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Archive 2010 · Zeiss Biogon 25 resolving power -400 lp/mm

antiart
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p.1 #1 · p.1 #1 · Zeiss Biogon 25 resolving power -400 lp/mm

So I was reading about digital sensors pushing the resolving power of lenses and I get to the resolving power of the Zeiss Biogon 25mm 2.8. It is 400 lp/mm! I can't seem to wrap my head around this because I am used to resolutions of 50 lp/mm and lower. Somehow, I am interpreting lp/mm incorrectly on charts like these here: http://www.lenstip.com/173.4-Lens_review-Leica_D_Summilux_25_mm_f_1.4_Image_resolution.html

On that site, the chart just only goes up to about 50 lp/mm and I have never seen any lens on that site even passing 60 lp/mm. This Biogon 25 makes the Leica look like some cheap $50 kit lens. So what kind of marketing flim flam are they using at the Zeiss website?

http://www.zeiss.com/c12567a8003b58b9/Contents-Frame/30536193ed0c97a7c125711c006fc2c2

Jan 02, 2010 at 11:24 AM

carstenw
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p.1 #2 · p.1 #2 · Zeiss Biogon 25 resolving power -400 lp/mm

The Leica 25mm Summilux is not that great a lens for resolution. It is not made to their usual standards. You should rather compare some some recent M or R lenses, like the 28/2.8M. I don't know if anything's up with Zeiss' resolution numbers, but that lens has a good reputation.

Jan 02, 2010 at 11:49 AM

mawz
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p.1 #3 · p.1 #3 · Zeiss Biogon 25 resolving power -400 lp/mm

Actually, the 25 Summilux is a very good lens, but it's optimized for speed and centre resolution, not cross-frame performance like the 25 Biogon is, and the Summilux is a severely retrofocus design while the Biogon is well, a Biogon, just about the best non-retrofocus wide design out there.

Note Lenstip tests on-camera, with an E-3 in the case of the 25 'Lux, and the E-3 is not renowned for its high resolution (it's probably the lowest-resolution 10MP DSLR due to an excessively strong AA filter).

Zeiss tests their lenses on an optical testbench, which allows testing of actual lens resolution. Lenstip tests on-camera with a test chart which tests system (camera + lens) resolution. Zeiss's specs are accurate for what the lens will do, but Lenstip's a better guide to what you'll get on camera provided their test camera has similar performance to what you're using (There's a big difference between say a 30D and a 7D)

Jan 02, 2010 at 01:01 PM

ocean2059
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p.1 #4 · p.1 #4 · Zeiss Biogon 25 resolving power -400 lp/mm

carstenw wrote:
The Leica 25mm Summilux is not that great a lens for resolution. It is not made to their usual standards. You should rather compare some some recent M or R lenses, like the 28/2.8M. I don't know if anything's up with Zeiss' resolution numbers, but that lens has a good reputation.

I respectfully disagree with what you said about PanaLeica 25 mm Summilux. I have been using it for sometime and I really think it is an excellent lens for 4/3. The lens has very good resolving power for the center part of the image at f1.4. The color rendition of this lens is a classic Leica lens all the way. I have own many Leica M and R glasses, including R28/2.8 ROM, M35/1.4 ASPH, and M50/1.4 ASPH. Based on my own experience, I don't think that PanaLeica 25 Summilux is a sub-standard lens at all.

Kind regards,

Jan 02, 2010 at 04:44 PM

Alex
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p.1 #5 · p.1 #5 · Zeiss Biogon 25 resolving power -400 lp/mm

The lens resolving power is a very imprecise term which means different things to different people. In this particular case Zeiss stretched the definition way beyond any practical sense. It is a clear case of a marketing hype.

What they say is that if they take a picture (with a film camera) of a black and white pattern with 400lp/mm they can detect some pattern in the image. They don't specify what level of contrast they detect in the image or if it is actually visible or only measurable with precise instruments.

The test sites usually report MTF50 which is a frequency for which the contrast is 50%. Looking on the Biogon 25m MTF charts available from Zeiss, my guess is that MTF50 for this lens is about 80lp/mm at f/5.6. Now doubt it is a very high number but it is not 400lp/mm

Alex

Jan 02, 2010 at 04:47 PM

Toothwalker
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p.1 #6 · p.1 #6 · Zeiss Biogon 25 resolving power -400 lp/mm

Alex wrote:
The lens resolving power is a very imprecise term which means different things to different people. In this particular case Zeiss stretched the definition way beyond any practical sense. It is a clear case of a marketing hype.

What they say is that if they take a picture (with a film camera) of a black and white pattern with 400lp/mm they can detect some pattern in the image. They don't specify what level of contrast they detect in the image or if it is actually visible or only measurable with precise instruments.

The test sites usually report MTF50 which is...Show more →

The lens resolving power is a rather precise term so long as the definition is provided. Zeiss speaks of the diffraction limit, which, by the Rayleigh criterion, approximately corresponds to MTF10. MTF10 is as fine a measure as MTF50, but of course people should not compare MTF10 numbers directly with MTF50 measurements.

Jan 02, 2010 at 07:05 PM

Jonas B
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p.1 #7 · p.1 #7 · Zeiss Biogon 25 resolving power -400 lp/mm

ocean2059 wrote:
I respectfully disagree with what you said about PanaLeica 25 mm Summilux. I have been using it for sometime and I really think it is an excellent lens for 4/3. The lens has very good resolving power for the center part of the image at f1.4. The color rendition of this lens is a classic Leica lens all the way. I have own many Leica M and R glasses, including R28/2.8 ROM, M35/1.4 ASPH, and M50/1.4 ASPH. Based on my own experience, I don't think that PanaLeica 25 Summilux is a sub-standard lens at all.

Kind regards,

The Panasonic 25/1.4 is an over priced and mixed bag of good and bad. The cneter sharpness (resolution and contrast) is very good for a fast normal. When leaving the center and checking closer to the borders it is unimpressive. That doesn't matter used wide open but the sad thing is that it doesn't improve much stopped down.

Then we can discuss the size and weight and the noisy AF, flare, the feel to manual focusing and the CA and the only reason buying this lens is that there is no other option but the Sigma 30/1.4.

It is cheap for being a Leica, but to be fair, it also isn't a Lecia in the same way we usually discuss Leica lenses.

How do you judge color rendition?

regards,

/Jonas

Jan 02, 2010 at 07:17 PM

antiart
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p.1 #8 · p.1 #8 · Zeiss Biogon 25 resolving power -400 lp/mm

Toothwalker wrote:
The lens resolving power is a rather precise term so long as the definition is provided. Zeiss speaks of the diffraction limit, which, by the Rayleigh criterion, approximately corresponds to MTF10. MTF10 is as fine a measure as MTF50, but of course people should not compare MTF10 numbers directly with MTF50 measurements.

Ah that clears up things quite a bit. So... how would you translate the 400 lp/mm at MTF10 to MTF50 (or vice versa) so I can bring this Biogon down to earthly levels?

I just went to Norman Koren's site about MTF again, so it is simply a matter of increasing or decreasing percentages to translate MTF percentages? I am assuming this is how Alex got his 80 lp/mm esitamation for the Biogon's MTF50 measurement. 400 / 5 = 80.

Well, even at 80, that is still damn high compared to my measly 40 lp/mm of my Canon 50mm 1.4 at f5.6.

Jan 02, 2010 at 08:27 PM

Toothwalker
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p.1 #9 · p.1 #9 · Zeiss Biogon 25 resolving power -400 lp/mm

antiart wrote:
Ah that clears up things quite a bit. So... how would you translate the 400 lp/mm at MTF10 to MTF50 (or vice versa) so I can bring this Biogon down to earthly levels?

I just went to Norman Koren's site about MTF again, so it is simply a matter of increasing or decreasing percentages to translate MTF percentages? I am assuming this is how Alex got his 80 lp/mm esitamation for the Biogon's MTF50 measurement. 400 / 5 = 80.

It's more like 200 lp/mm. See for example https://spie.org/x34304.xml

http://toothwalker.org/temp/diffmtf.png

Jan 03, 2010 at 07:52 AM

mawz
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p.1 #10 · p.1 #10 · Zeiss Biogon 25 resolving power -400 lp/mm

Jonas B wrote:
The Panasonic 25/1.4 is an over priced and mixed bag of good and bad. The cneter sharpness (resolution and contrast) is very good for a fast normal. When leaving the center and checking closer to the borders it is unimpressive. That doesn't matter used wide open but the sad thing is that it doesn't improve much stopped down.

Then we can discuss the size and weight and the noisy AF, flare, the feel to manual focusing and the CA and the only reason buying this lens is that there is no other option but the Sigma 30/1.4.

It is cheap for...Show more →

It's purely optimized for the f1.4-f2.8 range since the normal zooms on 4/3rds are so good there's little need to use anything else at smaller apertures (the 14-54/14-50 f2.8-3.5's are stunningly sharp, especially considering their low cost and the fact they're only marginally larger than the 25). It is massive and flare-prone. Manual focus feel is just fine though.

I'd agree that it's overpriced, but given the build quality and competition, it's worth the money nonetheless. I just wish it was weather-sealed and easier to find.

Jan 03, 2010 at 08:17 AM

thrice
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p.1 #11 · p.1 #11 · Zeiss Biogon 25 resolving power -400 lp/mm

I find my 25 ZM quite high res, but I usually shoot it at f/11 where diffraction as truly set in, in fact the lens is said to be diffraction limited at f/4.

http://gallery.photo.net/photo/10430731-lg.jpg

http://i9.photobucket.com/albums/a96/Nephilim666/25ZMCrop.jpg

Jan 03, 2010 at 08:25 AM

antiart
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p.1 #12 · p.1 #12 · Zeiss Biogon 25 resolving power -400 lp/mm

Toothwalker wrote:
It's more like 200 lp/mm. See for example https://spie.org/x34304.xml

http://toothwalker.org/temp/diffmtf.png

Wow. Then I guess it does the deserve the marketing hype of breaking records. Can this be the sharpest lens in the world at their sharpest aperture?

Thrice, it's funny I thought a photo can never be too sharp unless people over do it in Photoshop. I mean if you did not show me the close up of the sand, I would have thought you over sharpened it in Photoshop.

Jan 03, 2010 at 10:32 AM

thrice
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p.1 #13 · p.1 #13 · Zeiss Biogon 25 resolving power -400 lp/mm

looks a bit oversharp on the screen, looks stunning printed - which is what matters

Jan 03, 2010 at 05:55 PM

DoubleNegative
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p.1 #14 · p.1 #14 · Zeiss Biogon 25 resolving power -400 lp/mm

I have this lens and shoot it using both the Zeiss Ikon and Leica M8. While I can't say what the resolution "numbers" are (I've read all the same articles and MTFs)... What I CAN say is this lens is UNBELIEVABLE.

I have several ZM lenses, from 18mm up to 50mm. This one is easily my favorite, oddly - across both formats. Distortion and flare are nonexistent. From wide open it's sharp. Stupid sharp. At f/5.6 it really doesn't get any better - by any lens I've ever shot. Colors are contrasty and saturated. It has lovely bokeh.

If I had any complaint it's that I wish it were brighter. But seeing as how the only lens that fits that bill is Leica's 1,4/24 Summilux at $6-7k... I think I'll pass.

If you're going to buy one ZM, this should be it. Though the others are really something, too.

Many, many samples from this lens: http://litpixel.com/ee/list.php?search_row=lens&keyword=Zeiss+Biogon+T%2A+2%2C8%2F25+ZM&ee_lang=eng&u=6510

Jan 09, 2010 at 03:59 PM

Kingfishphoto
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p.1 #15 · p.1 #15 · Zeiss Biogon 25 resolving power -400 lp/mm

I had a Zeiss 25mm , made in Germany, for my Contax RTS111 and AX bodies, that gave fantistic resolution. I dont know if its the same optic as this discussion is about.

Jan 09, 2010 at 04:29 PM

mawz
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p.1 #16 · p.1 #16 · Zeiss Biogon 25 resolving power -400 lp/mm

Kingfishphoto wrote:
I had a Zeiss 25mm , made in Germany, for my Contax RTS111 and AX bodies, that gave fantistic resolution. I dont know if its the same optic as this discussion is about.

That's a Distagon, a retrofocus wide-angle with a good reputation despite being overshadowed by the better-performing 21 and 28mm siblings.

The lens under discussion is a Biogon, which is a symmetrical wide-angle in Leica M mount of significantly better performance than the equivalent Distagon.

Jan 09, 2010 at 05:37 PM

Kingfishphoto
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p.1 #17 · p.1 #17 · Zeiss Biogon 25 resolving power -400 lp/mm

mawz wrote:
That's a Distagon, a retrofocus wide-angle with a good reputation despite being overshadowed by the better-performing 21 and 28mm siblings.

The lens under discussion is a Biogon, which is a symmetrical wide-angle in Leica M mount of significantly better performance than the equivalent Distagon.
Hi.
Thanks for the clarification.

Jan 10, 2010 at 07:11 AM

freaklikeme
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p.1 #18 · p.1 #18 · Zeiss Biogon 25 resolving power -400 lp/mm

thrice wrote:
I find my 25 ZM quite high res, but I usually shoot it at f/11 where diffraction as truly set in, in fact the lens is said to be diffraction limited at f/4.

I just finished calibrating the LCD on my new laptop and yours were the first images I saw, Dan. Eye-popping color. Absolutely gorgeous.

Jan 10, 2010 at 07:06 PM


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