Difference between 40mm and 45mm APO-Componon-HM??
Schneider offer both 2.8/40 and 4/45 APO-Componon-HM lenses for 35mm use. I've looked on the Schneider web site and can't find anything that tells me how to choose one over the other beyond the obvious focal-length and aperture difference. There's been no reply to my email to Schneider. Does anyone know?
How big do you want to enlarge? I have the 45mm and at anything less than about 11" across image size I can't open my easel because the head is so low, so I only use it for 16x20 and bigger.
It's more intellectual curiosity than anything else. Two lenses, 10% difference in focal length, one stop difference in aperture, both in current production at nearly the same price seems strange. The only other significant difference seems to be that one of them has an illuminated aperture scale. There's no indication in Schneider's brochure (2.5Meg, received today by email) to advise how one would choose one over the other. I'll ping back Schneider again to see if I can get clarification, but I don't plan to invest a lot of time in this. To your point, I normally use a 63mm lens for 35mm to get more clearance, and I never enlarge beyond 11x14.
The 40/2.8 has two advantages over the 45/4.
1. It’s one stop brighter wide open. This can help you to focus and compose when making the largest prints as the projection is harder to see at higher magnifications.
2. It provides somewhat more magnification for any given negative-to-print distance. For example, at 800mm negative-to-print distance the 45mm lens gives 15.7X while the 40mm lens magnifies 17.9X. If you need that extra magnification to make the print you want, the shorter lens might make it possible if your projection distance limits what you can accomplish with the longer lens.
Assuming both lenses have optimum performance closed 2 stops (usually the case), the 40/2.8 will print in half the time at f/5.6 compared to using the 45/4 at its optimum f/8 aperture. For most home printers this is not important. But if you were choosing a lens for a high volume lab making hundreds or even thousands of prints per day in which the printing time was an operating cost, it might be important.
Last edited by Ian C; 09-23-2011 at 11:11 AM. Click to view previous post history.
Yes, those are the two obvious benefits, but the one datum that eludes me is whether the lenses are optimized for different magnifications. For example, does one correspond (roughly) to Rodenstock's Rodagon-G line in being intended for making very large prints? Nothing in Schneider's literature gives any basis for selection other than aperture, focal length, and illuminated aperture scale!
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Schneider doesn’t say much about the APO Componon HM series except to comment
“The APO-COMPONON HM is an apochromatic design that assures the highest resolution across the entire image. Designed with custom labs and the fine art photographer in mind, these six-element, four-lens designs produce the highest quality images at a wide range of magnifications including 1:1.”
Unfortunately, Schneider doesn’t elaborate on the “wide range of magnifications” for the APO Componon.
It’s likely similar to that of other standard enlarging lenses such as the Componon S, for which Schneider claims “It is a versatile design and may be used to make enlargements in the 2x to 20 magnification range.”
An enlarging lens designed to work well at 1:1 isn’t likely to produce its best possible image at the high magnification that the Rodagon G is designed for.
The Rodagon G enlarging lenses are optimized for greater magnifications such as we’d employ in making murals. There is, however, some overlap in the magnification ranges of standard lenses and the Rodagon G series.
For example, the only Rodagon G designed for 35mm enlarging is the 50/2.8. Its rated magnification range in the Rodenstock data sheet is given as 15X-25X(optimum)-50X.
Last edited by Ian C; 09-23-2011 at 02:14 PM. Click to view previous post history.
I'd save my money. Buy something else. Do you have a Jobo? A Bessa rangefinder? Nikon F100? Sensitometer?
Originally Posted by Steve Goldstein
To answer the original post, my impression as to why they offer two lenses is that one is a "wide angle" lens for 35mm and the other is just slightly longer than "Normal" for 35mm.
Originally Posted by ic-racer
Some older automated optical printers had different focal length lenses on a turret for different sized prints.
I have all of the Apo-Componon HM lenses _except_ the 40mm, which wasn't available when I bought my lenses (IIRC).
My guess is that it's intended for people making bigger enlargements from 35mm. Both the wider angle and the larger aperture argue for that application, since the brightness at the easel will decrease as the enlarger head is raised.
“Wise men talk because they have something to say; fools, because they have to say something.” - Plato