View Full Version : Jam nut for Aero - Ektar f/2.5 7 inch lens ?

17-Dec-2016, 16:18
Jam nut or flange mount for Aero - Ektar f/2.5 7 inch lens ?
Is there such a thing?

My wife found this lens in our Pile of Forgotten storage. I'm sure there are at least one or two more in there, but this one is so clean I'm motivated to ask so maybe I will try it.

The best I can measure is that the thread diameter is 77.3mm (3" ?) I am not an engineer. That's as close as I can measure.

So is there a common flange or jam nut for this monster?


Mark Sampson
17-Dec-2016, 20:23
The Aero-Ektar was designed for a 5" roll-film aerial camera. I don't know how they were attached, but often aerial lenses were mounted into 'cones' that attached to the camera body, permanently focused at infinity. Of course many of us have adapted Aero-Ektars, or had them adapted, to fit on Speed Graphics or other cameras. I would consult with SK Grimes or another camera repair service. Shouldn't be very difficult, or expensive, to get a retaining ring.

Jim Jones
17-Dec-2016, 20:44
The thread diameter is a little over 3 inches; 3.043 according to someone who had one to measure. This sounds about right according to my lens cone. It's 24 threads per inch.

17-Dec-2016, 20:46
I would guess (only a guess) that the thread is 32 TPI (turns per inch) if it's English rather than Metric.

32tpi was the most common thread used for large diameter fittings that needed a fine thread.

You could compare it with a modern #6-32 or #8-32 thread. They should mate if they're the same.

A metric thread would be the far less common 0.75mm pitch. 0.7 and 0.8 pitch are common, but not 0.75.

Any competent machinist (properly equipped) should be able to turn a mounting flange for you.

- Leigh

Jim Jones
17-Dec-2016, 20:52
Leigh, I cheked it again to make sure, and it's still 24 tpi.

17-Dec-2016, 21:05
Leigh, I cheked it again to make sure, and it's still 24 tpi.
Hi Jim,

I'll believe that. 24tpi is also a common thread.

I was typing when you posted your previous. I missed it. Sorry.

- Leigh

17-Dec-2016, 21:26
Check this;

I think I remember (in)correctly that the threads might be a square profile...

Consider plan B...

Steve K

Jim Jones
18-Dec-2016, 09:46
The Aero-Ektar has V threads that appear to fit my American thread gauge perfectly.

18-Dec-2016, 13:19
I have two of the original cones from AE lenses somewhere. I thought at one time I could just cut the front off them to use as a retaining ring but it was easier/safer to just commission a machinist to make them. I had a local machinist make about 5 of them for me way back.

19-Dec-2016, 14:49
Thank you, everyone for your expertise!

As an aside, after a thorough examination the Aerial-Ektar is not interesting in its outcome. Indeed that is only my opinion. I will be auctioning it off dirt cheap just to help in clearing out the glut in my house.

Really, so cheap that the trip to the post office will not be worth the sale but the walk will be healthy.

20-Dec-2016, 09:51
you have three Aero Ektars buried in your 'Pile of Forgotten storage' ?

hahaha - keep digging