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Sony 135 STF has arrived :)

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laguire View Drop Down
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Post Options Post Options   Quote laguire Quote  Post ReplyReply Direct Link To This Post Posted: 26 December 2006 at 21:27
I'm not exactly understanding the rationale behind the uv or polarizing filter thought to cut down on chromatic aberration or purple fringing.

The apodizing filter I believe is near the aperture (not near the opening of the lens - perhaps the word filter is the confusing part of the term) so you should not get a significant vignetting effect. It is not there to filter out the peripheral part of the image.

Rather it filters out a graduated amount of the out-of-focus light rays so that there is a smooth transition between focused and out of focused areas. THink of an aperture that is not solid black but gradually more opaque. (again this is further back and not at the opening of the lens)

A polarizing filter lets in light waves oriented in one direction (and filters out the rest). I guess if not designed properly it could theoretically filter out a particular wavelength more than another (but if it was that significant as to eliminate chromatic aberration, than you would have a definite color cast on the images - oh and chromatic aberration in only one orientation).

A UV filter would have to cut into the visible light range significantly (most good UV filters minimize the loss of light in the visible range) to affect chromatic aberration and would again cause a substantial color cast.

There really shouldn't be any different effect on the STF with a polarizing or UV filter than on any other lens unless I'm missing something. Of course a test photo would be great to try it out.

It is quite possible that the apodization filter does induce chromatic aberration. I'm still not totally clear about the design of this element but as with any element, it probably refracts different wavelenghths differently.

Of course H K F may be right and this may not even be chromatic aberration.
 



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cjc181166 View Drop Down
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Post Options Post Options   Quote cjc181166 Quote  Post ReplyReply Direct Link To This Post Posted: 26 December 2006 at 21:50
I was just reading through the manual for the 7f regarding STF. I does note that when using the STF mode on the 7f "When the subject is bright, STF is not possible. The aperture's background will appear bright." Is it possible that this same principle holds true for the lens as well? Pictures taken in bright light get CA, but in muted light a STF feel.
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laguire View Drop Down
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Post Options Post Options   Quote laguire Quote  Post ReplyReply Direct Link To This Post Posted: 27 December 2006 at 02:17
I assume the stf mode is not posible due to the need to sum up 7 exposures. in bright lighting, it would probably lead to overexposure.

Never had a 7f, just my best guess..
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H_K_F View Drop Down
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Post Options Post Options   Quote H_K_F Quote  Post ReplyReply Direct Link To This Post Posted: 30 December 2006 at 17:13
Great shots, Kiklop.

I was pretty frustrated about purple fringing (PF) in this "digital" age; I had a mix bag of observations...

When shoot raw + jpeg with a 5D, PF shows up more in raw than jpg. So some of it has to do with the processing unit in the camera. The stronger the sharpening, the higher chance PF shows up.

It happens mostly in wide angle or wide-open shots... I found thoses in 300 f2.8G step down to f8; also on other lens and even camera systems as well.

It happens more often with a 2xTC with a high contrast edge, I think it may attribute to "axial or longitudinal chromatic aberration"... more of a lens degrading issue...

I found the following worth reading...
The Dreaded Purple Fringe

Purple fringing
Dynax 7,9,A2,5D
Sony A700,A900,A99
17-35G, 24-70Z, 28-70G, 70-200G, 35G, 50D, 85G, 100D, 300/2.8G, 600G
NEX5,5R,A7Rii
10-18, 16, 18-200, 24-70Z, 35/2.8Z, 55/1.8Z, 85/1.8Z, 70-200/4
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kiklop View Drop Down
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Post Options Post Options   Quote kiklop Quote  Post ReplyReply Direct Link To This Post Posted: 30 December 2006 at 18:10
Well, i need to be honest and say that the PF issue isn't that much present as i have experienced the first day with the lens. Yes it's here (again, i wasn't expecting this since i never heard about any problem with this lens in this regard) but after several days of use i'm happy my first experiences hasn't proven to be a rule.
I love this lens and if it was an AF i would start saving for it. Since it's manual focusing only and we don't have FF DSLR (with bigger and more appropriate VF for manual focusing) i have some reservations on how much would i use it. Wide open, DOF is shallow enough to require absolute focusing accuracy which is something I'm not able to obtain all the time.
I hope i will receive CZ 135 soon (for testing) which may be just great alternative to STF lens (but i doubt there is any other lens, not only in minolta mount with such gorgeous bokeh performance)
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cjc181166 View Drop Down
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Post Options Post Options   Quote cjc181166 Quote  Post ReplyReply Direct Link To This Post Posted: 30 December 2006 at 18:32
Kiklop,

Is it fair to say then that the PF or CA, whichever you choose to call it, only occured in bright situations off of bright (white) subjects?
 



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kiklop View Drop Down
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Post Options Post Options   Quote kiklop Quote  Post ReplyReply Direct Link To This Post Posted: 30 December 2006 at 19:18
Originally posted by cjc181166 cjc181166 wrote:

Kiklop,

Is it fair to say then that the PF or CA, whichever you choose to call it, only occured in bright situations off of bright (white) subjects?


Yes, but there was some situations were i didn't expect it .. like in the sample image i showed in my first post (i taken "millions" time this frame even with some old m42 lenses and never saw this)
100% crop
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cjc181166 View Drop Down
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Post Options Post Options   Quote cjc181166 Quote  Post ReplyReply Direct Link To This Post Posted: 30 December 2006 at 19:26
Then I guess with the STF it is best to avoid bright (shiny/reflective) surfaces to get the most out of this lens. It would be interesting to take that same shot on and overcast day to see if the PF shows up. (another excuse to go outdoors and shoot somemore)
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Post Options Post Options   Quote kiklop Quote  Post ReplyReply Direct Link To This Post Posted: 30 December 2006 at 20:28
I need more time to write my final conclusions and i will leave more details for a future full review .. but .. here is just one comparisons between 135STF and 100/2 (an old lens which is supposed to be more prone to various issues because of older coatings and design).

Tested frame


100% crop 135STF & f4.5


100% crop 100/2 $ f2.8


(please don't judge sharpness since this wasn't taken with sharpness in mind)

I'm still recovering for some health problems but i hope i will be able to make interesting set-up at home that will be of some use for lens comparisons (i don't promise anything :)).
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Cekari View Drop Down
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Post Options Post Options   Quote Cekari Quote  Post ReplyReply Direct Link To This Post Posted: 30 December 2006 at 22:31
Oh, that made the stf look ugly :(

In the fishhead I could live with after some pp but not on the 2 last ones ..

But ok, if you know how to avoid those shots, but then it kind of made it for only this or that shots kind of and at a high price imo
Images https://www.flickr.com/photos/cekari/sets/ ,

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ab012 View Drop Down
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Post Options Post Options   Quote ab012 Quote  Post ReplyReply Direct Link To This Post Posted: 30 December 2006 at 23:42
ouch... what happened to that first shot? =)

Is it possible to re-do that shot just to remove any effects of OOF (or shake even? nearly/all of the colour patches are at the bottom of the lights and i have not seen the blue on the STF before..)

When you said CA I thought you were testing it on the a100... i am surprised so much showed up with the 7D.



Edited by ab012 - 30 December 2006 at 23:44
Bernard

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kiklop View Drop Down
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Post Options Post Options   Quote kiklop Quote  Post ReplyReply Direct Link To This Post Posted: 31 December 2006 at 11:48
This is an average shoot (which means i have much worst result but some better one too). I will upload more comparisons images once i come to some "final" conclusions.
Maybe i should stop writing about this since it can be wrongly taken as a huge issue which isn't; is here but isn't so severe as may seems from my samples.
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Cekari View Drop Down
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Post Options Post Options   Quote Cekari Quote  Post ReplyReply Direct Link To This Post Posted: 31 December 2006 at 15:54
I don't think it's a huge issue, if you avoid some of those situations and further more if you don't need to crop em a lot or print at very big sizes.

Images https://www.flickr.com/photos/cekari/sets/ ,

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Post Options Post Options   Quote ab012 Quote  Post ReplyReply Direct Link To This Post Posted: 31 December 2006 at 19:11
I agree with kiklop - it is not a hudge issue.

In my own expereince, on the 7D it is not even an issue worth being worried about - without a TC attached.

Basically - On the 7D, In all the pics i have taken with this lens - CA occasionally happens, but very rarely. The situation is so minor IME that I dont find the need to stay away from possible CA situations.

(It is more apparent on the a100 though)
Bernard

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