The Battle of the 85mm's
   
 
Minolta's Top Portrait Lenses Compared
   
 
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Flare Resistance
 
 
For the following test all lenses were placed in a position where full sunlight was falling directly on the front element to determine the level of flare and light scatter that they would suffer. All of the shots have been taken at f/4.
 
 
85mm f/1.7 MC
85mm f/1.7 MD
 
 
 
 
85mm f/2 MD
85mm f/2.8 Varisoft
 
 
 
 

Based upon the above images it is very clear which lens is the real winner in terms of resistance to flare. Without a doubt, the f/2 lens performs considerably better in this respect, recording no flare spots and virtually no contrast destroying light scatter. This is truly an outstanding performance given the fact that the front element of the lens was in full sun for this photo. Interestingly, similar results were achieved when I tested the later model 100mm f/4 MD macro against the earlier 100mm f/3.5 MD model, indicating that Minolta may have placed more emphasis in dealing with this issue in their later designs.

After the MF f/2 lens come the two f/1.7 lenses. While they also do not show any obvious flare spots, there is an obvious degradation of contrast when compared to the later model lens. After considering the full scans, I believe that the MD version records slightly less light scatter than the MC lens, resulting in better contrast.

Finally, there is the 85mm Varisoft. Not only does this lens have considerably worse contrast degradation, it also shows an actual flare band in the lower left corner of the image. It is obviously the worst performer of the group in this respect, despite being a late MD series lens with the best possible coatings.

Specific crops detailing the effect of contrast loss from flare are shown below:

 
 
85mm f/1.7 MC
85mm f/1.7 MD
 
 
 
 
85mm f/2 MD
85mm f/2.8 Varisoft
 
 
 
 

These crops amply demonstrate the performance of the lenses in this respect. The scans for these were from a Fuji Frontier rather than my Dimage Scan Elite 5400, and seem to highlight the grain more than the scans produced by the Minolta scanner (I believe because they have applied a sharpening mask to the scans).

While we are probably all aware of the importance of lens hoods when shooting, I feel that these results really drive home the importance of this fact. With a lens hood on, these lenses would likely have performed identically in this test. Moral of the story -always use a lens hood!

 
 
 
 
Lens Bokeh
 
  The term "bokeh" is derived from a Japanese word, and is used to describe how the out-of-focus parts of an image are rendered. The test below has been designed to demonstrate the bokeh of the various lenses, and has been conducted at f/2.8 to show how both lenses perform at a typical portrait aperture setting with shallow depth of field.  
 
 
 
The above image was taken with the 85mm f/2 at f/2.8, and provides an indication of the overall image. At first glance, the bokeh of the lens appears reasonable. We will be comparing specific crops of the image to determine the performance of all lenses.
 
 
Good and bad is hard to define, and additionally can be a very personal judgement. That said, what many define as good, neutral and poor bokeh can be shown below:
 
 
 
 

On the left is an example of bad bokeh. You will note that it has a sharply defined outer rim, and is darker towards the centre. In the middle is an example of a highlight from a lens that we would say has neutral bokeh. It is an evenly illuminated circle, with a well defined outer edge. Finally, on the right is an example of an out of focus highlight from a lens with good bokeh. It has an undefined edge, and is not distracting.

The different types of bokeh are caused by spherical aberration. I won't try to explain it in detail, but basically, if a lens has good bokeh for backgrounds, it will have bad bokeh for foregrounds, and vice versa. This is due to under or over corrected spherical aberration. Given that "good" bokeh is actually caused by imperfection in the design, most lenses are actually designed to achieve neutral bokeh.

Now that that has been explained, let's have a look at how the various lenses perform in this respect.

 
 
85mm f/1.7 MC
85mm f/1.7 MD
 
 
 
 
85mm f/2 MD
85mm f/2.8 Varisoft
 
 
 
 

Best of all the lenses appears to be the 85mm f/1.7 MC lens which shows neutral-good bokeh. While the shapes of the aperture blades are still identifiable in some cases, the semi-highlighted background has blurred very nicely.

The 85mm f/1.7 MD and the 85mm f/2 lenses are very close for second, both exhibiting neutral bokeh. I think the f/1.7 lens just marginally outperforms the f/2 lens here, but it's a tight contest.

Finally, and very surprisingly, is the 85mm Varisoft. It is quite obvious that the Varisoft shows poor bokeh, with out of focus highlights that are quite distracting. This was naturally a big surprise for me, as the lens was specifically designed as a professional portrait lens. However, after considering the matter, I realised that the lens actually has a variable capacity to reflect out of focus highlights due to it's very capacity to vary the spherical aberration of the lens. For example, in the image detailed below, I have used the soften function to vary the sperical aberration, firstly to halfway to the first notch, and then all the way.

 
 
Varisoft @ f/2.8 Setting 0.5
Varisoft @ f/2.8 Setting 1
 
 
 
  Well, the tests and crops detailed above demonstrate to my satisfaction that while the Varisoft appears to have poor bokeh set at zero, with even the tiniest adjustment on the softness scale this improves. Given that at f/4 or f/5.6 a small touch on the softness dial will not even be noticeable, it seems appropriate that where your background is distracting, you should adjust the softness control marginally to adjust the spherical aberration and improve the bokeh of the lens.  
 
Summary
 
 

Well, based upon my analysis of the lenses I believe that the 85mm f/2 is the best performer of the group. It has outstanding sharpness and resistance to flare that is considerably better than the other lenses. It's bokeh is neutral but pleasant. The f/2 is closely followed by the 85mm f/1.7 MD. With sharpness almost the equal of the f/2, and excellent flare resistance, it provides brilliant overall performance.

The 85mm f/1.7 MC, while an older design and hence not quite as sharp as the later lenses, has lovely bokeh, and as a portrait lens is an excellent choice. Due to it's low resistance to light scatter, you should always use a hood with this lens. Finally, the Varisoft was least impressive performer of the lenses in the standard tests detailed above.

So given that the Varisoft is so expensive, is not resistant to flare, and has worse bokeh when not using the soft focus function, why would you choose to buy it over one of the other lenses? Well first of all, I would say that you wouldn't. Personally, if I had to choose between them, I would keep my 85mm f/2 over the Varisoft, as it is, in my opinion, a truly outstanding lens. However, given I don't have to choose between them, the reason you purchase a Varisoft is to be able to take photos like this.

 
   
   
   

85mm Varisoft at f/2.8, Softness Setting 1 - No problems with bokeh here!

   
 

While not to everyone's taste, the Varisoft is an amazing lens, and an interesting one to learn to master. I am certainly a long way from using it to it's best capacity yet, and some more experimentation is required. However, that will be for another review on another day.

For everyone who has any one of the Minolta 85mm lenses, I congratulate you on your good fortune. I am sure that you will join me in acknowledging that any one of these lenses is a pleasure to own and use.

 
     
 
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