Modifying a Petzval projection lens for Waterhouse stops

[IanG]

Has anyone modified a Petzval projection lens to add Waterhouse stops ? It's a cheap lens I picked up at a Flea market and has no focus knob/gear (it's missing).

Ian

[Mark Sawyer]

No, but I've seen a few modified by others, including some very nice early Voightlanders, CC Harrisons, and the like. Sadly, it's often done with a hacksaw or grinder, leaving an ugly, butchered lens. I'd recommend having a machine shop do it, if you don't have the right tools.

[Drew Bedo]

IanG:

Don't do this. These lenses are becoming less and less plentiful each day. There are other antique lenses either manufactured for use with waterhouse stops, or modified some time in the past. While this lens may not be a desirable collector item, it is still an antique thast will not be made again. If you need a Petzval lens with waterhouse stops, get one that is already set up that way; they are out there.

Please consider yourself to be the steward of this piece rather than its owner. I have a "vintage" Zone VI (mid 1980s) and a much older, perhaps antique, Kodak 2D from the mid 1930s. I feel that I am only holding these cameras for whoever will have them next. Both can be solid working LF cameras well into this century—and I hope the next.

[Pete Watkins]

Hi Ian,
If you want to do it yourself use a piercing saw for the slot. Clean the inside of the barrel below the slot that you've cut so that you're back to the brass and soft solder a couple of pieces of rounded sheet brass into the barrel to accept the base of your WH stops. If you use a thin piercing saw it will allow you to use card stops instead of metal pieces.
See ya soon,
Pete.

[Pete Watkins]

Ian,
I've just seen Drews post, old (1880's) magic lantern petzvals are plentiful in the UK. Personally I wouldn't pay more than £30 UKP for one of these lenses, and that's peanuts. It's your lens and it you want to modify the lens do it. However if you think that the lens is historically important consult those millions more knowledgeable than me and consider their advice.
Pete.

[Mark Sawyer]

BTW, the more you stop down a Petzval, the more its images look like those from other more conventional lenses...

[Jac@stafford.net]

If the focusing knob is missing, but the shaft is still there and the track is good, then replacing the knob would be easy. Can elaborate if you wish.

Regarding the Waterhouse stops, you can place an aperture in front of the lens for similar control, but I would try to find an ND filter first to maintain the rendering of the lens.

[IanG]

If the focusing knob is missing, but the shaft is still there and the track is good, then replacing the knob would be easy. Can elaborate if you wish.

Regarding the Waterhouse stops, you can place an aperture in front of the lens for similar control, but I would try to find an ND filter first to maintain the rendering of the lens.

The shaft and bit that holds it all in in place is missing as well.

These lenses are very easy to find in the UK and Pete Watkins was I think with me when I paid very little for it :D if someone wants to buy it and save me modifying they are quite welcome.

I wolud have just remounted the front/rear cells in a homemade barrel but the lens isn't made that way, the elements fit the barrel itself.

Ian

[ridax]

you can place an aperture in front of the lens

Quite true. More so, the earlier Petzvals were actually made for the stops to be in front of the first element, and any Waterhouse or iris inside the barrel would just be wrong for those.

So for an unknown lens, try putting stops in front and inside first and compare the results obtained before you reach for that saw.

[Steven Tribe]

I agree that front stops are a quick and non-destructive way of introducing stops. An internal split brass ring to hold the stops is quite easy for most designs. However, there must have been a reason why WHS became almost universal from around 1860.
Some of the pre-WHS petzvals which have been modified to take central stops have their own special charm! Sometimes with the engraved section cut away and moved to another part of the brass sleeve and others where the slot could just be fitted with side entry and with tantalising loss of part of the engraving!

Anyway, I can't see the historical/cultural legacy problem of installing them on projection Petzvals. I would advise "undercutting" of the square hole in the sleeve and getting the final "square" with a set of key files. If you get the slot 0.5mm off perpendicular it won't matter and the thickness of a hacksaw is about right!
The two internal ring forming the edge light seal are easily made from split rings and can be soldered into position. But you will have to relacquer.

[Jac@stafford.net]

Most WH housings have retaining edges aside the slot. If you are lucky, you might find auto or motorcycle piston rings that will press-fit, or spring into place. You might have to trim them using a high-speed Dremel cutting wheel.

[IanG]

Thanks for the ideas. It's quite a small Petzval and it's coverage is limited so I'll need to use it on a baby Busch Pressman. I'll try it with front mounted stops initially to see what it's like, I can make some stops that fit between the front mounted shutter & the lens. It's likely it'll get used on a DSLR as well.

Ian

[Roger Hesketh]

I have a new to me Dallmeyer 14" Projection lens which appears to be to me of Petzval type. Four strong reflections from the front group. Two strong and a weak reflection on the rear group. It is coated and would appear to have a maximum aperture of 5.6. It is marked as having been made for Johnsons of Hendon. The rear group has inscribed upon the side of it XXVII. A series XXVII lens?

This is the lens http://www.ebay.co.uk/itm/Dallmeyer-14-lens-/181315675732?ssPageName=ADME:L:OU:GB:3160 . Is anybody familiar with this lens please?

I am new to Petzval types. Is soft focus gained with Dallmeyer Petzval types by increasing the separation between the two rear cells or by unscrewing the whole rear group? I am confused. It does not take much these days.

I found this thread whilst considering cutting a slot to fit Waterhouse stops. I am now planning to try fashioning some external stops to place before the front element. This thread has given me much food for thought.

If it is alright to use stops external to the lens barrel with Petzval lenses. Why not employ external stops placed in front of the front element of other lenses too? Their must be a compelling reason why not to, but I do not know what it is. I would be grateful if you would share your thoughts on this matter, If the reason for the placement of the iris diaphragm in it's conventional place is only marginal and not critical it would open up the possibility of pressing into service lenses that are currently unused due to having damaged irises but are otherwise undamaged but the iris is beyond economic repair. I have a 12 1/2 inch series IIIB Aviar that has a damaged Iris and falls into that category.

Thank you in advance for any help.

Roger

[goamules]

Hi Roger,
Nice job if you bought anything with glass in it that has a 14" focal length for $8!

Your two most pressing questions seem to be, "is this a Petzval" and "why not put external stops in front of lenses"? On the first, you should easily be able to unscrew the rear and front elements and inspect their config. If the front is a cemented doublet, and the rear two loose pieces of glass, it's a Petzval. I would not worry about altering it for stops and all, I would just shoot it wide open. The "soft focus feature" on a couple Petzval designs is a gimmick. It does very little, other than UNfocusing. Use a Petzval for what it was made for, a fast, sharp lens. Are you sure of your math? A 14" lens that small around cannot be F5.6 unless it has a 2.5" front entrance diameter (not just glass measurement).

On stops in front, it's usually not done. Multi element lenses have to have the stops at about the nodal point - between them, to be most effective. True, meniscus lenses like landscapes and soft portrait lenses put them in front. But if you have multiple elements, it goes between.

[Roger Hesketh]

Thanks Garret. The maths was wrong. Well actually not the maths, but the measuring. I had it in my head that it was 2 1/2 inches in diameter. It is not it is 2 1/4 inches. Thank you for that. Actually that is better. It suits my purpose better. 1/2 a stop slower is better for me. I am not keen on razor thin depth of field at portrait distances anyway. Just another thing to potentially go wrong.

The front and rear groups unscrew but I am not keen to disassemble further due to a proven history of incompetence and boxes full of partially disassembled and once working photographic apparatus to my credit. Looking at reflections again now the front group appears to show four reflections and the rear one three but once again I could be and probably am wrong.

Thanks for the advice Garrett. I hope your weather in Arizona is better than here. We are on the coast in the NW of England and are current experiencing winds gusting to 100mph. It is chucking it down. The rain is horizontal and the Met office has issued a warning for snow later in the night. Terrific.