Vignetting problems with Magnifax 4

[fabio_giacuzzo]

Hello to everybody! I bought a Meopta magnifax 4 five years ago, brand new! I have also the complete set of condenser for the 24x36 and for the 6x9, and a very good set of lenses, 50 and 80 mm componon s.

Some days ago, I was printing a "particular" negative 24x36, the subject was a sand dune even lighted large as the complete negative . The espected result was an even lighted sand dune print, on the contrary with disappointement I obtained a dune with the both side clearer! So i performed a test:I take out the negative and I printed a strip of paper long about 40 cm without any negative, only the enlarger light. A bad surprise! The strip is darker at one side and lighter at the other, the enlarger suffer of vignetting, I think about half stop or a little bit less. If you print a normal landscape with a lot of tone variation it is impossible to check. But if you have a long even lighted subject it is quite annoyng. I have performed other test: cleaning the condensers, changing lamp (150 W), using different lens aperture, cheking enlarger alignement, (it was ok). At the end only one explanation, probably an about 1/2 or 1/3 of stop vignetting from the center to the border is the limit of the equipment,sic!

Many thank for every comment or suggestions.

[ed farmer - mount laurel,]

A couple of things you can try:

 

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If the condensors are adjustable, try settgin them up for the next

larger neg size and retest. Or, use the 6x9 condensor to make a

print from a 35mm neg.

 

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Try printing a 35mm neg with the 80mm lens and the larger condensor

set.

 

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It is unclear, to me, is the vignetting on both sides, or only one

side. You may have a mis-alinged lens, or carrier.

 

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1/3 stop difference would actually be pretty good. This is may many

printers recommend "edge burning" when printing.

 

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Don't trust any tests without a negatvie in place. You may be seeing

a reflection of the rear element of your lens in the lower

condensor. This can have a serious affect on the apparent evenness

of the light. Instead make a print with a processed, but unexposed

negative in the carrier.

 

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Report you results back here.

[fabio_giacuzzo]

Thank you Ed first of all. I have just done all the test that you

suggest, all the test was performed with an unexposed negative, here

is the results:.

a) cheking alignement, the "vignetting shape" are perfectly centered

on my easel, so the alignement is perfect!

b) changing condenser, 6x9 instead of the 24x36 (printing 24x36

negative; the vignetting was going worse! I dont know why, in fact it

will be logical suppose that with a larger condenser the light will be

uniform on a larger area, but with the 50mm lens is not true,(this

fact is confirmed by the Meopta official site).

c) condenser 6x9 and 80 mm lens, the vignetting is about the same of

the normal configuration.

d) condenser 24x36 and 80 mm lens the vignetting is about the same of

the normal configuration.

e) measuring the light down on the border: printing a 30x40 picture

the borders are down of nearly 1/2 stop than 1/3 stop.

Thanks again, Fabio.

[ed farmer - mount laurel,]

Interesting results!

 

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I don't understand why the 6x9 condensor should have more problems

with unevenness than the 35mm condensor. This makes no sense, but I

will take the word of Meopta. Is it possbible that the condensors

are installed upside down? I would expect much more fall off in that

case, but it is worth checking. What aperture are you using for your

test? This lens should work best at around f5.6, but the light might

be more even at smaller apertures.

 

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I am not familier with this enlarger, it is possible that this is

simply the best performance you are going to get. You a great

enlarging lens, I am sure that this is not the problem.

 

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Did you purchase this enlarger new, or used? If it was used, you may

want to get a manual and make sure that the enlarger has been

assembled correctly.

[trevor_crone1]

Fabio if all else fails treat yourself to their VC head its illuminination is quite even. I used it a lot with 6x9cm negs. for many years with excellent results. I even used the 6x9 mixing box with 35mm with no ill effects. Highly recommended.

Good luck,

[fabio_giacuzzo]

Ed, I bought the enlarger new, and all the pieces, condensors included

are mounted correctly. For the test I have used the lens at f8.

I don't know why with the 6x9 condensor I have more problems with

unevenness than the 35mm condensor, it is strange also for me;

probably it depend by the fact that the focussing point of the 50mm in

compared to the 105 mm lenses is very different, (to focussing with

the 50mm is necessary yo mount the ring adaptor up side down).

I agree about the fact that probably it is the limit of my enlarger!

Many thanks also to Trevor, anyway I think that it will be better to

change the whole enlarger!

[frederik_boone]

Hello Fabio,

Probabely there is something wrong with your lens, I had simular

problems with my new componon-s 50/2,8. I did not notice it for quite

some time until I made a 12x enlargement of a negative which was

completely sharp but had one corner unsharp and it was lighter too. I

was also convinced that it was my enlarger, in my case it was an old

Leitz focomat. After working on my enlarger for several hours and not

finding any problem with it, I tried an other lens, an old leitz

focotar and everything was sharp again. That lens was replaced under

warrenty.

The serial nr. of that lens was 14665804, probabely a bad production

serie.

Or your lamp is probabely a bit out of the center. Some enlargers can

change the position of the lamp. When doing this, remember your lens

is putting the immage upside down. So if your upper right corner has

not enough light, you have to move your lamp to the left down.

I hope it helps you,

Frederik

[volker_schier1]

I have been working with a Magnifax 4 for many years both with

condesor head and multigrade head and never experienced the described

problems. In fact in comparison with many other enlargers on the

market I think it one of the best in terms of quality and especially

handling. The problem sounds more related to the lens, since the

condensors in a Magnifax are correctly centered and a lightfall off to

only one side sounds strange. I can highly recommend switching to the

very good multigrade module, which is very even in illumination.

[fabio_giacuzzo]

Many Thanks, to Trevor, to Frederick, and to Volker, may be that the

cause will be the lens, anyway I tested others two type of them: one

80 mm., and one 105mm. all with proper condensors and the difect

remains; it is about half stop from the center to the four borders.

I also called by phone a big shop here in Italy: They know the

problem!

They told me that this is a well knowed defect, very common also to

other type of enlargers. For the Magnifax 4, they suggest me to reduce

the distance from the lamp to the condenser. I need to make this a

little bit of time because the enlager has not a regulation in this

sense, so I must take off my tools...I'll write again with other news!

Many thanks to everybody.

[volker_schier1]

I fear you will find no enlarger that will give you what you are

looking for if you insist on a condensor. A condesor is a focused

system and light falloff is a rule, not the exception. Buying

another condesor enlarger will not affect what you experience. In

fact 1/3 f-stop falloff is more or less what all condesor systems

have. As mostly, dealer do not know much about the equipment. Since a

condesor is focused it is no good idea to alter the distance of lamp

to condensor. This is optimized and calculated, since -- together with

the lens -- it is a closed optical system. You would sacrifice

acutance that way, which is the main purpose of employing condesor

systems in an enlarger. The only way to get more even illimination is

a diffusor system (a glass diffusor is already included with your

Magnifax and should provide more even illumination). The multigrade

head is very even. On the other hand: You will not notice the falloff

on your prints anyway. Generations of photographers have printed that

way and did not complain. Again, the Magnifax is an excellent piece of

equipment and I do not see how you could improve by buying a different

system.