Durst L1840 Enlarger 8x10 10x10--Everything you wanted to know...

This thread is intended to document my restoration of a Durst L1840 and also to serve as a collecting ground for information on these enlargers. Those of you that own these enlargers, please feel free to contribute pictures of your enlargers and share your experiences with the care and feeding of this beast.

If anything, I hope it will at least provide some entertaining reading.

So, the first thing is to find a little home for the Durst somewhere in the darkroom. Just by chance my choosen spot is right under the 220 feed to my wife's Oven in the Kitchen. In fact, a new oven was just installed last week (so, Daddy also gets a new 'appliance'; thus the wife's OK for the enlarger....)

The new oven draws 30A and the enlarger draws about 7A (1500W/220V). The line to the oven is protected by a 50A breaker, so I will be able to use that same circuit for both the enlarger and the oven.

I have some pictures of the enlarger as it was found. It was purchased new in 1988 with the Aristo cold light head and a 300mm Rodenstock lens for almost $20,000. It was used make full sized lith enlargements used in screen printing large banners. It looked like it had spend most of its life in the horizontal position. It had been used on a track and projected onto a wall.

Both motors, the ECU and the coldlight seemed to function correctly.

I was not too happy with the way the coldlight was attached to the enlarger, though, it did seem that was the way the enlarger was delivered back in 1988.

There is a thick plastic plate that looks home made into which sheet metal screws are used to hold the coldlight. The connection was wrapped in black tape and this covered, and defeated, the heads built in filter drawer.

The enlarger was hard-wired right into the building's power grid, so I needed to cut the power to the room where the enlarger resided, and use a flashlight to remove those handy boxes on the back of the enlarger column.

My original intention was to use an enclosed car trailer for transport. It turns out that the vehicle that hauls the trailer was a Suburban. After some measuring, we thought the enlarger would just fit in the back of the Suburban, thus eliminating the need for the car trailer.

The enlarger was stripped as much as possible and loaded into the Suburban. One thing we could not get around was the need to have the enlarger's weight on the black knob on the side of the camera. I could not see an easy way to remove this knob, so we just padded things well and hoped for the best.

It turns out there was no damage to the knob.

These pictures are from the unloading process. I was too busy to take pictures while stripping the enlarger and loading it.

If not for the assistance of my brother (who did most of the lifting) this project would have never happened. He was also patient, because I was contunually slowing things down to make shure nothing got bent, scratched or broken during the transport.

Using the dolly did not help as much as one would think because most of the weight was centered over the camera (mid-column), rather than the base. The base is, in fact, aluminum.

Once I got the enlarger safely in the darkroom the cleanup process started. It seems that some of the paint on the base was permanently damaged by one of the process chemicals. Perhaps acetic acid? The good news was that most of the other chemicals (fixer and dev.) came off quite easily.

The ECU also cleaned up well.

The power supply had a rattle, so I opened it up to check things out. All looked good, excpet this little screw which holds the wires on the on-off switch, had come loose.

After cleaning I was able to do a mechanical assessment. So here is the to-do list:

Remove the plastic adapter and paint it so it does not look home made
Re-mount the cold light using black foam rubber, so the black tape is not needed, and so the filter drawer is functional.
Re-do the very cheap looking angle brackets holding the coldlight to the adapter.
Take the trim off the column and remove the 3 cosmetic bellows on the column. After having built a bellows from scratch, I think I know how to fix up these bellows.
Look into some matching touch up paint from the auto parts store

For power I wound up running a separate 20A 240v line with 12 gauge wire. The socket for this line is about the same size as a standard 120 socket but the slots are horizontal instead of vertical. Those large 50A 240 sockets for appliances that take 8 gauge wire are not the correct item.

After firing it up I realized the slow focus was not working. (In some dry runs, this was actually not a problem as focusing with the fast speed was fine but I like to have everything working correctly) So, I set out to see if I could fix it. I followed the diagnostics in the repair manual and traced the slow signal deep into the 24v motor control circuit board.

I came to the Quad Op-amp and there are some very strange readings, making me think that this 45 cent part is the culprit. One output pin it is supposed to read low voltage when a 13volt signal is mixed with a 15 volt signal at the inverted input. Seems the output pin is reading 33 volts which is not the correct answer for this logic circuit. This high voltage is keeping the motor pulse counting chip in reset mode and basically freezing the circuit. At least that is what I think. I will replace the OP amp and see what happens.

Knowing (or believing to know) the exact problem with the power supply, I continued with assembly of the enlarger.

I have started to work on the cold light. I opened it up and it has the W45 lamp that I can use for multicontrast printing (Yeh!). The number is printed right on the glass tube.

I just set the coldlight on top of the enlarger and did a dry run to get a feel for how high the column needs to be to make a 11x14 or a 16x20. This picture shows the position of the head, table and lens stage for a focused 16x20 print (300mm lens, 8x10 negative).

Sweet...space:-) Thanks for sharing this great adventure. So is that the highest position the head will go? what is the maximum size print it can print with the 300mm lens?

Robert

Quote:

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Originally Posted by fuegocito

Sweet...space:-) Thanks for sharing this great adventure. So is that the highest position the head will go? what is the maximum size print it can print with the 300mm lens?

Robert

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One good thing about the coldlight vs the Durst color head is that the coldlight will allow the enlarger to go all the way to the top of the column and still have a few inches of clearance!

With the baseboard all the way down (to 'zero' on the scale) and the head all the way up (until it reaches the automatic stop), an 8x10 negative projects onto the entire baseboard with a few inches to spare around the edges. The baseboard is 43 inches, so I think the projected image is around 40 x 32 inches. This is all with a 300mm lens.

Since I can only process up to 16x20, I am able to have the baseboard all the way up (to save my back) and still have some room at the top of the column for a little cropping, if needed.

Even though I have a tape measure (and know how to use it :) ) pictures like this had me worried that the enlarger was not going to fit.

I never knew for sure how much room I was going to have until yesterday when I finally got it wired and plugged in and ran the head all the way up.

A few words on alignment. This is the point where I would launch into a multiple-page posting on the fine points of critical alignment.

Well, I checked the 4 corners of the largest projected image on the baseboard (40x32 inches) and they were all sharp with the lens wide open at 5.6.

WOW!

I could get out the laser and check it, but if it is a little off, what am I going to do? It already is sharp on all 4 corners (and center) with the grain magnifier, and that is the gold standard for me.

Thanks for sharing! I used one of these (and other big Durst's and DeVerre's) in the eighties and ninties at a pro-lab, and they are great machines, I tired to make that most ours went to good homes when it was "time".
All we have now is a bunch of computers!
Keith

While eating lunch I saw a RadioShack and recalled that they still sell a few ICs. I went over to check and of the ten or so chips they sell, one was a quad OP amp with pin locations that matched perfectly! SoI replaced the OP amp chip (for $1.25), but the new chip also gave 'faulty' results. Hmmm.... maybe it is me that is faulty.

So, I re-read as much as I could on Op amps and it turns out the inputs don't subtract from each other if a certain one of them is larger than the other.

Then I was off changing resistor values to get the reference voltage on the one pin of the OP amp to be lower than the other. This did not work, it just lowered both voltages.

Then I realized the I was misreading the scale on the voltage graph. Well, there is NO SCALE on that graph, but it looked like the voltage needs to get way beyond 13.8 volts. The way it gets there is by charging the little capacitor (C5). To get this to charge IC6 (a SPST solid state switch) needs to turn on. This is not turning on because the counter chip (IC5) is dead.

I was ready to replace the counter chip, when I saw on it's data-sheet that the CLOCK pin on this chip is not a clock output. It is a clock INPUT! So where is the blasted clock to run this chip? I had been under the impression the counter chip (IC5) had a built in clock. I searched all over the board for a 555 timer chip and there is none.

The counter input leads to the logic circuit for telling which button is pressed. Hmm, do you have to keep pressing the buttons on-and-off to get the counter to work? This had me puzzled.

Then I traced out one of the logic circuits and they are using a positive feedback loop to get one of the logic circuits on IC3 to oscillate. This looked burned out, as it was not oscillating. There are a resistor and capacitor in the circuit to slow it down (it's supposed to oscillate at 600Hz) so I lowered the resistor value and the thing took off to 7K Hz.

At this point all things down stream started working and the slow button was now working!!!

I spent about 3 hours soldering and unsoldering various resistors to get it to oscillate at 600 Hz, but it was very unstable. The frequency was all over the place.
The capacitor checked out OK, so I suspect the logic IC3 is near its end of life and I suspect that if I replace IC3 the oscillations will be more stable and then can be fined tuned back to 600Hz. So, at this point I am 99.9% there. BTW the new IC3 chip is a whopping 26 cents! ($4.00 shipping, though :()

Quote:

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Originally Posted by ic-racer

While eating lunch I saw a RadioShack and recalled that they still sell a few ICs. I went over to check and of the ten or so chips they sell, one was a quad OP amp with pin locations that matched perfectly! SoI replaced the OP amp chip (for $1.25), but the new chip also gave 'faulty' results. Hmmm.... :()

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I am so glad my old Elwood 810 does not have any electronic bits in it, my level of handiness is that the world falls apart if a screw and nut does not match...:D

At this point I am not sure if I am going to keep the coldlight. It looks like it has the W45 lamp which is not suited to VC printing. I guess all I would need to do would be to get a new lamp and some VC filters, though I suspect these two purchases may be more than the enlarger cost ($20 each for the filters and $350 for the V54 lamp). I suppose I could just do it the old fasioned way and use graded paper and do all the contrast control with a spot meter and variable negative development time.

While I am trying to figure that out I wanted to give the power supply a good work over.

The power supply is just abox with a big transformer for 480V inside. The transformer says it was made in Hong Kong in 1978. I tried to open the lid but it is filled with tar or something.

There was also a 'mistry box' with three wires coming out of it.

Opening this up I found a 240V relay. This will allow the 240V timed output from the Durst to control the coldlight.

To eliminate some of the cords, I re-mounted the relay inside the coldlight supply. This also let me mount a 3 way switch on the coldlight supply. Now I have ON, OFF, and DURST TIMER. With this setup it can be used like any other coldlight in the ON positon, or it can be controlled with the 240 v relay in the "DURST TIMER" position.

Here is the coldlight power supply with the relay mounted inside. I also shortened the cord to the Durst so that it is only about one foot long.

What an inspiring project. Thanks for showing these photos. I have a few questions... Why are you limited to 16 by 20?
How much ceiling height do you need for the enlarger?
Can it work as a horizontal enlarger?
Do these come up for free sometimes, and do they come from labs that have gone digital?
Thanks
-Brad

Quote:

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Originally Posted by Brad Rippe

Can it work as a horizontal enlarger?
Do these come up for free sometimes, and do they come from labs that have gone digital?
Thanks
-Brad

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If you will look at all the photos posted in this thread, you will see that this enlarger came from a location where is was used exclusively as a horizontal enlarger. Look at the tracks on the floor. The Enlarger has wheels in the base to run along tracks if so desired.

Yes, many times, with diligent looking, you can find these for free, or very little money.
The trick is to find one close to your location (wherever that may be) so you don't have high expense in getting it to you.

Quote:

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Originally Posted by Brad Rippe

What an inspiring project. Thanks for showing these photos. I have a few questions... Why are you limited to 16 by 20?
How much ceiling height do you need for the enlarger?
Can it work as a horizontal enlarger?
Do these come up for free sometimes, and do they come from labs that have gone digital?
Thanks
-Brad

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Well, my trays are 16x20 and my largest easel is 16x20. My archival washer is 20x24, so I could go larger with a bigger easel and bigger trays. Though the bigger trays might hang over the edges of my counter. I have thought of trying to process RC B&W paper in a big drum in the Jobo. That might be a better option for real big prints.

The column is about 91 inches tall. You need a little extra to be able to tip it up from horizontal or from a dolly. With the coldlight, the head does not extend much past the top of the column (though with the CLS 1840 head it extends about an additional fifteen inches).

The focusing rails DO extend up beyond the column, however, the extent to which they extend depends on a lot of factors, so it would be hard to calculate. With a focused image on the baseboard all the way down, my focusing columns were just below the level of my joists (though they could extend up through the joists if needed)

Do they come up for free? I have read on the internet that some have recieved 8x10 enlargers for free, but I had to pay for this one. In terms of availability, my experience was that one came available just after I stopped looking. See this thread that I started about a year ago ( http://www.largeformatphotography.in...ad.php?t=25445) out of frustration that none of these enlargers ever are available in my part of the country. Then, who would have guessed that a shop I drive by on the way to work would want to get rid of one! I asked them if digital put them out of buisness, but they said no because they felt their 'old fashioned' screen printed banners had better ink stability than those that come out of a big digital printer.

My enlarger was used on a track as a horizontal enlarger. They used it to enlarge separations to full size for big screen-printed banners. The film was in big rolls (still available if anyone wants it, though it is some kind of positive lith film) and was tacked to the wall for the exposure. They used huge, sinks to process the film.

Here is a shot of the new components in place for the oscillating circuit. Trimmer and tantalum capacitor.

I re-did the mounting of the coldlight. The prior mounting looked like some type of down-on-the-farm repair of the hog feeder. It worked, but was not suited to a $20K enlarger.

Cold light?

I think it is somewhat of a misnomer. For the thing to be consistent it has to be hot! I have never owned a coldlight, so I was interested in what is in the box. Here is the heater. It is just 4 power resistors short circuited to the mains! Kind of curious as to why there are 'cooling vents' on the top of the case? There is a thermostat in the circuit also.

This thing leaks light in a bad way. So I still need to cover up those vents.

Test of enlarger last night--the good and the bad.

THE GOOD:
The fine focus worked very well.
I made a Blue and Green filter from Roscoe jels and swapping these in-and-out of the filter holder was not as bad as I had thought. I was able to just open the tray about half-way and then swap the filters. For those of you that have not done 8x10 enlarging, this filter swap is done by feel, reaching over your head in the dark.
The split printing technique worked very well and was easy to manage.
The enlarger is rock-steady during filter swapping, no chance of movement.
As hoped, the diffused light reduced dust specs and imperfections on the glass carrier. I think if I give it another cleaning I might be able to get by without replacinig it. If I were using this glass for contact printing it would be no good because of some small scratches. However, these scratches are minimized with the diffused light.


THE BAD:
The Aristo unit leaked light all over the place
The edges were not illuminated well, but I expected this because this mounting rig it came with has the diffuser too far from the negative.

My plan to fix the light source is to keep the tube mounted where it is, but to re-mount the diffuser screen down by the negative carrier. Right now they are separated by about 3.5cm. I think I can route a lip on the under side of the adapter, and the existing diffuser should be able to fit right in.

The top arrow in the photograph shows where the diffuser is now mounted. The lower arrow shows where I am planning on putting it.

To get the diffuser to a position just above the negative I needed to route a cavity for it in the bottom of the plastic adapter plate.

I also enlarged the opening. Even though the Durst glass negative carrier is only a little over 10 inches on a side, the coldlight has an extra inch all around.

I did not want to cut up the coldlight's original diffuser (in case this did not work out) so I could go back to the original configuration if needed. That's why the routed area is so big. If I had cut the diffuser, or got a new smaller one, the route would only have to be a cm or so.

So, how does it work? It reduces the light falloff at the edges, but the whole tube array has some inconsistency. I'm not shure how perfect I can get it. I suspect I will have to make due with something less than perfect.

It seems that the corners where the tube dives exits the light chamber are dark. Perhaps I might try some highly reflective silver paint in these areas.

The cosmetic bellows that hide the large 8" central column were all in bad shape. The outer fabric had separated from the inner pleats.

There are 3 cosmetic bellows. The top and bottom ones seemed to be the same size. The center one is the longest.

I used the same 3M "77" spray glue that I had used to construct my Century's bellows. However, this spray is not re-positionable. So, it was very difficult to get the bellows fabric to lie in the correct troughs of the pleats. The whole bellows cannot be spread out flat because there is a fabric strip on the back of the bellows that supports the column of pleats and prevents hyperextension. This fabric strip is sewn to every 4 or 5 pleats. To lay the thing out flat would involve removing this fabric strip and re-sewing it in place.

It would not occur to me to SEW a bellows because of the obvious light holes, however, this cosmetic bellows already had the fabric strip sewn to the back of it. So, to keep the front fabric in place I ran a line of black thread along each trough of the bellows. This was a lot of sewing, but it wound up looking better than the piece on which I had tried the spray glue.

Once fixed up, they easily compressed to a small size and can be removed or replaced without having to remove the column sides.

I really like 'before-after' photographs. Here are a couple showing the power supplies and the lower bellows.

Quote:

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Originally Posted by ic-racer

........The whole bellows cannot be spread out flat because there is a fabric strip on the back of the bellows that supports the column of pleats and prevents hyperextension. This fabric strip is sewn to every 4 or 5 pleats. To lay the thing out flat would involve removing this fabric strip and re-sewing it in place.

..... to keep the front fabric in place I ran a line of black thread along each trough of the bellows. This was a lot of sewing, but it wound up looking better than the piece on which I had tried the spray glue.

Once fixed up, they easily compressed to a small size and can be removed or replaced without having to remove the column sides.

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That's a very interesting solution. I had the same problem, and I had to remove the fabric strip and extend the bellows flat before I could reglue the fabric. Then I re-attached the strip. Sewing the folds sounds like a better solution.

Also, after I re-glued the bellows, I compressed it fully and let it stay compressed several days to acquire a "set", before I re-installed it.

I didn't know the cosmetic bellows could be installed without removing the enlarger sides. Good tip.

That small tag sitting on top of the power supply is actually the Durst quality control tag. It has a small, un-opened bag, with some fuses in it, stapled to the back.

From the way it looks, that little tag had been sitting on the power supply since 1988. All the other documents for the enlarger had been stored in a separate folder.

Now that I look at the photograph closer I can see some tape residue on the side of the power supply. So, I suspect the tag was taped there for 10 years or so, until the tape crumbled and fell off.

Quote:

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Originally Posted by resummerfield

That's a very interesting solution. I had the same problem, and I had to remove the fabric strip and extend the bellows flat before I could reglue the fabric. Then I re-attached the strip. Sewing the folds sounds like a better solution.

Also, after I re-glued the bellows, I compressed it fully and let it stay compressed several days to acquire a "set", before I re-installed it.

I didn't know the cosmetic bellows could be installed without removing the enlarger sides. Good tip.

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Yes, once it is all compressed nice and small it will rotate in the slot and come right out. (Didn't try it on the big middle one, though)

I scanned my L1840 Owner's Manual into a PDF file that I would like to distribute to all Durst owners, or potential owners, that don't have one.

I'd just post it here but the file is just over 6MB. Please PM me and I will send it out.

Just a note on the power supply that I forgot to mention when I was fixing it.

There are two taps on the power transformer primary side, intended for 220v or 240v. They are NOT MARKED on the transformer, but they are mentioned in the owner's manual.

My power supply came with the connector on the 220v prong (this is the way it is delivered, per the owner's manual).

My power main supply in my darkroom measured to be 240v. With this situation (ie 240v input to the 220v transformer tap) the printed circuit board voltages were slightly high. The shop manual stated 30v but I was getting 32v. Now some of the ICs on the board have an operating range from 15v to 32v, so this is getting close to the limit.

By switching my connector to the other prong (the un-marked 240v primary input on the power transformer) my voltages on the PC board dropped to about 30v, which was more in line with the voltages specified in the shop manual.

Here is a scan of the original sales record for my enlarger. The prices are in US dollars. The date was 1988.

Here is the location I decided for the 240/220v line. Again it is just wired with 12/2 wire and a 20A dual breaker. I need to thank Eric Summerfield for encouraging me not to tap into 50A line to my wife's new oven (which is just 3 feet from by eventual outlet location).

Now that I am using the enlarger I have noticed a loud metal-on-metal squeal when lowering the head. Time to open up the column and have another look inside (I had it apart once but did not see anything unnusual).

Even with it open I could not pinpoint the squeal. So, the plan was to lubricate all moving parts and see if that makes it better.

The vertical screw was moist with oil, so I left that for last (mistake...)

There are a number of ball bearings that act as wheels and center the head apparatus on the 8" round column. Each ball bearing unit has a metal-to-metal contact with the column. Each bearing also has a little felt piece to hold lubrication. The bearings along the bottom of the apparatus have the felt piece mounted on the underneath side. A little hard to oil with a gravity oiler. I decided to use a spray oil that is made for things like motorcycle chains. It is thick and will stick on an underneath surface, but it also penetrates well. It does not evaporate easily, also.

I am not recommending this brand, just documenting what I did. I used Tri-flow. I sprayed all the ball bearings, making sure the felt got soaked also.

It still had the horrible grinding, so I sprayed the lube in the little copper tube that leads to the vertical screw. This solved the problem. It also incresed the speed that the head goes up and down. This little copper tube lines up with a hole in the side of the column panel when the head is all the way down. Therefore, you can supply the lubrication to the vertical screw without having to take things apart. This is covered in the supplement sheet to the owner's manual. (Free pdf for the asking...)

The enlarger has the capacity to adjust the height of all 4 wheels. Three of them have milled knobs and the 4th requires a hex driver.

Getting the enlarger level and keeping the same pressure on all 4 wheels is actually somewhat challenging. Durst realizes this and some of the dedicated horizontal enlargers only run on three wheels to make leveling easier.

With adjustments at all 4 wheels it is very easy to make the L1840 run on only three wheels also. :) (but, of course, this is NOT what you want, because then it will wobble)

I spend a lot of time getting radio controlled cars to have a balanced setup with 4 wheel independent suspension, and have applied some of the same principles to the Durst. Here is my technique.

I use a level along the foot, and level it front-to back. And I also place the level across the feet, to level it side to side. This is not that hard, but it is easy to end up with the weight of the enlarger on only 2 or 3 of the wheels. So, just because it is all level, does not mean it won't be wobbly.

To make sure it won't wobble, you need to make sure the pressure on all 4 wheels is the same. You can do this by twisting each of the wheel height adjusters. Wheels that are in the air and not touching will be easy to identify because the wheel adjuster will twist very easily. If the enlarger is resting on just two wheels, then those two adjusters will be very hard to twist.

So what you may wind up with is two diagonal wheel supporting the entire weight of the enlarger, and the other two diagonal wheels up in the air, or with less pressure. By lowering the two wheels that are supporting the enlarger, you can even the pressure out. In the end you want all 4 adjusters to twist with the same force, indicating equal pressure on all 4 wheels. If your adjusters are rusty...LOL!

After getting equal pressure on all 4, check the level again. It will probably be off, so this whole process can takes some time to get right.

I'm not sure of these cooling holes in the top of the Aristo unit. Did they use the same top piece from one of the other units that has the transformer up top? This 1414 unit is special in that it was designed to allow the head of the Durst go all the way to the top with out being higher than the column. To do this they moved the transformer to a separate box. This works great with the Durst L1840, because it has a little tray to hold the transformer.

Anyway, there is a thermostat in the box, so my first impression is to just cover up these holes. I used Electrical tap that is rated to 105 degrees C.

I let the box warm up good and ran the tube for about 5 minutes (the maximium 'on time' they recommend) and the box temp. stayed at about 38 to 40 degrees C.

Again, the reason I want to tape these vents is that they light up the whole room.

So, after not thinking about it for a few days I dove back into the power supply. The problem is that the slow UP focus is way too slow. You can almost not even tell the lens stage is moving. The slow DOWN works fine.

There is a confusing graph of the capacitor that bleeds the back EMF voltage so that the speed is constant. The axes are not marked, but once I figured out the Y axis goes from +15 to zero going up I realized there is nothing wrong with the circuit board.

When I put the head horizontal, the UP and DOWN both opeate at the same speed. Again making me think there is nothing wrong.

There is a 'drive time' check, but it requires a 'scope to test. I did think that if the drive time were too short, the motor cannot even start to move before it is pulsed off again. So, I thought I would just tweak the drive time resistor and see what happens. The resistor is number R44 and mine came with a 33ohm resistor in there. It was marked 33 ohms and it measured 33 ohms. The manual says a smaller resistror will increase the drive time, so I swapped in a 10 ohm resistor and.....it worked perfectly!!! So now my UP and DOWN are the same speed and the focusing is much improved. It was so slow before it made it difficult to see any change in the grain.

The third line down in the graph pictured (C5) seems to only make sense with the way the circuit is functioning if zero on the Y=axis is UP. If one interprets the graph as zero being down, then the more load on the motor, the slower the circuit will make it go. This is what I initially thought was wrong, as my motor was going slower under load. But, alas, it works fine now, so I know that they did not build mine backwards :)

Now that I am done fixing it up, I have moved the enlarger into is new home.

congratulations ic-racer. That is quite a project and I am glad you shared it with us.

lee\c

A few notes on my research of this Rodenstock Rodagon 300mm 5.6 lens.

I had noticed glennview selling a Rodagon-G 300mm lens for a premium, so I did some research so see if that lens is better than the one that came with my enlarger.

Specs on the Rodagon indicate it is a 6 element, 4 group lens. The filter thread is 86mm.

Magnification range is listed as 2-8x with 4x being optimum

The Rodagon-G is designed for high magnification. Its range is listed as 8-30x with 20x being optimum.

Both lenses are designed for use with 8x10" negatives.

So, in practical terms the Rodagon will have best performance enlarging an 8x10 negative from 16x20 to 64x80. With the optimum being 32x40. This last size is just about the largest the enlarger will do on the baseboard. With respect to my darkroom, the SMALLEST size range of the Rodagon is the LARGEST print size I can currently process.

What about the Rodagon-G. In practical terms it is optimized to enlarge an 8x10 negative from 64x80" to 240x300" Thats a little big for my darkroom.;)

An additional note on the range of the Rodagon. As you may know, there is a point where an enlarging lens can no longer form an image. With the 300mm Rodagon, this point is just below the 1:1 magnification level. I tried to do some 1:1 prints and the focusing at this level is very strange. It is difficult to get it in focus, because it is right on the verge of the point where focusing is not possible. I was able to make some 8x10 prints, but compared to contacts, they were clearly inferior. This does show me that to make 1:1 prints, a process lens would be superior.

The owner's manual describes the various lensboards that are available, but there are no pictures.

Here are the pictures.

The first one is Unipla. It is like an adapter for the smaller lens plates.
The second one is Lapla. The Lapla comes in different thread sizes, to match different lenses. As you can see the Lapla fits in the middle of the Unipla.

The larger lenses, like the 300mm Rodagon, can fit right on an 8" lensboard called the VAPLA. My VAPLA also came with a stalk and a red filter. If I decide to go with 'under the lens' multigrade filters, I will have to make a filter holder, becasue, Durst did not make one. I don't want to destroy the red filter to make it into a filter holder.

glennview sells a replica of the VAPLA for about $200.



Here is a post by someone that found an 8" pan at Wall-Mart that works as a VAPLA:

Posted on Monday, March 11, 2002 - 03:37 pm:
"I recently discovered that I can make the equivalent of a Durst VAPLA lensboard by buying a shallow 8" diameter aluminum cooking pan at WalMart (for $3.88 + tax), and drilling the right size hole in the middle. These pans have a beveled edge, just like the real VAPLAs have. In fact, I'm tickled at the discovery. "

The first picture is the real Vapla and the second is the one that you can get from glennview.
I don't have a picture of the Wall-Mart pan, but I would like to get one so that I can make an adapter like the UNIPLA, that will hold the lens cones and boards from my Omega enlargers. This way I can put the 150mm on and enlarge 4x5s.

I have a 5x7 Durst 138s and it did not have any of the lens boards for my enlarger. I bought 3 off ebay for 5 or 7 dollars a piece and I took them to a machine shop that is located across the street and they enlarged the holes to fit each lens I wanted to mount.

lee\c