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~80mm rec for FX?


count_chocula

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Hi all,

 

I'm looking for a fixed focal length lens - something around 80mm or so - for my D810. I have around £500 to spend, and would like to get something as sharp as that budget allows. It's for a photogrammetry project. I already have a sigma ART 24mm, but need a longer focal length to complement it.

 

I'm on a tight timeline, so probably need something I can grab off amazon here in the UK or similar... Thanks much in advance.

 

Allie

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In any case, there are myriad quality lenses for Nikon F mount in the ~75 to ~105mm range.

Some versions of the Nikkor 105mm are among the best lenses ever made by Nikon.

I have the older Tamron 90mm macro and it is also a great lens.

 

Aside from no-name cheapies, it's really hard to go wrong in this focal-length range.

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Depending a little on what you want...

  • The discontinued 85mm f/1.8 AF-D is decently sharp, but (if you care) has quite ugly bokeh from the images I've seen.
  • The current 85mm f/1.8 AF-S is also decently sharp, but has highly visible LoCA (the background is very green). This one I have personal experience of; I replaced it with the Sigma Art.
  • The discontinued 85mm f/1.4 AF-D is very good stopped down, and extremely soft off-centre wide open, in a way that reads to some people as "great subject isolation" and to me as "unnatural ugly mush".
  • The current 85mm f/1.4 AF-S is decently sharp, but in the tests I've seen looks like it might have similar LoCA issues to the f/1.8 version, and is very expensive.
  • The Samyang 85mm f/1.4 is reasonably sharp (sharper than the f/1.4 AF-D wide open) and cheap; the bokeh is decent. It's also manual focus, which is tedious, and probably doesn't quite have the edge of the latest lenses. I had one, but got bored of trying to keep people in focus at f/1.4 so I got rid of it for the 85mm f/1.8 AF-S.
  • The Tamron 85mm f/1.8 VC is reputedly quite decent and has VC (Tamron's version of VR), which is nice.
  • The 85mm f/1.4 Zeiss Otus and Milvus are both very (very) good, manual focus, and substantially outside your budget. I happened to see the Otus range during a visit to Park Cameras on the weekend, and was curious that the 85mm doesn't look any longer than the 55mm. Weird (though they're both retrofocal designs).
  • The Tamron 90mm VC macro is slightly outside your budget, but optically very good, especially at short range (obviously), although I've been fine with it at moderate distances. The previous, non-VC, version which I own is also very good and would be in your budget - although it has a little LoCA wide open which the new one allegedly fixes.
  • The Sigma 85mm Art is really an exceptional lens as far as I can tell, and it's cheaper than the latest f/1.4 Nikkor. If you wanted an 85mm and could afford it, I have no hesitation in recommending it - except that it's twice your budget and weighs a lot. If you wanted the best sharpness at a large aperture, this would be your choice. The previous Sigma is reputedly okay, but not brilliant.
  • If this wasn't obvious, ignore the Nikkor 85mm macro - it's a DX lens and doesn't have full frame coverage.

Of these, I assume you don't need to tack sharp wide open for your use and don't care about bokeh, unless you want to have a general-purpose portrait lens while you're shopping. I'd get the 85mm f/1.8 AF-S or possibly the older Tamron 90mm macro (if you'd rather have a macro lens than a fast one), with the Samyang as an option if you really want f/1.4 inside your budget. But if you can stretch your budget, both the Tamron 85mm VC and Sigma Art have a lot to be said for them.

 

I hope that helps!

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These are amazing recommendations, and with special props to @Andrew Garrard for an insanely wonderful breakdown. I'm running with the Nikon 85mm f/1.8 for now. The Sigma ART would be wonderful, but I can't fit it in the budget at the moment... it's on the wish list though. Thanks all. I'm sure this thread will be useful to others looking for something similar in the future.
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The 85mm f1.8G (used) is a no-brainer. I had one and found it to be incredibly sharp, and didn't have the CA my older Nikon 85mm f1.8D had. I don't think anything else is really close to the 85mm f1.8G. I would not buy another 85mm f1.8D.

 

Kent in SD

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Here's another thought:

 

Do you really need 36mp for this specific project? Or is ~15mp in DX crop mode sufficient?

 

If the latter, then I would suggest a Zeiss 50mm ZF.2 Planar or the Sigma 50mm ART. If those are beyond your budget, then find the best 50mm you can afford.

 

Interesting. Is it your opinion that there exists a £500 50mm lens that, when used in DX crop mode, would actually produce sharper images than the best £500 85mm lens in full-frame mode?

 

(Note: I am assuming that the images from both lenses/modes would have the same final output size.)

 

If not, what would be the reason to prefer such a setup, if cost is the same?

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Interesting. Is it your opinion that there exists a £500 50mm lens that, when used in DX crop mode, would actually produce sharper images than the best £500 85mm lens in full-frame mode?

 

(Note: I am assuming that the images from both lenses/modes would have the same final output size.)

 

If not, what would be the reason to prefer such a setup, if cost is the same?

 

IMO, none of the 85mm lenses in your price range would be sharper and have less distortion than the Zeiss ZF.2 50mm/1.4 Planar that I mentioned, especially since you will be stopping down and in DX mode, any edge or corner weakness (if any) is mitigated. The only downsides are: 1) ~15mp only in DX mode and 2) manual focus.

 

The Zeiss 50mm/1.4 ZF.2 is $725 USD at B&H (~546 pounds). I do not know if that pricing holds true if you buy it in the UK.

 

The macro lenses will arguably have better center sharpness compared to the 50mm/1.4 ZF.2, but you may have to deal with some light fall off / vignetting. Also, would the FOV from those lenses (60mm, 90mm, 105mm) be more/less useful to you for this project as the FOV from a 50mm in DX crop mode (FOV of a 75mm lens).

 

So, assuming none of the above are deal breakers, the choice boils down to the ZF.2 in DX crop mode or one of the macro lenses in FX mode. Which lens has more utility to you BEYOND this project?

Edited by photo_galleries
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IMO, none of the 85mm lenses in your price range would be sharper and have less distortion than the Zeiss ZF.2 50mm/1.4 Planar that I mentioned, especially since you will be stopping down and in DX mode, any edge or corner weakness (if any) is mitigated. The only downsides are: 1) ~15mp only in DX mode and 2) manual focus.

 

It may (or may not) be true that the Zeiss 50mm you mentioned is sharper than every 85mm lens, but that doesn't answer the question, which is this: If you take a DX-cropped image with that very sharp 50mm lens, and an FX-sized image with a sharp 85mm lens (even one that is a little less sharp than the Zeiss 50mm, let's say), and you resize both images to the same pixel dimensions (say 6000 x 4000 pixels), will the cropped 50mm image be sharper than the uncropped 85mm?

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It may (or may not) be true that the Zeiss 50mm you mentioned is sharper than every 85mm lens, but that doesn't answer the question, which is this: If you take a DX-cropped image with that very sharp 50mm lens, and an FX-sized image with a sharp 85mm lens (even one that is a little less sharp than the Zeiss 50mm, let's say), and you resize both images to the same pixel dimensions (say 6000 x 4000 pixels), will the cropped 50mm image be sharper than the uncropped 85mm?

 

6000 x 4000 exceeds the ~15mp that the D810 DX crop mode yields, so, the DX crop would require sizing UP. For that size, you are better off with the FX lens.

 

OTOH, the D810 in DX crop mode is the equivalent of a 15mp DX body (all else being equal). Resizing DOWN an FX image from a D810 to the same dimensions as the D810 in DX mode would not give you the same level of image detail.

Edited by photo_galleries
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It may (or may not) be true that the Zeiss 50mm you mentioned is sharper than every 85mm lens, but that doesn't answer the question..., ?

 

You forgot to add: "IN THAT PRICE RANGE." Since your original post was about "as sharp as my budget allows," it does answer your question. My contention is that the Zeiss 50mm/1.4 ZF.2 is sharper than an 85mm within your budget.

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You forgot to add: "IN THAT PRICE RANGE." Since your original post was about "as sharp as my budget allows," it does answer your question. My contention is that the Zeiss 50mm/1.4 ZF.2 is sharper than an 85mm within your budget.

 

Well, my original reply to you did include the £500 stipulation for both lenses.

 

But it's an interesting question. I concede that the Zeiss 50mm has slightly higher maximum center resolution (3960 LW/PH at f/5.6, according to OpticalLimits.com) than the Nikon 85mm f/1.8G (3872 LW/PH at f/4). However, I would expect that if you were to take a full-frame photo with the 85mm and downsize it to the same size as a DX-cropped photo taken with the Zeiss 50mm, the downsized photo would actually wind up sharper than the cropped one.

 

I'll go into my reasoning about this later. Right now I have to eat dinner. ;)

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Okay, here's my reasoning behind the speculation that the downsized 85mm photo will be sharper than the cropped 50mm one. You know what a circle of confusion (CoC) is, right? Now, I do not know how to calculate a CoC (in millimeters) from an MTF measurement (in line widths per picture height), but I'm pretty sure these numbers are inversely, linearly proportional. So, since the Zeiss 50's best MTF is about 2.2% higher than the Nikon 85's, it follows that its CoC is 2.2% smaller.

 

When you scale a full-size FX photo down to DX size, everything in the photo becomes 1/3 smaller—including the circle of confusion. So what was originally a 2.2% larger CoC in the full-size 85mm photo becomes a 32% smaller CoC in the downsized 85mm photo compared to the cropped 50mm photo. This means the 85mm photo is now 32% sharper than the cropped 50mm one.

 

Admittedly, this calculation does assume that we are using a perfect image scaling algorithm, which doesn't exist in real life except when using nearest-neighbor scaling with an integral downsizing factor. However, I would venture to guess that the best available scaling algorithms (such as, perhaps, Photoshop's Bicubic Sharper) are so good that you lose only a little of that theoretical increase in sharpness.

 

I have neither a Zeiss 50mm ZF.2 Planar nor a Nikon 85/1.8G, so I can't test this prediction. I do have a Nikkor 50/1.4 AI-s and a Nikkor 85/2 AI-s, but I don't know which one is inherently sharper, so the test would be close to meaningless. If anyone happens to have both the Zeiss and the Nikon in question, it would be great if you could do the test.

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Let me clarify what I wrote earlier: Sizing down from an FX image to the same size as an Auto DX crop image will have image degradation if the cropping includes resampling. If it's just resizing without resampling then the downsized image should have the same level of sharpness as the Auto-DX crop. It will NOT be sharper.
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Well, you're just denying my conclusion without stating any reasons. You're just stating it as a fact that should be intrinsically obvious to any intelligent person.

 

Perhaps you are right; I am an unusually stupid person.

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Just to chime in, while I don't doubt the improved rendering of the Planar, it's definitely true that the very cheap 50mm f/1.8 AF-D (or the manual focus versions with the same optical design) is sharp stopped down. Horrible wide open and with ugly bokeh, but sharp stopped down. :-) I'm not really sure what the demands may be on aperture for this project - I assume you want depth of field, but I don't know if light gathering capacity is a limiting factor (if you need a fast shutter for aerial photos, for example).

 

With a little digital correction (DxO, Photoshop, etc.) and stopped down a little, I suspect the 85mm f/1.8 will be just fine. I'd be surprised if it was worse than upscaling a DX crop, no matter what short lens was used. But I've been wrong in the past. :-)

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