Biogon 35/2 and C Biogon 35/2.8

[noimmunity]

Thanks, Zoran, for taking the time to really go into what you see. I find it very useful and think it may encourage others to offer their perspectives, too.

It appears that you took a small step back

It was raining when I took the photos, so it was more like a walk back and forth to get cover in order to change lenses. I made no serious effort to take the photos from exactly the same spot, and that was kinda silly.

Looking at Oxford College, CBio4 and Bio2.8 appear to have just about the same amount of blur
of the background and midrange objects ...
Therefore, Bio2.8 and Cbio4 is a more relevant comparison to me. And between these 2 images,
I do not see as much difference as others have pointed out.
This depth of field difference seems to be present throughout the Oxford College series.
I do not see it on other images.

If you see this discrepancy on only one series, that could indicate my error in noting apertures, yet i really really doubt that is what happened...

yet I have the impression that in general the C Biogon has a different OOF response compared to the Biogon. In fact, I had this impression even before I got the lens. In the images that were taken by a japanese photog on flickr and mentioned on RFF in another thread, we noticed an unusually attractive bokeh for a 2.8 aperture. I really don't know enough to assess this at all.

What I see on some other images is that the lighting conditions seem
to be slightly different between the shots and that may give the appearance that the lenses are quite different.

I think the lighting conditions were fairly stable, since it was heavy overcast and rain the whole time. But a clear sunny day would be better.

On some other images, CBiogon seems to show a bit of vignetting at 2.8.

This is consistent and noticeable. I think it is also somewhat present when the Biogon is used wide open at f/2, although it seems more pronounced on the C Biogon.

on Garden 2 Biogon seems to have much more shadow detail on the left side of the image than the CBiogon. This is contrary to what others have been saying.

It seems to me this discrepancy is due to the greater vignetting noticeable on the C Biogon, although I notice that even the roof tiles in the center of the image are different on the two, suggesting exposure variation. Although I used AE, I made sure the shutter speeds and apertures were the same, but obviously the only way to assure that consistency is to use manual mode.

Near the center of the Garden 1 is a dark area at the end of the arcade. This area has much greater detail in C Biogon than Biogon.

I'm afraid, however, that the comparison was undertaken in too casual a manner to be definitive.

Undoubtedly the sun will come out again (reports say it may rain for another week) and then I may decide to dust off the tripod and try again.

 

[jjovin]

Jon,
I actually think you did well with your experiment.
My impression is that Zeiss wanted to produce compact lenses
at the expense of maximum aperture but without compromising optical quality. And I think your experiment confirmed this as I am hard pressed to find differences in quality between the two lenses. This is not exactly what the consesus on the web so far seems to be.

Please keep in mind that sunny conditions tend to reduce differences between lenses in case you decide to do a similar experiment when the sun comes out. Many years ago I was talking with a sports optics dealer in Germany about getting a pair of birding binoculars. He said that on a sunny day one can not tell the difference between Leica and Zeiss binoculars since those two were my final choices. However, he said, on a misty or a fogy day when the viewing conditions are difficult, Zeiss binoculars noticeably outperform the equivalent Leica binoculars. I had many opportunities afterwards to confirm his claim.

In any case, thank you again for posting the images. I think both lenses are great, and I am very happy to own a Biogon. Ultimately, I think, what will make the difference for people is an extra stop, compactness, or price. They are sure to get a great lens whichever way they go.
Best wishes,
Zoran

 

[noimmunity]

I think both lenses are great, ... Ultimately, I think, what will make the difference for people is an extra stop, compactness, or price. They are sure to get a great lens whichever way they go.

My feelings, too (as I wrote above). The rendition of both lenses in colour is very very appealing. I will try some black and white soon. So far, I find a subtle difference between the two at f/2.8: the C Biogon has a dreamier look (which I attribute to a combination of unusually good bokeh and a little vignetting). The Biogon is more understated, and for that reason very convincing. Yet it is impossible to really nail it down given the casual method of comparison. It's just too bad that the price overseas does not reflect the significant difference in Japan between the two lenses.

 

[EtoileFinder]

After weeks of thinking, reading, and searching on the net, I finally order a black c biogon. This time, i go for compactness, because I already have the nokton 1.2, which is a big 35mm lens. Thanks a lot noimmunity for your comments and pic.

 

[aizan]

how much does the price differ in japan? i really dig the c biogon's look.

 

[noimmunity]

After weeks of thinking, reading, and searching on the net, I finally order a black c biogon. This time, i go for compactness, because I already have the nokton 1.2, which is a big 35mm lens. Thanks a lot noimmunity for your comments and pic.

Net-Viseur (EtoileFinder), Since I have the Big Nokton, too, I opted for the C Biogon as well. And yeah, I got it in black, too.

All my other ZM lenses but one are in silver (though this is my third one in black). I still find the silver ones have a slightly better damping in the aperture and focus rings (buttery smooth with just the right amount of a little resistance). But black is a compelling color for a small lens on a black or silver body.

how much does the price differ in japan? i really dig the c biogon's look.

the C Biogon is list priced only about 3,000 yen higher than the 50/2 Planar. Street price in Japan is probably around 70,000 yen/approx $650 (69,900 yen on Map Camera's website), which is 20% or more off ebay ($798 at Matsuiya) and Popflash ($817) US dollar prices. Since my next trip to Japan is not definite and the difference, considerable though it is still wasn't enough money to trouble my friends there, I ordered on ebay from Matsuiya, who provide prompt, reliable, and friendly service. Heck, Zeiss oughtta give me a "subscriber's discount" given my fidelity to their ZM line 😀

 

[jjovin]

Jon,
I think I know why CBiogon gives the impression of more shadow details. Many of your images are taken at 2.8 where CBiogon shows distinct vignetting, which is missing from the Biogon images at 2.8. See the Offering Burner, for example.
Since you used automatic exposure (I think you said this in one of your postings) and the exposure metering on Ikon (I assume this is the camera you used, but it also holds for Leica and Bessa and other range finders) is center-weighted the centers of Cbiogon images receive more exposure than the centers of Biogon images in order to compensate for the light fall-off at the edges. Then, clearly if one exposes more shadows one sees more details. Now, if one goes to the ares of the Offering Burner which appear to have the same brightness, both images seem to have the same amount of shadow details. And at the edges Biogon shows more shadow detail. On any image eyes is always first drown to the bright area especially if it is in the center of the image. So, unless enough time is spent examining an image one may be left with the impression that CBiogon offers more shadow detail. Of course, people may like the slight effect of vignetting, but I think if you use manual exposure, the impression of extra shadow detail will be completely gone.
Anyway, this is my theory.
Zoran

 

[noimmunity]

I think if you use manual exposure, the impression of extra shadow detail will be completely gone.

Zoran,
I did use AE.
I made sure that the shutter speeds in the VF were the same for each shot with the two lenses at the same aperture. For the photos of the offering burner, I distinctly remember the shutter speed was 125 at f/2.8 for both lenses. Given this parity, please tell me if using manual exposure would have made any difference? I'm interested. Thanks.
Jon

 

[jjovin]

Jon,
if you see 125 in AE mode that means that 125 is the closet
number that the camera can show to the true exposure determined by the camera. The true exposure can be anywhere in the range 125 +- 0.5EV. In manual mode 125 is the exact exposure that will be used by the camera. Since the CBiogon experiences vignetting at 2.8 and the Biogon does not (or much less) if you want the center of a scene to be exposed equally on both lenses then use the manual mode. Otherwise the shutter speed using the CBiogon
will be smaller than that using the Biogon by some integer multiple of (1/12)EV (if you are using an Ikon). 1/12 is the f-stop resolution that Zeiss is reporting on the Ikon. It is some other number on other cameras.
I think this is what we are seeing on the Offering Burner image.
Regards,
Zoran

 

[noimmunity]

It's a good theory, Zoran.
In this case, because the shutter speeds were nominally the same, it seems to me the basis for comparison is quite solid. But perhaps on the Ikon, as on some other cameras with AE, the actual shutter speed varies somewhat from the LED number in the VF?
At the very least your ideas bring us back to the conclusion that a lens test should be undertaken with a tripod, on manual exppsure, under constant lighting conditions!
Hopefully the auspicious conditions for such a test will arrive while I still have access to both lenses and I can make further efforts.

 

[noimmunity]

Jon,
if you see 125 in AE mode that means that 125 is the closet
number that the camera can show to the true exposure determined by the camera. The true exposure can be anywhere in the range 125 +- 0.5EV. In manual mode 125 is the exact exposure that will be used by the camera. Since the CBiogon experiences vignetting at 2.8 and the Biogon does not (or much less) if you want the center of a scene to be exposed equally on both lenses then use the manual mode. Otherwise the shutter speed using the CBiogon
will be smaller than that using the Biogon by some integer multiple of (1/12)EV (if you are using an Ikon). 1/12 is the f-stop resolution that Zeiss is reporting on the Ikon. It is some other number on other cameras.
I think this is what we are seeing on the Offering Burner image.
Regards,
Zoran

Zoran, we both posted at almost exactly the same moment! hahaha!
Yes, I suppose there was an incremental difference in the shutter speeds, even though the AE reported number is the same.
Lens testing turns out to be really kinda fun.
Best,
Jon