APO or Non-APO, is it worth it?
I'm looking to extend the range of lenses in my Mamiya RB system, the longest I currently have is the 140mm Macro which is great but not quite long enough to isolate flowers against an uncluttered background. In 35mm I would usually use a 200mm macro for this, so am looking at the 250mm (about 120 mm equivalent focal length/angle of view) or the 350mm (equivalent to 170mm on 35mm). At the moment I'm erring towards the 250mm. The new KL version of the 250mm comes in two flavours, APO and non-APO, one being twice the price of the other. Is it worth it, does the APO really make that much difference? Of course there are quite a few Sekor C 250mm's floating around as well, I don't know how these perform compared to the KL versions. Any advice would be most welcome!
If the lens is not APO then each color within your flowers are going to focus on a different plane. Are you using an APO lens now? If i were you I would try and keep all my equipment as homogenous as possible. Although it is important to understand the effects that different features will have on the final product/print, and to find equipment that fits your vision completely and thoroughly; keeping you equipment consistent allows you to more accurately predict how everything will respond in any given scenario. this is important because it means you shoot less film in order to produce a given number of photographs, and allows you to keep track of your variables more easily.
If you are working with an APO lens now and you are happy with it, then buy an APO macro. Better yet, borrow one from a friend. You get to check out a new lens, and see how well it works for you before buying one.
I hope I was of some help.
Apo is worth it if you plan to drum scan right to the edge of enlargeability or if you might put a ZD or similar back on it eventually. Bear in mind that even the costliest rb lenses are a fantastic bargain right now. I just don't see the point in buying a pre-KL lens right now, unless finances are a major issue. But any of the newer RB lenses offer tremendous bang for the buck.
The 210 KL is, in particular, one of the very best MF lenses on the market. Take into account that you can shoot 6x8 with it on the rb and it arguably is the best.
I might be interested in your 140 macro if you are putting it up for sale, by the way
So much about the theory behind it. In reality a lens carrying the Apo-designation is a claim by the manufacturer refering to a higher level of quality. If you have a look at e.g. the specs for the Rodenstock Apo-Radagon 2,8/50mm it has very high resolution and very good contrast but its most prominent abberration is longitudinal colour i.e. it is not focussing all visible colours in the same plane of focus.
Some lenses actually do fit the above definition but your'e better of checking the actual type of lens (or even sample) if the Apo-feature is important to you.
In general an APO lens is better corrected.
Originally Posted by xtolsniffer
- The upside is that the better correction allows the lens to be used at wider aperatures. This in turn allows the lens to have higher resolution because it is no longer as diffraction limited.
- The downside is the depth of field is reduced.
The result is that less of the image is sharper.
For enlarging and copy work with process cameras - where depth of field isn't an issue - this trade-off makes sense. For 3-color copy work the apo color correction is needed to keep colors in registration. To take advantage of the increased resolution it is usually necessary to use glass or vacuum carriers and maintain precise alignment.
Apochromatic correction in a camera lens may be worthwhile where depth of field isn't that much of an issue and you can use a wider f-stop to take advantage of the increased resolution. Many apo camera lenses (Rodenstock being the prime example) aren't, strictly speaking, apochromatic, though they are extremely well corrected for color aberrations; in these cases 'apo' is an indication of a higher grade of lens.
To see any improvement you will need a tripod and precise focusing with a 6x magnifier. With an SLR the collimation-mirror alignment needs to be perfect because depth of field will be zilch and mirror lock up is probably mandatory.
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Interesting info on APO and non-APO, thanks Nicholas.
I have the 140macro, 180, 250 and 360; all non-apo KL, and like them all, equally, as a set. I know that's not saying anything for a comparison but I like keeping with the less exotic, and more familiar. I have no desire for the APO types because I'm sure I wouldn't notice, or appreciate, the difference in performance of one type over the other. If the depth-of-field is reduced with the apo types, I would probably notice that.
"Pictures are not incidental frills to a text; they are essences of our distinctive way of knowing." Stephen J. Gould
Just so this is not misunderstood: this, of course, is the downside of using a lens at wider apertures.
Originally Posted by Nicholas Lindan
Not of being better corrected.
No. APO does NOT means better correction to be used at wider apertures. APO does not mean faster. The fastest and highest resolving lenses I know are NOT APO. Apochromats (and most so-called APOs are not) have higher levels of color correction. True apochromats are designed to bring three wavelengths into focus in the same plane. They don't need to provide higher resolution nor better correction to any aberration other than chromatic to be a true APO. Many APOs I'm familiar with are, in fact, designed to be used at rather small apertures and provide low levels of spherical and chromatic aberration but less than stunning resolution.
Originally Posted by Nicholas Lindan
Wow, thanks for that folks, a very useful discussion. I get the feeling that the APO tag may not be worth spending twice as much on a lens - especially since about half of what I shoot is black and white anyway, where chromatic aberration is not exactly the main consideration. All I have to do now is decide between 250mm and 350mm. I've never really liked a 135mm focal length on 35mm, so the 250mm on 6x7 is looking less likely. Of course I could just save my pennies, use the 140mm and just get closer to the subject!
Um, er, ah, chromatic aberration can be as bad a problem with black/white as with color. It makes it impossible for the plane of best focus to be in perfect focus. Before color film was available there were soft focus lenses, e.g., the Boyer Opale, that used chromatic aberration to get the soft focus effect. According to a friend who has several, Opales produce horrible effects on color film ...
But the OP's question wasn't a vague general question. It was whether the difference in performance between two 250 mm lenses, one engraved "APO", the other not, in the Mamiya RB system justified the APO's higher price. None of the answers so far addressed the question directly, but one, from panastasia, pointed out that panastasia's non-apo RB 250 is a good lens.
xtolsniffer, since it seems that no one here has shot the two lenses you're considering against each other and since none of us is exactly as exacting as you are, you'd do best to rent both, if possible, and run the test yourself.
Last edited by Dan Fromm; 05-16-2008 at 05:19 AM. Click to view previous post history.