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  #1  
Old 23rd January 2022, 04:45 PM
Subfrequenz Subfrequenz is offline
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Default Meopta Opemus 6 light falloff?

Hi All. I'm new to medium format enlargers and wanted to ask about light falloff. I've attached an image of what I'm seeing. It's set up with a 75mm lens, 75 watt Philips bulb (enlarger lens), and mask for 120. I haven't wet printed yet but did pop a negative in the carrier and take a photo on my phone of the image being projected onto the baseboard. It ended up with a hotspot in the middle of the image, which was darker than the rest after inverting it in Photoshop.

I guess my question is, is it normal to expect such dropoff and will it show up in a proper darkroom print rather than my quick test. Thanks!
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  #2  
Old 26th January 2022, 12:56 PM
Terry S Terry S is offline
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I think you will only know, when you actually make a print. And then the questions can begin if so...

Terry S
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Old 26th January 2022, 01:31 PM
JimW JimW is offline
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Is the lens stopped down at all? This might reduce the amount of fall off...
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Old 26th January 2022, 01:38 PM
Richard Gould Richard Gould is offline
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I have used a Meopta 6 enlarher for both 120 and 35mm for around 25 years, and find it a fine enlarger, for 120 I use a 75 mm lens, and have never had any light fall off, it is even over the whole image, and I can't say I have ever seen a hotspot as in your picture, so I don't quite know what is going on, check everything, including everything is properly aliineged, and that the condenser's are clean, apart from that I can't think of anything else
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Old 26th January 2022, 02:54 PM
alexmuir alexmuir is offline
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It looks like there is something missing in the light path, or perhaps misaligned. Is it a condenser head, or is it fitted with the colour head? If I remember correctly, Meopta produced a colour head that was interchangeable between the Opemus and the Magnifax models. It used different sized diffusion boxes, depending on the film format in use. If it is a colour head, it may have the wrong box for your negative size, or the box may be missing.
Otherwise, if it is the condenser model, check that they are the correct type, and properly fitted. Falloff towards the corners is a feature of most enlargers, but it is normally relatively small, and without any great effect. You can measure it with an exposure meter moved around the projected image area. The other thing to check in the condenser type is the bulb placement. On some enlargers, the bulb can be moved up and down to find the position which gives the best overall illumination. I hope you find a solution. It is a good enlarger.
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Old 26th January 2022, 02:56 PM
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skellum skellum is offline
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Just to be clear, this is a photograph of the light being projected onto your enlarger baseboard? Not a picture looking UP at the light source?
The white surface looks quite glossy and reflective, and the photograph looks as it it was somehow taken quite 'square-on'.

Also: It ended up with a hotspot in the middle of the image, which was darker than the rest after inverting it in Photoshop

Again, for clarity: You put a neg in the carrier, projected an image onto the baseboard, and took a digital picture of it. That would be a negative image. You then inverted in Photo-shop, to give a positive. The positive image had a dark spot in the middle?

Last question for now, is it a colour head (with the dial in filters) or a condenser machine?

The more we know the better the suggestions we can offer.
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Old 26th January 2022, 03:21 PM
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MartyNL MartyNL is offline
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Something definitely going on. Some more pics would be helpful to gauge your set up.
And again, just to be clear, you first inserted a negative, focussed on the negative, then removed the negative and took a photo?
And the head, condensers, negative masks and lens all match to the enlarger type and negative format?

Should be an interesting bit of detective work!
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Old 26th January 2022, 04:17 PM
snusmumriken snusmumriken is offline
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I don't know the Meopta enlargers, but I found descriptions online here. I think AlexMuir covered almost everything for the colour models, but if you have the b/w model, the following applies:
<<The lamp is opaline 150W/E27 fitting with 70 mm envelope (not included). Diffuser is inserted in filter holder.>>
I don't know what the 70mm envelope means (bulb diameter?), but is your bulb opaline (pearl)? Do you have a diffuser in the filter holder? Do you have the right condenser for medium format?
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Old 26th January 2022, 06:08 PM
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Uwe Pilz Uwe Pilz is offline
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Is the condenser in place? It has two lenses, the convex sides to the middle.

I had some lightoff with a to large bilb. But this extrem, something strange happened.

BTW: Have you a lens in the enlarger?
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Old 26th January 2022, 06:20 PM
Richard Gould Richard Gould is offline
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With the opemus 6 enlarger ( which I use) you only have 1 condensed to cover all formats,a rather large double one, as far as the bulb is concerned, the 150 bulb is the largest, but the 75 watt phillips photocrebsta is the correct bulb, the size of the bulb envelope, which is the size 9of the globe, will not make a diference, I have been using an led bullb, which is slightly smaller, forn a few years mow with no hotspots, Meopta made a black and white MG head as well as the condenser and colour, but if the OP is using a Phillips bulb it is a condenser head, aas far as using the diffuser, it is sikmply a sheet of ground glass, I never used it and never had this problem, sorry to be so negative, but this is a mystery to me, as a long term user of the same enlarger,only other thing I can think of is a lens problem, it could be a cheap 3 element lens, or a lens that has been damaged by a drop somehow, any chance of trying another lens? but the Meopta enlargers themselves are a simple enlarger, but very well made and normally last a lifetime with no trouble
Richard
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