I "inherited" an Omega enlarger that came with 3 lenses, a Schneider Componon 50 mm (f4), Schneider Componon 80 mm (f5.6) and Schneider Componon 135 mm (f5.6) - I know next to nothing about enlarger lenses, but I suspect they are the weakest link in my "quest" for sharpness. What would be the "top of the line" equivalent to the Componon 80? Rather than blindly throwing money at the problem, I did a little testing: projected som USAF target slides onto 16x20 paper (the largest I want to go). With a grain focuser, I can clearly resolve line pairs that cannot be seen on the developed print. Wouldn't this suggest that the lenses do project more than adequate and that the weakest link is actually the resolving power of the paper? If that's the case, upgrading the lens wouldn't do any good. Thus my question: Has anyone ever observed a sharper print by using a more modern lens than the Componon???

On a related note: I also had some trouble establishing the "best f-stop". Using the grain enlarger, I saw best resolving power of the lens at f8 (one f-stop below max), closing the lens any further reduced resolution (due to diffraction I suppose). However, the line pairs where I observed this diffraction effect could not be resolved when printed onto paper, no matter what the f-stop. Judging from the prints, I found the best f-stop to be f16. Why this discrepancy???

-- Andreas Carl (andreas@physio.unr.edu), April 30, 2000

Answers

Andreas: The best "top of the line equivalent" to your Componon 80mm lens would be a Componon 80mm lens. They are the top of the line. The difference you see between your grain magnifier and the print is with the paper, not the lens. Paper does not resolve as many lines per millimeter as does the lens, just as film does not relsolve as many lines as does the modern taking lenses. If you are are having trouble with resolution on your prints with a Componon the problem lies somewhere else besides the lens. The film and paper resolution are the weakest link in the system with modern optics.

-- Doug Paramore (dougmary@alanet.com), April 30, 2000.

I could be wrong as always but I don't think Componon lenses are Schneider's top of the line enlarging lens. The current top of the line is the Componon S series. I don't think Componons are made any more.

-- Brian Ellis (bellis@tampabay.rr.com), April 30, 2000.

Andreas, Componon lenses have been made mor many years. The latest are certainly excellent. But some of the old ones where good at some magnification ratios only and had to be used at small openings to deliver sharp corners. The best is to print some sharp negatives at different ratio's (you can print just the corners to save some paper) and see for yourself. For large prints (16 x 20" and above), you can save yourself an enlarger lens and get very good results with an Apo-Symmar or equivalent.

-- Paul Schilliger (pschilliger@vtx.ch), April 30, 2000.

Brian: You are right, but I doubt there is much difference in the formula between the "S" and the older Componons. I don't profess to be a lens "expert", but I know from long use that the Componons are doggone good lenses. I have used both extensively for black and white and color printing and I can't tell much difference. Of course, I was using them and comparing prints, not test charts. I do not sell lenses, so I have no interest in pushing Componons. I just know from use any of the Componons are good lenses, including an 80mm that I have had for more than 20 years.

-- Doug Paramore (dougmary@alanet.com), April 30, 2000.

If you use the lens at the aperture you found to be 'best' with the grain focuser you should get the most in your images. If the times are a bit short, try a neutral density filter between the light & the neg to lengthen it a bit, not more stopping down as that will degrade the image. While the paper won't render all you can see with the grain focus help, by using the best tested aperture the separation in the fine silver particles will be better and appear sharper when using the best aperture. Stopping down, while it may still give you excellent results, will also give less than the best the lens is capable of, especially in the fine detail that isn't quite sharp due to paper limitations. If you want the sharpest appearing image, use the lens at its optimum aperture. If you want just a bit better, take a look at the newer Apo lenses from both Schneider and Rodenstock.

-- Dan Smith (shooter@brigham.net), April 30, 2000.

I didn't mean to suggest that there was anything wrong with Componon lenses. However, he asked what would be today's top of the line and Componons are no longer that, with introduction of the Componon S series.

-- Brian Ellis (bellis@tampabay.rr.com), April 30, 2000.

Andreas: IMHO the Componons are top of the line. I've been using several for over 30 years, and now have 50, 60, 80, 105 and 150mm on my Omega enlargers. While the "S" Componons may gain you something, it would be largely theoretical as a practical matter. One thing about the older Omega enlargers. My D5 is solid as a rock, yet I will still brace the top of the column to the wall after I finish the darkroom remodel. If the enlarger you inherited is one of the older (say, D2) models I would recommend your supporting the column to eliminate any loss of sharpness due to vibration in the enlarger. This is especially important if you print BIG!! Should you decide to discard those 3 lenses, I might be willing to send you my address so you can just toss them into my mailbox. Fat chance, I'm sure. Best regards. Paul

-- Paul Szopa (kpszopa@aol.com), April 30, 2000.

Interesting responses, seems the consensus is, the lenses are "good enough". I took a closer look at the test prints I made yesterday. There certainly is detail visible on the test negative that does not translate into print. On the other hand, using a loupe there is significantly more detail visible on the prints than to the unaided eye, thus the limitation posed by the paper resolution does not appear to be significant in the real world (where people don't study prints with loupes). Finding the best f-stop appears to be a balancing act between degradation by diffraction (which on my setup certainly starts at f8) of the finest detail - which "fortunately" is unprintable anyway - and the improved corner sharpness, forcing me to close down to f11 or perhaps even f16.

I am still considering replacing the Componon 80 with a Componon-S 100, mostly because of light-fall-off with the 80mm lens on my 6x9 negatives. Makes sense???

-- Andreas Carl (andreas@physio.unr.edu), May 01, 2000.

I highly recommend Ctein's book -Post Exposure- if you're seriously concerned about getting the sharpest prints possible. He specifically adddresses matters such as optimum apertures and optimum focus. In tests, he also found a big discrepancy between the "best focus" obtained using a grain magnifier and the real best focus obtained by bracketing the focus.

-- Mike Dixon (burmashave@compuserve.com), May 01, 2000.

I have directly compared an older chrome Componon 80 and a Componon-S 100 for colour printing from 6x6. The two lenses had significantly different colour casts, which might drive you nuts if you mix a Componon-S with your older lenses and try to match colours across different formats.

In terms of sharpness, they were impossible to tell apart for 10x8s, but at 16x20 magnifications the Componon-S was noticeably better in the corners. I would recommend trying to rent or borrow one of the modern lenses to see if the differences are significant for you.

It's pretty common to find that the best f-stop for sharpness in the centre of the print is larger than the optimum stop for the edges. This is because aberrations like coma and astigmatism - which are improved by stopping down - don't exist on-axis. Which f-stop is best depends on how much of the negative you are printing from and what size print you are trying to make.

Also, if you have young eyes with good accomodation it is possible to focus on the wrong plane with a grain focusser. You need to ensure that the crosshairs are in the correct place and that you concentrate on keeping both them and the grain in focus simultaneously.

-- Struan Gray (struan.gray@sljus.lu.se), May 01, 2000.

The 80mm lens is not designed to cover a 6x9 negative. You need to 100mm lens for that.

-- Darron Spohn (dspohn@photobitstream.com), May 01, 2000.

Darron is correct, the 80mm Componon won't cover 6x9. I've had good results printing up to 11x14 prints from 6x7 negs with mine, but got the 105mm lens for 6x9 negs. Paul

-- Paul Szopa (kpszopa@aol.com), May 01, 2000.

Comparing 150mm samples of late Componon and Componon-s lenses side-by-side, there is a noticeable difference in their construction. They're both 6 element; 4 group, but the front and rear curvature is greater on the Componon-s. Also the Componon-s has a slightly greater front to rear glass distance, and the front and rear cemented doublets are thicker than in the older Componon. There doesn't appear to be any difference in the transmitted colour.

So what does this all mean in practise? Not a lot, they're both damned good lenses and to be honest the prints they produce are indistinguishable.

-- Pete Andrews (p.l.andrews@bham.ac.uk), May 02, 2000.