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07-06-2014, 05:27 PM   #76
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QuoteOriginally posted by fuent104 Quote
On the need for fast primes...I was shooting a wedding the other day with the Canon 135f2. it was an outdoor, low light situation. f1.4 would have been amazing (one of the other photographers had an 85f1.2).

There's simply no substitute for a fast lens with autofocus, and it would be nice if Pentax added more of them to the lineup, particularly in longer focal lengths. And yes, I know they would be larger, but sometimes you really do need a fast lens.
It's impossible to shoot an F/2 lens while getting more than an eyelash in focus.

07-06-2014, 05:47 PM   #77
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QuoteOriginally posted by fuent104 Quote
On the need for fast primes...I was shooting a wedding the other day with the Canon 135f2. it was an outdoor, low light situation. f1.4 would have been amazing (one of the other photographers had an 85f1.2).

There's simply no substitute for a fast lens with autofocus, and it would be nice if Pentax added more of them to the lineup, particularly in longer focal lengths. And yes, I know they would be larger, but sometimes you really do need a fast lens.

A 135mm f/2 is less than ideal in that situation, DoF is too small. What's best is a camera with a sensor like the Sony A7S (fingers crossed Pentax uses this some day in a full frame body):

http://www.stevehuffphoto.com/2014/07/01/the-sony-a7s-digital-camera-review-wow-period/
07-06-2014, 06:35 PM   #78
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Speaking of weather sealing, I wonder why or if it would be beyond the realm of possibility to retrofit the standard Pentax primes with weather sealing?

Anyone feeling entrepreneurial?
07-06-2014, 06:49 PM - 1 Like   #79
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QuoteOriginally posted by nater Quote
A 135mm f/2 is less than ideal in that situation, DoF is too small. What's best is a camera with a sensor like the Sony A7S (fingers crossed Pentax uses this some day in a full frame body):
Too small for what? You don't even know what I was shooting.

I didn't notice I couldn't use the lens I was using while I was actually using it. Neither did the photographer using the 85 f1.2. I guess all of the files should be deleted because we couldn't use those lenses.

I guess all fast lenses might as well be thrown in the trash, too, because you can't use them. Should we just shoot everything at iso 100,000, at f8?

07-06-2014, 09:07 PM   #80
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QuoteOriginally posted by fuent104 Quote
Too small for what? You don't even know what I was shooting.

I didn't notice I couldn't use the lens I was using while I was actually using it. Neither did the photographer using the 85 f1.2. I guess all of the files should be deleted because we couldn't use those lenses.

I guess all fast lenses might as well be thrown in the trash, too, because you can't use them. Should we just shoot everything at iso 100,000, at f8?
In my experience shooting when fast glass with a narrow depth of field the risks become very high in terms of being able to nail the exact right point of focus at a live event, and also compositionally constraining in terms of what is and isn't in focus. A camera's AF system cannot necessarily predict what you exactly want to focus on, and sometimes working around that by choosing a specific focus point and manually triggering/suppressing AF or pre-focussing on a specific point in anticipation of where you subject will be is at times insufficient due to the dynamics of the situation.

Now let's talk specifics. You mentioned a Canon 85mm f/1.2. Let's assume a EOS 5D Mark III because if you're dropping $2.2k on a lens, you might as well drop $3.4k on a full frame body. Being a portrait lens, I'll take a guess that the subject would be about 15 feet away (let me know otherwise and I can re-do the calculations). The total depth of field would be 8.04 inches. For me at least, that's risky. I would not recommend shooting everything at ISO 100,000 and f/8 since the shots would look more like something out of a point and shoot because the DoF has expanded to 5.7 feet which I would think would be compositionally too generous, I'm not sure where you got the idea I would recommend that. However, shooting at f/2 (1.12 ft DoF) or f/2.8 (1.59ft DoF) would seem to be a good way to go and gains the benefit of getting closer the lens's sweet spot when it comes to resolution, wouldn't you agree? Combine that with having the ability to bump up the ISO and not loose quality would seem to me to be an excellent combination.
07-06-2014, 09:26 PM   #81
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It's still nice to have the viewfinder/AF performance of an F/1.4 prime, even when you're shooting at F/2 or F/2.8. Depends on the AF and screen of course.
07-06-2014, 09:43 PM   #82
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QuoteOriginally posted by ElJamoquio Quote
It's still nice to have the viewfinder/AF performance of an F/1.4 prime, even when you're shooting at F/2 or F/2.8. Depends on the AF and screen of course.
A sensor as sensitive as the one in the A7S when combined with a mirrorless body is a kind of game-changer, though. A mirrorless body can have an electronic viewfinder, and the A7S has one. So the A7S high ISO performance isn't just an ability to take pictures in the dark, it's an ability to autofocus in the dark (because the sensor is that sensitive) and show an electronic viewfinder image as if it was daylight (because the sensor is that sensitive and the viewfinder is 2.4 million dots of OLED). The A7S reduces the advantage of an f/1.2 or f/1.4 lens to one of composition where the photographer should use those lenses when they need to shoot with narrow depth of field. Now while an advanced mirrorless body doesn't hold advantages in all areas over a more traditional SLR, we are seeing progress in the traditionally weak areas, with improvements in contrast detection AF and the introduction of hybrid contrast and phase detection on-chip AF. Costs are high now, but I wouldn't be surprised to see prices fall in the future and features to trickle down. Things are definitely changing.

07-06-2014, 09:48 PM   #83
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QuoteOriginally posted by nater Quote
A sensor as sensitive as the one in the A7S when combined with a mirrorless body is a kind of game-changer, though..
It's a third to a half stop improvement in SNR. I wouldn't call it a game-changer. It's about the difference from a F/2.8 lens to a F/2.4 or so. The difference between the K-7 and the K-5 was much higher.

AF might be better, I don't know, but I wouldn't say the A7 AF is up to Nikon/Canon speed yet anyway, so I'd be surprised if the A7S was.

On top of that the A7 doesn't have enough native lenses to be a wedding system yet. It might in the future. If you do the mirror-adapter you just lost all the SNR that you hoped to gain.
07-06-2014, 10:28 PM   #84
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QuoteOriginally posted by nater Quote
In my experience shooting when fast glass with a narrow depth of field the risks become very high in terms of being able to nail the exact right point of focus at a live event, and also compositionally constraining in terms of what is and isn't in focus. A camera's AF system cannot necessarily predict what you exactly want to focus on, and sometimes working around that by choosing a specific focus point and manually triggering/suppressing AF or pre-focussing on a specific point in anticipation of where you subject will be is at times insufficient due to the dynamics of the situation.

Now let's talk specifics. You mentioned a Canon 85mm f/1.2. Let's assume a EOS 5D Mark III because if you're dropping $2.2k on a lens, you might as well drop $3.4k on a full frame body. Being a portrait lens, I'll take a guess that the subject would be about 15 feet away (let me know otherwise and I can re-do the calculations). The total depth of field would be 8.04 inches. For me at least, that's risky. I would not recommend shooting everything at ISO 100,000 and f/8 since the shots would look more like something out of a point and shoot because the DoF has expanded to 5.7 feet which I would think would be compositionally too generous, I'm not sure where you got the idea I would recommend that. However, shooting at f/2 (1.12 ft DoF) or f/2.8 (1.59ft DoF) would seem to be a good way to go and gains the benefit of getting closer the lens's sweet spot when it comes to resolution, wouldn't you agree? Combine that with having the ability to bump up the ISO and not loose quality would seem to me to be an excellent combination.
Both lenses were rentals, in this case. I was shooting aps-c, the other photographer was shooting full frame. f2 is where I was shooting. Yes, I do agree that having great high iso's is wonderful. However, when you don't have that, there is simply no substitute for a fast lens. That is the point I was originally getting at. Sometimes you just have shoot and get what you can get, especially when you can't control all of the variables. This was one of those times.

The 85 was used to shoot everything from full-body shots to closer shots. I used the 135 for everything from the waist-up to closer shots.
07-06-2014, 10:59 PM   #85
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QuoteOriginally posted by fuent104 Quote
Yes, I do agree that having great high iso's is wonderful. However, when you don't have that, there is simply no substitute for a fast lens. That is the point I was originally getting at. Sometimes you just have shoot and get what you can get, especially when you can't control all of the variables. This was one of those times. The 85 was used to shoot everything from full-body shots to closer shots. I used the 135 for everything from the waist-up to closer shots.
I will also add, from personal experience (sans the clickbait), that the Canon 135 f2 is also one of the most accurate and fastest focusing lenses available. The bargain-priced Canon 85mm f1.8 is also very accurate and fast in auto-focusing. Both lenses are highly valued for indoor sports and action--something which it seems like the mystical Sony models are especially mediocre at covering.

M
07-06-2014, 11:16 PM   #86
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QuoteOriginally posted by ElJamoquio Quote
It's a third to a half stop improvement in SNR. I wouldn't call it a game-changer. It's about the difference from a F/2.8 lens to a F/2.4 or so. The difference between the K-7 and the K-5 was much higher.
Maybe I'm misreading things, but I'm looking at the A7S vs. K5 vs. K7 under "Measurements" and "SNR 18%":

Sony A7S versus Pentax K5 versus Pentax K7 - Side by side camera comparison - DxOMark

My understanding is that 1 stop is approximately 3db. Looking at ISO 1600 (the last ISO before Pentax applies a proprietary noise reduction to the RAW file in the camera body), the K-7 is 25.2dB, the K-5 is 29.1dB, and the A7S is 34.3dB. So the K-5 is 1.3 stops better than the K-7, and the A7S is is 1.73 stops better than the K-5. Now things do change once we move out to ISO 6400 (Pentax RAW smoothing territory), where the K-5 is 2.43 stops better than the K-7, and the A7S is is 1.3 stops better than the K-5. (I'm not including the K-3 since it doesn't perform better in ISO SNR.) Go all the way out near ISO 51200 and I see the A7S is 1.86 stops better than the K-5. Looking at the DxO SNR graph, it doesn't seem to match the "third to a half stop improvement in SNR", and Sony seems to have a real improvement here, unless I'm reading/calculating things wrong? Also I'm not sure I'd qualify the K-7 and K-5 difference as much higher, unless you count the high-ISO Pentax RAW smoothed territory, but up there the K-7 wasn't really usable (and as a general rule I don't shoot my K-5 over ISO 1600 for quality reasons).
07-07-2014, 01:33 AM   #87
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QuoteOriginally posted by ElJamoquio Quote
It's a third to a half stop improvement in SNR. I wouldn't call it a game-changer. It's about the difference from a F/2.8 lens to a F/2.4 or so. The difference between the K-7 and the K-5 was much higher.
Even compared to the A7 / A7R ,the difference is very much 1 stops above the k5 in term of SNR 18%
07-07-2014, 06:20 AM   #88
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QuoteOriginally posted by nater Quote
Maybe I'm misreading things, but I'm looking at the A7S vs. K5 vs. K7 under "Measurements" and "SNR 18%":

Sony A7S versus Pentax K5 versus Pentax K7 - Side by side camera comparison - DxOMark

My understanding is that 1 stop is approximately 3db. Looking at ISO 1600 (the last ISO before Pentax applies a proprietary noise reduction to the RAW file in the camera body), the K-7 is 25.2dB, the K-5 is 29.1dB, and the A7S is 34.3dB. So the K-5 is 1.3 stops better than the K-7, and the A7S is is 1.73 stops better than the K-5. Now things do change once we move out to ISO 6400 (Pentax RAW smoothing territory), where the K-5 is 2.43 stops better than the K-7, and the A7S is is 1.3 stops better than the K-5. (I'm not including the K-3 since it doesn't perform better in ISO SNR.) Go all the way out near ISO 51200 and I see the A7S is 1.86 stops better than the K-5. Looking at the DxO SNR graph, it doesn't seem to match the "third to a half stop improvement in SNR", and Sony seems to have a real improvement here, unless I'm reading/calculating things wrong? Also I'm not sure I'd qualify the K-7 and K-5 difference as much higher, unless you count the high-ISO Pentax RAW smoothed territory, but up there the K-7 wasn't really usable (and as a general rule I don't shoot my K-5 over ISO 1600 for quality reasons).
Stops are the grid markers on the horizontal line. You see that at any given dB, the horizontal distance between the K-7 and the K-5 is about a stop.

For the A7 and the A7s (for the printable portion of the ISO range) the difference is much less.

The K-5 was a great improvement over the K-7, moreso than the A7S over the A7R.

I never compared the A7S to the K-5; I compared the difference (leap forward) between the A7S and the A7R vs. the difference between the K-5 and the K-7.

---------- Post added 07-07-14 at 06:22 AM ----------

QuoteOriginally posted by aurele Quote
Even compared to the A7 / A7R ,the difference is very much 1 stops above the k5 in term of SNR 18%
Again, I never compared the A7S to the K5. We were talking about improvements, i.e., 'game-changers'. The K7 to K5 improvement was twice the game changer of the A7R to the A7S.
07-07-2014, 06:57 AM   #89
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QuoteOriginally posted by ElJamoquio Quote
It's a third to a half stop improvement in SNR. I wouldn't call it a game-changer. It's about the difference from a F/2.8 lens to a F/2.4 or so. The difference between the K-7 and the K-5 was much higher.

AF might be better, I don't know, but I wouldn't say the A7 AF is up to Nikon/Canon speed yet anyway, so I'd be surprised if the A7S was.

On top of that the A7 doesn't have enough native lenses to be a wedding system yet. It might in the future. If you do the mirror-adapter you just lost all the SNR that you hoped to gain.
I would say that most wedding photographers use a combo of 24-70 f2.8 and 70-200 f2.8 zooms. Those in combination with any NEX series camera will be quite unwieldy. Putting the A7s sensor in an SLR body would be more useful for weddings, even if the lenses were there for the full frame NEX cameras.
07-07-2014, 07:33 AM   #90
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QuoteOriginally posted by Rondec Quote
I would say that most wedding photographers use a combo of 24-70 f2.8 and 70-200 f2.8 zooms. Those in combination with any NEX series camera will be quite unwieldy. Putting the A7s sensor in an SLR body would be more useful for weddings, even if the lenses were there for the full frame NEX cameras.
Right, I just care about the Sony cameras because it helps me see what sensors might be down the road for Pentax. The K-5 has a Sony sensor, the K-3 has a Sony sensor, the 645Z has a Sony sensor (no more Kodak sensor like the 645D!) Nikon uses Sony sensors. I figure Sony is taking the best sensors for themselves first, and other makers will get them eventually. I already have a 28-70mm f/2.8 and 70-200mm f/2.8 for my Pentax, and they got a terrific upgrade going from my K200D to the K-5. I'm looking forward to another upgrade with a future Pentax body (that will likely have a Sony sensor).
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