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06-18-2012, 09:47 AM   #16
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For portraits the 50mm can do very well but pentax 35mm is more alround or the sigma 30mm but it depends on your shooting style.
I think that for your kids and as a general lens that a zoom would be more useful.

with f/2.8 you get quite a small area when around 50mm that is in focus with f/1.4 that would be quite a bit harder to focus with.

06-18-2012, 10:28 AM   #17
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QuoteOriginally posted by slip Quote
That said, for the price and low light performance, you can't beat the 50 1.4. it will be 75mm on your camera, which is just right for portraits. At around F 4 is is very sharp as well.
No it won't . It will be 50mm on any camera. Lenses don't magickally stretch nor shrink when they're place on different bodies. Different-size frames (film or sensor) see different amounts of the projected image, is all. The frames crop the image, hence the crap.factor. Saying that a lens becomes something else on another camera is just crap.factor confusion.

I'll skip the lecture on equivalent FOVs and DOFs and 'normal' focal lengths and all that stuff. I will say that we often have favorite focal length ranges for certain types of shots. And IMHO the best way to figure out which focal lengths work best for any specific type of shooting, is to experiment. Use the 18-55 and 55-300 kit lenses, see what focal lengths you USE, and which you WOULD use if you had a faster aperture. This should guide you to future lens acquisitions. (After you get the FA50/1.4 and Tamron 17-50/2.8, of course.) Have fun!
06-18-2012, 06:32 PM   #18
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QuoteOriginally posted by RioRico Quote
No it won't . It will be 50mm on any camera. Lenses don't magickally stretch nor shrink when they're place on different bodies. Different-size frames (film or sensor) see different amounts of the projected image, is all. The frames crop the image, hence the crap.factor. Saying that a lens becomes something else on another camera is just crap.factor confusion.

I'll skip the lecture on equivalent FOVs and DOFs and 'normal' focal lengths and all that stuff. I will say that we often have favorite focal length ranges for certain types of shots. And IMHO the best way to figure out which focal lengths work best for any specific type of shooting, is to experiment. Use the 18-55 and 55-300 kit lenses, see what focal lengths you USE, and which you WOULD use if you had a faster aperture. This should guide you to future lens acquisitions. (After you get the FA50/1.4 and Tamron 17-50/2.8, of course.) Have fun!
Thanks for clearing this up, as it still not easy to understand, even when it is explained.

Randy
06-18-2012, 08:26 PM   #19
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QuoteOriginally posted by slip Quote
Thanks for clearing this up, as it still not easy to understand, even when it is explained.
Here's my favorite example. (There's an illustrative post around here somewhere but I can't find it now.) Cut a picture from a magazine. On in, draw a 60x45mm rectangle. Inside that, draw a 36x24mm rectangle. Inside that, draw a 24x18mm rectangle. And inside that, draw an 18x12mm rectangle. These are respectively about the sizes of 645, FF, APS-C, and m4/3 frames. The picture has not changed. But each frame contains ('crops') a different portion of the image.

06-19-2012, 04:51 AM   #20
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Thanks that is so much easier to understand

Randy
06-21-2012, 04:34 AM   #21
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Thanks for everyones help! I will be going though many pics this weekend to see what my most used focal points it.. I was thinking maybe I should just go for a prime, 35mm or 50mm, seeing as though I do have the other two lenes at the monent. I guess it would be good to play around with a prime lence once to see what they are like. Then you never know after that I might even buy the 17-50mm sigma or the Tamron 17-50/2.8 and sell the 18-55.. One thing I know is that if my wife would use the 50mm 1.4 I would say she would find it hard to understand..

Thanks again

Daniel
06-21-2012, 10:44 AM   #22
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QuoteOriginally posted by RioRico Quote
No it won't . It will be 50mm on any camera. Lenses don't magickally stretch nor shrink when they're place on different bodies. Different-size frames (film or sensor) see different amounts of the projected image, is all.
True, but he still managed to draw the correct conclusion despite the technical error: a 50mm lens on APS-C is potentially good for portraits in precisely the same way that a 75mm lens is good for portraits on FF. That is something the analogies to cutting up prints never quite manage to capture, and why the "crop factor" will continue to live on - there really is a sense in which a 50mm lens on APS-C is similar to a 75mm lens on FF in practice.
03-13-2013, 02:08 PM   #23
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Hello All, just a quick question.. does the Tamron SP AF 17-50mm F/2.8 XR Di II LD ASPH l And the sigma17-70mm f/2.8-4.0 have a constant F Value thoughout the lens?

03-13-2013, 02:50 PM - 1 Like   #24
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The Sigma doesn't have a constant aperture throughout the zoom range...the Tamron yes.
03-13-2013, 02:52 PM   #25
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Really, thats good to know, so with the Tamron SP AF 17-50mm F/2.8 at 50mm I can still use 2.8?
03-13-2013, 03:06 PM   #26
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QuoteOriginally posted by dannydza Quote
Thanks so much for your reply, I very much appreciated it, I will have a look at the Tamron 17-50/2.8 like you had said.. I have so much to learn

Thanks


Daniel
I second the Tamron 17-50 f2.8 recommendation. I have this lens, and find it great for all the same reasons mentioned above. I got as good price on a new one by buying on ebay from a Taiwan company, $389, but delivery was slow, and warranty is not honored since it was bought out of market, but these lens are quite reliable anyway. The Tammy 17-50 is a sticky lens; I mean it is so useful and gives such good results that it tends to stay on your camera all the time even when you have some better prime lens!
03-13-2013, 03:11 PM   #27
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QuoteOriginally posted by HSV Quote
The Sigma doesn't have a constant aperture throughout the zoom range...the Tamron yes.
The Sigma does in fact have a constant 2.8 aperture. See the comparison between the three competitive lens, Sigma, Tamron, and Pentax:

DA* 16-50mm vs. Sigma and Tamron 17-50mm F2.8 Comparison - Introduction - PentaxForums.com

The Tamron, by the way, comes out very well in this comparative review, and this is one reason I decided to buy my Tammy 17-50.
03-13-2013, 03:22 PM   #28
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QuoteOriginally posted by ivanvernon Quote
I second the Tamron 17-50 f2.8 recommendation. I have this lens, and find it great for all the same reasons mentioned above. I got as good price on a new one by buying on ebay from a Taiwan company, $389, but delivery was slow, and warranty is not honored since it was bought out of market, but these lens are quite reliable anyway. The Tammy 17-50 is a sticky lens; I mean it is so useful and gives such good results that it tends to stay on your camera all the time even when you have some better prime lens!
thanks ivanvernon
03-13-2013, 03:28 PM   #29
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Hello, Danny!
My 2 cents... In my experience it will be a serious challenge to find a zoom that will equal the image quality and speed of the Pentax FA 50mm 1.4.
I own that lens as well as the F 50mm 1.7, and recently picked up the FA 35mm 2.0. Three amazing lenses that didn't put me in the poor house.
The 16-50 is a truly wonderful lens, but a new one will go for about $1200 or so and still won't get you the IQ that owners of primes have come to expect.

I found my 50s to be a bit long on occasion, so I bought the 35... Done!
I will eventually buy a super wide prime but for now, I'm good.

Food for thought.
03-13-2013, 03:32 PM   #30
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A few shots from the 35mm right out of the box:
https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/218243-fa-35mm...ml#post2310225
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