Gundlach lens info

<p>Is anyone familiar with the Gundlach Anastigmat 6 1/2 inch f6.8 lens? I just got a very nice example and would like to know more about it. It's in a Wollensak Gammax No. 2 shutter. I found it in the old Gundlach catalogue, but does anyone know about it's design or has anyone else ever used one. I am curious. Thank you! Robbie</p>

Kingslake (A history of the photographic lens p.98) lists the Gundlach Royal Anastigmat as a

symmetrical quadruple doublet, with two cemented

achromat doublets on each side of the aperture in a

mirrored back-to-back arrangement. Having 8

elements in total; 4 positive and 4 negative.

 

It's relatively easy to count the elements in a lens

by looking for the number of reflections you get

from a single bright light source. A single un-cemented element gives 2 reflections. Whereas a

cemented doublet gives 3 reflections (2 strong and

one much weaker from the cemented surface). So

if this is a Royal Anastigmat I'd expect to see 4

strong and 2 weak reflections from each half of the

lens, and for each half to show an almost identical

pattern of reflections.

<p>Thank you Joe, I should have earlier mentioned that one of the strange things is that this lens seems to have four elements, but not like a Tessar. Instead of two in front and two in the rear it has one in the rear and three in front. I certainly am no expert on lens design. I just can't find exactly what this might be. I thought about buying the Kingslake book but it is a bit more than I wanted to spend! Thank you again Joe.</p><div></div>

<p>Should be a Tessar clone. From 1931 catalog coverage 5x8 inches, studio use for portrait and group. $28.80 in shutter $18 in barrel. I use a Gundlach 12" f/6.3 on 8x10. Even illumination with good coverage, fine images for an uncoated lens. Gundlach made the Turner-Reich convertible lenses and the Korona view cameras.<br>

Chris</p>

Robbie, are you sure you got an original lens and

not a "bitsa" (bits of this, bits of that)? Sometimes

front or rear elements get scratched or lost and,

since shutters have pretty standard threads,

someone just fills up the hole with a completely

different half.

 

Good quality lenses may have a serial number

stamped on both halves. In any case the style and

finish of the brasswork should match.

 

Is there any sign that your lens isn't wholly original?

<p>Christopher, Thank you. I imagine the 12" would just be a big brother of the 6 1/2. The image on my ground glass looks very nice. I should be shooting something with it this weekend.<br>

Joe, You make a great point and I should have checked that. The whole thing looks so good I just assumed the back matched the front. But the finish of the rear is a bit different. The lens did not cost much, but still, now I am a bit paranoid about it! Oh, Well...Thank you! </p>

 

<p>Your lens may be as RJ says, a BITZA, or its incorrectly assembled.<br>

This 1920 catalog page 36 http://piercevaubel.com/cam/catalogs/1920gundmanlp194.htm "the small number of components and moderate curves of the surfaces" gives one clue.<br>

This 1922 catalog page 16 http://piercevaubel.com/cam/catalogs/1922gundmanlp286.htm states " has 4 components in 2 combinations".</p>

<p>A Lens Collectors Vade Mecum does not list the lens other than to mention its existence. It does list several lens diagrams, most of which are for the Turner Reich series. The Q4 design is referenced for a Turner Reich. The Gun 005 is the only other 4 component, 2 combination diagram listed.<br>

If either of these diagrams are correct for your lens then the shape of the elements will match the shapes drawn in the diagram. Correct spacing is unknown.</p><div></div>

<p>Correction: neither of the two previous diagrams are correct for your lens.<br>

Page 13 of the 1925 catalog http://piercevaubel.com/cam/catalogs/1925gundmanlp407.htm has the correct diagram.</p>

<p>Do your elements match the diagram? Are there proper retainer rings and element stops to assemble it correctly?</p>

Smart detective work Charles!

 

The diagram given in that last link is a Cooke "Aviar" type lens, designed by Arthur Warmisham of Taylor, Taylor-Hobson sometime prior to 1916, when it was introduced as an arial reconnaissance lens. Arthur Cox (in Photographic Optics) classifies

it as a triplet type where the rear element has been

split into two, giving a near symmetrical design.

 

Many high quality reprographic lenses were of

similar construction, using high refractive glasses to give apochromatic correction.

 

Of course the classification "anastigmat" covers a whole raft of lens designs, and there may well be a Gundlach anastigmat with 3 elements before the iris and 1 to the rear. Though I can't remember ever seeing such a diagram from any maker.

<p>OK...So sorry to take so long. I really appreciate all of this detective work! Today I un-mounted the lens and made pictures. First I must admit that I was careless in my first counting of the elements. This time I used just a bare light bulb a couple of feet away. There are more than I first saw. In the front there are four and the rear has two. If it is a 'BITZA' is a good one. When I focus on a small bright item about 20 feet away from the camera and then pan and tilt the camera from one extreme corner to the next (and also side to side and up and down) the item stays in focus and shows absolutely no distortion or light falloff at all. It does get slightly softer, just slightly, and sharpens up after about two stops. So I do think this is a complete lens. Here are photos:</p><div></div>

<p>Rear</p><div></div>

<p>Being you are reflection counting I wonder if you are getting extra reflections from the air spaced elements.<br>

It looks like 4 elements, 2 each side looking the the cell edges to me.<br>

Put it on a camera with some film and ask it, I'll bet it says I complete and properly assembled, just need a cleaning.</p>

<p>Since I know just about enough about lens design to be considered dangerous I am sure you are correct. The four elements would sure make a lot of sense. I am about to shoot with it...probably this weekend. The rear cell is actually very clean. The front has some dust in the air space but it looks like there is not a way to get in there. It's really not bad. I will report back with photos. Thank you again Charles!</p>

<p>And Thanks again to you Joe!</p>

<p>The front barrel appears to be internally threaded. Use a hollowed out rubber stopper or similar and unscrew the retainer ring that doubles as a trim/name plate. If the threads appear stuck they may have a thread locker applied. Use nail polish remover on the threads and let it sit for several minutes to dissolve the thread locker.</p>

<p>Charles, You are a genius. I found a plastic bottle top that fit the ring perfectly. I attached a little double-sided tape and the ring screwed right off. I cleaned it all out and now it is spotless. It truly is like a news lens. I can't thank you enough!!</p>

<p>And Chris...You were correct all along. I guess it really is a Tessar clone....Thank you!</p>

Those look like the reflections you'd get from a

Cooke Triplet design to me. Nothing wrong with

that. I have a 6" Cooke Triplet on a quarter plate

reflex camera and it gives extremely sharp results.

<p>Joe, That well could be. The only triplet I have is a 103mm Graflex Trioptar and the reflections do seem similar. Here is the inside of the back:</p><div></div>

<p>It may also be a Gundlach Ultrastigmat...something like this:<br>

http://www.oldlens.com/ultrastigmat%2050mmf075.html</p>

<p>See those notches 180° apart (your thumb is over one of them in the posted picture). Use a lens spanner wrench and unscrew the retaining ring. The edges look like they could use a cleaning.<br>

I doubt its a Ultrastigmat. I think you will find its 4 elements in 2 groups with 2 elements in 1 group in front and 2 elements in 1 group in the rear.</p>

<p>How many elements are there in the front, 2?</p>

<p>OK, I cannot say for sure how many are in the front. The front element came out after unscrewing the front ring but the inner element is sealed in there. So it is impossible to tell for sure. I unscrewed the rear element. It looks as it there may be two glued together. The line is so fine it is difficult to see. I had a devil of a time getting it back together but it all seems well now. Here is a pic of the rim of the inside glass. If it is a glue line it is very faint.</p><div></div>

<p>That's normal edge of a single piece of glass. Cemented pairs are quite obvious when viewed on edge.<br>

Rear cells tend to be in a barrel .0005 inch larger than the element. The element slides in easily as long as its a perfect 90° to the barrel, a PITA when they are not. Inner element in the front will be retained by a second ring, a few lens were crimped in. The outer element of the rear should have as separate ring holding it also.<br>

The internal retaining ring may be threaded, retained by a set screw, both or pined in place.<br>

The curvatures should match the diagram in the 1925 catalog.</p>

<p>In a previous post by RJ</p>

<blockquote>

<p>The diagram given in that last link is a Cooke "Aviar" type lens, designed by Arthur Warmisham of Taylor, Taylor-Hobson sometime prior to 1916, when it was introduced as an arial reconnaissance lens. Arthur Cox (in Photographic Optics) classifies it as a triplet type where the rear element has been split into two, giving a near symmetrical design.</p>

</blockquote>

<p>This is what A Lens Collectors Vade Mecum has to say about the Aviar</p>

<blockquote>

<p>Series 11 f4.5 AVIAR This series switched to the Aviar 4-glass dialyt type after WW1 and became famous for its sharpness. Typically it was offered in 6.0, 7.0, 8.25, 11, 12.5, 13.5in as well as big aero versions such as the famous 14in f5.6. Late civilian examples were sold coated and are something to look out for. It was suggested to use 6.5in for 5x4.( Layout Tay005.)</p>

</blockquote>

<p>Therefore the Gundlach Anastigmat Series IV is a Dialyt not a Tessar clone.<br /> Note the differences in the element shapes between the 1925 and Tay 005 diagrams.<br /> Lens types are based on the element types and spacing not their size or powers.</p>

<p>Light travels the direction of the arrow in lens diagrams.</p><div></div>

<p>Thank you very much Charles. The thing is that the rear element I showed in the photo is the only element in the back. I think I was not very clear in my description. There is no outer element. That's it in the back. It is possible there are three in the front. There is the one shown in my photo (front) and the 'sealed' one inside- which I really do not want to unscrew- might be two. Thank you very, very much. You really have been very kind and generous with your knowledge and I do appreciate it. When I get some prints done I will show them...Robbie</p>

<blockquote>

<p>The thing is that the rear element I showed in the photo is the only element in the back</p>

</blockquote>

<p>Very interesting. The lens was made/put into use 40+ years before I came into being. All I know is from the published reference materials referenced in this thread.</p>