How to mount modern filters on Voigtlander Nokton 50mm f/1.5 lens for Prominent

Wesley Snaps

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Hello there,

I have an old 1950's Prominent camera set, from which I'm planning to digitally shoot the Nokton 50mm f/1.5 lens. I'm planning to keep it wide open, to sample that distinctive character. Many situations will necessitate attaching an ND filter. I've been combing the internet for information about just how this can be done. I've seen the filter thread stated as being 49mm, 44mm, but also it being a different threading that wont play well with modern filters.

Essentially what I need is a step up ring to attach my 52mm 3 stop ND filter. Any tips?

Much appreciated,
Wesley
 
I used to have a Prominent and its standard Ultron f2 lens but cannot recall its filter diameter - though my vague impression was that it was 40.5mm. I do seem to recall that some of these had a different threat pitch to those normally used today and as a result these would only partially mount filters (though I think enough to hold them in place - sort of).

Having said all of that I had a quick look on Google for references to the Nokton for Prominent and it suggests that it came in several versions - and in two different diameters - 47mm and 49mm (presumably referring to the filter diameter). I do not know it 47mm stepping rings are available but 49mm ones definitely are of course and the only question is which thread pitch they use on the filter ring. Assuming you need a 49mm diameter one, given you can buy a 49mm to (whatever diameter you need) stepping ring for a couple of bucks on eBay I would suggest buying one and trying it. If it works, it works. If not, you have wasted a couple of bucks.


And this article gives some interesting comparisons with the modern copies and some nice photos from the original.

 
I just belatedly realized that another option is to try a clamp fit lens hood for a 49mm lens diameter (assuming this is what you have) I am thinking of something like the one in linked immediately below. The obvious advantage is that any clamp type fitting of this sort avoids hassles with different thread pitches. Such hoods have an actual internal diameter of about 51-52mm as they are designed to fit on the exterior of a 49mm lens filter ring and allowance needs to be made for the thickness of the metal. But if it says it is designed for a 49mm lens this should give you the required clearance to allow you to fit it assuming the metal in the Nokton is not too thick.


The point about such hoods is that with some such hoods (as with the one depicted) the actual hood part itself screws off it's mounting base (the bit with the thumb screw and clamp ring) and it is possible, if you can find the right diameter filter, to drop in the filter and then screw the two metal parts of the hood back together such that the filter is sandwiched between the two parts.

Indeed I have seen some such hoods designed exactly to do this - you will see them referred to as series 7 lens hoods as they are each designed to accommodate a series 7 filter which drops into a filter holder between the two parts in just this manner. I do believe I have one somewhere though I cannot recall if mine screws onto the lens or has a clamp fit. It may be necessary with some hoods to remove the filter glass from its metal ring to do the above.

This may well be your best bet if the thread pitch is wrong for your ND filters. Though old metal lens hoods like this are often sold for relatively high prices on eBay.
 
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The filters made for the Polaroid 180 and 195 will fit. It is some off 44.5mm size. The original filters from Voigtlander are push-on type.

Peter's idea of using a clamp on series VII or series VI adapter would be easy, and allow a large selection of filters.
 
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I think that there are three versions of the lens, each a bit different. This is my copy, the thread size near the name ring is 44mm.




I think that my copy is the last version, with the knurled ring at the front of the lens barrel that accepts 49mm Voigtlander screw on filters, as seen in the third pic. My lens will also accepts a 47mm slip-on filter. I also think that finding a suitable clamp-on filter ring is the way to go.
 
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PS Also if your lens filter ring diameter is an odd size you can sometimes pack the clamping ring on a slightly larger clamp fit hood etc using something like felt material glued in place on the inside of the hood's fitting ring to pack out the diameter till it is tight when clamped using the thumb ring. I have done this with 2 hoods that were designed for another lens than the one I am using them on and were a bit too large in diameter for the lens I intended to sue them with. When the thumb ring on the hood id cinched up tight the lens is firmly in place. The best felt is the thick stuff bought from a hardware store in small rectangular sheets and is designed to glue onto the bases of display objects / art works etc. so as not to scratch table tops etc. These are usually a couple of mm's thick and also come pre installed with glued backing.
 
This is great guys, thanks for all the detail in your replies. I have tried a 49mm stepping ring and it's definitely a bit big, plus the threads are external on modern rings, where the native Voigtlander UV filter I have (it's the same as the one you shared in your pictures, Dexdog) are internally threaded, and also much deeper.

I think I'll go with your suggestion for the clamp on lens hood. This one for example. I opted for 58mm because my 58mm stepping ring provides a little extra space to slide over the native Voigtlander UV filter, but is it enough space to glue in some felt? Hmmm maybe I need 62mm. I checked the 62mm and the gap is massive, probably not bridgeable by 2mm felt... unless I doubled it up. That's a great suggestion about the hardware store felt. Thank you. I think I'll pick some up and try it on my stepping ring prior to purchasing the clamp on hood.

Sorry about the delay in replying I've not had a chance to sit at my computer and actually think since I posted this. New fall schedule is set into motion. Thanks so much for your help on this. Here's my Prominent:20240908_132637.jpg20240908_132642.jpg20240908_132721.jpg
 
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