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Jupiter 11 / 4 Can you see any significant CA?
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PostPosted: Wed Jul 09, 2014 10:55 pm    Post subject: Jupiter 11 / 4 Can you see any significant CA? Reply with quote
This shot of the church clock is my test for CA, if anything can create the dreaded purple fringe this shot can. I shoot wide open, the clock is at an angle so focusing on the centre makes the top and bottom slightly out, the contrast of the black and white clock face is very high, and if the sun is on it then it's 10 times worse.
This is straight out of the camera, just resized, ISO 250 @ 1/2500 and f4. I was staggered by the lack of CA from this old lens, I think it is coated as there are magenta and gold reflections, whatever - it works! There is a trace noticable in the 100% crop, but it's possibly the least I've seen out of my many lenses





PostPosted: Fri Jul 11, 2014 9:52 am    Post subject: Re: Jupiter 11 / 4 Can you see any significant CA? Reply with quote
Lloydy wrote:
This shot of the church clock is my test for CA, if anything can create the dreaded purple fringe this shot can. I shoot wide open, the clock is at an angle so focusing on the centre makes the top and bottom slightly out, the contrast of the black and white clock face is very high, and if the sun is on it then it's 10 times worse.
This is straight out of the camera, just resized, ISO 250 @ 1/2500 and f4. I was staggered by the lack of CA from this old lens, I think it is coated as there are magenta and gold reflections, whatever - it works! There is a trace noticable in the 100% crop, but it's possibly the least I've seen out of my many lenses


Glad you got an adapter to try it out. Yes I do see the slight fringing on the crop, but it is not noticeable on the
original. Yours seems pretty sharp at f4. seems like mine is softer. I hope you enjoy using it. I like it's small size
besides the results I get.


PostPosted: Sat Jul 12, 2014 7:39 pm    Post subject: Reply with quote
LLoydy, the jupiter 11a's that i have are the same really hard to see CA on them both have different colour finish


PostPosted: Sat Jul 12, 2014 10:09 pm    Post subject: Reply with quote
I agree - negligible CA.
A very good lens from the results
Have you tried it with back-lighting?
OH


PostPosted: Sat Jul 12, 2014 11:34 pm    Post subject: Reply with quote
The clock is guaranteed to show CA, the white face is opaque glass and the sun reflects off it strongly, and the black face markings are all going in different directions, I've had some horrors from the church clock!

Here's another shot that would normally show CA , it was shot wide open and focused on the gravestone, the grass was blowing about wildly and in front and behind focus, the strong sidelight would be enough to make CA. But this is very good, you have to go to 100% and beyond to start to notice any. No PP at all, and way overexposed. Even after adjusting the levels it's good



I can't think of many lenses I've got that show this little CA, And it is a great lens in all respects, a little gem.


PostPosted: Sat Jul 12, 2014 11:49 pm    Post subject: Reply with quote
Lloydy wrote:
The clock is guaranteed to show CA, the white face is opaque glass and the sun reflects off it strongly, and the black face markings are all going in different directions, I've had some horrors from the church clock!

Here's another shot that would normally show CA , it was shot wide open and focused on the gravestone, the grass was blowing about wildly and in front and behind focus, the strong sidelight would be enough to make CA. But this is very good, you have to go to 100% and beyond to start to notice any. No PP at all, and way overexposed. Even after adjusting the levels it's good



I can't think of many lenses I've got that show this little CA, And it is a great lens in all respects, a little gem.


Agree
OH


PostPosted: Sun Jul 13, 2014 1:55 am    Post subject: Re: Jupiter 11 / 4 Can you see any significant CA? Reply with quote
Lloydy wrote:
This shot of the church clock is my test for CA, if anything can create the dreaded purple fringe this shot can.


The posted image is not totally completely free of chromatic aberration, but the level is very low and almost imperceptible. It seems that the Jupiter 11 is a copy of Carl Zeiss Sonnar 135mm F4, which is a fantastic lens. No surprise, therefore, that the Jupiter 11 produces excellent images.

I would like make a few general comments about chromatic aberration:
1) All lenses suffer from chromatic aberration, including those called APO.
2) The chromatic aberration can appear, or not, in a photo, depending on the image content.
3) There are two types of chromatic aberration: lateral and longitudinal.
4) The coating has no effect on chromatic aberration.

When people speak of chromatic aberration, they are usually thinking about lateral CA, which produces color fringes on strong contrast transitions. The lateral CA vanishes in the very center of the field, but its intensity grows continuously with increasing distance from the center, so the lateral CA is largest at the corners. A nasty characteristic of the lateral CA is that it almost does not vary with aperture, unlike other aberrations (spherical, coma, astigmatism, etc.) that diminish rapidly with decreasing the lens aperture.

The other type of chromatic aberration is the longitudinal CA, whose intensity is more or less constant along the field. However, the longitudinal CA decreases rapidly as the lens aperture is closed down.

In my opinion, the posted photo is not very appropriate to show lens lateral CA because the clock is centered in the image. I can see only a small amount of purple fringing in the crop, but in this type of photo only a crappy lens would exhibit significant lateral CA.

The photo is not appropriate to show longitudinal CA, too, because there are no strong point sources of light ("stars"), or reflections from bright light sources.

I hope that it does not sound pretentious, but I would like to show how to test a lens with respect to chromatic aberration. I will use for demonstration a Pentacon 135mm F2.8 lens, which I believe has a similar performance to that of the Jupiter 11.

Lateral CA test
What you need is a test chart with black squares on a white background. The sides of the square should be in the radial and tangential direction.



Below is a crop of the central region occupying an area equivalent to the clock in the OP. The USAF1951 diagram is in the center of the photo.
For the reasons previously commented, you can hardly see any lateral CA in the central region of the image.

Pentacon 135mm F2.8 at F4 – test chart center - 100% crop:


The top left corner crop shows the lateral CA at maximum intensity. Notice how the color fringes appear only on the edges in the tangential direction, and not on the edges in the radial direction. Also note that the colors of the color fringes are complementary, blue and yellow-green for the Pentacon 135mm F2.8.

Pentacon 135mm F2.8 at F4 – test chart upper left corner- 100% crop:



Longitudinal CA test
You need strong point light sources to "excite" the longitudinal CA. A good idea is to shoot a night scene with distant street lights, as shown below.

Pentacon 135mm F2.8 wide open – street lights - FULL IMAGE:



Pentacon 135mm F2.8 wide open – street lights - 100% CROP:



Note the colored halos around the strong lights in the center of image. In particular, the blue halos around the mercury-vapor lamps are highly visible in the 100% crop. Around the other bulbs (I believe they are sodium-vapor lamps) the halos are magenta and of lower intensity because the sodium-vapor lamp emission of blue is relatively weak.

As said before, the longitudinal CA can be controlled by stopping down the lens. The photos below show how closing just one stop was enough to make the halos practically disappear. Also note how the sharpness increases considerably because of the reduction of the spherical aberration.

Pentacon 135mm F2.8 at F4 – FULL IMAGE:


Pentacon 135mm F2.8 at F4 – 100% CROP:


PostPosted: Sun Jul 13, 2014 7:50 am    Post subject: Reply with quote
I agree Gerald, there is some CA in the pictures I posted - as you say "all lenses suffer from CA". The clock is a rough and ready test for sure, and I generally use it as a general test for any lens, shooting it at an angle I get front and back oof and I can get a good feel for a lens shooting the clock and the gravestones in the churchyard, it's easily repeatable.

I've only used the lens a couple of times, and it is impressing me a lot. It's raining hard today so I can't see me trying the ultimate test of bright sun shining through the trees onto the stream. I have high expectations from this lens. Wink


PostPosted: Sun Jul 13, 2014 7:52 am    Post subject: Reply with quote
Just to give you some idea of how much I rate the J11 - I have four copies and three copies of the Sonnar 4/135 it is copied from. Smile


PostPosted: Sun Jul 13, 2014 8:32 am    Post subject: Reply with quote
I can see why Ian.



This is a shot I took at a junior cricket team practice the other night.


PostPosted: Thu Jul 24, 2014 1:42 am    Post subject: Reply with quote
i dont see CA anywhere, actually in my opinion these shots are amazing
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