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04-15-2011, 05:36 PM   #106
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This is first ive heard of a new Sigma 135 f/2.
You have to give sigma credit for bringing out these and picking up Pentax's slack in the new lens department.

04-15-2011, 05:40 PM   #107
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QuoteOriginally posted by Winder Quote
Rumor is Sigma is releasing 3 more "pro" grade primes for FF bodies. 24mm, 35mm, & 135mm.

The final lineup will be:
24mm
35mm f/1.4
50mm f/1.4 (current)
85mm f/1.4 (current)
135mm f/2
150mm f/2.8 OS Macro (on its way)

Look at the cost for the latest 24mm & 35mm pro-grade glass from Sony/Zeiss, Nikon & Canon. There is definite room for Sigma to enter the market.

The 135mm f/2.0 is basically a fast 200mm prime on your Pentax. You get the lens that renders like a 135mm, has the DoF of the 135mm, the size and weight of the 135mm, but the reach of a 200mm. It is a good length for indoor sports and F/2 is welcome in those indoor venues.

As a long time Canon user you could not have paid me to take Sigma lenses on a job. Nothing about the old Sigma lenses appealed to me. Since the new 50mm f/1.4 and HSM I have been very impressed with what they have produced.
I read about that too here.

The 24 was also rumoured to be a f/1.4, like the grownups

But yeah, lots of room in the market for good, fast AF primes!
04-15-2011, 05:43 PM   #108
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QuoteOriginally posted by TOUGEFC Quote
This is first ive heard of a new Sigma 135 f/2.
You have to give sigma credit for bringing out these and picking up Pentax's slack in the new lens department.
What do you want to bet it'll be tiny
04-18-2011, 07:17 AM   #109
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You are talking about Field of View. Look at Pentaxor's post for perspective. If you started in 2010, you gotta be open-headed enough to learn instead of calling people idiots and ignoramules. How about trying out an 18mm and a 500mm and show proof there?

QuoteOriginally posted by Pentaxor Quote
I hope that geometric formula can solve or equate the perspective differences of these images taken by corresponding lens focal lengths...

now, can we see some images if that formula works?
This is lovely!

04-18-2011, 07:54 AM   #110
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QuoteOriginally posted by icypepsi Quote
You are talking about Field of View. Look at Pentaxor's post for perspective. If you started in 2010, you gotta be open-headed enough to learn instead of calling people idiots and ignoramules. How about trying out an 18mm and a 500mm and show proof there?
I see you didn't even try to get what that little statement shows. It proves every spot will be reflected into relatively the same point of the sensor, no matter what the size it has and it only depends on the range and FOV.
As for Pentaxor post I don't see how it relates to the subject. Everyone knows about different perspective distortions when using different focal lengths.
04-18-2011, 10:02 AM   #111
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QuoteOriginally posted by Emacs Quote
I see you didn't even try to get what that little statement shows.
You have proved nothing in the diagram. You are only stating facts for parallel lines and alternate angles therein. These are theorems that already exist. And by the way, how do you expect people to understand what's in your mind? Should you not write statements to explain? You haven't even mentioned what P' and QED are. Is it left for readers to assume?

QuoteOriginally posted by Emacs Quote
It proves every spot will be reflected into relatively the same point of the sensor, no matter what the size it has and it only depends on the range and FOV.
This is true only for a given lens of a certain FL (Xmm), when you shift between sensors of two different sizes. The moment you bring in another lens with a different FL (Ymm), the way every 3 dimensional point is rendered on the same sensor is different for both lenses (at Xmm & Ymm). Just like how it is different for different FL in Pentaxor's example (forget theory, the example is practical proof that it is different. Forget mathematics, you can see it with your own eyes). This is what is perspective. It is the relative distance between points on the 2D sensor, rendered differently for the points in 3D by different FL. So, when it is different for two FLs, how can you get the same effect out of one single lens (considering primes only). This in turn proves that you cannot replace a 77mm or 85mm with a cropped 50/55mm image. Let alone the loss in resolution.


QuoteOriginally posted by Emacs Quote
As for Pentaxor post I don't see how it relates to the subject. Everyone knows about different perspective distortions when using different focal lengths.
Then when you agree it's different, how can you reject the "difference" saying you can produce it all in a single lens? What is your point?
04-18-2011, 10:39 AM   #112
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QuoteOriginally posted by icypepsi Quote
You have proved nothing in the diagram. You are only stating facts for parallel lines and alternate angles therein. These are theorems that already exist. And by the way, how do you expect people to understand what's in your mind? Should you not write statements to explain? You haven't even mentioned what P' and QED are. Is it left for readers to assume?
Well, I see I need some more explanation. So, each spot P in FOV will be reflected on the point P' placed at the sensor. No matter what the sensor size is. The latest relation shows the relative position of P' only depends on P and has no dependance on sensor size.
QuoteQuote:
Then when you agree it's different, how can you reject the "difference" saying you can produce it all in a single lens? What is your point?
My point is "same FOV ≡ same perspective".
04-18-2011, 02:50 PM   #113
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QuoteOriginally posted by Emacs Quote
Well, I see I need some more explanation. So, each spot P in FOV will be reflected on the point P' placed at the sensor. No matter what the sensor size is. The latest relation shows the relative position of P' only depends on P and has no dependance on sensor size.
... all this, as long as FL is constant. (Some how, and I'm feeling it's deliberately, you are missing on this statement again and again).

QuoteOriginally posted by Emacs Quote
My point is "same FOV ≡ same perspective".
Wrong at the basics.
1. different Lens FL = different perspective.
2. Different sensor size = different FoV.

Sensor size is not related to the Lens FL. If it were, everybody would buy only a single lens for a DSLR they bought!

And by the way, your geometry does not take into account the perspective. So with your stuff, you do not have a relationship with perspective. So then, without any proof, you believe that one can buy a fish eye lens and crop the image to get any larger FL!!!??

In Pentaxor's pics, did you not find any difference between those taken at different FLs? If you didn't, then u either don't understand FoV or perspective. I'd suggest you google and do some readup.

Sorry Pentaxians, I'm going way off topic here. I was just pissed that someone called people names mindlessly and said the 85mm was not required at all. I'm going to stop


Last edited by icypepsi; 04-19-2011 at 07:25 AM.
04-18-2011, 04:25 PM   #114
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Listen, dude. Learn the definitions: the EFL, the FOV. Then try to realize how senseless your assumptions are.
04-18-2011, 04:36 PM   #115
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ok guys. I think we have enough of all the scientific mumbo jumbo. now let's get back to what this thread is all about, Sigma 85 real world images. now where are some of those new samples?

anyway, I'm going out again tomorrow and try my luck if they have a copy for the K-mount for trial. if I get convinced on shelling out some 1k of mad money, expect me to post some photos soon. but that's one tough decision to make, especially where my present finances stand.
04-19-2011, 12:21 AM   #116
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QuoteOriginally posted by Winder Quote
Rumor is Sigma is releasing 3 more "pro" grade primes for FF bodies. 24mm, 35mm, & 135mm.

The final lineup will be:
24mm
35mm f/1.4
50mm f/1.4 (current)
85mm f/1.4 (current)
135mm f/2
150mm f/2.8 OS Macro (on its way)

Look at the cost for the latest 24mm & 35mm pro-grade glass from Sony/Zeiss, Nikon & Canon. There is definite room for Sigma to enter the market.

The 135mm f/2.0 is basically a fast 200mm prime on your Pentax. You get the lens that renders like a 135mm, has the DoF of the 135mm, the size and weight of the 135mm, but the reach of a 200mm. It is a good length for indoor sports and F/2 is welcome in those indoor venues.

As a long time Canon user you could not have paid me to take Sigma lenses on a job. Nothing about the old Sigma lenses appealed to me. Since the new 50mm f/1.4 and HSM I have been very impressed with what they have produced.

85/1.4, I'd rather just keep my FA* for the $100 delta.

Now, 135/2 is a different story altogether (There is the A*135/1.8, but 135mm for MF is really at the limits of my MF ability )
Looks like I need to wait and save up on this one.
04-19-2011, 01:25 AM   #117
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QuoteOriginally posted by pinholecam Quote
85/1.4, I'd rather just keep my FA* for the $100 delta.

Now, 135/2 is a different story altogether (There is the A*135/1.8, but 135mm for MF is really at the limits of my MF ability )
Looks like I need to wait and save up on this one.
Agree, I have exactly the same thought. A* 135 is the special, at least I prefer its rendition to one of the canon's 135L, but I would choose 135L because of the AF. On the other hand, 135 of sigma can be better than canon, since sigma 50f1.4 is better than canon 50f1.2 and 85f1.4 is on par with 85L f1.2 IMO.

Last edited by Emacs; 04-19-2011 at 01:31 AM.
04-20-2011, 02:13 AM   #118
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QuoteOriginally posted by icypepsi Quote
Wrong at the basics.
1. different Lens FL = different perspective.
Not quite correct.
FL of the lens has indirect effect on perspective.
What actually does matter is distance between sensor/film plane and subject.
Easy exercise to is, slap zoom on your camera and take a series of shots of the same subject from the same spot. Then take the widest shot and crop it to match the framing on the longest shot and then compare. The perspective will be the same.
What does change perspective is when you change the distance between camera and object. With the same zoom, take a picture on long(ish) end and then zoom out and recompose to match framing. Then compare your shots.....

QuoteQuote:
2. Different sensor size = different FoV.
If you keep the same lens, this is correct but if you change lens with the same ratio as sensor size then it's incorrect.

QuoteQuote:
In Pentaxor's pics, did you not find any difference between those taken at different FLs?
as I wrote above, the perspective didn't change because of different focal length but because the photog was moving from close to farther with each longer lens.
Shooting the same model from the same spot with different lenses wouldn't change the perspective.

QuoteQuote:
If you didn't, then u either don't understand FoV or perspective. I'd suggest you google and do some readup.
I'm not quite sure you are the one to give this advice based on your previous posts, unless I misread something

QuoteQuote:
Sorry Pentaxians, I'm going way off topic here. I was just pissed that someone called people names mindlessly and said the 85mm was not required at all. I'm going to stop
No need to apologize, the forum is here to discuss stuff....

is 85mm required on APSC? for the same purposes as 135 on film, definitely so, but but 85mm on APSC and 85mm on FF system are two very different things IMO.
If someone likes shooting that long on APSC then by all means the Sigma seems to be one helluva lens....
04-20-2011, 03:21 AM   #119
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QuoteOriginally posted by icypepsi Quote
A certain FL (Xmm) lens's perspective will be the same no matter what sensor you use it with.
This is only true, again, if you don't change the camera subject distance! If you put the 85mm Sigma on Pentax 35mm SLR and then on APSC K-7 DSLR you will have to flinch quite a bit to match the framing and that will change the perspective!
QuoteQuote:
It can never be replaced for the same perspective by another FL (Ymm) lens just because the FoV is the same.
Wrong again.
55mm on APSC will have offer the same or at least very similar perspective as as 85mm on FF. Why? Because thanks to differences in sensor sizes both cameras will the same (approximately) distance from subject...
QuoteQuote:
Perspective is...cut out nonsense.... how the subject appears...cut out nonsense.....at that subject distance.
Now it's correct...

Case rested. Back to pictures please.
Peter "asahiflex" can't wait for your comparison of the Sigma 85 with FA* and 77ltd. Please make the post big and visible!
It was partially you with quite some results that swayed me to give DA*55 another chance. Lately I have kind of lost my faith in Sigma glass but you may do the trick again

Regards
04-20-2011, 03:52 AM   #120
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I can't wait for the comparison! I now have the FA* 85, A* 85 and FA77 at home, but no Sigma to compare it with

By the way, as I have shown before (and it's quite logical): 55mm f/1.4 on APS-C is almost the same as 83mm f/1.9 on FF with regards to relative subject's size and DOF, while the camera is at the exact same spot.

Proof (and actually I should have stopped down the Takumar a little bit to f/2.1 to make the bokeh comparable):

DA* 55/1.4 on APS-C:


83mm f/1.9 Takumar on FF:
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