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Author Topic: Debunking the myth: 35mm lenses sharper than LF  (Read 4274 times)
Graham Mitchell
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« on: November 01, 2006, 07:56:31 AM »
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Every week I see someone in a forum somewhere stating that 35mm lenses are far sharper than large format lenses, on the same film/sensor. I doubt this is true but perhaps we can resolve it in this thread.

I checked the Schneider website and their LF lens range is rated at "90 to 200 line pairs per millimeter". (Isn't this in fact better than most 35mm lenses?)

Our finest digital sensors are rated at more like 70lppm, so it would seem that the LF lenses do not place a significant limit on the end resolution.
« Last Edit: November 02, 2006, 09:24:08 AM by foto-z » Logged

Graham Mitchell - www.graham-mitchell.com
Dustbak
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« Reply #1 on: November 01, 2006, 08:13:25 AM »
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Check the resolution on the top 35mm lenses and compare. Zeiss claims for its 35mm planar line up to 340lp/mm.

Purely based on numbers this would mean these 35mm lenses do outperform LF lenses in this area.

This not withstanding. LF lenses cover a much wider image circle and together with that they can resolve a lot more detail when used with a larger recording surface (when all else is equal).

I am open for all other ideas naturally.

Edit:

Don't go changing things to most 35mm lenses where you start with all 35mm lenses. You are comparing the top of the line LF lenses to 35mm lenses. So also take the top of the line 35mm lenses. Because with that analogy you could also say the top 35mm lenses do outperform most LF lenses, euh.. no actually all LF lenses.
« Last Edit: November 01, 2006, 08:19:01 AM by Dustbak » Logged
Graham Mitchell
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« Reply #2 on: November 01, 2006, 08:17:57 AM »
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Yes those new Zeiss lenses have high ratings, but they are not typical of the breed. The performance is also wasted on today's sensors. They still won't give a sharper image on the same sensor, afaik.
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Dustbak
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« Reply #3 on: November 01, 2006, 08:22:48 AM »
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That is true but was not the question here.

I wonder how long it will take before the sensors will be outperforming these lenses.
« Last Edit: November 01, 2006, 08:28:02 AM by Dustbak » Logged
Graham Mitchell
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« Reply #4 on: November 01, 2006, 09:50:50 AM »
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I kind of wish you hadn't brought those Zeiss lenses into it, as 1) they are in a league of thier own and 2) 90% of the time it is a Canon users making these claims

I'd be interested to see the lppm ratings (centre and corner) for a range of Canon primes.
« Last Edit: November 01, 2006, 09:51:23 AM by foto-z » Logged

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« Reply #5 on: November 01, 2006, 10:14:02 AM »
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Definitely true.

I know some of the Canon primes and some of the Nikon primes have very good resolution. Can't find how many lp/mm

BTW the D2x is claimed to resolve 90 lp/mm, sofar the highest resolving sensor. (no wonder with an APS size and 12.4MP).

Zeiss now has a fairly decent range of 35mm Planars. I am definitely looking at the 50 & 100 Makro as well as the 25. (already own the 85 and 50).

These are not cheap either but still not astronomically priced.
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Sheldon N
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« Reply #6 on: November 01, 2006, 11:41:31 AM »
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There's a couple Large format photographers who have gone through the trouble of testing a large number of large format optics and publishing their resolution findings.

The tests are done at f/11, f/16 and f/22, which is probably more in the range of where LF shooters operate than digital shooters. At f/22, most every lens performs pretty close to the diffraction limited resolution of 60 lp/mm. The best large format lenses can put out resolution in the 70-80 lp/mm range at wider apertures.

There are also some tests of MF optics, which show slightly higher resolutions in the 90-100 lp/mm range.

Keep in mind that these are measurements of resolution on film, which may be different than pure optical resolution.

The large format test is at:

http://www.hevanet.com/cperez/testing.html

and the medium format test is at:

http://www.hevanet.com/cperez/MF_testing.html
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erikhillard
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« Reply #7 on: November 01, 2006, 11:49:06 AM »
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I work with Canon camera and MFDBs constantly.  There is a HUGE difference in sharpness between them.  MFDB are sharp and Canon is "Canon Sharp"..  :-)
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Erik Hillard

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Morgan_Moore
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« Reply #8 on: November 01, 2006, 12:23:45 PM »
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Quote
I work with Canon camera and MFDBs constantly.  There is a HUGE difference in sharpness between them.  MFDB are sharp and Canon is "Canon Sharp"..  :-)
[a href=\"index.php?act=findpost&pid=83251\"][{POST_SNAPBACK}][/a]

Even if the MF have less lines per inch you get more inches

For a true comaprison you need for factor in sensor size to get a feel of 'resovlable image quality'


So even if MF lenses have lower LPI that is far from the whole story for which device is better for resolving

I would imaging you need twice the LPI to resolve the same for a chip half the size assuming that the LPI of the lense rather than pixel density or an other factor is not the limiting one

I am sure MF solutions resolve better as a package SMM
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eronald
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« Reply #9 on: November 01, 2006, 12:38:25 PM »
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Quote
I work with Canon camera and MFDBs constantly.  There is a HUGE difference in sharpness between them.  MFDB are sharp and Canon is "Canon Sharp"..  :-)
[a href=\"index.php?act=findpost&pid=83251\"][{POST_SNAPBACK}][/a]

Canon wides have a rep for softness which is deserved if I look at my 24-70 and 24 TS/E. I don't know whether I'd bother using them on a digital back.

On the other hand, most Canon shooters I know have a converted Zeiss lens somewhere in their bags - I have the 20 (or is it 21 ?) Distagon on an adapter and it's razor sharp, but distorts - I don't know what the image circle is like. The Zeiss people at Photokina told me they get requests but cannot make a new version with the same formula  because the glasses don't exist anymore.

There are some cheap 28 mm Zeiss lenses around, and some of those might be worth trying on a back.

I've seen a photo using the Nikon 17-35 on a Phase back which was very good.

Edmund
« Last Edit: November 01, 2006, 01:21:42 PM by eronald » Logged
erikhillard
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« Reply #10 on: November 01, 2006, 12:38:57 PM »
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Yes I understand your point.  It wouldn't be a fair comparison otherwise.

I guess personally all I care about is the final image quality.  MFDBs and lenses constantly produce sharper images than Canon.  Especially with Canon zoom lenses.  Canon primes are a lot better.

Then again such captures at ISO800 is another entire conversation..  :-)
« Last Edit: November 01, 2006, 12:39:32 PM by erikhillard » Logged


Erik Hillard

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BJL
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« Reply #11 on: November 01, 2006, 02:44:42 PM »
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It is no myth: when you compare smaller and larger  format lenses covering the same angular FOV, the smaller format lenses overall consistently have higher absolute resolution, measured by MTF at equal l/mm.

Since you mention Schneider, go to the LF lens information at its website http://www.schneideroptics.com/ecommerce/C...ay.aspx?CID=162 and check the MTF graphs for various large format lenses, and then look at similar graphs for Canon and Nikon lenses. Canon here: http://www.usa.canon.com/consumer/controll...fcategoryid=111

Schneider mostly gives curves at 5, 10 amd 20 l/mm, and
- the performance at 10 l/mm is typically distinctly worse than for Canon and Nikon primes at the same 10 l/mm
- the performance at 20 l/mm is typically worse than for the 35mm lenses at 30 l/mm.

The Schneider Digitar's are different, performing fairly well up to 60 l/mm but they are not large format lenses but "digital medium format" lenses, with image circles to small for even 4"x5" LF. The only other lenses with 60 l/mm MTF charts available are Olympus Zuiko Digitals, which again outresolve the Digitar's; even the good 4/3 format _zooms_ typically outresolve the far more expensive larger format Digitar _primes_.


This is not a boast about Canon or Olympus, just evidence of the absolute resolution (l/mm) benefits of downsizing lens designs for a smaller format.


P. S. Of course others are right in saying that  in practice "line per picture height" (l/ph) is probably a more relevant measure, or in other words print resolution in l/mm on equal sized prints. There I would expect larger format primes to have some edge.

Another point from earlier posts: most LF work is done at rather high f-stops, nice because the resolution can end up being mostly diffraction limited, with aberrations effects quite low. When using 35mm format allows using a significantly lower f-stop, the diffraction effect is reduced, and a 35mm format lens that gets reasonably close to diffraction limited will resolve higher l/mm. But measuring diffraction limits in l/ph, or "l/mm on equal sized prints", the diffraction limits are the same when DOF is the same.

So if good LF lenses are close to the diffraction limit, 35mm format lenses cannot do significantly better in l/ph, and might do a bit worse due to the somewhat greater aberrations expected at a lower f-stop.
« Last Edit: November 01, 2006, 02:56:43 PM by BJL » Logged
narikin
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« Reply #12 on: November 01, 2006, 05:46:31 PM »
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probably the ultimate Digiback lens is the 80mm Zeiss Planar for the Sinar M range,

http://www.zeiss.com/C12567A8003B8B6F/Embe...r_2-8_80_06.pdf

ultra sharp, latest Zeiss production, fast, and AF to boot.
it's a crying shame it isnt in a Contax or Hasselblad mount.
pretty please Zeiss?
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