To APO or not to APO?

[ageorge]

I thought I would see many posts on this question, but searching did result in much.

I am new to LF and currently have a couple of non-APO lenses, the Nikkor 90mm f8 and the Nikkor 210mm f5.6. I am looking to fill the gap with a 150mm and am wondering if I should consider an APO lens. Your input is much appreciated.

In what practical situations would an APO lens have an advantage over a non-APO lens? In what way would the differences manifest themselves, sharper image, more contrast, etc.?

Thanks in advance,
-alan

[Christopher Perez]

Assuming they originate from a common point, true APO lenses converge colors from various parts of the spectrum to a common point. This helps an image appear sharper than non APO optics near the edges of the field where the physics related to aberrations comes into play.

In practice, modern optics (including your existing Nikkors) are largely equal. The APO "effect" is nearly impossible in many cases to detect, even at 160x magnification.

Talking with lens designers, there is no way a plasmat (6 element 4 group) design can ever be truly APO. Designers can come close and marketing can put the APO moniker on an optic, but that doesn't mean it really is APO.

To your question, I feel that many 150mm lenses from lens manufacturers produced after 1980 or so will be largely equal in terms of on film performance.

I hope this helps.

[Ole Tjugen]

In what practical situations would an APO lens have an advantage over a non-APO lens?

None.

"APO" is put on many lenses which aren't truly apochromatic in the strictest sense, and there are several apochromatic lenses that aren't marked as such. The only situation I can think of where it would be nice to have an APO lens is if I were selling it on ebay...

[ageorge]

Thanks, much appreciated.
-alan

[Bob Salomon]

Sorry but the above answers are not correct for a caqmera lens for your application and, as I have been working shows for the past 2 weeks and don't feel like getting into a flame war, you should check the Optonics Dictionary for optical purchasing agents. It will detail what the two common definitions are for an Apo. One for microscophy and one for photography.

What a modern Apo will mean to the user is that color fringing in high contrast fields with fine details is eliminated. In black and white that means sharper lines. In color it means no fringing.

So for your application fine lines will be sharper.

[Kirk Fry]

Listen to Bob,

Everything else not "Apo" needs to be sold on Ebay immediately so I can buy it.

[Christopher Perez]

Hmmm... that's what I was thinking. So instead of a flame war on LF Forum we can have a bidding war on e*ay?

Listen to Bob,

Everything else not "Apo" needs to be sold on Ebay immediately so I can buy it.

[Daniel Geiger]

... check the Optonics Dictionary for optical purchasing agents. It will detail what the two common definitions are for an Apo. One for microscophy and one for photography.

Is this available on the web, or only in print? Could not find anything with google. Only found http://www.photonics.com/directory/ and it does not distinguish between microscopy and photography. www.optonics.com is certainly not what you had in mind. Thanks.