tsdevine
Offline
• • • • •
Upload & Sell: On
|
Steve Spencer wrote:
You are right, you could get a 28mm lens and crop to 45mm, but it is a 1.6X crop if you do so. That means in depth of field even with an f/1.4 lens you will only have the depth of field of a 45 f/2.3 lens. You certainly would be giving up some shallow depth of field capability at the long end as well as some megapixels (even with a 60MP camera you are down to 24 MP or so). Can you see why some might prefer that 45 f/1.8 60MP file more than the 45 f/2.3 24 MP file? Even at 35mm, there would be a small advantage of the zoom. The prime would have the depth of field of a 35 f/1.8 lens but you would be down to a 39MP file.
Of course the prime does have shallower depth of field and could have a faster shutter speed on the wide end and you get a full file. So, you would get that advantage if you used the prime at the wide end, with a bit of a penalty at the long end. It seems to me that if you want to primarily use the wide end then yes the fast prime approach makes sense, but as you start to use the middle and long end of the zoom, then the zoom would have an advantage albeit not that big of an advantage that difference may or may not matter to the shooter.
Personally for travel where weight is very important I like the approach of taking fast primes for the focal lengths I most want to use and cropping to fill in other focal lengths when I have to do so, but when I am not concerned about weight I try to crop less. Of course, YMMV. ...Show more →
This has probably veered way off topic at this point (just a general comment, not directed at you Steve). Good luck finding an AF 28mm prime that is faster than f/1.8 in E mount (other than the Sigma 28/1.4 which is also large and heavy).....so hypothetically on paper the getting a faster 28mm and cropping is an option, but not really, at least right now.
A f/1.4 prime is 2/3rds a stop faster. Not insignificant, but not huge either. For me, f/1.8 is fast enough and allows me to not take a fast prime (again YMMV). When I'm taking primes, I take a lot of primes, and the weight adds up. My all zoom setup is the Sigma 14-24/2.8, 28-45/1.8 and 70-200/2.8 GM II (along with the 1.4x TC). That covers UWA to long'ish telephoto in 3 lenses. And a relatively fast f/1.8 in the wide to normal range. All weather sealed and internal focus. Sure there is a gap between 24/28 and 45/70, but when I have my primes there are always gaps. I've been using a Mountainsmith Descent sling and the Mindshift PhotoCross 15 as my means to carry these lenses. Both discontinued, but I already had the Descent laying around and I got a killer deal on the PhotoCross on a B&H DealZone deal.
Would everyone want to carry larger and heavier lenses? No. Is it 100% crazy, again, I don't think so. And at the end of the day, choices are good. Pick what works for you, respect others choices.
But back on topic, the GM 28-70/2 would pair nicely with the kit I described above and you'd have almost no gaps. Swap the 14-24 above with the GM 12-24/2.8 and you'd have sort of a killer Sony trinity that also gives you a stop more than the GM II 24-70/2.8.
The original Canon 24-70/2.8 was 950 grams, which is the same weight as the Sigma 28-45. The GM 28-70/2 is a bit lighter. Sure you use 24mm, but it can be covered by another lens. If you must have 24mm on the same lens that covers the normal range, then of course these lenses that start at 28mm aren't ideal.
And no reason to fault people who prefer to carry primes instead of zooms. I'm super picky about zooms, they need to be in the same zip code as my excellent primes. I've found an "on paper" exercise when it comes to lenses isn't always reflective of actual use of a lens. For me, the proof comes in actual use of a lens.
|
.
