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The 50 1.4 shoot out
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PostPosted: Sat Feb 23, 2008 10:12 pm    Post subject: The 50 1.4 shoot out Reply with quote

These are all at 1.4 surprise leader of the pack in terms of sharpness anyway, look for the loose red threads on the left edge of the blue tie for the true test!
in order from memory from worst to best

Revunon (I think tomioka)
http://farm3.static.flickr.com/2016/2286901380_b831aa490b_o.jpg

Super tak non smc
http://farm3.static.flickr.com/2372/2286908880_47ec31d833_o.jpg

Oly
http://farm4.static.flickr.com/3080/2286893724_803f43e382_o.jpg

Contax Zeiss planar
http://farm3.static.flickr.com/2350/2286099395_cd543a4e09_o.jpg

Yashica ML
http://farm3.static.flickr.com/2287/2286879504_b6406796c0_o.jpg


PostPosted: Sat Feb 23, 2008 11:10 pm    Post subject: Reply with quote

Bob, it seems to me that the Planar shot is front-focused.
I'm not a big fan of this kind of tests, but I think that you should remake it shooting an identical scene (the scenes here are different), and taking, for each lens, at least 5 photos with slight focus adjustments - in other words, focus-bracketing - and then pick for each lens the most focused one.
-


PostPosted: Sat Feb 23, 2008 11:54 pm    Post subject: Reply with quote

Yes I couldn't believe the tests my self, obviously at 1.4 the focus is critical so I redid the ML and Planar tests 3 times and this was the result I achieved. I still have the lenses so I could retest just these two. Certainly there is potential for copy variation to account fo the difference.


PostPosted: Sun Feb 24, 2008 1:11 am    Post subject: Reply with quote

hacksawbob wrote:
Yes I couldn't believe the tests my self, obviously at 1.4 the focus is critical so I redid the ML and Planar tests 3 times and this was the result I achieved. I still have the lenses so I could retest just these two. Certainly there is potential for copy variation to account fo the difference.


If you are interested in going on, I think you should photograph something flat, like a newspaper page hanged on a wall. Line up the tripod with a bubble lever and this way you should remove all possible variation factors except your manual focusing - for which a 5 or better 7 takes braketing will do. I remember the last time I made such a test, I took 11 takes with just slightly different focusing adjustments - well you may not believe that but all 11 of them were distinguisheably different - a proof that even a very slight touch on the focusing ring can make a difference.

Oh I forgot to say - such test only tells about near range performance. Infinity performance can be different.


PostPosted: Sun Feb 24, 2008 5:35 am    Post subject: Reply with quote

So can middle distance, depending very crucially on the focal length of the lens and the intent of the designer. All lens design is basically a series of trade-offs and unhappily cost control often wins. On the other hand tests like this can get us looking critically and really making comparisons. Thanks Bob, and thanks to Orio for being our referee.


patrickh


PostPosted: Sun Feb 24, 2008 5:40 am    Post subject: Reply with quote

My own feeling is that the Planar is definitely front focused - if you look at the lettering in the bottom left corner it really seems to show. On the other hand I dont feel there is a bad one there.


patrickh


PostPosted: Sun Feb 24, 2008 8:49 am    Post subject: Reply with quote

I have also shoot out all my 1.4/50 lenses against the Zeiss Planar ZS. To my surprise, the other lenses Supertak, Mamiya Sekor, Tomioka make darker images at f1.4 as the Planar.
I think, the real aperture is f1.8. The cause is probably the light yellow cast of this lenses.

The Zeiss Planar was optimized for middle and far distance. At this point shines this lens against all other 50s.

Ingo


PostPosted: Sun Feb 24, 2008 9:10 am    Post subject: Reply with quote

Ingo wrote:
I have also shoot out all my 1.4/50 lenses against the Zeiss Planar ZS. To my surprise, the other lenses Supertak, Mamiya Sekor, Tomioka make darker images at f1.4 as the Planar.
I think, the real aperture is f1.8. The cause is probably the light yellow cast of this lenses.


The aperture value is always 1.4, it is geometrically defined as the focal length of the lens divided by the diameter of the aperture irrespective of the light transmission capability of the lens. You'll need this real f-value for DOF calculations. Of course, for setting the exposure you'll need an adjusted "f-value" which takes into account all the various losses in the real, physical lens.

Veijo


PostPosted: Sun Feb 24, 2008 9:42 am    Post subject: Reply with quote

Perhaps I got you wrong, Veijo, but f1.4 is f1.4. That means that any lens that shows f1.4 can be compared with any other f1.4 lens (unless there is some kind of cheating by the manufacturers).
That is the reason why the f-stops have been invented in the first place, to be able to compare different lenses.

So not only the geometrical relation between aperture and barrel length has to be considered when a manufacturer "names" a lens, but also the character of the lenses inside.

Of course, you will always find some differences, because some manufacturers interpret f-stops more "tolertant" than others.

I have used an f1.8 lens that (at f1.8), in practical usage, was about as fast as f1.4 lenses normally are (at f1.4). And I have got 2.8/135 lenses that (at f2.8) do not make any difference to my Zeiss 4/135 at f4.
But this is not like it is supposed to be.


PostPosted: Sun Feb 24, 2008 9:44 am    Post subject: Reply with quote

patrickh wrote:
On the other hand I dont feel there is a bad one there.


Given all the vagaries of MF focusing, the only lens which sticks out is the old Takumar with its slightly lower contrast and higher lens flare. Under the circumstances for which most people buy these fast lenses, i.e. for low light shots, even the Takumar might be well nigh impossible to tell apart from the rest, and the focus is likely to be off, anyway, as a 1.4/50 has an about 13 cm DOF at 2 m on a 5D and only about 8 cm on a crop body, that is, the traditional DOF, which is no good for pixel peeping. These days, I do rather use a slightly smaller aperture with correspondingly higher ISO in order to increase the DOF even at the expense of slighly increased noise or grain.

Veijo


PostPosted: Sun Feb 24, 2008 9:56 am    Post subject: Reply with quote

LucisPictor wrote:
Perhaps I got you wrong, Veijo, but f1.4 is f1.4. That means that any lens that shows f1.4 can be compared with any other f1.4 lens (unless there is some kind of cheating by the manufacturers).
That is the reason why the f-stops have been invented in the first place, to be able to compare different lenses.


Yes, you got it wrong. For really comparing lenses you'd need a T-number instead of an F-number. A T-number takes into account all the factors affecting exposure and is often indicated on cine lenses and even some "normal", especially zoom lenses. See e.g. http://www.photography-forums.com/t34962-tstops-.html

This is, for comparing the required exposures. Say, we have two geometrically equal Zeiss Tessars made of the same types of glass, one MC and the other uncoated. Due to the losses at the six uncoated glass-air surfaces, the uncoated Tessar will require about 0.6 stop more exposure at a given aperture setting. An uncoated Tessar made of some older types of glass may require even more compensation. However, at equal f-settings, equal FL lenses will have equal DOFs.

Veijo


PostPosted: Sun Feb 24, 2008 11:24 am    Post subject: Reply with quote

Ah, yes, of course, you're right. I forgot about the "t-stops" which I had read about some time ago, but failed to remember.

So, a t-stop of "1.4" is the same with any lens, since it indicates how much light really "comes out at the end", not an f-stop. If two lenses are said to have a t-stop of "2.0" then these two lenses will expose the same. With two lenses with "f2.0" there might be a difference.

Keeping that in mind (this time), my above mentioned experiences with the lenses make a lot more sense.

How could I forget that?! Sorry! Embarassed


PostPosted: Sun Feb 24, 2008 11:29 am    Post subject: Reply with quote

vilva wrote:
... 1.4/50 has an about 13 cm DOF at 2 m on a 5D and only about 8 cm on a crop body...


Why is that? I always thought that the DoF of one lens is the same, no matter which sensor size is used...
I thought that the different DoF of different sensors is a result of different focal lenghts that must be used to get the same FoV... Question


PostPosted: Sun Feb 24, 2008 5:06 pm    Post subject: Reply with quote

LucisPictor wrote:
vilva wrote:
... 1.4/50 has an about 13 cm DOF at 2 m on a 5D and only about 8 cm on a crop body...


Why is that? I always thought that the DoF of one lens is the same, no matter which sensor size is used...
I thought that the different DoF of different sensors is a result of different focal lenghts that must be used to get the same FoV... Question


OK, I have found that:
"The DOF changes because of the way we handle the recorded images. The CCD records a smaller portion of the projected image. Thus, that image must be enlarged more to produce the final photograph. This, by itself, would yield less DOF. But, we move further away from the subject so we can get identically framed photographs. The longer subject distance increases the DOF. Subject distance has a stronger influence on DOF than does image enlargement. Thus, the DOF is greater in the DSLR photograph."
Here: http://www.dofmaster.com/dof_dslr.html

(Sorry for the OT, Bob.)


PostPosted: Mon Mar 03, 2008 9:45 am    Post subject: Reply with quote

Comparing the Revuenon to Yashica, the exposure looks different. Maybe that is the coatings. If you gave the Revuenon a little more light it might be the same as the Yashica.


PostPosted: Mon Mar 03, 2008 12:59 pm    Post subject: Reply with quote

LucisPictor wrote:

So, a t-stop of "1.4" is the same with any lens, since it indicates how much light really "comes out at the end", not an f-stop. If two lenses are said to have a t-stop of "2.0" then these two lenses will expose the same. With two lenses with "f2.0" there might be a difference.


Which also means two lenses with the same t-stop and different f-stop, while exposing the same, will have different DOF.

Thought experiment: an lens at f/1.4, a second lens at f/4 and a third lens at f/1.4 with a 4-stop ND filter on the front. One and three have the same DOF. Two and three need the same exposure.