AnalogfotoRostock
I’m having the following problem with photo development: my enlarger doesn’t expose the image fully when I’ve turned on the magenta filter to boost contrast. The photos are only properly exposed in the centre; they become too bright at the edges. Without the magenta filter, the exposure is even. It’s not down to the camera; the negatives and digital scans are evenly exposed. I am using a Meopta Opemus 5 enlarger with a Meopta Meochrom 2 colour mixing head.
Does anyone on this forum know what the reason might be? I would appreciate any feedback!
Wolfgg
Hello,
In that case, the light won’t be mixed properly. There will be a gap in the light path. Normally, there’s a mixing box and often a frosted glass panel in the light path as well. The instructions should explain what needs to be used where and how.
Have a look here and see if you notice anything:
https://analoge-fotografie.net/selbst-entwickeln/dunkelkammer/#Der-Vergrerer
Addendum:
To test it in the film studio, put a piece of white paper inside, remove the lens and then look in from below (hold a mirror underneath if necessary). When screwing in a filter, the paper must glow evenly in the filter’s colour.
Another observation: the filters reflect the light they block backwards. In my case, this light once escaped through the ventilation slits and was reflected onto the paper via the wall. Therefore: the wall behind the enlarger should be black (use black paper, felt or simply paint it black).
Regards, Wolfgang
AnalogfotoRostock
Thank you very much for the tips; that sounds like a good place to start – I’ll have a look and let you know how it goes. I do have a frosted glass panel in the enlarger, with a sort of drawer between the lamp and the negative frame… is that what you mean? Best regards, Malte Wolfgg wrote
: Hello,
then the light isn’t being mixed correctly. Part of the light path will be missing. Normally there’s a mixing box and often a frosted glass panel in the light path as well. The instructions should say what needs to be used where and how.
Have a look here and see if you notice anything:
https://analoge-fotografie.net/selbst-entwickeln/darkroom/#Der-Vergrerer
Addendum:
To test it in the film stage, put a piece of white paper in, remove the lens and then look in from below (hold a mirror underneath if necessary). When screwing in a filter, the paper must glow evenly in the filter’s colour.
Another observation: the filters reflect the light they block backwards. In my case, this light once escaped through the ventilation slits and was reflected onto the paper via the wall. Therefore: the wall behind the enlarger should be black (use black paper, felt or simply paint it black).
Regards, Wolfgang
Wolfgg
Hi Malte,
Yes, most enlargers have this filter drawer so that filters can be inserted into the light path even without a colour mixing head. On some models, you still need to fit the frosted glass pane into the colour head. Simply check with a sheet of paper in the film stage to see if the illumination becomes more even.
Perhaps someone else with the same enlarger will join in and have a look at theirs.
If the machine was bought second-hand, it’s also worth unscrewing the colour head. Not just to check that everything is still in order, but above all to remove any dust.
Regards, Wolfgang
AnalogfotoRostock
Yes, the device was actually bought second-hand... but back in 1984, by my parents for me when I was a teenager!
KlausWehner
Hello Malte,
I haven’t seen the device myself.
So I can only comment in general terms.
It’s possible that the light fall-off is particularly noticeable only when the contrast is high (magenta filter).
In that case, there could be many possible causes.
Sometimes it can help to look through the lens (or even without a lens) from the base plate towards the light source.
Something must be obstructing the beam path somewhere.
You can carry out this inspection using a hand mirror. That’s a bit more convenient.
(I’ve just noticed that Wolfgang had the same idea).
Best regards,
Klaus
AnalogfotoRostock
Hello Klaus,
Thank you very much for your reply! Could it be that I’ve fitted the wrong bulb? I replaced the bulb back in the eighties. The link that Wolfgang sent states that 12 V halogen bulbs should be used in magnifiers with a diffuser head.
Best regards,
Malte
Wolfgg
Hi Malte,
Perhaps the lamp isn’t in the right position and needs adjusting.
Here are a few links:
https://archive.org/details/opemus-iii-manual
http://www.jollinger.com/photo/enlargers/meopta.html
https://de.scribd.com/doc/240827142/Opemus-5-Manual
Regards, Wolfgang
KlausWehner
Hi Malte,
Yes, the light source is of central importance.
But first, we need to clear up a point of confusion:
Do you have a colour-mixing head or an opal incandescent bulb in the unit?
The information on this is somewhat contradictory.
Different light sources are required for each.
Then we can continue troubleshooting.
Best regards,
Klaus
Wolf_XL
...it might also be the filter itself. Perhaps it has slipped slightly out of its holder, which is causing the problems...
AnalogfotoRostock
Hello Klaus, I have a colour-mixing head, a Meopta Meochrom 2, fitted to a Meopta Opemus 2 enlarger. I’ll have a look at the weekend to see what sort of lamp is fitted and whether anything is stuck. Best regards, Malte wrote
Klaus WehnerHi Malte,
yes, the light source is of central importance.
But first, we need to clear up a point of confusion:
do you have a colour mixing head or an opal incandescent bulb in the unit?
The information on this is somewhat contradictory.
Different light sources are required for each.
Then we can continue troubleshooting.
Best regards,
Klaus
[hr]
Analogfoto Rostock wrote
Opemus 5, sorry! Opemus 2 would be a real old gem from the sixties! Hello Klaus, I have a colour mixing head, a Meopta Meochrom 2, on a Meopta Opemus 2 enlarger. I’ll have a look at the weekend to see what sort of lamp is fitted and whether anything is stuck. Best regards, Malte wrote to
Klaus Wehner Hi Malte,
yes, the light source is of central importance.
But first, we need to clarify one point:
do you have a colour-mixing head or an opal incandescent bulb in the unit?
The information on this is somewhat contradictory.
Different light sources are required for each.
Then we can continue troubleshooting.
Best regards,
Klaus
KlausWehner
Hi Malte,
Thanks for this important information.
What does the shadow look like: more circular (in which case the corners are primarily affected) or more rectangular (in which case the sides are affected evenly)?
Does the colour mixing head actually fit the device?
What type of magnifying lens is it, and is it screwed in correctly?
Best regards,
Klaus
AnalogfotoRostock
I’ve taken the unit apart; everything is in place, fits perfectly and works as it should. The filters are pushed in front of the lamp by a mechanism, which is also correctly positioned. The unit and head belong together, as you can also see in this link:
https://de.scribd.com/doc/240827142/Opemus-5-Manual
The lens is a Berophot 1:3.5 F-50 mm and is correctly fitted.
The image is brighter in the corners because less light reaches them, not at the edges. I no longer think this has anything to do with the filters; even without filters, the light cone is darker at the edges. Perhaps the bulb is the wrong one or too powerful? It is a 100 W Osram HLX halogen lamp. Or could it be that the brighter edges simply highlight the limitations of this technique? Perhaps I should increase the aperture? So many questions – I’m curious! Best regards, Malte
Wolf_XL
...I had one of these devices back in the eighties too... As far as I can remember, the light is mixed inside an integrating sphere – it’s possible that the coating on the inside is no longer even...
The colour controls on the colour mixing head should also be treated with caution – for example, turning the control from 0 to 60 produces a different filter effect than turning the same control from 40 to 60. That nearly drove me mad back then when I was doing colour enlargements. So, for reproducible results, always set the control from the zero position to the target value...
KlausWehner
Hello Malte,
It is likely that the beam path is being cut off behind the integrating sphere (mixing box).
There aren’t really that many options.
You can try the following experiment (though I’m not sure if it will work):
1. Remove the image stage
2. Place a white sheet of paper in the enlarger in place of the image stage.
3. Switch on the light and observe the bright spot of light on the paper.
The spot of light must have a diameter of at least approx. 45 mm. Is it smaller? Can you see any shadowing?
It might help to mark the position of the window for the negative (the aperture) on the paper.
If a sufficiently large (unobstructed) spot of light can be observed, the shadowing of the beam path is more likely to be found below the image stage.
In any case, you should also look through the enlarger from below towards the light source (using a mirror).
This might reveal what is blocking the beam path.
Best regards
Klaus
AnalogfotoRostock
Attached is a view from below (or from the side) of the negative frame lined with paper, with and without a filter...
[hr]
...and here is the result of the enlarger frame being fully illuminated only in the centre. Can you see the attachments? If not: the paper clamped into the negatives appears to be evenly illuminated with and without a filter, but the enlarger frame is not evenly illuminated, even for a 35 mm negative, being brighter in the centre than at the edges.
KlausWehner
Hi Malte,
I’m afraid I can’t see the pictures.
I’m not sure if I’ve understood you correctly.
On the image plane, is the spot of light large enough and free of shadows?
If so, the shadowing must be occurring below the image plane.
Please have a look (using a mirror) from below through the lens towards the light source.
Perhaps you’ll see the cause.
Best regards,
Klaus
AnalogfotoRostock
Hi Klaus,
Is it possible to attach files to forum posts? The site has a function for this, but the attachments aren’t being saved....
From below (or from the side – you can swivel the device), I looked towards the image stage; there’s no obstruction there – it’s just the bellows between the negative frame and the lens. The paper in the image stage is already slightly lighter in the centre than at the edges. I get the impression that the lamp is too bright or that a diffuser is missing somewhere; could that be the case?
Best regards, Malte
Wolf_XL
...silly question – is the condenser actually inside the unit?
This is what it looks like – it’s basically situated between the lamp housing/colour mixing head and the image stage...
https://a.allegroimg.com/s1024/0ca431/fc8b355449d394d93c6993ad346d
KlausWehner
Hi Malte,
By looking from the direction of the lens towards the light source, you should be able to identify the cause of the edge shading.
If you can rotate the magnifying head by 90°, you’ll have the ideal conditions for this.
You can also remove the lens to do this.
Move your head slightly from side to side so that you can view the light source from different angles.
It should actually appear as a uniformly lit surface.
In your case, the brightness will decrease towards the edge. You can see that.
The shadow is at the edge, which is why it becomes visible when you look into the device at an angle (approx. 45°) rather than directly from the centre.
You’ll need to work out for yourself why this is the case with your device.
Then you can also see whether a diffuser plate might help.
You can certainly check the manufacturer’s documentation to see if such a plate is provided.
I don’t see any reason for a diffuser plate at the moment, but I’m not familiar with the device either.
Two further general considerations: there is certainly room for improvement regarding the quality of your lens.
If you have to enlarge using strong gradations (magenta filters), your negative development may not yet be quite right.
You can expect good results if everything works and is set up correctly. Otherwise, it will be frustrating in the long run.
Best regards
Klaus
