Petzval radial drive

[psychoanalyst]

Hello,

I have a 5" Benjamin French Petzval that has a slot for a waterhouse stop (no stops though) and a radial drive.

I am going to mount it on my Speed Graphic.

I had a couple of clarifications:

1. I can see that the radial drive increases the spacing between the front and rear group of elements. What effect will that have?

2. Do I need to tape over the waterhouse stop slot to prevent light from entering into the camera?

Sorry for the noob questions, but I am an LF noob.

Thanks to all.

Avi

[goamules]

Hi, usually with Petzvals, the focus knob moves both the front and rear glass at the same time. Basically, the entire inner barrel moves fore and aft. It was just for focus. Some rare lenses actually changed the spacing, but they're not common.

I've never taped the waterhouse slots. The light doesn't get in that way, most have a "shelf" inside to block it.

Also, if your focus shaft lays across the barrel, on a tangent, it's not a radial drive. The radial drives were earlier, and the shaft goes straight into the barrel.

Enjoy using the lens, it should work fine.

[Jon Wilson]

The radial drive will allow you to fine tune your focus. There should be no reason to coverup the waterhouse stop slot. If it makes you feel more confident to tape it, especially if you have a once in a lifetime image opportunity, then I would tape it.

At least the above has been my experience. Sounds like a nice petzval. I love my french petzvals. I too use my "short" ones on my Pacemaker with its focal plan shutter.

I look forward to seeing some images posted.

Jon

[psychoanalyst]

Garret and Jon,

Thanks a ton for the info.

Here is my Petzval:

http://farm7.static.flickr.com/6135/5985283283_ce18742b73_m.jpg http://farm7.static.flickr.com/6004/5985845736_6194a54f79_m.jpg
http://farm7.static.flickr.com/6136/5985846440_3eb1b17ec4_m.jpg

Its an absolutely gorgeous lens, one of my favorites already. But I have had a massive problem mounting it on to my Speed Graphic board. I got the dimensions mapped out in AutoCAD and even located a local machine shop in Atlanta that can waterjet the central hole and screw holes for the flange, but USPS lost my graphic board!!

But I bought a board off Ebay and dropped it off this time. Can't wait to mount the lens onto the board and see the swirlies!!! Its been painful waiting for so long, but can't wait to start.

Avi

[goamules]

Garret and Jon,

Thanks a ton for the info.

Here is my Petzval:

Its an absolutely gorgeous lens, one of my favorites already. But I have had a massive problem mounting it on to my Speed Graphic board. I got the dimensions mapped out in AutoCAD and even located a local machine shop in Atlanta that can waterjet the central hole and screw holes for the flange, but USPS lost my graphic board!!

But I bought a board off Ebay and dropped it off this time. Can't wait to mount the lens onto the board and see the swirlies!!! Its been painful waiting for so long, but can't wait to start.

Avi

Holy Mackeral! Mapping out a lensboard hole with a CAD program, and outsourcing cutting it by a a high tech waterjet cutter seems like overkill. What's your board made out of titanium?! Just get a hole saw at Home Depot for $19 and use a hand drill.

Looks like a great lens. The tiny petzvals are as hard to find as the super large ones. Be careful about lens flare since it's missing a hood. You might want to make one out of black cardboard.

[psychoanalyst]

Garrett,

Well...AutoCAD was easy since I use it all the time for my work and my university provides the software.

The machine shop is charging me $30, so I thought that would be better than cutting it myself.

Thanks.

Avi

[Fotoguy20d]

Nice lens - enjoy it. Overkill or not, I cover the waterhouse slot with black electrical tape. I usually keep lenses with a focus knob racked all the way back - I figure keeping the center of gravity of the lens as close as possible to the board is a good thing.

Dan

PS Autocad seems reasonable to me. I've modeled boards in 3D using Pro/Engineer. I've always gone the route of Harbor Freight hole saw in a drill press, though.

[Two23]

I have a 4.5 inch BF Co. Darlot Petzval and love it to death! I made an f32 stop for it, and with that it is sharp!


Kent in SD

[psychoanalyst]

Kent,

Does your lens have the name Darlot engraved on it?

Mine says benj French and co., but no mention of darot although bf and co. Were the major importers.

Avi

[Steven Tribe]

Darlot changed their policy towards the foreign selling agencies. At one time they were uninterested in having their name on items sold on the the UK and USA market.
French were the big agents in the USA and Marion was an early UK selling agents.
Both of these sold many Darlots under their own name. Your "Darlot" (probably) with the more unusual B.F & Co. engraving is one of these. I have a Marion landscape meniscus which has the "AD" stamped on some of the brass parts. And a Marion was sold on e**y a few days ago that could only have been the 3 lever Darlot RR.
There might be similar AD stamps hidden inside on your "Frenchy".
Darlot changed their marketing system and insisted that the Darlot name and/or trademark initials came on the barrel/sleeve.

[psychoanalyst]

Steven,

That is fascinating information.

Thanks a lot!

Avi

[Two23]

Kent,

Does your lens have the name Darlot engraved on it?

Mine says benj French and co., but no mention of darot although bf and co. Were the major importers.



No, it doesn't. I took it apart (except front lens group, which is stuck) and didn't see any marks. Lens does appear to be an older version with large lens shade. I'll try & post a photo. No movements on 4x5 & slight vignetting, but it has the classic look. It is very well made.


Kent in SD

[Richard Rankin]

You can also check the front lens element. Sometimes it will still have a Darlot written on the side. I've also seen it on the rear flint on a couple of larger lenses.

I've been using petzvals for years and never use the focus knob thing. I roll the lens as far back into the camera as possible and tape it so the focus knob can't move it. Using the camera to fine focus is easier and less error prone, at least for me using caps to put on and off the front. If you have a shutter, it might be useful, but I can't really see any reason to use it unless you have a tailboard that is difficult to fine focus.

The focus knobs don't lock into position, so pushing on them at all can move the lens focus. I make enough errors without inviting another one....

Richard

[goamules]

Richard makes a good point, I've never used the focus knob on any of my lenses either. It's kind of amazing that they kept putting them on them for 50 plus years. As far as the lens slipping, some lenses (voigtlanders I know) had a felt lining between the barrels, that made the focus a little firmer. But most lenses are missing that now and are quite loose. I've had a downward tilted lens slowly slide forward while I'm trying to take a still life!

[psychoanalyst]

I will check again, but the last time I did, I could not find any lettering.

But the good thing about my focus knob is that its quite stiff and I don't think I will have the problem with the lens sliding.

Avi