More dumb questions about the LPL C7700

[mrtoml]

I have finally got the enlarger and assembled it. It seems to work fine and has a timer and 2 lenses with it.

Question 1. On my old Meopta there was a red filter that went in front of the lens to stop exposing the paper. Is there supposed to be one with the LPL? I cannot see how to stop exposing paper when using B&W materials. I guess with a colour enlarger colour paper is sensitive to red:rolleyes: I just hadn't given this a thought.

Question 2: How do I get the lens off. I cannot unscrew the lens to change over from the 80mm already in to a 50mm for 35mm negs. The lens just seems to rotate in the plate. I can take the plate off, but cannot see how to get the lens off the plate.

Thanks in advance,
Mark

 

[Pinholemaster]

Enlargers haven't been equipped with that red filters for decades. Simply turn off the enlarger. I'd remove the filter, and put a variable contrast filter holder in its place.

You need a spanner wrench to remove the retaining ring that holds the 80mm to the lens board. The same wrench is used to tighten the ring to your 50mm lens. You can use the 80mm with 35mm negs, but the enlarger head will end up much higher on the column. You can't use the 50mm lens on 120/220 film for which the 80mm is designed.

 

[Akki14]

Mine has that red plate. It doesn't stay on, it falls off, It's useless, I never used those red filters anyway because my teacher instilled a mistrust of them in me. If you really want the filter, I'd be happy to send you mine. But really, this enlarger is meant to be operated with a timer, imo.

If you can't get the lens out of the mount (I had this problem a few months ago), As a last resort, put the plate and the lens in the freezer until cold and they'll come apart easily. Here's my thread on my stuck lens. (there was a url link here which no longer exists)

 

[mrtoml]

Enlargers haven't been equipped with that red filters for decades. Simply turn off the enlarger. I'd remove the filter, and put a variable contrast filter holder in its place.

You need a spanner wrench to remove the retaining ring that holds the 80mm to the lens board. The same wrench is used to tighten the ring to your 50mm lens. You can use the 80mm with 35mm negs, but the enlarger head will end up much higher on the column. You can't use the 50mm lens on 120/220 film for which the 80mm is designed.

It has been decades...

I don't understand the wrench bit. The lens turns easily, but then stops and won't go any further. I don't want to force it. There are 3 screws at the back of the lens, but I assume they are holding the rear element on. I am not sure what the 'retaining ring' is.

 

[simulatordan]

Hello Mark,

I've got the LPL C6700 which is the same but with a slightly smaller head and will only do up to 6 x 7cm negatives. mine has the swivelling red filter which I used without a problem until I changed to a 'Stop Clock Pro' fstop timer.

The red filter is fitted to the end of a metal rod, which has a keyway,that secures into the lens plate carrier and is held by a set screw. If the set screw is loose or the rod is not correctly orientated into the slot the whole lot will work loose and fall out.

With regards to the lens itself, on my enlarger the lens is screwed into an adapter ring which is then screwed into the lens board. If one or other of these has been over tightened it can be a problem to seperate the parts. I would be very loathed to used any metal adjustable spanner or 'Mole' grip which could slip and do considerable damage to your lens or enlarger. If you cannot seperate the lens/adapter ring fronm the lens board I would suggest heating with a hair dryer as a first move. Another thing to try is to tighten very slightly then try loosening. To remove the Lens from the ring while it is still in the enlarger Try a strap wrench or one of those things for taking the lids of jam jars and the like.

I have gone on a bit but as a engineer I've seen the results of the ' Bull in a China Shop' approach and the expense incurred when a bit of lateral thinking has come up with the answer.

regards Daniel

 

[RH Designs]

Question 1. On my old Meopta there was a red filter that went in front of the lens to stop exposing the paper. Is there supposed to be one with the LPL?

Question 2: How do I get the lens off. I cannot unscrew the lens to change over from the 80mm already in to a 50mm for 35mm negs. The lens just seems to rotate in the plate. I can take the plate off, but cannot see how to get the lens off the plate.

Hi Mark

I have a C7700 colour; it does come with a red filter which can be swung under the lens but I soon discovered it's not actually safe for b+w paper so I never used it. It's attached to the lens board via a rod held in place by a thumbscrew.

The lens is attached via a standard screw thread to a circular plate which is held onto the lens board with a thumbscrew system. The thumbscrew is on the right hand side of the lens board - unscrew it (keeping your other hand beneath the lens to catch it) and the plate and lens should drop out. If they don't, a gentle nudge or tap should free them. After that, you can unscrew the lens from the plate. If it's been there a while it may be tight, but no spanners are necessary. A strap wrench might help if it's really tight. Some lenses (like my El Nikkors) rotate fairly freely to a stop in both directions, so you can get the aperture readout positioned conveniently - you may find if you simply apply a bit more pressure after it's reached the stop, it will unscrew.

I'm not near the enlarger at the moment but if necessary I can probably take a couple of digipix showing the relevant assemblies.

 

[mrtoml]

Thanks for all your replies. Useful as always.

I figured the safest thing was just to buy a new plate to put my 50mm lens in. They are not that expensive. It really is stuck fast and has probably been in there for years.

I guess I will have to learn to live without a red filter, but I vaguely recall using one a lot in a previous life.

 

[mrtoml]

I now have the plate and have started using the 50mm lens with 35mm negatives for the time being.

One issue now is that the exposure times seem long. I timed a maximum black density for Acros and Prescysol (using a blank frame) and it came to 21 seconds at f4 for a normal grade 2 10x8 print (dialling in yellow and magenta). So if I stop down the lens to f8 it takes over a minute for the exposure. Isn't this rather long?

 

[Akki14]

Why are you having to dial in yellow and magenta? I thought grade 2 was no filtration... Make sure the cyan dial isn't turned all the way up or anything like that (unless this is the B&W head and not the colour one... I think mine's technically the C7700MX so I'm not sure what the differences are).

 

[mrtoml]

I thought there were 2 ways of dialling in. One is that you just use magenta to increase and yellow to decrease contrast with grade 2=no filtration, but then the exposure times change which is a pain. And the other way to use yellow and magenta together and keep one time for all grades (I am using the settings in Ilford's documentation - grade 2=41Y+32M).

 

[Akki14]

Hm So you could change the situation by just doing single filtration instead of double... I don't find the exposure times change that much, maybe a few seconds per "grade" of added magenta. I print as grade 5 loads, not so much on anything below grade2...

 

[mrtoml]

The thing that puzzles me is when reading about other people's printing they often say things like 'I made a test print at 10 seconds, f8'. Even with no filtration on in my enlarger there is no way I will ever get down to 10 seconds even at f4. Not that this is a terrible problem, I'm just curious...

 

[mrtoml]

Just for the record I have solved the problem. I replaced the bulb and now I have very short times much like the ones I read about. Now I can get less than 10 seconds with f5.6.

The bulb was very dirty and obviously old. I didn't realise that these halogen lamps could deteriorate so much without actually blowing.

 

[Dave Miller]

J

The bulb was very dirty and obviously old. I didn't realise that these halogen lamps could deteriorate so much without actually blowing.

They can, and as you found do. One factor to look at is the condition of the lamp socket, this also deteriorates and is worth replacing periodically, say every second lamp. Both the current flow and heat produced are high, which means the contact life can be short. When corrosion sets in the electrical resistance goes up, and illumination down as the current flow is restricted.

 

[mrtoml]

They can, and as you found do. One factor to look at is the condition of the lamp socket, this also deteriorates and is worth replacing periodically, say every second lamp. Both the current flow and heat produced are high, which means the contact life can be short. When corrosion sets in the electrical resistance goes up, and illumination down as the current flow is restricted.

Thanks for that info. I noticed that the socket looks a bit iffy. It took a bit of wiggling to get the bulb to come on. I presumed because of dirty contacts inside the socket. I will look into getting a new socket now too.