away was not at infinity for this setup.   I setup on the other terrace and shot a building 4.5km away, then yesterday working on the project noted that a building 8.43km out was still not infinity.  I give up.  In the same test conditions, with only the 180 infinity is far but I find it at the 3.65km mark for sure.

Here is my question.  Is this typical infinity performance on an R camera for the 180 + 2X extender setup?  Don't get me wrong, I am surprised and pleased that this contraption works at all with an M camera.  The only reason I question is that with my typical tiny lenses for an "infinity" shot, I just wring the lens to the stop, f/8 and don't be late.

 

Edited 7 hours ago by KFo

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[romanus53]

So if you are using the M10P with longer uncoupled lens, remember infinity is really infinity and only under best circumstances. Use EVF with magnification to adjust focus. Back in the good old days longer lenses had an infinity-index but could be focused beyond because the position of the final focal point on film or sensor depends on weather, atmosphere, filters, tolerances of equipment. Just scale-focusing will not be precise enough.

[KFo]

That is a good point.  One thing though — don't interpret my remark about how I operate my typical 28 or 35 M lens as how I am using the 180/360.🤠

For focusing, I am using the LV function, zoomed and with  a loupe.  I find that just the LCD is to small to properly evaluate focus vs not "wide open" even with focus peaking on.  Although peaking does help — except at very long distances (8km) last time out there was not enough contrast for peaking to latch onto anything past about 6km.

 Next trip out I will also take a dark cloth to shield from the sun as it is  proving to be unhelpful to focusing.

I am going to wind up using  this like a bizzare view camera.

I have a monastery that is 34.5 km out if, I ever see a clear enough day, I can check to see if that qualifies as infinity!

[Carlos cruz]

My wild guess is that the sum of tolerances on each adapter adds to error moving infinity closer. You could try R bellows to have more control on focusing. With extreme focal lengths good tripod and stable ground is everything, with longer exposure times even wind has to be taken into account. 

[jaapv]

And don't forget that even a clear atmosphere can optically distort the image for long range by movement in the air, giving the impression of not being in focus. The colder and more still the air the less distortion. At such distances a scoping setup should be more practical. - though mot necessarily better.  
Also, with the lens at f8 and a 2x extender you are well beyond the diffraction limit. This lens and APO extender will likely yield the best results at 4.0. You should also get a cheap M adapter; they usually focus beyond infinity .

This is a very special lens. It was designed as a surveillance lens which means that it was as close to diffraction limited as they could get and optimized at infinity wide open. 

[KFo]

49 minutes ago, jaapv said:

And don't forget that even a clear atmosphere can optically distort the image for long range by movement in the air, giving the impression of not being in focus. The colder and more still the air the less distortion. At such distances a scoping setup should be more practical. - though mot necessarily better.  
Also, with the lens at f8 and a 2x extender you are well beyond the diffraction limit. This lens and APO extender will likely yield the best results at 4.0. You should also get a cheap M adapter; they usually focus beyond infinity .

This is a very special lens. It was designed as a surveillance lens which means that it was as close to diffraction limited as they could get and optimized at infinity. 

That is the reason I choose this particular setup.

The beyond infinity focus is what is surpring me. At 8km the 360 is still a little shy of infinity or the stop!

I found on my setup, M10P with the 360 conglomulation, f/5.6 produced a slightly better result compared to wide open.  I choose it to get a little more DOF; trading shutter speed into the mix as well.  

With the 180 setup best is about f/6.7.  definately not wide open.

When I was testing, in the morning, I could already see heat waves from the sun heatng up the communication tower!  I was glad to be finished.

Picky picky this long range pbotography!