View Full Version : DIY Soft Focus Lens

29-May-2011, 12:59
A while back I mentioned that I was given a Rollei Heidosmat 150/2.8 on the front of a 6x6 projector. Also mentioned was that it covered 5x4 but not 5x7.

This evening I was shopping for a diopter set off the auction site, to use with the Goerz 180/6.8. Whilst waiting for a listing to finish I searched my parts boxes/bags for a diopter to save some cash.

Instead of finding a suitable diopter, I found a lens element that perfectly fit the front of the Heidosmat!

The front element is flat on the rear side and has a large convex shaped front. This second front element (from a rubbish M42 lens) is also flat on the back but with a shallow front. In reality this means the lens is of a slightly longer focal length.

The good news is that it now covers 5x7, it focuses to infinity on the modified Contessa Nettel, and the barrel still fits in the front of the Copal 3s!

The bad news is the lens isn't sharp wide open. It's very, very, very soft. Imagine you put an image on Adobe Camera Raw and set the clarity to -50, that's what the image looks like. Stopping down a stop makes the image almost sharp, two stops and it's crisp. That's pretty okay with me.

I now have a super fast adjustable soft focus lens of around 165mm that covers 5x7 :D

Hope to take a few shots with it tomorrow and post them in the evening.

Mark Sawyer
29-May-2011, 13:48
Hope to take a few shots with it tomorrow and post them in the evening.

We're waiting! :D

29-May-2011, 13:53
wohoo, college :-)
in this moment i waiting for last parts for my DIY 250/5,6...

29-May-2011, 14:10
Won't be long, only 24 hours ;)

I've held it up at the closest focus to the bare bulb in the room... There's a significant aura around the image causing the hazy soft look wide open at f/4. By f/8 it's sharp and the aura's gone.


30-May-2011, 11:45



For the first two it's stopped down enough to be sharp, but when enlarged some soft-focus flare is visible. The final shot was meant to be wide open, but I accidentally opened the preview lever instead of cocking the shutter!!

These were rushed test shots, the second was in between rain showers, and I managed to underdevelop the side as well.

30-May-2011, 12:41

This is the alternative with worse framing but more glow

30-May-2011, 13:52
I bet they don't sell 5x7 film at jessops!

30-May-2011, 14:00
They'd sell out if they did!