[Jewelltrail]

question mark definition

question mark

1. a mark of punctuation (?) put after a sentence, word, etc. to indicate a direct question, and also used to express doubt, uncertainty, etc.; interrogation mark
2. ☆ an unknown factor

jct us101 Could you imagine how well a Sigma nifty fifty lens would sell if they made it? Why haven't they yet?

Hey, JCT101, Yes, I can imagine a Sigma nifty 50 because I read a lot about it at our lens review forum. If you have never visited that part of our forum yet, let me know & I'll provide a link to it. There are so many lenses coming and going that it is virtually impossible for anyone to know them all.

If you need any more help, just ask another question bro.

[Blue]

question mark definition

question mark

1. a mark of punctuation (?) put after a sentence, word, etc. to indicate a direct question, and also used to express doubt, uncertainty, etc.; interrogation mark
2. ☆ an unknown factor




Hey, JCT101, Yes, I can imagine a Sigma nifty 50 because I read a lot about it at our lens review forum. If you have never visited that part of our forum yet, let me know & I'll provide a link to it. There are so many lenses coming and going that it is virtually impossible for anyone to know them all.

If you need any more help, just ask another question bro.

I'm not your bro. One more time, he wasn't asking for help. Go look up "rhetorical question" and figure it out. Finally, the humor in his question was that the current Sigma lens lineup and pending lenses have been listed and linked to in this thread.

Here is some more words for you to look up "son." 1. humor 2. sarcasm 3. subtle

You implied that I and a few others go around mocking people for asking questions on which you are full of .

[Jewelltrail]

Wow, telepathic too? Reading into my words, what work for you? My point is made--I'll move on--be good now.

Blue: I'm not your bro.

You are confused again--read the post, this bro was meant for JCT.

Just one more question though---what is the use of my question marks above?

[Blue]

Wow, telepathic too? Reading into my words, what work for you? My point is made--I'll move on--be good now.

You are confused again--read the post, this bro was meant for JCT.

Just one more question though---what is the use of my question marks above?

Whatever they are, they are not complete sentences.

---

Last edited by Blue; 05-08-2010 at 10:15 PM.

[yilmazurgun]

Sigma 85? I'd start saving for Carl Zeiss 85.

Thats the magical word. I think the same. zeiss is top winner at wide aperture. Its manuel but after using some time, our hands may work like auto

[Digitalis]

"Sigma 150 2.8 macro: Pentaxians cry like schoolgirls that this is not available. Brilliant."

- you should see what the SMCP FA*200mm f/4 ED IF Macro can do, it has leicaphiles throwing themselves off tall things... the sigma 180mm f/3.5 APO EX DG isn't bad either, just don't try using to focus on something that is further than 8 feet away; the image quality degrades very sharply.

the FA31 beats the 30mm f/1.4 in corner sharpness, though the centre portion of the image from the sigma is remarkably sharp - though it can't be used on film.

sigma 100-300 f/4 APO EX DG is a bit over rated I own one and to be honest, you have to stop the thing down to f/8~f11 (depending on focal length and how close your subject is) to get consistent image quality. apart form that it's not bad.

sigma 50mm f/1.4 - I hate this lens. it's bokeh is artificial and flat. the voigtlander nokton 58mm f/1.4 is optically superior.

Sigma 50-150mm f/2.8 - never used it. but it's generally a well thought out lens it's DX only though.

70mm f/2.8 - I don't like short macro lenses, for starters they aren't Apochromatic. APO lenses below 100mm don't exist. I never have had a need/use for them. Though I appreciate how sharp it is.

[Class A]

70mm f/2.8 - I don't like short macro lenses, for starters they aren't Apochromatic. APO lenses below 100mm don't exist.

In what way does it affect the Simga 70/2.8 that it isn't an APO lens? I certainly has no issues with CA. Given how many Pentax lenses have severe CA issues it would be appropriate to translate PF to "Pentax Fringing" rather than "Purple Fringing". Many <100m macro lenses aren't designated as APO (Tamron 90, Tokina ATX 90mm) and are considered great or even legendary.

What is the relationship between APO and the focal length being lower than 100mm? Do you have a pointer to a technical discussion?

BTW, there are 90mm and 60mm counter examples to your statement.

---

Last edited by Class A; 05-10-2010 at 03:14 AM.

[Digitalis]

In what way does it affect the Simga 70/2.8 that it isn't an APO lens? I certainly has no issues with CA. Given how many Pentax lenses have severe CA issues it would be appropriate to translate PF to "Pentax Fringing" rather than "Purple Fringing". Many <100m macro lenses aren't designated as APO (Tamron 90, Tokina ATX 90mm) and are considered great or even legendary.

What is the relationship between APO and the focal length being lower than 100mm? Do you have a pointer to a technical discussion?

BTW, there are 90mm and 60mm counter examples to your statement.

Apochromatic lens designs aren't going to guarantee that a lens is going to perform superbly. I was merely stating that there are precious few of them below the 100mm mark due to the fact that such a degree of correction for chromatic error isn't likely to be observable,let alone practical; I don't think I have heard of anyone calling into question the chromatic error present in the DA15mm f/4..why? because the error is masked by the fact that our cameras are unable to resolve it...yet. (I'm talking about more than simple PF which I do believe is inherent in lens design digital sensors merely exacerbate it).

Manufacturers for years have called lenses that have optical correction approximating the level of correction found in an apochromatic lens to them,"APO" is nothing more than a marketing catchphrase. The difference between an actual apochromatic design and a design that has similar levels of correction to an apochromatic lens are mostly noticeable in both the in focus and the transition to the OOF portion of images. The voigtlander 125mm f/2.5 is a superb example of apochromatic design the Pentax FA77mm f/1.8 is not.


Your example of the schneider lens; I'll take schneiders word for it so APO lenses do exist below the 100mm mark. though I'll point out it is made for a much larger format than full frame. I should have been more specific that there aren't any Apochromatic lenses wider than 100mm for the standard 24X36 standard full frame cameras. so I stand corrected(so to speak)...though take a look at it's price mate: take a look at the Schneider 28mm f/3.5 APO sironar 10K - what did they make that lens's barrel with? unobtanium??

the Voigtlander 90mm APO-Lanthar is a bit of a misnomer, the lanthar lens design is based on the heliar design which offers very good suppression of astigmatism,coma, and axial aberrations at the shorter focal lengths. It's in the longer ones where apochromatic levels of correction are required to bring the axial aberrations under reign. Because when you make a lens longer you're also increasing the margin for chromatic error.

[Class A]

(I'm talking about more than simple PF which I do believe is inherent in lens design digital sensors merely exacerbate it).

PF is caused by CA (other explanations aren't very convincing, AFAIC) and is indeed an inherent problem in lens design.

The difference between an actual apochromatic design and a design that has similar levels of correction to an apochromatic lens are mostly noticeable in both the in focus and the transition to the OOF portion of images.

I've never heard anyone making that claim. An APO lens is characterised by the fact that it manages to focus three wavelengths at the same focal plane. For these three wavelengths it manages zero CA. I'd be surprised if that automatically had implications on OOF transitions (other than they are less colourful).

After I read your response, I don't get the drift of the post I replied to initially. You seem to be saying that you don't like lenses that inherently don't need the APO correction that longer lenses need? You don't like them because they don't have something (APO) that they don't need?

I might be wrong but with PP CA correction, PF and other CA issues have become less of an issue so whether a lens is an APO lens or not seems less relevant than it used to be and other criteria (e.g., bokeh) can assume higher priority.

[Derridale]

the sigma 180mm f/3.5 APO EX DG isn't bad either, just don't try using to focus on something that is further than 8 feet away; the image quality degrades very sharply.

Seems like a lot of arguments going on in this thread, instead of discussing the new Siggie lenses - the 8-16 and the 85/1.4

Re the statement above by Digitalis - I wouldn't agree with that at all. I have a Siggie 180, and it is an amazing lens.

See:



and:



Just two examples taken with the 180 from quite a distance...... First one was a good 20 metres away, the second about 30 metres. Both on that Siggie that you imply is no good at any distance

Anyway - back to the original topic - I have the 8-16mm on pre-order with Adorama, and given that I already have a Pentax 77mm LTD, I'm wondering if there is anything to be gained by trying the Sigma 85/1.4?

[Digitalis]

"PF is caused by CA (other explanations aren't very convincing, AFAIC) and is indeed an inherent problem in lens design."

I have no idea what is causing it,I don't buy into some of the hokey explanations that others ascribe to. Zeiss lenses are well known for doing it and they are supposedly designed to be relatively unscathed by such egregious lens design bloopers.

"An APO lens is characterised by the fact that it manages to focus three wavelengths at the same focal plane. For these three wavelengths it manages zero CA. I'd be surprised if that automatically had implications on OOF transitions (other than they are less colourful)."

That's exactly what i'm saying, the transition between the in focus and out of focus areas will be free of any colour fringing. The FA77 is a text book example of this type of fringing. the voigtlander 125mm f/2.5 APO Lanthar is a superb example of apochromatic correction.

"After I read your response, I don't get the drift of the post I replied to initially. You seem to be saying that you don't like lenses that inherently don't need the APO correction that longer lenses need? You don't like them because they don't have something (APO) that they don't need?"

I don't like it when a company labels a lens APO when it really isn't. It puts an unfair expectation on the performance of the lens(even if it is exceptional) and is more often than not used as an excuse to hike the price up - But these companies can basically do what the want, I'm just a consumer like everyone else.

I have nothing against apochromatic lenses, in fact; I wish someone would make a fast fifty apochromatic...that would irk leica photographer to no end. because it's optical aberrations would be largely cancelled out by the APO corrections and theoretically, the only resolution limiting factor to such a lens would be diffraction itself. I don't even want to know what a 50mm f/1.2 APO lens would cost though - seriously, I own a noctilux 50mm f/1.0 that is the most expensive 50mm lens I will ever own.


"I might be wrong but with PP CA correction, PF and other CA issues have become less of an issue so whether a lens is an APO lens or not seems less relevant than it used to be and other criteria (e.g., bokeh) can assume higher priority."

But the aberrations are still there - you can correct and image till the cows come home but it isn't going to look as good as an image taken with a lens that didn't have the same flaws. The differences may be slight, but they are there.

[Digitalis]

"Re the statement above by Digitalis - I wouldn't agree with that at all. I have a Siggie 180, and it is an amazing lens."

I have the sigma 180mm f/3.5 APO EX DG as well, so I know how good it is at macro work. however all I was saying that it is abysmal for telephoto work approaching the infinity focus setting.


"Just two examples taken with the 180 from quite a distance...... First one was a good 20 metres away, the second about 30 metres. Both on that Siggie that you imply is no good at any distance "

Then I propose a test; three images at the bottom of this post were taken with three lenses. one was taken with a zoom lens, another with a lens I use as a book end, and one was taken with the sigma 180mm f/3.5 - all the same exposure 1/320th @ f/5.6 ISO100 -focused at infinity- tripod with mirror lock up jpg saved at quality 8

I know you won't be able to see much but I suggest you pay attention to the detail in the foliage -tell me which one was taken with the sigma 180.


"Anyway - back to the original topic - I have the 8-16mm on pre-order with Adorama, and given that I already have a Pentax 77mm LTD, I'm wondering if there is anything to be gained by trying the Sigma 85/1.4?"

- the FA77 will do fine, the built in lens hood will most likely outlast anything sigma can come up with. And the FA77 will most likely need far less focus adjustment given sigmas track record.

[Derridale]

Well that seems like a bit of a silly game, as it is a pure 1 in 3 guess, obviously. And from the point you're trying to make, perhaps the right-hand image is the Siggie 180. But, methinks you may just have a sub-optimal copy?

All I can tell you is that those two images posted above (and I have loads more) are pretty clear, have lovely bokeh, and were taken at the distances quoted. The spider web in particular was a challenge, as it was handheld, taken in the last dying rays of sunset, and the web was strung across two trees about 30 metres away and just caught the light for a few seconds, during which I lifted the camera, focussed, and shot. There is no post-processing on that image either.

So, needless to say, I'm quite happy with my copy. But I certainly agree that it is a brilliant lens for macro work.

Anyhow, once again back to the original topic - yes, my thinking is in line with yours re the Sigma 85/1.4 My Pentax 77mm Ltd is a brilliant lens, and I can't see any advantage to be gained with the Siggie, unless I want to get one for my wife who uses a K10D. However, that 8-16mm is looking like the goods, and my preorder is still delayed, with no shipping date yet in sight.

Once I have it and shot some photos with it, I'll put them up here.

[Digitalis]

"Well that seems like a bit of a silly game, as it is a pure 1 in 3 guess, obviously. And from the point you're trying to make, perhaps the right-hand image is the Siggie 180."

Don't be condescending, it's not a silly game. I'm making a point based on image quality which is a relevant factor here. Be thankful i'm not some ignorant twit who quotes Lp/pm numbers for a variety of sources that have no relation and treats them like gospel. go ahead, prove me wrong!

"But, methinks you may just have a sub-optimal copy?"

The thought that mine is sub optimal had occurred to me,it's not impossible. Though I cannot see anything wrong with it's optical performance at 1:5 to 1:1 magnification range so I'm content to use it in that capacity. besides, I have other lenses that are designed for long distance work. It's such a nuisance that my FA*200mm f/4 ED Macro is off for repairs, then I would have something to benchmark the sigma 180 against - admittedly an unfair comparison, but it would help if I could test mine against something with similar capabilities.

[cmitch]

Sweeeeet.
I'll be all over it.