[Winder]

It looks like you are wrong here.
According to the DxO, 1.4G is much sharper on wide apertures than the Sigma (Nikon AF-S 85mm f/1.8G versus competition - DxOMark). As for the 1.8G, it's good without a doubt. However, its DOF will be so much alike to my K-3+DA*55, then what's the purpose of moving to FF?

I guess it depends on if you get a good copy of either lens:
IR (SLR GEAR) Sigma Lens: Primes - Sigma 85mm f/1.4 EX DG HSM (Tested) - SLRgear.com!
"Sigma meets the performance offered by the Nikon 85mm, and in some cases, exceeds it. We noted an odd patch of softness in the center of the frame when using the Nikon lens at ƒ/1.4; the Sigma, by comparison, is quite sharp."

The DA* 55mm has to be stopped down to get really sharp images unless you have a good copy. There seem to be some DA* 55mm lenses that are quite sharp at wide apertures, and some that are quite soft. The Nikon 85mm F/1.8G is a good bit sharper wide open than the DA* 55mm.

What is it you are shooting that you need really thin DoF? I was a Canon shooter for years. My favorite lens was the 85L. At the time it was the best you could get. Today its an average lens in its class. I set out to master F/1.2 and quickly realized that on my Canon 5D, 85mm at F/1.2 has such a narrow DoF its extremely hard to get sharp shots unless your subject is stationary and you well braced or on a tripod.

This is a comparison of the Fuji 56mm F/1.2 (regular and ADP) and the Canon 85mm F/1.2. I prefer the look of both the Fuji lenses over the Canon 85mm, and narrower DoF of the FF Canon does nothing for this portrait. THE REAL DIFFERENCE: XF56 vs XF56 APD vs FF (GUEST POST – NIKO VILLEGAS | JAN GONZALES) | RANDALL CIPRIANO . COM

Show me an example of what you are trying to achieve with the 85mm F/1.4 that you can't do with the F/1.8G?

[B Grace]

I am trying hard to come up with some option that will let me have both systems I so much like the results all my lenses can deliver! It's very very hard to sacrifice them... At any case I am not going to sell my FA*85/1.4 and 31/1.8 Lim at the moment. Maybe I will test the systems side by side and then will decide what to leave and what to sell. In the meantime I have a feeling that optically FA*85/1.4 is better than 85/1.4G.

I'd second the suggestion that you keep your current kit of Pentax gear intact. At least rent a D750 and one of the Nikon lenses you're considering for a weekend and see what you think. Or check with your local store to see if you can borrow a combo for a day. You've set a pretty high bar for the Nikon kit to clear.

[skyer]

To be honest, I didn't like the images shot by Canon 1.2L and both Fujis in your example.

Here is a photo I shot with my FA*85/1.4 - https://cloclo15.cloud.mail.ru/weblink/thumb/xw1/b2c311089ba5/sample-2.jpg?x...les5%40mail.ru I like the look and the colors very much! All I want is I getting some more space in the picture but with the same blurrinness of the background. Now it is too... cropped
Also I would like to get such looks from FF: http://neilvn.com/tangents/images/models/olive/DSC_0308.jpg (shot with Sigma 50/1.4 Art) and http://shotkit.com/wp-content/uploads/2014/03/Drew-0001.jpg (shot with Nikon 58/1.4G). It's obvious to me that it's impossible to get something similar with a crop camera.

Also I would like to note that now I am addicted to a good bokeh. I like the look delivered by FA*85/1.4 so much, even when shot not wide open. Images from 85/1.8G look too straight to me. They are sharp, have good blurrinness of the background but they still miss something. I hope 85/1.4G is closer to FA*85/1.4 than 85/1.8G.
As for the softness of DA*55 at f1.4, it is so. However it's a portrait lens and it's great to have so much different looks it can deliver with different f-stops. I think that DA*55 is very much alike to 58/1.4G. Unfortunately, the latter is so much more expensive.

[tuco]

Also I would like to note that now I am addicted to a good bokeh.

First understand good bokeh is a property of a particular lens and not how much out of focus the scene has or the camera format. In other words, just because a lens is fast that is no guarantee that it will have good bokeh.

[skyer]

I'd second the suggestion that you keep your current kit of Pentax gear intact. At least rent a D750 and one of the Nikon lenses you're considering for a weekend and see what you think. Or check with your local store to see if you can borrow a combo for a day. You've set a pretty high bar for the Nikon kit to clear.

In my city there is no D750 for rent. Now I think that I need to try D750 with some good lenses and decide for myself which combo is better for my needs: Pentax or Nikon.
One of the reasons I am looking to D750 is because at first in many reviews its AF was regarded as very accurate and fast. I have some issues with AF accuracy of Pentax. It is said that Pentax AF is outdated and has very big AF spots. With portrait lenses at close to medium distances K-3's AF is very accurate at the widest f-stops of all my lenses (I can almost always focus at eyelashes at f1.4). At longer distances AF accuracy is inconsistent. Especially it's obvious with FA*80-200 at 200mm, f2.8 and at distances from 10m and farther. I thought D750 could help. Now I have some concerns because more and more users say that sometimes D750's AF accuracy is also inconsistent. I am a bit puzzeled. I don't wether it is actually possible to nail focus at 200mm at f2.8 from 10m+. So I'd like to find out it for myself.
As for AF.C, I don't usually need it but it'll be a good bonus too.

First understand good bokeh is a property of a particular lens and not how much out of focus the scene has or the camera format. In other words, just because a lens is fast that is no guarantee that it will have good bokeh.

I understand this, maybe I just expressed myself not clearly.

[Winder]

To be honest, I didn't like the images shot by Canon 1.2L and both Fujis in your example.

Here is a photo I shot with my FA*85/1.4 - https://cloclo15.cloud.mail.ru/weblink/thumb/xw1/b2c311089ba5/sample-2.jpg?x...les5%40mail.ru I like the look and the colors very much! All I want is I getting some more space in the picture but with the same blurrinness of the background. Now it is too... cropped
Also I would like to get such looks from FF: http://neilvn.com/tangents/images/models/olive/DSC_0308.jpg (shot with Sigma 50/1.4 Art) and http://shotkit.com/wp-content/uploads/2014/03/Drew-0001.jpg (shot with Nikon 58/1.4G). It's obvious to me that it's impossible to get something similar with a crop camera.

Also I would like to note that now I am addicted to a good bokeh. I like the look delivered by FA*85/1.4 so much, even when shot not wide open. Images from 85/1.8G look too straight to me. They are sharp, have good blurrinness of the background but they still miss something. I hope 85/1.4G is closer to FA*85/1.4 than 85/1.8G.
As for the softness of DA*55 at f1.4, it is so. However it's a portrait lens and it's great to have so much different looks it can deliver with different f-stops. I think that DA*55 is very much alike to 58/1.4G. Unfortunately, the latter is so much more expensive.

If you really love good bokeh then the Sony 135mm STF or Nikon 58mm F/1.4 are kings. The Sigma 50mm (OLD) F/1.4 is known for excellent bokeh, but its just creamy and smooth where as the 58mm Nikon has more character (just as creamy and smooth). I don't know if its worth the money, but the 58mm is pretty special. The DA* 55mm is a good lens, but I prefer the Fuji 56mm F/1.2 for its sharpness and transition. I don't think the DA* 55mm has nearly as much pop as the 58mm, but the DA* 55mm is obviously a better value. The 58mm is not 2x as good.

Good bokeh is of course subjective. Some people like the more impressionistic bokeh of the 77mm LTD. I prefer the smoother, creamier bokeh of the Sigma 85mm. Its not all about aperture. A lens that smoothly moves from focus to out of focus quickly will give better bokeh than a faster lens that doesn't transition as smoothly or as quickly. There are a lot of F/1.4 lenses, but they don't all have pleasing bokeh. There is more to it than just speed.

[tuco]

I understand this, maybe I just expressed myself not clearly.

The Nikon 105/2DC and 135/2DC have adjustable bokeh. Some reviews recommend them.

[skyer]

Thank you all for your comments on my issue!

Winder, I also prefer a smooth and creamy bokeh. When I glanced at my pictures from 77/1.8 for the first time I was unpleasantly surprised. A foliage in the background was so distracting at f1.8! However, what I then discovered about Pentax lenses gave me some encouragement. A bokeh of many Pentax lenses changes drastically from one f-stop to another. A bokeh of 77 at f2.2 is super creamy! Maybe only FA*85 has almost the same creamy bokeh no matter how much it stopped (of ccourse, the amount of blur changes as long as an f-stop changes).
58/1.4G may be in its own leage but I still presume that DA*55 is close to it. I am not talking about DA*55 images on crop cameras here. As you may know, DA*55 is a full frame lens (but I have never tried it on Sony A7-s).

tuco, the lenses you mentioned must be great but I don't want to shoot with any specialized lens at the moment. I just want to find "ordinary" Nikon mount lenses with a bokeh similar to my Pentax lineup in its greatness. I mean that surely Nikon's bokeh may be different but it must be great anyway.
I don't know much about the old Sigma 50/1.4, I've just heard that the new one is better its predecessor in any regard. Some even say that it's better than 58/1.4G. I think I'll stick with the 50mm Art version. Now I need to choose something for a wide angle. 24/1.4G is too expensive. Does anyone know wether 28/1.8G's bokeh on FF Nikon is smoother than FA*24 on a crop camera (if we'll be shooting at "equivalent" distances)?

[Winder]

I am not talking about DA*55 images on crop cameras here. As you may know, DA*55 is a full frame lens (but I have never tried it on Sony A7-s).

The 55mm has been used on FF A7 bodies. There is blog where someone used the 31mm, 55mm, *300mm. The 31mm did great, the 55mm had a good bit of distortion that can't be corrected with the A7 and I don't remember how the 300 performed. If you can you it on a FF I think it will require a good bit of software correction.

[skyer]

The 55mm has been used on FF A7 bodies. There is blog where someone used the 31mm, 55mm, *300mm. The 31mm did great, the 55mm had a good bit of distortion that can't be corrected with the A7 and I don't remember how the 300 performed. If you can you it on a FF I think it will require a good bit of software correction.

Maybe it's true, I didn't see many DA*55 images on FF. I just thought that if it's good on a crop camera it would be even better on FF.
Anyway, I am not planning to use Sony A7 series at the moment. I like to shoot action not staged photographs, so manual focusing will be a limiting thing to me.

[skyer]

Has anybody here owned both the K3 and the D750? I'm still on the fence as to if I should keep the D750 or return it and get a K3 instead. Would love to know if the AF on the K3 has gotten near Nikon levels and also curious about low light performance of the K3.

What lenses do you have for D750?

[rawr]

Would love to know if the AF on the K3 has gotten near Nikon levels

From what I can tell with the D610 (which has a slightly less sophisticated AF than the D750), I'd call it a total draw for AF-S, but a 25% advantage for Nikon in AF-C. But AF-C is complicated for both systems - there's just about as many options and parameter adjustments possible in the K-3 as there are in Nikon in order to tailor AF-C performance to various shooting scenarios.

K-3 low-light performance is confident. Black cat in a coal-mine stuff. On paper, it even does better than the D750, since while both the K-3 and D750 will AF down to -3EV light levels, only the K-3 will also meter exposure down to -3EV too, which helps with exposure and scene detection, as well as AF. The D750 stops exposure metering at 0EV.

One day I would like to see a side-by-side VERY low light AF test of all the cameras that claim to AF down to -3EV and lower - the K-3, K-5II/s, D750, Canon 6D, Canon 7D2, Sony A7s, Samsung NX1, Panasonic GH4/G6/GX7/GM1/GM5. Would be interesting.

[rawr]

and leans me toward returning the D750 and getting a K3.

Now I will be to blame for any K-3 or D750 buyers remorse you may experience

But for a US$796 vs US$2296 [B&H prices today body only] camera decision, unless you really need the features or capabilities of the D750, I must say the scales certainly tilt towards the K-3.

[neostyles]

Its a pretty well known that pentax is still playing [URLhttps://www.youtube.com/watch?v=gPAu0q6rRSE]catch up with regard to aufofocus[/URL]. You wont get any advantage in low light. I guess there is the metering thing but i usually use manual exposure for low /light stuff. My d600 had no trouble metering at night in downtown (there are some pics on my flickr.) During day time, the af will destroy the k3. You have amazing subject tracking (even with with subjects moving towards you which have typically posed enormous challenges.) Go watch the drtv review. The hit rates on their af tracking tests were basically 100%. So, i dont know, a little advantage at night (for something thats not really af) or a huge advantage for the d750 during the day. This is seems like a no brainer. Im also seeing some reports of underexposing.

If you use wi fi too (and i believe this is something that can com in handy for many photographers), the d750 destroys the k3 here too as its all built in and much, much less painless. No need to sacrifice one of your sd card slots. Much better video too on the d750 as well. The k3 doesnt even have continuous af in video. The k3 records at low bit rate and from what ive seen video on the k3 just looks tedious. With the d750 you can get modded firmware that lets your record at a whopping 64 mbps. Part of the upside about nikon is that you get access to a much larger selection of 3rd part things. You will be giving up the full frame advantage. Full frame gives you better sharpness, dynamic range, etc.

I would say that imho nikon has the advantage when it comes to lenses too. Nikon offers a wider selection of lenses. For a little over $200 you can get the nikkor 50mm which fits both full frame and aps c cameras. It has fantastic image quality and near silent af. If you want to get the same thing with pentax.. well there isnt really anything like it. Alot of pentax's lenses tend to be pretty noisy which poses problems for video.

Bottom, line is that the d750 is all around very solid package for stills and video. There are lots of things that can be expressed in a specs sheet. I love the sleek, modern look of nikon cameras, how easy everything is to do in the menus. Shooting in live view is almost zen like. I didnt even bother cracking the menu when i got my d600 and i was still up and away shooting. Plus, you have to consider that you are trading a $2000 camera for an $800 one.

[skyer]

During day time, the af will destroy the k3. You have amazing subject tracking...

Alright, according to the specs of Nikon's AF.C you may be right. But what about AF.S? Is its accuracy at wide apertures tend to 100%?
I've read so many revews of real D750 owners complaining that AF.S of their D750 sometimes is inconsistant. On the other side, some say that AF.S has become "super accurate" and one can easily focus with 50mm lens at f2.8. To me it looks very discouraging. What's the benefit of fast AF if it's not accurate?
Now I have Pentax K-3 and the hit rate of AF.S with 24/2.0, 31/1.8, 55/1.4, 85/1.4 at f1.4-1.8 on distances up to 3m tends to 90% (I mean that it is really tack sharp!). I don't even talk about shooting at f2.8 and above, the DOF will be so great that everything will be in focus.
The most significant complaint I have about K-3's AF.S accuracy is shooting with FA*80-200/2.8 at 200mm and f2.8 on distances farther than 7m. Now the hit rate comes lower to about 50%.

I would like to address my question to the Nikon D600-D810 owners. How would you describe the AF accuracy of your cameras when shooting with 70-200 at 200mm and f2.8 at distances farther than 7m? Is it almost always very accurate or is it rather usual that front/backfocus can be about 5-7cm? For example you're focusing on a man's face but in the image ears look sharper than the eyes.

Nikon offers a wider selection of lenses.

Can you advise me with what Nikon-mount lenses I can easily substitute Pentax FA*24/2.0, 31/1.8 Lim and get a super-creamy bokeh without spending a fortune? (Sigmas are great but their bokeh doesn't come close to Pentax.)