Which first Zeiss ?
/forum/topic/1000383/2

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Picture This!
Registered: Aug 03, 2010
Total Posts: 1754
Country: United States

i'll post another shortly

While we're at it guys, can you recommend the second Zeiss to get ? I'm drawn toward the 100MP and 21. Considering selling my Nikon lenses to get these. I was worried something like this might happen.



Jochenb
Registered: May 25, 2010
Total Posts: 1634
Country: Belgium

melbmanu wrote:
i'll post another shortly

While we're at it guys, can you recommend the second Zeiss to get ? I'm drawn toward the 100MP and 21. Considering selling my Nikon lenses to get these. I was worried something like this might happen.



First of all congrats on the 35/2.

Which one to get next is really up to you.
Look at what you need most: a wideangle or a tele?



wayne seltzer
Registered: Dec 22, 2007
Total Posts: 3968
Country: United States

carstenw wrote:
j.liam wrote:
The thread here is "Which first Zeiss?" so aside form pixel peepers and for practical purposes, the 35/2 and 50MP are essentially flat-field lenses.


Well, no. I can see the soft corners wide open on the 50 MP even at web resolutions. They aren't nasty and smudged, but they are clearly less sharp than anywhere else in the image. I am not saying that this is a sensible reason for most people not to buy one, but it is there, and this lens cannot be considered a flat field lens, unless stopped down significantly or shooting at infinity.


So every lens that has sharpness fall off in the corners wide open is considered to have FC?



Rodluvan
Registered: Sep 01, 2010
Total Posts: 651
Country: Sweden

melbmanu wrote:
Also most places seem to be out of stock on the 35 1.4 .2..


It's just on the verge of being released.



carstenw
Registered: Dec 26, 2005
Total Posts: 14909
Country: Germany

wayne seltzer wrote:
carstenw wrote:
j.liam wrote:
The thread here is "Which first Zeiss?" so aside form pixel peepers and for practical purposes, the 35/2 and 50MP are essentially flat-field lenses.


Well, no. I can see the soft corners wide open on the 50 MP even at web resolutions. They aren't nasty and smudged, but they are clearly less sharp than anywhere else in the image. I am not saying that this is a sensible reason for most people not to buy one, but it is there, and this lens cannot be considered a flat field lens, unless stopped down significantly or shooting at infinity.


So every lens that has sharpness fall off in the corners wide open is considered to have FC?


C'mon, work with me here I have posted other shots in the Z thread where the extreme corners are suddenly sharp, way in the distance compared to the subject in focus. Go look and stop arguing so much. It is really true



Bobu
Registered: Apr 22, 2004
Total Posts: 1343
Country: Germany

Carsten, I also think that the soft corners of the 50MP are not the result of FC. When I tested the lens, I focused with lifeview and 10x zoom on the corners and they are still soft. Maybe the lens has in some sitatuations (read distances) also slight FC, but this is not the main reason for the soft (extreme) corners at apertures f/2.0 - f/4.0.

Boris



carstenw
Registered: Dec 26, 2005
Total Posts: 14909
Country: Germany

If I post a shot where the main subject is in focus at 10m, and the background directly behind it is blurred at about 30m, but where the same background starts to come into focus near the extreme edges and corners, will you believe me then? I have already posted several such images in the Z thread:

Look at the trees directly behind the central subject, and then look at the sharpness of the little house on the left edge, at roughly the same distance:

Sample 1

In the next one, look at the grass on the lower left, close to the tree, and then look at the extreme corner: totally soft. Look at the bushes behind the trees near the centre, and now look at the fairly sharp branches in the upper right:

Sample 2

In this final one, you can also see that the top right corner is sharper than it should be, given the distance.

http://www.fredmiranda.com/forum/topic/860134/281#9493885

Somewhere in my library, I have shots which show it perhaps more clearly, but hopefully you will start to believe me at this point. I do notice that when focusing closer, such as on flowers or machinery in the foreground, this phenomenon doesn't happen. The subject has to be a bit further away than that.



wayne seltzer
Registered: Dec 22, 2007
Total Posts: 3968
Country: United States

Carsten, after seeing your post here about 50 MP having FC and LC's claim that there was FC causing sharpness differences in his Death Valley machine comparison example, I went to Stanford church plaza area and photographed at wide open with both 50's slowly adjusting the focus pt from the church towards me in increments and then examining the tiles on the floor of the plaza to check for FC and didn't even see it in the extreme corners. I looked for the plane of focus to bend backwards or forwards and didn't see it. It just went blurry in the extreme corners.
Most macro lenses have very flat/planar fields of view with no FC.
To me it is like the 50MP design's image circle was not made quite large enough to keep from having this blurring in the extreme corner at f2-f4, IMHO.




carstenw
Registered: Dec 26, 2005
Total Posts: 14909
Country: Germany

Wayne, could you please comment on my samples? I don't know what was different in your testing, but I have some specific samples which demonstrate what I am saying, and I would like to discuss them.



cputeq
Registered: Jun 25, 2008
Total Posts: 4241
Country: United States

Melbmanu Glad to see you enjoy your 35/2 as much as I enjoy mine. We even have similar shots, though yours is a bit better than mine







I took it to a rose garden recently and nearly every shot was with the 35/2. Fun to shoot and my poor 24-105 and 85 f/1.8s were stuck in the bag nearly the entire time.









AhamB
Registered: Jul 11, 2008
Total Posts: 4857
Country: Germany

wayne seltzer wrote:
To me it is like the 50MP design's image circle was not made quite large enough to keep from having this blurring in the extreme corner at f2-f4, IMHO.

Hence, in Carsten's second sample, the upper right corner is sharp, even though it's way behind the plane of focus? There is no blur there.



Bobu
Registered: Apr 22, 2004
Total Posts: 1343
Country: Germany

carstenw wrote:
If I post a shot where the main subject is in focus at 10m, and the background directly behind it is blurred at about 30m, but where the same background starts to come into focus near the extreme edges and corners, will you believe me then? I have already posted several such images in the Z thread:

Look at the trees directly behind the central subject, and then look at the sharpness of the little house on the left edge, at roughly the same distance:

Sample 1

In the next one, look at the grass on the lower left, close to the tree, and then look at the extreme corner: totally soft. Look at the bushes behind the trees near the centre, and now look at the fairly sharp branches in the upper right:

Sample 2

In this final one, you can also see that the top right corner is sharper than it should be, given the distance.

http://www.fredmiranda.com/forum/topic/860134/281#9493885

Somewhere in my library, I have shots which show it perhaps more clearly, but hopefully you will start to believe me at this point. I do notice that when focusing closer, such as on flowers or machinery in the foreground, this phenomenon doesn't happen. The subject has to be a bit further away than that.


Carsten, maybe we are speaking of different things. I'm pretty sure that the softness of the extreme corners of the 50MP at aperturers of f/2 - f/4 has nothing to do with FC. And you want to proof that the 50MP has FC. Maybe we are both right. In your example you can only judge the edge and not the corner and in your second example all 4 corners are soft. More interesting is your third example, but it is too small to judge the corner sharpness. Could you please post some 100% crops of the third image.

Boris



Bobu
Registered: Apr 22, 2004
Total Posts: 1343
Country: Germany

About 15-20 month ago I did some tests with the 50MP that clearly showed the soft corners. When I use the search function I don't find any posts older than 15 month. Any idea how to find these old posts?



Jochenb
Registered: May 25, 2010
Total Posts: 1634
Country: Belgium

Bobu wrote:
About 15-20 month ago I did some tests with the 50MP that clearly showed the soft corners. When I use the search function I don't find any posts older than 15 month. Any idea how to find these old posts?


Here you go Boris:
http://www.fredmiranda.com/forum/topic/864916/0



Bobu
Registered: Apr 22, 2004
Total Posts: 1343
Country: Germany

Jochenb wrote:
Bobu wrote:
About 15-20 month ago I did some tests with the 50MP that clearly showed the soft corners. When I use the search function I don't find any posts older than 15 month. Any idea how to find these old posts?


Here you go Boris:
http://www.fredmiranda.com/forum/topic/864916/0


Thanks Jochen, and how did you find it? Did I made a mistake with the search function or is there a special trick?



Jochenb
Registered: May 25, 2010
Total Posts: 1634
Country: Belgium

Don't use the search function of the forum, it's cr*p.
Instead: just use google



Bobu
Registered: Apr 22, 2004
Total Posts: 1343
Country: Germany

Thanks Jochen. I just read my old thread again. And here is one citation that summarizes my findings pretty good: "As you can see, there is a slight effect of field curvature. But even with focussing on the corner, you have to stop down to at least f/5.6 to reach good corner performance."

So yes, the 50MP has some FC, but this is not the main reason for the soft extreme corners.

Boris



Gunzorro
Registered: Aug 28, 2010
Total Posts: 6067
Country: United States

carsten -- That is a very interesting phenomana! It is the reverse of what I call "horseshoe focus" very common on Nikon AIS (and more recent) wide angle lenses.

This would be "reverse horseshoe", and is easily seen on the ground of the second photo, trailing off from front to back along the right side (the tree trunk obscures where it would show on the left).

These oddities can work to a photographer's benefit, as long as you know they are there, and this particular one can contribute to the "3D effect" by producing that halo of OOF around the central subject, accentuating the subject.

I'm interested to see ways this effect can be put to use fro subject isolation.

BTW -- the Nikon effect is terrific for group shots with people spread in an arc, center being furthest away. Small groups of people, as well as products and landscapes benefit from increased subject sharpness at lower apertures -- sort of a "curve/tilt".

Thanks for your heads-up research.



AhamB
Registered: Jul 11, 2008
Total Posts: 4857
Country: Germany

Bobu wrote:
So yes, the 50MP has some FC, but this is not the main reason for the soft extreme corners.


I think that the softness is not the phenomenon that Carsten was emphasizing, since he didn't photograph flat subjects extending into the corners. His samples just show the curvature of the focal plane at the edges and corners towards infinity, which can influence the bokeh at certain focus distances in an obvious way (i.e. no bokeh at all in the far background in the corners, because it comes into focus).



carstenw
Registered: Dec 26, 2005
Total Posts: 14909
Country: Germany

Geez, you guys are making me work hard. Okay, here is an example I concocted on the way home from work, where I tried to find not only a background which was in focus when it shouldn't be, but also walked around a bit trying different things in order to maximize it a bit. First an overall shot, with crop indicators:







The distance to the subject is about 8m. The top right is about 3x that, i.e. about 24m, and already there you can see that the texture of the building is starting to sharpen up more than in the centre, but the big "surprise" is when you move towards the top left corner, where one balcony is quite unsharp, and then one further away from the centre is much sharper.

Now if that isn't field curvature, I want more of whatever drugs I am taking.

The quality of the focus in the corners is not nearly as good as the quality of focus in the centre, that much is also clear. No matter what the distance, they just aren't tack sharp, so there is regular falloff involved too. I guess this is what Boris refers to, but the FC is definitively, very strongly, present, both in the corners and along the short edge.

Note that if the subject is at 6m, the FC is much weaker. The distance is very important. I haven't tried infinity.



















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