50mm 1.8G or 85mm 1.8G?

<p>I've read several threads on this topic, but since each situation is different, I'll post here in the hopes of some thoughtful responses as always.<br>

I would like to get a prime lens for my D7000. I'm having trouble deciding between the 50mm and 85mm focal lengths. I am interested in using it primarily for portraits of children and families. I currently use the 18-200mm DX and I'm just not happy with the (lack of) sharpness on that lens. I'm hoping a prime will provide the sharpness I'm looking for.<br>

So will a 50mm or 85mm be the better choice? Respectively, I'll be working in the 75 or 127mm length, yes? My concern is the distance from the camera to the subject. I like being about 10-12 feet away (occasionally closer for tighter shots), so as not to make subjects (esp children) uncomfortable with my proximity. Since I need to take into account the 1.5x crop, I'll be standing further away with either of these lenses than with the DX correct?</p>

<p> </p>

<p>Set your 18-200 to 50 and 85mm, respectively, and see which one works better for you. No need to take any crop factor into account when using either a DX or an FX lens on a DX camera; that distinction becomes only "meaningful" when comparing field-of-view of an FX lens when mounted on a DX vs an FX camera.</p>

<p>Happily, your exisiting 18-200 is the <em>perfect</em> tool to figure out the answer to your question. Just set the zoom ring on that lens to 50mm, and then to 85mm, and see how that treats your composition/framing and the resulting working distance (and thus <em>perspective</em>) as you shoot with familiar subjects. You'll very quickly know if you find 50 or 85 to be a better choice.</p>

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<p>I'll be working in the 75 or 127mm length, yes?</p>

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<p>No, you'll be working in the 50mm or 85mm length. The focal length of the lens is the focal length of the lens, period. If you're personally used to working with 35mm film cameras, then you might find it convenient to refer to those other (longer) focal lengths as a familiar reference ... but what matters is the angle of view that your current camera format (Nikon's DX, which is the size of APS-C film) gives you with lenses in the focal lengths you're considering.<br /><br />Your 18-200 is the ideal laboratory to figure out what you like, FL-wise. When it says 50mm on the zoom ring of the lens, that's is exactly what a 50mm prime lens is going to do, composition-wise. 50mm is always 50mm. Don't get distracted by discusions of "equivalent" focal lengths. You're not switching back and forth between camera formats, you're using one DX-format body. So, get to know the focal lengths you like with that format. And you're all set to do just that. The numbers won't lie.<br /><br />Oh, and just in case you don't know, with precision, just where the zoom ring is set, just take a shot and look at the image info on your camera's LCD. You can switch that display to show you image EXIF data, which will include the exact focal length at which the zoom was used. That way you can easily nudge the zoom position one way or the other a bit to get it (close enough) to 50mm or 85mm while you test.</p>

<p>OH boy! All this time I thought if I purchased a 50mm prime, it would be like I was looking through a 75mm lens. So basically, there's<em> no conversion to consider </em>when I choose the lens?</p>

<p>Dieter is correct with regard to the 'crop-factor' DX/FX maths etc.</p>

<p>However, the effective Field of View or 'How Much You Get In @ a Certain Distance' is relevant here. </p>

<p>If you're taking family portrait groups, especially indoors, I'd worry about not being able to get far enough back with the 85mm. Outdoors, there's not usually a problem. </p>

<p>For individual 'targets', either is fine.</p>

<p>This <a href="http://www.wega2.vandel.nl/">http://www.wega2.vandel.nl/</a> software will show you the focal lengths of what you've taken so far, so <strong><em>SHOULD</em></strong> indicate which you'd use more often.</p>

<p>No, you do not have to consider any conversion as long as you compare different lenses on the same body format (DX in your case)</p>

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<p>So basically, there's<em> no conversion to consider </em>when I choose the lens?</p>

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<p>Right! 50mm is always 50mm. Lenses that are DX-specific don't use a different measurement for focal lengths, they're just built a bit smaller because they're designed for use on cameras that have smaller sensors, and thus the lens doesn't need to project as large an image into the camera body (to cover a larger sensor, like an FX body's). So, a 50mm DX lens is still 50mm, but if you were to use it on an FX body, the whole FX sensor wouldn't be effectively used.<br /><br />When you buy a lens that's good for FX (like the two you mention), they're still perfectly usable on a DX body like yours, it's jus that the lens projects a larger image into the camera body, and some of that image circle is wasted since you're using a smaller sensor. No harm done! There aren't many DX-only prime (fixed-focal-length) lenses out there, but there are some. Nikon even makes an 85mm DX-only lens, but it's slower (it only opens up to f/3.5) and is intended for macro use. In your case, you're looking at lenses that will work with either DX or FX - and if you're headed into a career involving portraiture, it's not a bad idea to buy lenses that also lend themselves to use on the larger-format bodies, should you get one down the road.<br /><br />And in case you're confused, the piece of software Mike H. is recommending is used to crunch the statistics on your previously shot images (so, it has to have access to them all, in all of the places you keep them) to let you know which focal lengths, statistically, you've been using. That can be helpful, but it can also be confusing if the images you have it look at aren't consistent in their composition.</p>

<p>Exactly what Dieter and Matt have said.<br>

Maybe another thing (not so much for consideration, but to share): the 85 f/1.8G is brand new, and I've not yet seen any real test reports of it. However, I do have both the old AF 50 f/1.8D and the new f/1.8G, and the new lens is really much much nicer, I think. If Nikon pulled the same level of improvement with the 85 f/1.8 (going from D to G) - now that would make a really really seriously nice lens! But as it is now, it's still an unknown.<br>

Ad do consider that on your D7000, the older non-AFS lenses will work just fine too, there is no (technological) reason to only consider the new ones.</p>

<p>Don't worry Lorraine, in-a-way, you're correct. You mount a 50mm lens on a DX camera and what you see through the viewfinder would look like a 75mm lens did on an old film camera. <strong>BUT IN COMPARISON TO YOUR 18-200MM ON YOUR D7000 EVERYTHING IS THE SAME!</strong></p>

<p>35MM FILM CAMERAS > DX DIGITAL > CROP FACTOR</p>

<p>So to capture the same FOV as you used to get on a film camera with a standard 50mm, you do need to divide by 1.5, ie get a 33mm lens.</p>

<p>EG., in a 4m square room with your back to one wall, your targets lined up on the opposite wall (like an ID parade!). With a 35mm film camera and a 50mm lens you get 6 people in; with the same lens on a D7000 you get 4 people. To get 6 people in you need to change your lens for a lens between 30-35mm focal length.</p>

<p>(These figures are approximate and aim to show the principle not a mathematical equation)</p>

<p> </p>

<p>Lorraine, 50mm is just that, but on different format cameras (and Dx is a format), they produce different <em>crops </em>out of the available viewing circle (which varies). So while you are still using a 50mm lens on your Dx camera, the view will not look like it does on a FF camera, or a 50mm on a medium format camera, or a 47mm Super Angulon on a 4x5.</p>

<p>Yes, it will look very close to a 75mm lens on a FF camera. Don't let the techophiliacs confuse you too much here.</p>

<p>The answer to your question is readily available, as has been mentioned already by Dieter Schaffer and others by using your 18-200 at your prospective focal lengths of 50 and 85mm.</p>

<p>Alrightey then. So a 50mm is not going to give me as much "North South East & West" on a DX as it does on an FX. But since a DX is all I know, I really have nothing to comapre it too. And the suggestion that I might not have enough room indoors with an 85mm is a worthy consideration. So it looks like I should go with the 50mm.</p>

<p>Well, you have the 50mm and 85mm 'marks' on your 18-200mm to compare it to.</p>

<p>If you set your 18-200mm at the 50mm mark, then the viewfinder and final photo will show you what you'd get with a 50mm prime, and set @ the 85mm mark what you'll get with a 85mm prime, etc just sharper!</p>

<p>.....and yes, 85mm is a bit long indoors!</p>

<p> </p>

<p>I'll stick with saying you should just set your <em>existing</em> lens to 85mm, and see what you see in terms of working distance. Only you can judge if a given focal length is a good match for your style and shooting circumstances, but the important thing is that you already own just the tool to answer that question for yourself.</p>

<p>I use both lenses extensively (50 1.8G & 85 1.8D). 50 AF-S 1.8G is really good. Beyond f5.6, it is tack sharp. Fairly good bokeh too, but cant match 85 1.8. 50G is almost as good as 85 1.8D. But they have their purposes. I would definitely own both. But if I have to choose, it is very difficult one. I will go for the 50 1.8G. Lot more versatile, you can crop always.... Very sharp and lovely rendering. Great price performance ratio.</p>

<p>Thanks everyone! After finding out I don't need to think of primes as xxmm mulitplied by 1.5, I have been doing just what others have suggested and used my 18-200mm to help me figure it out. Your responses are most helpful!</p>

<p>When you have an idea of what you want, you should go lens shopping with Cynthia...:-)</p>

<p>Maybe by that time the 85/1.8<strong>G</strong> lens will be a lens one can buy.</p>

<p>Both are great lenses, and as other observant posters point out, factor in the 1.5x crop factor. Next, consider what you want to do with the lens. The 85mm will approximate to 127.5mm, which is a mid-telephoto effect. This will serve you well for headshot portraits at a modest distance from your subject. The 50mm will approximate to 87mm on DX format. This is also a good portrait lens for head, should and partial body shots. On DX a 35mm lens might be a great choice if your wanting to do 1/2 to 3/4 body shots and/or capture environmental context. A 35mm lens approximates to 50mm on DX format - this is close to a "normal" view. I like normal perspective for say, capturing a father playing checkers with his son at the dinner table, or a group portrait of three people.<br /> Good luck on your purchase(s). I own the great 50mm 1.4D lens. I shoot on full-frame so that's the perspective I get. It's my general purpose go-to lens. Isn't it great to be able to use pretty much any Nikon Autofocus lens from the 1970's on? :)<br />Oh, and useful tip - never buy a DX format lens again. Go with an older 35mm lens, or one of the newer G lenses if you're feeling rich. You're wasting your money and limiting your options to expand in the future. AF compatibility shouldn't be an issue with the D7000, and you'll maintain compatibility if you decide to upgrade your body to FX format.</p>

<p>Hi. I've done some maths! I've assumed a working distance of 3.3m (I do metric I'm afraid) and the D7000. A 50mm lens gives you a 1 x 1.5 meter maximum subject size. An 85mm would give you 0.9 x 0.6 meter subject size.</p>

<p>For a tight head shot, say a 0.4m subject height in portrait mode, a 50mm lens would have a working distance of 0.9m and an 85mm lens gives 1.5m working distance.</p>

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<p>The 85mm will approximate to 127.5mm, which is a mid-telephoto effect. This will serve you well for headshot portraits at a modest distance from your subject. The 50mm will approximate to 87mm on DX format.</p>

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<p>After all what's been said and explained above, someone must come and muddy the waters again. A 85mm lens will be an 85mm lens no matter what camera you attach it to - it doesn't magically acquire a 127.5 focal length. Some fuzzy math going on there to make that 50 into a 87 - never mind that it stays 50 no matter what.<br>

It's high time that some people get their head around that DX vs FX is a matter of image circle size the lens projects. And that FOV is what changes when you mount a lens to different format cameras, not the focal length.<br>

Any discussion involving "35mm equivalent focal length" makes sense (???) only when different sensor formats are considered - which isn't the cast here as the OP wants to use the lenses in question on a DX camera - hence absolutely no need to invoke the "35mm equivalent focal length".<br>

All the questions the OP has can be answered, as pointed out already by setting her 18-200 to 50 and then to 85 and see which one suits her better. No math involved and necessary - good old experimentation is here to save the day.</p>

<p>Lorraine,<br>

The advice to use your current lens to simulate the 50 or 85 remains the practicable method.<br>

If you want an idea of the <em>effect </em>of a lens ( focal length) when used on DX or FX camera then try <br>

<br /><a href="http://imaging.nikon.com/lineup/lens/simulator">http://imaging.nikon.com/lineup/lens/simulator</a><br>

I'd imagine you plan to keep your current camera body.<br>

Joe </p>

<p>There is a caveat with the 18-200mm. The 'real' focal length is not the same as that indicated in the EXIF data at shorter focusing distances. So the 85mm setting at, say 3m working distance may be less than that. What matters, as Dieter said, is the field of view and how big your subject is at a given focusing distance and focal length.</p>

<p>The 85 will throw the background better than the 50 at a given aperture, at similar distances. I use the 80mm end of my 80-200 2.8 all the time around the backyard with my family, but I found the 50 a little awkward on DX. Personal preference - as stated use your zoom at 50 & 85 and give it a test run for a few weeks. The primes will smoke your 18-200. </p>

<p>Also consider the 35mm f1.8 DX for a prime for a D7000 if 50 isn't wide enough. Since I got my 35, I almost never use the 50.</p>

<p>Lorraine..<br>

I just went through some of this yesterday... when comparing the 85 1.4 to the 85 1.8.<br>

I bit the bullet today and went with the 85 1.4 since I see a full frame coming into my future .. LOL<br>

I have done the test of the viewing of my files for about a year now and I have kept my longer lens at 85 to just judge about what I am going to be getting out of the lens. It won't create the bokeh that you are looking for from the lens but it will teach you how you are going to zoom with your feet or compose your shots in any spaces you are going to be shooting in (studio, outdoors, in home etc). <br>

I have tried other name brands and haven't been happy in the past .. ergo, I am keeping with my Nikon glass as I haven't thought one time of one penny that I spent on the 24/70 by Nikon. I compared it for 2 weeks with Tamaron and a Sigma (similar) and the Nikon won hands down..<br>

I have to say you came to the right place for assistance and knowledge.<br>

Love to hear what you choose. Keep us updated.</p>

I apologize for repeating the myth - informative to be for sure when I had actual salesmen tell me the opposite.

 

That being said, this brings up another question... so if only FOV changes, then you're still getting the same characteristics of the focal lengths your shooting at, only the image is cropped down. Am I correct? If I strap on a 35mm DX on an FX body, ill still make peoples noses bigger with the frame size of a 50mm?