Schneider Componon 150 HM APO

[Gene M]

I've been experiencing very short exposure times (2-3 seconds) when printing with my new Schneider Componon 150 HM APO. I'm doing 8x10 and 11x 14 prints with 4x5 negatives. I do strictly B&W.The bulb in my Beseler colorhead is the right one. The lens is mounted in the special lensboard required.Take a look at the photos below and tell me if I've got the lens mounted incorrectly or something.

http://www.westfordcomp.com/question

[Donald Miller]

It looks as if it is installed correctly to me. Have you checked your negative densities?

[Frank Filippone]

The lens, wide open is a F4. I just made some full frame 8x10 from 4x5 negs ( #2 contrast) on my Saunders 4500 with a Componon S 150/5.6. The times were 8.5 seconds at F8. For F4, this would be around 2 seconds at F4.

WHat F stop were you printing at?

[Bob._3483]

As Frank suggests these are not unreasonable times if your lens is wide open and you have a 200-250W lamp and little or no filtering dialed in on the colour head. What was your previous lens - did it have a smaller maximum aperture and did you use that wide open too? Did you use multigarde paper before and are now using graded (i.e. no longer adding filtering which cuts a lot of light).

Most enlarger lenses seem to have their sweet-spot two stops down from wide open which would give you more practical times. If you prefer even longer times, an ND filter on the lens will do the trick if you do not have a built-in ND in the lamp housing (I'm not familiar with the Beseler).

Cheers,

[Gene M]

I'm printing two stops down from wide open. This lens is sharpest at that setting according to Schneider. I use VC paper and my negatives are normal density.

Thanks

[Frank Filippone]

I guess you are discounting my previous reply on maybe the current resultsyou are getting sound right. I also guess you are printing at F8 ( 2 stops down from F4.)

There are only a few things that can shorten exposure time: negative density; F stop of the lens; bulb power/brightness; paper speed; developer and developer concentration; print VC filter density. I don't think there is anything else.

Which of these have you satisfied yourself are not ploblems? Which are NEW parameters in your printing? Which are the same as you have had in the past. and show longer print times? In other words, what has changed in your process?

[Gene M]

Frank. The only things that's changed in my darkroom is my enlarging lens. I've printed 35mm, 6x7 and 4x5 with appropriate focal length lenses (50 90 and 150) and had longer exposure times, (8-10 seconds.) When I switched to the APO version of the Componon-S my times shortened. I can't dodge or burn when exposure times are two seconds.

I use Ilford VC paper and dial in about 60 on the magenta scale. I could dial in an equal amount of blue, yellow and magenta to cut down on light intensity but then I'd be defeating the purpose of the colorhead.

I use Dektol 1:3. As you correctly noted, there are only a few things that determine exposure time. I could stop down the lens further but I'd like to use it at it's sharpest aperture. I doubt anyone would notice a difference between f8 and f11 but you know LF photogs are obsessive about sharpness.

[Bob._3483]

Are you exposing at the same f-stop as with your previous 150mm lens? If you were using f16 or so, then the times obviously make more sense, in which case an ND filter looks like your only option to stay at f8 with reasonable exposure times if your head does not have a built-in ND filter (better in a filter drawer than on the lens obviously).

On the Ilford site (http://www.ilford.com/html/us_english/bw.html) there is a file (CONTRAST CONTROL) which details using Magenta and Yellow in combination to set contrast. This reduces the light reaching the paper considerably and minimises the need to change exposure time when changing grades.

Cheers,

[Frank Filippone]

OK.. Nothing seems to have changed....

I will repeat myself just to be sure... Same enlager and bulb and head and settings and power supply Same negatives Same paper from same box Same developer dilution from same stock solution The lens got changed.

One possibility...... do you have a light meter that you could put under the enlarger and measure the incident light from the optical path? If yes, then set a given ( preferably blank or overall any shade of grey ) negative in the carrier, focus and measure the light coming from the optical path. Use your old lens. Without changing the negative nor the settings nor the position of the meter, change the lens. Measure again.

What I am searching for is the possibility that the old lens was somehow improperly meaked or calibrated at F-whatever. The old lens and the new lens SHOULD get the same measurement for te same indicated F-stop. If not, then there is a calibration difference.. the old lens was producing less light through its optical path than the new lens.

Why is the old lens not producing the right output at the same F-Stop? Overall fog, maybe just plain dirty, or maybe the old lens was in the wrong lens tube iris assembly, and it is just marked wrong.

[Gene M]

Frank. Good idea. I'll do that tonite.

Thanks

[John D Gerndt]

Note too that bulbs do not always run consistantly. They can burn brighter at times especially just before they burn out!

If you need more time just stop down the lens. At the enlargements you are operating at I challenge you to note the difference the theory implies and you will gain the controll you need to...make a better photograph!

Cheers!

[Michael S. Briggs]

Since you have a color head, the easiest solution is to dial in equal amounts of each filter, thereby adding some neutral density to obtain a convenient exposure time while keeping the lens near its optimum aperture. This doesn't defeat the purpose of the color head -- the purpose of the enlarger head is to enable you to make prints. What does it matter (other than a minuscle cost of electricity, etc.) if on some prints you waste a small amount of light? If you ever make some very large enlargements, you can leave out the ND filtration and use the brightness of the head to keep the exposures times from being inconveniently long.