M39 enlarger lens image circle

petrochemist wrote:

Viernes wrote:

D Cox wrote:

Viernes wrote:

I was thinking of using my old enlarger lens on a DIY belllows to shoot macro, but I was wondering what the image circle was. It's a M39 mount Nikon.

Thanks!

What focal length ? The longer the focal length, the larger the image circle.

Any EL-Nikkor from 50mm up will work fine for macro on the full frame (or smaller) formats. The 63mm is particularly good.

The further the lens is from the sensor, the larger the image circle.

Use an aperture of about f/11 to avoid diffraction blur.

Sorry, you’re right, I skipped some information.

It’s a 50mm f2.8.

Yesterday I did some freelensing with an Olympus EM5.

Other than massive purple fringing the results where fine.

I was thinking of making a bellows that could attach different bodies/mounts (I use Pentax K and m4/3 bodies).

You may find a helicoid set up is more robust than bellows. E-bay has a large range of M42 helicoids, which would be easy to fit to both your ranges of bodies, and also take a simple step down ring to M39.

A "simple step down ring" is likely to have threads of filter pitch, which is much finer than the threads on lenses. What you are suggesting would be called an "adapter M39 lens to M42". It should be easily found.

I use a combined C-mount/short M42 adapter on MFT to give the largest adjustment range on the helicoid, with this a 36-90 helicoid probably wont quite reach infinity focus with your 50mm but the extension will take you beyond life size. The next size down I remember is around 25-55 which would definitely give infinity on MFT, and also be a useful macro range on the Pentax.

I expect the entire helicoid set up MFT-M42, PK-M42, helicoid & M42-39 can be brought for less than two PK adapters for my BPM bellows!