Yecch!!!, opening a Perkin and Rayment Optimus

[snuck]

Well it arrived in the mail much to my delight, so I set about trying to clean it up. It' a cannon at 3 1/4 inchs wide, and over 4 inche long.Thankfully the ebay picture was interpreted correctly, and despite it's orrible' looking pic, the glass elements cleaned up to almost perfectly! There is nary a microbubble in this lens (to think that they once claimed that bubbles made your pics better....

I found one glued element up front, and an air spaced element on back. Petzval if I'm not mistaken.... very, very happy. After cleaning up the lens elements, I set about cleaning up the mechanism. Years of sitting on the shelf had taken their toll. much to my suprise, after dousing off the focus mechanism and aperture with ronsonol, the black coating on the interior started coming off with a rub of my cloth! Much to my horror, it appears that they used some kind of sooty candlewax to darken the interior of the brass lens at the turn of the previous century. Now I have to clean out all of this crud and respray the interior with matte black!. Ah well, at least I'm happy. I'll post pics later.

Course I should actually take a picture with the lens first before crowing about it!

[Joseph O'Neil]

Much to my horror, it appears that they used some kind of sooty candlewax to darken the interior of the brass lens at the turn of the previous century.

-snip-

Yepper, that is exactly what is it - it's called "lampblack". Do a google or yahoo search, you'll turn up many references. I have a couple modern reprints of photo catalogs from the late 1890s, early 1900's, and you see the term used quite often.

joe

[C. D. Keth]

-snip-

Yepper, that is exactly what is it - it's called "lampblack". Do a google or yahoo search, you'll turn up many references. I have a couple modern reprints of photo catalogs from the late 1890s, early 1900's, and you see the term used quite often.

joe

I always assumed they sprayed it with a fixative like you might a charcoal drawing. Guess not :D

[Jimi]

Lamp black is originally just the remains of burnt kerosene, I've been told.

EDIT: found this on wikipedia: "Lampblack is easily produced experimentally by passing some noncombustible surface, such as a tin can lid or glass, closely through a candle flame. Lampblack produced in this way is among the darkest and least reflective substances known."

Don't blame me if your lens goes up in flames. ;)

[Ernest Purdum]

When a welder first starts up an oxy-acetylene torch, he (okay, or she) opens the acetylene valve only. This produces a very high-quality lampblack with extremely low reflectance. Chemically, I am guessing that it is very pure carbon.

[snuck]

so does this mean that to touch up the coating, in order to get the blackest backs, I should be burning a big candle and holding the thing over it until it blackens? I was just going to apply matte black enamel to the interior....

[Joseph O'Neil]

I'm not sure how lampblack was first applied when it was used 100 years ago, the few times I ran into the stuff myself it was so messy, i figured I didn't want to find out. :)

joe

[Jimi]

I think candle flame to the inside of the bare barrel (without lens elements, of course!) or the welding torch method seems doable. If it doesn't work, you can always resort to other methods.

BTW, show us some photos of and with the lens when you have put it together again.

[Ernest Purdum]

I guess it depends on how much you want to maintain original condition. Some modern flat black paints have quite low reflectance. Some are really not all that flat, though. It might take a little experimentation to find a really good one. Brass can also be chemically modified to a black surface. Either of these methods would be more durable than a lampblackened surface, but once the lens is reassembled, as long as no loose excess is present, durability shouldn't be a factor.

Please let us know how things work out.

[Donald Qualls]

Yep, you have what was then called a "smoked" surface. A miner's lamp (a very small acetylene burner) makes a very fine smoker for this (if you can still find one, and the carbide to make it light up), though the lampblack from a candle, which includes some waxy residue, will stay stuck on the substrate better. Don't need a big candle, though; in fact, a very thin taper of the sort used for lighting other candles is best, so it doesn't drip wax. You can also get good lampblack from a wick carrying olive or corn oil, again including an oily residue that helps the carbon adhere to the surface being darkened.

FWIW, the blackest paint I'm aware of is Krylon Ultra Flat Black, but it comes only in a spray can, which makes it hard to apply inside a lens barrel (even a big one); even in my 9 inch diameter telescope tube, I'd have had to do some serious improvising had I not been able to apply the stuff with the tube laid flat, before closing the seam to form the tubular shape. In addition, there's a technique to applying it so it's really flat; if you apply too much in one coat, or recoat too soon, it'll lose most of its flatness (which comes from surface texture produced by a powder carried with the paint). Smoking is so easy to apply, and works so well, I don't think I'd bother with paint (which has a very strong tendency to gum up mechanisms, and may not adhere well to brass without serious cleaning and a zinc chromate primer).

[Randy H]

The railroad industry uses a flat black primer for a lot of their paint applications. It is indeed very flat black, and very much so non-reflective. If I remember correctly, it is an Anchor brand product. It cleans up very easily with water, while it is still wet, in case you get it on yourself, or make a mistake. But once it dries, you can't bust it with a jack-hammer. I was fortunate enough to get about a half pint of it about a year ago, and love the stuff. Has stuck good so far to wood, aluminum, brass and two pair of jeans. Jeans still have black splotches after a year of washings.

[Ernest Purdum]

Donald Qualls suggestion of "tapers' sounds like it might be a fairly easy way of applying the soot. Your nearest Catholic church probably has a lot of them and the Pastor would likely be happy to donate one to the good cause. A church supply house would probably only sell them in large numbers.

[snuck]

I think I will try a candle

CHeers

[snuck]

Ok, it is late, and I am tired so i won't post pictures just yet, but I finished working on this thing. The lampblacking procedure, provided that I got it right, was fairly simple. Much easier than I thought actually.

As it turns out I used a smoky candle in a bowl that was shooting out a fairly tall, (2 inches) flame. Holding the lens with an old ratty towel to protect myself from the heating brass lene, I rotated so that the flame played evenly over the interior of the lens ... All I can say is that this method is pretty dependent that there's nothing in your lens that is flamable.

[snuck]

here are pics of the lens. The very last pic is the ebay auction pic, which is completely yechtacular. the rest are my pics. The glass cleaned up beautifully. You can't see the lampblacking since it's on the inside... although at some point in time I should lampblack the hood as well.... Photos taken with this lens are sure to follow soon. I keep thinking that for some reason I put the rear element back into the lens in the wrong orientation.. How would I be able to tell this?

[Ernest Purdum]

The rearmost element of a Petzval is bi-convex. The one in front of it is a meniscus type.

[Donald Qualls]

All I can say is that this method is pretty dependent that there's nothing in your lens that is flamable.

Smoking with real smoke was ever so... ;)

The photos look good, looking forward to seeing how it performs. For the rear element, best I can suggest (since you didn't make careful enough note of it during disassembly, tsk, tsk) is to set up perpendicular to a flat wall and look for a ring of best focus to travel from center to edge and back when you rack the focus back and forth (due to field curvature); one orientation will be better than the other. Use the better one. :)

[snuck]

I dunno.. I figured that I'd be able to keep track of just a few elements. I suspect that my unsurety is just my paranoia speaking. In any case, the biconvex element had one side more convex than the other. The more convex side is the one that points toward the film, and the less covex side points toward the meniscus. It looks good on the ground glass, with REALLY SHALLOW depth of field when close, even at f11. I exposed 2 5x7's (using the Jim Galli shutter), so we'll see what happens when I process them tomorrow night.
Cheers

[Ernest Purdum]

The original Petzval design had the bi-convex element the other way around, but there have been many variations over the years and this may certainly have been one of them.

Congratulations on your first exposures.

[Donald Qualls]

I exposed 2 5x7's (using the Jim Galli shutter), so we'll see what happens when I process them tomorrow night.
Cheers

Well? We're all waiting on tenterhooks, here... ;)

[snuck]

yeah I'm waiting myself... unfortunately right now I'm teaching my kids cyanotype (I'm a teacher), so some of my equipment is up at the school and it's hard for me to cart back and forth. I'll probably get some results some time next week... Of course it doesn't help that my first run negatives had a processing disaster. I'll give it another go this weekend.
:(

[snuck]

Welcome to the land of my dusty hideous contact prints. I'm having a dust control issue in my darkroom because well.. it's not exactly a darkroom as much as a dusty workshop in the basement. It's in progress... I'm still ironing out the widgets here, including some issues with my new unicolor drum. For the longest time I was part of the Hart House Camera Club here in toronto, so I have never had a need to build my own darkroom. But now that I'm not at U of T anymore I've been building my own thanks to the generosity of a certain person.

Well I do like this lens. the only compaint I have is that it's probably more suitable to 4x5 coverage rather than 5x7. this should be no suprise, given that the focal length of this lens seems to be approximately 7". In any case, at portrait extension, the lens does cover 5x7, so used purely as a portrait lens, it's not bad.

Looking at the car pictures, we can notice a few things. For one the dof on this thing is nice and shallow. If you look at the truck, you can see that at f4 even at a distance the fan is nicely isolated and the rest of the truck gets soft pretty quickly. That fan is NOT very far behind the front bumper at all. You can also see that the lens can do sharp, very sharp, at least in the center at f22, compare the first two pics and the last two. Both are taken at f4 and f22.

Of course, it s a petzval, and therefore is swirl swirling away! That makes me happy.

Exposed on HP5, processed with Rodinal 1:50, slightly colder than usual, and contact printed with an Aristo cold lamp.. Unifiltered. I think that I should filter it because it has incredible contrast, or at least more than expected....Printed on agfa RC. Can't wait to getting to stuff like.. uh.. actually making some decent prints of these.

Conclusion? I like it, but hey, I own it.. and I gotta be more concious of the vignette. thanks to Dowdall for the trip.

[snuck]

here's another pic

[Steve H]

Very VERY cool....I like your choice of subject matter (tubes rock!). Im envious about your lens; I had the chance to get a Perkin about a year or so ago, and passed it up (It was 14"...abit too long for my 4x5 tastes). Hopefully one day I'll find a copy like yours.

[snuck]

[QUOTE=Steve H;193024]Very VERY cool....I like your choice of subject matter (tubes rock!). /QUOTE]

Yeah the other thing that I like to do is try my hhand at restoring tube amps (zzzap). Well about cars, I certainly can't claim that I wasn't influenced! Here's to you Jim....