~80mm rec for FX?

[rodeo_joe1]

If a DX crop and manual focus is satisfactory, then a 55mm f/2.8 or 3.5 Micro-Nikkor would be more than suitable. They can be picked up for well under $150. Unlike any Zeiss lens.

 

The resolution of a 55mm Micro-Nikkor will exceed that of any DX sensor currently on the market.

 

Back to full-frame: The old 85mm AI-s f/2 Nikkor often gets maligned for being 'soft', as does the Samyang 85mm f/1.4. Personally, I see nothing wrong with either lens WRT sharpness. However, the Samyang suffers from LoCa 'Bokeh fringing' quite a bit, and also shortens its focal length considerably with close focusing. By my estimation it only has a 70mm focal length at minimum focus. Probably not a good feature for photogrammetry.

 

If good and predictable geometry are necessary, then those are the parameters I'd be comparing. Because there's barely a lens on the market in this focal length range that won't give excellent sharpness at f/5.6 and smaller.

[chulster]

With a little digital correction (DxO, Photoshop, etc.) and stopped down a little, I suspect the 85mm f/1.8 will be just fine.

You're referring to the 85/1.8D, right? I've never seen anybody say the G lens needed help to be sharp.

[Dieter Schaefer]

(3960 LW/PH at f/5.6, according to OpticalLimits.com) than the Nikon 85mm f/1.8G (3872 LW/PH at f/4)

Splitting hairs - that's a difference that's hardly detectable in an image and also way inside the sample variation for each lens (aka, pick another pair and the results may well be reversed).

You're referring to the 85/1.8D, right? I've never seen anybody say the G lens needed help to be sharp.

I suspect that Andrew is referring to the LoCA that both the D and G versions show in abandon when used wide open (or close to it). I owned both and would trade my G for the Sigma Art in a heartbeat if I was willing to deal with the bulk and heft (and price).

[Andrew Garrard]

I don't know that the 1.8D isn't sharp - the objections I've heard to it are about the bokeh. Although now you've mentioned it, DxO does seem to give that impression - I don't think DxO existed when I was looking at it. In any case, the 1.8G is very sharp (my objections were to the LoCA); DxO still tends to pull back a little sharpness, and the Sigma does have the edge at the widest apertures. I found DxO most useful on the 14-24, although going back to some older 18-200 images it's had a good go at it.

 

The Samyang actually seemed decent to me in terms of sharpness (albeit on a D700, which is a soft target). It's not quite up there with the newer and more expensive designs, but it's decent - though I might have been stopping down a bit more if I'd been using it on a 36MP body. I didn't find the LoCA too intrusive, although perhaps I wasn't looking - I really got rid of it because I found manual focus too painful, given that I was usually chasing a moving subject. So far the Sigma's LoCA (and it's not absolutely perfect) seems appreciably less intrusive than the 85mm f/1.8G - it was enough to put me off using the latter. I've not owned the Sigma for long, though. You can certainly feel the weight if you try to shoot it one-handed (especially with the grip on a big L-plate on the body), but two-handed it's no worse than the 70-200.

 

And yes, stop down a little and all of these are perfectly respectable. To get an 85mm or 50mm lens not to look good at f/5.6, you really need to be looking at a zoom!

[chulster]

I owned both and would trade my G for the Sigma Art in a heartbeat if I was willing to deal with the bulk and heft (and price).

(Boldface mine.)

 

In other words, you're not willing to trade your G for the Sigma Art. ;)

But you would, if all the counterfactuals were true. ;)

[chulster]

It's for a photogrammetry project.

 

@count_chocula

Allie, what are the desirable qualities in a lens for photogrammetry, anyway? Sharpness, sure. Is geometric flatness (straight lines are rendered perfectly straight) also important? I'm guessing bokeh would be a secondary consideration. ;)

[Dieter Schaefer]

you're not willing to trade your G for the Sigma Art

Got me :D

[mike_halliwell]

It's a v.big focal-length jump from the Sigma 24mm Art all the way to 85mm.... just saying;)

 

Did you determine your length required by looking through a cheap tele-zoom and 'zoom-to-framing-needed' ?