Vignetting problems with Magnifax 4greenspun.com : LUSENET : B&W Photo - Film & Processing : One Thread
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.
-- Fabio Giacuzzo (firstname.lastname@example.org), August 09, 2001
A couple of things you can try:
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.
Try printing a 35mm neg with the 80mm lens and the larger condensor set.
It is unclear, to me, is the vignetting on both sides, or only one side. You may have a mis-alinged lens, or carrier.
1/3 stop difference would actually be pretty good. This is may many printers recommend "edge burning" when printing.
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.
Report you results back here.
-- Ed Farmer (email@example.com), August 09, 2001.
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.
-- Fabio Giacuzzo (firstname.lastname@example.org), August 10, 2001.
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.
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.
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.
-- Ed Farmer (email@example.com), August 10, 2001.
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,
-- Trevor Crone (firstname.lastname@example.org), August 12, 2001.
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!
-- fabio giacuzzo (email@example.com), August 13, 2001.
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
-- Frederik Boone (firstname.lastname@example.org), August 13, 2001.
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.
-- Volker Schier (Volker.Schier@fen-net.de), August 26, 2001.
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.
-- Fabio Giacuzzo (email@example.com), August 27, 2001.
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.
-- Volker Schier (Volker.Schier@fen-net.de), August 27, 2001.