65 filter thread size?

[Thom Bennett]

Anyone heard of this filter thread size? The seller measured the threads and says they are 65mm. He tried a 62mm and a 67mm filter and neither fit. This is older Congo lens (branded Commercial Astragon).

[Emmanuel BIGLER]

65 filter thread size?

I had a quick check at the Heliopan price list, usually you find many sizes there (this is my reference document, if it is not listed there, it means that the diameter / thread pitch might be hard to find; hopefully, the 'net has more resources than one might think !) and unfortunately they do not have anything between M62x0.75 and M67x0.75
http://www.heliopan.de/Preisliste.pdf
If everything else fails, you could ask for a quotation at S.K. Grimes in the US or SRB Griturn in the UK for a custom step-up ring to M67x0.75 ... and hope that manufacturing this ring is not as expensive as the lens itself...

[Bill_1856]

Probably intended for a slip-on filter adapter.

[Thom Bennett]

Such as a Series filter holder? It's in a Copal 3 and I thought the Series filters were for older lenses. Maybe this one dates from the early days of lenses going into Copals. If I decide to get the lens I'll follow up with whatever I learn from having the lens in hand.

[Bob Salomon]

Such as a Series filter holder? It's in a Copal 3 and I thought the Series filters were for older lenses. Maybe this one dates from the early days of lenses going into Copals. If I decide to get the lens I'll follow up with whatever I learn from having the lens in hand.

What lens is it? Then I can check the sizing guides from Heliopan and B+W.

[Thom Bennett]

Thanks Bob. It's a Commercial Astragon 360mm f6.8; Copal 3. From what I have gleaned it is a rebranded Congo and they list their 360mm as having a 67mm filter size.

[Bob Salomon]

Thanks Bob. It's a Commercial Astragon 360mm f6.8; Copal 3. From what I have gleaned it is a rebranded Congo and they list their 360mm as having a 67mm filter size.

I will be back in the office a week from tomorrow and will check. I am not sure that the books incldes Congo or Astragon lenses however.

[John Koehrer]

It just may take a Series adapter, they came in hundreds of sizes. That would be something like 1.62"/64mm -> S8.
Why didn't they make it a 67mm? Mystery to me.

[Brian Ellis]

It just may take a Series adapter, they came in hundreds of sizes. That would be something like 1.62"/64mm -> S8.
Why didn't they make it a 67mm? Mystery to me.

I've always suspected that the lenses themselves are just loss leaders, that the real money is in the filters. So they make sure that every lens you buy requires a slightly different filter than one you already own. I've got an Ilford box that originally contained 100 sheets of 8x10 paper filled with circular filters in numerous different sizes, as well as about 15 step-up/down rings, none of which fit on any lens I now own.

[Thom Bennett]

Yeah, I'm tempted to buy the lens just for the challenge of finding a filter that fits! :)

[Doremus Scudder]

Series VIII is 65mm thread.

See here: http://www.graflex.org/helpboard/viewtopic.php?p=8273&sid=3f62e6248bd4e619c272bf4fa3f2fe42

You can probably find a series VIII to 67mm adapter to use more modern sizes. IWCTW, you can always have one made.

Best,

Doremus Scudder

[Thom Bennett]

Doremus, thanks for that link! It must be a Series VIII. BTW, S.K. Grimes can fashion a filter adapter for $85.

[Emmanuel BIGLER]

If it is a Series VIII filter, they are listed in the Heliopan catalogue on page 7
My understanding is that Series VIII filter are drop-in filter, not threaded filters.
If so, there should be a retaining ring somewhere to hold it like in the old-C
Hasselblad Distagon lenses (see below)
diameter for a series VIII filter according to Heliopan is 63.5mm(2"-1/2)
thickness = 5.6mm
Hasselblad had this kind of filters on its catalogue, or very close to, under the name 'serees 63' for the old-C distagons 50 & 60
Hasselblad 63 filters are very easy to find as used items.

[Chauncey Walden]

That's interesting. 67mm filters screw into Series VIII filter holders on my cameras. Thread top to thread top on a Series VIII holder is 66mm so a 65mm thread outside to outside would just fall in. Thread top to thread top on a Series VIII retainer is 67mm not 65mm. A Series VIII filter ring (unthreaded) is 65mm so it will drop into the holder.

[Thom Bennett]

Chauncey,

This is what I wanted to hear! So, quite simply, a 67mm filter will screw directly into a Series VIII (65mm) holder?

[Chauncey Walden]

Uh, a 67mm filter will screw into a Series VIII holder. But the only thing that is 65mm is the diameter of a Series VIII filter which has no threads and drops into the 66mm cavity of a Series VIII holder and is held in place by a retaining ring which has ~67mm threads. Is that more clear?

[Thom Bennett]

Yes. If the lens in fact uses a Series VIII filter holder then I can simply put my 67mm filters on top of that.

[Doremus Scudder]

Thom,

Careful! I may have misled you. The graflex.org link seems to list the diameter of the filter itself as thread size, an error. Further research (Wikipedia, etc.) shows that series VIII thread size is 66.7 mm, so very close to the 67mm modern size and will likely take modern 67mm filters if you don't screw them in too tightly and jam them.

What I think is the case, is that your lens needs a "special adapter ring" to step it up to series VIiI (a common practice in times past). These screwed into the front of the lens and contained the series VIII-size holder. I doubt that you could use 67mm filters in a lens with a 65mm thread. If you could, however, get one of the special adapter rings for that 65mm thread to series VIII, you could then screw your 67mm filters into it, it seems. (My WF Ektar 100mm has a similar set up on it).

If you can't find a ring, you'll have to have one custom-made. At any rate, the thread on the lens you have is likely not series VIII.

Hope this clarifies,

Doremus Scudder

[Bob Salomon]

Some lenses that used series 8 filters had retaining rings with the sa me diameter a nd thread pitch as common 67 mm filters so 67 mm filters would screw into them properly. Many others used a different diameter and thread pitch so 67 mm filters would not screw into them. So it never hurts to try one. If it starts to screw in more then one turn it is the same diameter and pitch. If it immediately binds it is not.

[Chauncey Walden]

Thom, if the inside thread of your lens is 65mm then the outside diameter of the tube must be, what, at least 69mm. These days I would guess your odds of finding a 65mm screw in Series VIII adapter are zero. Since the outside diameter of the lens is larger than the normal range of Series VIII slip on adapters, it would probably require a Series IX slip on adapter. Again chances of finding one are slim. If it were my lens, I would take a Series VIII retaining ring that is inside threaded on the top to take a Series VIII hood (or another retaining ring or a 67mm filter;-) and just file enough of the threads off the bottom portion to get a slip fit into your lens. Then a little cement and presto, your lens now takes 67mm filters.