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12-28-2010, 05:25 AM   #31
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I think the reason you dont see any APS-C zooms faster than 2.8 is because the size, weight and cost would be prohibitive. With today's improving sensor technology, 2.8 should be plenty fast in most shooting situations,. unless you are trying to play God and turn night into day.

Jason

12-28-2010, 07:19 AM   #32
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QuoteOriginally posted by Lowell Goudge Quote
If this is your reason for switching brands, you will be dissatisfied with every brand out there.

There are no zooms faster than F2.8.

fast lenses, i.e. F2 and faster are the world of primes
QuoteOriginally posted by CWyatt Quote
OK there is one example, but show a nikon, canon or sony example. You will be hard pressed to find on in a major brand, and a 4/3 sensor suffers badly with respect to field of view at wide angles and also for noise

I can't see anyone goinf from pentax to Olympus for a single lens, given the other weaknesses of a 3/4 system
12-28-2010, 07:22 AM   #33
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QuoteOriginally posted by Jasvox Quote
I think the reason you dont see any APS-C zooms faster than 2.8 is because the size, weight and cost would be prohibitive. With today's improving sensor technology, 2.8 should be plenty fast in most shooting situations,. unless you are trying to play God and turn night into day.

Jason
at any given field of view, an ASP-C F2 lens is smaller than the full frame equivelent because it is also shorter, weight and size are not the issue.

Additionally improved sensor technology does not give narrower Depth of Field when you want it.

While sensor technology does account for lesser needs for low light, for artistic reasons narrower depth of field will always have a place and that is what fast lenses offer
12-28-2010, 07:35 AM   #34
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There was an Angenieux f2.6 zoom... Not sure of this is of much interest over f2.8.

12-28-2010, 11:23 AM   #35
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QuoteOriginally posted by Lowell Goudge Quote
at any given field of view, an ASP-C F2 lens is smaller than the full frame equivelent because it is also shorter, weight and size are not the issue.

Additionally improved sensor technology does not give narrower Depth of Field when you want it.

While sensor technology does account for lesser needs for low light, for artistic reasons narrower depth of field will always have a place and that is what fast lenses offer
And you dont see many (any?) F2 full frame lenses either...for either format, would be very big/heavy.

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12-28-2010, 11:33 AM   #36
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I do find it ironic that people select an APS-C only brand, and then complain that they can't find fast enough lenses for low DOF work.

For most people, f2.8 is plenty. I very rarely shoot below f2.8 even when I have the option, because the DOF is so prohibitively small. Lots of people complain that they want even less in focus. While that is find, wouldn't it just be a lot easier to shoot full frame? You can compensate on APS-C by buying faster lenses, but you reach an upper limit and something like the FA 50 1.4 would be much better for low DOF on a full frame body.

As for zooms, well f2.8 is it, folks. If you need DOF, buy a full frame camera. As a test run shoot a roll of film...
12-28-2010, 02:01 PM   #37
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Again, APS-C formats still have plenty of fast lens options, just not zooms. Primes do fine - don't be lazy, zoom with your feet.
12-28-2010, 02:24 PM   #38
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QuoteOriginally posted by Ash Quote
Again, APS-C formats still have plenty of fast lens options, just not zooms. Primes do fine - don't be lazy, zoom with your feet.
Agreed! Want speed, go prime. They're better in most respects anyway, unless the number of lenses is severely prohibitive in your situation. Even so, fast zooms can be the size of multiple primes!


QuoteOriginally posted by Lowell Goudge Quote
I can't see anyone goinf from pentax to Olympus for a single lens, given the other weaknesses of a 3/4 system
That is so true- this f/2 zoom is a clear outlier, and the differences between 4/3 and Pentax bases make that switch more to think about than the one lens.

12-28-2010, 03:14 PM   #39
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QuoteOriginally posted by PePe Quote
As an ex K10 user I can assure you the K 7 was a major leap forward in AF performance, and the K 5 is a further improvement. The K10 was a big hit when introduced, but in the world of DSLR´s four years and three camera generations really make a difference.
Yup ... what he said. (tho I still have my K10D to use as a 2nd body or manual focus rig)
12-28-2010, 11:33 PM   #40
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QuoteOriginally posted by Frogfish Quote
I've heard nice things about the Samyang 85/1.4 and over here there is also a Walmex 85/1.4 (which I am assuming is the same lense rebadged).

A quick check and I found (all 85/1.4) FA for US$1,200, Samyang US$380, Rokinon US$300 and Walmex US$400, the Nikon is US$1,1,00, Sigma US$800, Sony US$1,400, Planar T US$1,100, Contax Zeiss US$700 - 1,100 : adaptors for some of these run around US$100 over here).
Also the FA 77mm LTD. Sure, it's not 85mm and it's "only" F1.8, but the difference in FOV between 77mm and 85mm is negligible, and the 77mm is widely regarded as one of the top lenses ever made. Also, it's cheaper than a lot of the ones you listed above.
12-29-2010, 04:19 AM   #41
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QuoteOriginally posted by Framed Quote
...
I currently am still shooting with the K10d. It's always had focusing issues even after having the auto focus motor repaired. It does pretty good with the 50mm but my Sigma 2.8 zoom is all but useless on it.
...
As it's been said you're judging Pentax lineup and performance from the experience of a 3-generations-old defective camera. Perhaps you could find somebody (private or shop) with some new gear and have a test for yourself. I think things have moved on a good deal since the K10s, especially now with the K5.

One more thing: the difference in FOV between 50 and 77mm (on APS-C) is quite relevant...

50mm - 18° vertical, 27° horizontal, 32° diagonal
77mm - 12° vertical, 18° horizontal, 21° diagonal

12-29-2010, 10:38 AM   #42
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QuoteOriginally posted by Huck Finn Quote
As it's been said you're judging Pentax lineup and performance from the experience of a 3-generations-old defective camera. Perhaps you could find somebody (private or shop) with some new gear and have a test for yourself. I think things have moved on a good deal since the K10s, especially now with the K5.

One more thing: the difference in FOV between 50 and 77mm (on APS-C) is quite relevant...

50mm - 18° vertical, 27° horizontal, 32° diagonal
77mm - 12° vertical, 18° horizontal, 21° diagonal

You have all done a great job correcting me on the lens issue I thought I had with Pentax. After taking a closer look I can see it really wasn't an issue at all. If it were only a lens issue my dilemma would be solved. However, out dated camera or not, I'm still seeing lots of complaints about focus issues on even the newer Pentax bodies. As a children's portrait photographer it's becoming a deal breaker. Many times you only get once chance to get the shot. I'm very tempted to try the K5 once they get the sensor issue resolved but at the same time I'm quite leery to take that chance. I need reliable focus on any lens I choose to use and Pentax doesn't seem to be able to offer that. I apologize I know this discussion needs to move out of the lens folder.
Thank you all so very much for your thoughtful replies!
12-29-2010, 10:51 AM - 1 Like   #43
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QuoteOriginally posted by Framed Quote
Thanks for the quick replies! I really appreciate it. Sorry I misspoke about the zoom lenses. A 24-70 2.8 is the lens I've been coveting that belongs to a Nikon friend. Also would love an 85 1.4/1.8 prime which I know Pentax use to make but I have yet to find one. I have been eyeing the 77 limited but I'm not sure it's going to give me enough of a difference over the 50 to warrant the cost. I'd much rather spend the money on a good fast zoom.

I currently am still shooting with the K10d. It's always had focusing issues even after having the auto focus motor repaired. It does pretty good with the 50mm but my Sigma 2.8 zoom is all but useless on it.

I do mainly portraits so I'm after a fast lens for the bokeh. Love me some bokeh. ) Low light is one of the reason I want to upgrade my body but even so, I love shooting wide open.

I'm looking to upgrade either to the K7 or Nikon 700 in the next couple of months. Lens choice is my driving factor right now. Hmmm perhaps I will be happier with the Sigma on a new body?

I really appreciate the replies.
you came up with the answer i would suggest, I've got the sigma 24-70 2.8 and it's a great lens, and with current K7 pricing you could get the pair for about the same as the nikon body only. If manual focus is acceptable the Rokinon/bower/what ever other name they have 85 is a steal of a lens and excellent for portraits (where af isn't as needed IMHO in any case)
12-30-2010, 01:42 AM   #44
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Looks like every post in this thread try to keep you with pentax - so me too ;-) Also seems like the thread is off-track a bit.

QuoteOriginally posted by Framed Quote
I do mainly portraits so I'm after a fast lens for the bokeh. Love me some bokeh. ) Low light is one of the reason I want to upgrade my body but even so, I love shooting wide open.
I do portrait most of the time, bokeh is a must. I m using k20, umbrella and my lens for portrait is da*50-135.

The aperture does not be wide open all time, but should not be smaller than f4. By planning distance to subject and distance to background, I get the bokeh I want. For a typical living room with some open space like the entry or kitchen, when distance subject-background>3m/10feet and distance to subject>2m/6feet, the bokeh is just perfect. I don't really care which pentax body I use, as long as the light is good and I can keep the safe distance for DOF portraiture.

Give the lens a try. Let me know if you need sample image.
Best regards.
12-30-2010, 06:57 AM   #45
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You might Also PM Todd Adamson who has both Nikon and Pentax and shoots primarily Portraiture for his input. He's new to Pentax and seems to really love it
If I'm not mistaken he has both a Nikon D3 and a K5
(and apparently just took the leap back and bought a Bronica SQai 6x6 Film camera)
I know he actually prefers manual focus to AF even when the lens has the option but he could give a good read on the system differences.
I just went from the K10 to the K7 and I can tell you the AF is dramatically better IMHO despite complaints to the contrary. If you are shooting the kid portraits in low to no l;ight or in tungsten then yep it will be slow (so will pretty much any camera built - Tungsten Focus is an issue for all cameras to some degree.) One big difference though is having the proper AF assist on the camera I noticed it right away.
and I believe others have convinced you the lens selection isn't the issue.
I didn't have many focus issues under Studio light conditions with the K10, I doubt I'll have any with the K7, though I've yet to put it to the test.
Also you could get a K7 and a 77 1.9 for less than the D700 body alone without even trying.
If you shopped used judiciously you could likely also score a 50-135 before you'd even approach the price of a D700 with a decent lens, and still have all your existing gear and in body SR opening up tons of lenses to full stabilized shooting (not a portraiture concern, but I'm guessing it isn't the only thing you shoot, and as time goes on your style can change)
BTW you also might have a look at Benjikan, He shoots Fashion for all the high end magazines and uses pentax almost exclusively, fashion shoots from the ones I've been at are just as fast paced as children, though the models are more co-operative sometimes
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