I have what many people call a "walk-around" lens; it's an 18mm - 250mm, and I'll confess that most of my photography is done with it. I go out shooting fairly regularly with a friend who is constantly changing her lenses (I don't know what her lenses/their ranges are) and she envies me my walk-around lens. I do also have a 50mm prime lens, the 18-55mm kit lens that came with the camera, a 70-300mm zoom from my Minolta film days (that works fine, but is heavy and hard to keep steady), and a couple other random lenses, including a 100-200mm lens I picked up at a thrift store that works great and has fantastic glass.
My question is -- because I'm not much of a gear head -- if I lock my 18-250mm lens at 35mm or 50mm and shoot with it set there, is that equal to shooting with my 50mm prime lens, or my nonexistent 35mm prime lens? Am I unnecessarily duplicating lenses and adding weight to my camera bag by carrying these other lenses that I don't switch to all that often? Or are there good reasons to shoot with a 50mm prime rather than locking an 18-20mm lens at 50mm and using it like that?
Sorry for my ignorance, and thanks for any information!
Shannon, here's the best answer I found to that question:
"Provided you keep focus distance, ISO, aperture & shutter speed the same, and you zoom your 18-55mm lens to exactly the same focal length as the 50mm prime (which wont be exactly 50mm) then the images will very extremely similar when viewed as a whole.
On closer inspection you will see differences in the level of distortion, sharpness, contrast and possibly colour balance, as well as a possible change in the focal plane in the corners of the image (due to different levels of field curvature). Bokeh and out of focus highlights (if present) will look slightly different due to differing number of aperture blades."
There are other things to consider, since I use both zoom lenses and prime lenses. The image quality on the prime is better. The speed of the prime is also better. More and more, I find myself deciding up front what I intend to photograph and I use the prime lens that best suits my objective. I save my zoom lenses for when I really don't know what I'm going to shoot and want some versatility.
Quality and speed. Your zoom lens is probably f4-5.6. The prime lens is probably going to be f1.8. If you spend a few more dollars f1.4. Also a prime lens is tuned exactly at 50mm. Your zoom is tuned to be OK everywhere, not excellent at one specific value.
The angle of view, the field of view should be the same, but as others pointed out the prime lenses will typically be much sharper, and (probably) will allow you much wider apertures as well. The 18-250 must be the Sigma? It is a good walk around lens and gets the job done, but will never be as sharp as a prime. True for all "zoom" lenses of course. Lots of extra glass for the light to traverse as the lens bends and straightens the light rays. Even if the glass is perfect, there will be degradation.
@kannafoot@mcrt@frankhymus Thanks for the information. I'm beginning to understand... which will help me to make informed choices when putting a lens on my camera.
Frank, actually my 18-250mm lens is a Sony lens, not a Sigma. The 100-200mm lens I picked up in a thrift store is a Minolta lens, and it takes excellent images. I think the70-300mm lens might be a Sigma...I've had that one since my Minolta film camera days.
I am leaving for vacation Monday and have been thinking about what I want to take along, as I will not have a Sherpa and would prefer to travel light. I'll probably take the 18-250mm and the 50mm prime and hope for the best. :)
I have Sigma 18-200 which is my walkaround, but more than often I have my nifty 50 attached! as someone said it is f/1.8 compared with f/5.6 or so on the zoom. I am addicted to the quality I can get with it, the ability to get sharp low light shots ( I hate flash and I don't much like going above 400iso). Id love for the zooms to be the same at the same point - but fact is they just aren't. :(
All good answers I recently bought a prime 50mm and can control depth of field far easier with this lense plus it has a lower appeture 1.4 so allows more light to the sensor
@sjoblues Where is your thrift store? That's awesome. They never have anything but 1950's 35mm when I am there. You know, the ones that have a leather case that goes around them with the 1/2 inch screw hole in the bottom for the tripod. :)
@adambralston I live in Mason, Ohio, which is suburb of Cincinnati and/or Dayton, depending on your perspective. :) The thrift store in question is a St. Vincent de Paul store, and it is within walking distance of my house. In the same shopping plaza is a Goodwill BOUTIQUE. Yes, you read that correctly. They sell donated, used goods in there that I usually can't afford at the Goodwill price! (I remember a new,unworn pair of designer-brand dress slacks, still with the tags on them, originally $400, Goodwill price $80. Still more than I'd pay for dress slacks!) Mason is a fairly affluent community, so the caliber of donations to the local thrift stores is, for the most part, pretty good. I both donate to and shop at them. The St. Vincent de Paul often has cameras or lenses available (in the locked case under the register), but unfortunately for me what I usually see is Canon or Nikon stuff. I was excited to see the Minolta lens and trotted out to my car to collect my Sony DSLR in order to try it out, and it was in perfect shape, so I bought it. The day I bought it I shot the photos that are on my 20 October and 21 October slots here in my main album (mushrooms!). It's a nice lens.
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"Provided you keep focus distance, ISO, aperture & shutter speed the same, and you zoom your 18-55mm lens to exactly the same focal length as the 50mm prime (which wont be exactly 50mm) then the images will very extremely similar when viewed as a whole.
On closer inspection you will see differences in the level of distortion, sharpness, contrast and possibly colour balance, as well as a possible change in the focal plane in the corners of the image (due to different levels of field curvature). Bokeh and out of focus highlights (if present) will look slightly different due to differing number of aperture blades."
There are other things to consider, since I use both zoom lenses and prime lenses. The image quality on the prime is better. The speed of the prime is also better. More and more, I find myself deciding up front what I intend to photograph and I use the prime lens that best suits my objective. I save my zoom lenses for when I really don't know what I'm going to shoot and want some versatility.
Frank, actually my 18-250mm lens is a Sony lens, not a Sigma. The 100-200mm lens I picked up in a thrift store is a Minolta lens, and it takes excellent images. I think the70-300mm lens might be a Sigma...I've had that one since my Minolta film camera days.
I am leaving for vacation Monday and have been thinking about what I want to take along, as I will not have a Sherpa and would prefer to travel light. I'll probably take the 18-250mm and the 50mm prime and hope for the best. :)
I'm still using my kit 18-55 quite a bit and pondering replacing it but I'm not sure what to replace it with.