Player one Neptune C (IMX178 colour sensor) back focus distance

[Leo.G (Leo)]

Does anyone know the correct back focus distance for the player one Neptune colour camera with the IMX178 sensor?
I've been through every instruction I can find online but am either blind or stupid ( possibly both)

I'm trying to get a normal Nikon full frame lens focused and thinking it could possibly be 55mm approximately like many cameras seem to use (12.5mm from face to sensor). I played with the 42mm (x 0.75 pitch) to Nikon adapter but just couldn't get the correct spacing and setting the lens focal position on 0.8 metres and focusing on something exactly 8 feet away didn't help.
I have purchased an assortment of 0.75mm pitch x 42mm adapters from AliExpress and they should be here next Monday or Tuesday but I should have something here till they arrive. I guess clouded skies it doesn't matter for a few days.
Once I get it close in the house I can go out and play at infinity.
It works fine as it is with a telescope if I can remember where I set the focus, it will be jotted down in one of 100 note pads somewhere with a bit of my gear......

[Leo.G (Leo)]

I got my extension tubes from Aliexress and am very happy with the quality of the units so now it's just a matter of trial and error and pray for clear skies. I grabbed 3mm, 5mm, 7mm and 20mm which give me quite a good range of mix and play sizes.

[Dekker (Derrick)]

Hi Leo,


I have the same camera and recently purchased a M42-mount TT Artisan 100mm F/2.8 full frame lens. The back focus distance will depend on your lens mount type: I had to add a 25mm M42 spacer to get it to focus properly to infinity.


It was easy enough to get a ball-park spacer distance by mounting lens to camera without any spacer. While viewing the camera output using capture software, disconnect the lens and, holding it in your hand, slowly move it away from the sensor until you achieve focus.

[Drac0 (Mark)]

Hi Leo,

If I'm thinking correctly (not always guaranteed) I believe from the rear flange of the lens to the sensor you will need 46.5mm for a Nikon lens (Nikon cameras focal plane is 46.5mm from the front flange). So ~34mm from the face of the face of the Player One to the rear flange of the lens.

Cheers,
Mark

[Leo.G (Leo)]

Thank you Derrick and Mark!


I tried the hand held solution, it would have worked better when I was sub 60, now I'm not sure if it's my hands that shake or the earth has become less stable. I like to think it's the latter. I know, a short length of plastic or aluminium C channel does wonders, I have both here (yes, hoarder extraordinaire).


I can get 34mm with my spacers and an adjustable collar on my M42 to Nikon adapter. The adapter has a separate collar I can vary and lock in place with thread lock or big washers if required (big drill bits, Dremel, lathe, plasma cutter).


Time to play!


Thank you again gentlemen!

[Leo.G (Leo)]

Originally Posted by Drac0

Hi Leo,

If I'm thinking correctly (not always guaranteed) I believe from the rear flange of the lens to the sensor you will need 46.5mm for a Nikon lens (Nikon cameras focal plane is 46.5mm from the front flange). So ~34mm from the face of the face of the Player One to the rear flange of the lens.

Cheers,
Mark

34mm was spot on Mark, thank you very much!
Not easy to get with the nice quality K&F concept Nikon to whatever the Player one big thread is (Oh, M42x0.75, I forgot) but with the aid of one small adapter ring 0f 3mm and a lathe I got it spot on at 34mm and focus is impressive. Due to weather it's only been tested in the house at a measured distance of 2 metres and the lens set at 2 metres but I can see the dimples in a canvas print hanging on my wall as clear as anything.


I tried an assortment of adapter rings I'd purchased and I was 1mm out with the smallest 3mm adapter. They don't come smaller or there's no thread capacity so I rigged something up myself by reducing the collar on the K&F adapter by exactly 1mm. It has a locking ring on the base which goes from a smaller thread to what I needed. It needed to be 1mm closer to the mount so when the 3mm collar was fitted it was spot on after the machining. Easier to remove 1mm of alloy then add it because a washer wasn't going to be a good fit (nothing I had here to add 2mm exactly) and I can't find a length of alloy I'd usually turn down for small projects, just one length of 40mm stuff I've had laying around I misplaced.
I need to buy some but it's expensive to have small pieces cut from long bars, unless I buy 6.5 metre lengths in which case it's expensive.