[Philoslothical]

Was stuck with an FA 100-300 that time, so I borrowed the D5100 for a while which had a fast fifty on it. Not sure if the lens affects AF speed with those lenses...

I would not be surprised if that had a major impact. In fact, a fast 50 will likely AF faster and better on your Pentax than a 100-300 would, being a slower lens.

I think they are both (D5100 and K-r) APS-C cameras... the Nikon just has more MP in it~

Exactly. The Pentax sensor is 0.2mm larger on the vertical axis, but it's the MP count that differentiates them. It's hotly debated, and perhaps becoming an obsolete guideline with some sensors, but generally larger pixels mean less noise and better IQ. That said, I'm sure the D5100 sensor is just as good in any real world scenario.

Don't be taken in by the 'you can use all the old lenses on Pentax' story. This is no real advantage. None of the older lenses suit me - they are made to odd FL's - modern lenses are lighter as well. SR on Pentax is overrated compared to Nikon or Sigma built in VR systems.

This is a ludicrous statement. It shows that you know nothing about old lenses and don't want to learn. That's fine, and your choice, but putting it like this feature is some kind of scam just reeks of fanboyism on your part. By all means enjoy your Nikon, but don't bs people.

[elho_cid]

Haven't used a D80 yet, but I've used my friend's D5100, and it does focus faster than my K-x in low light (or at least in that occasion where I used it - a bit past sunset). Was stuck with an FA 100-300 that time, so I borrowed the D5100 for a while which had a fast fifty on it. Not sure if the lens affects AF speed with those lenses...

I believe the AF speed depends mostly on the lens. I remeber I was debating over K10D, 30D and D80 several years ago and K10D seemed able to track AF on an incoming car while the D80 could not. I bought the K10D and became pentaxian. Later I witnessed on several ocassions how good the AF of D300 is with really good lens. But each time I met someone with D80 and some cheap lens I outperformed it with even with K10D.
Now with K-5 the AF is virtually instant with IF/RF lenses or small primes but takes ages with lenses like 55-300. With Nikon D5100 cheap lenses won't focus quickly as they only depend on built in motor. But I believe it could be extremely fast with expensive lenses like AF-S 17-55.

[geezer52]

. With Nikon D5100 cheap lenses won't focus quickly as they only depend on built in motor. But I believe it could be extremely fast with expensive lenses like AF-S 17-55.

You probably know this but it read funny to me, so to clarify

Nikon's D5100 does not have an in body AF motor. AF depends solely on an AF system built into the lens used.

The KR of course has an in-body AF motor and can use AF lenses of both types.

[wax]

"I prefer VR lenses - quiet, highly accurate and quick to focus compared to Pentax noisy focus motor..."

With my K-r I use:
Pentax 50mm f1.4
Pentax 50mm f1.7
Pentax 55mm f1.8
Pentax 28mm f3.5
Pentax 18-55mm kit lens
Pentax 35mm f2.4
Pentax 135mm f2.5
Carl Zeiss Planar 50mm f1.7 MM (US70)
Sigma 18-200mm f3.5-6.3
Vivitar 70-210mm f2.8-4.0
Samyang 18-28mm f4-4.5
And also M42 lens Posibility

If you are a miliionaire you can buy all this lens I have, and all of them work great, on Nikons VR system. Maybe 2 VRs good ones.


Don't be taken in by the 'you can use all the old lenses on Pentax' story. This is no real advantage. None of the older lenses suit me - they are made to odd FL's - modern lenses are lighter as well. SR on Pentax is overrated compared to Nikon or Sigma built in VR systems.

Modern lens are lighter because they are all plastic, and with time you´ll feel how they start to get loose missing accurancy. Old lens work even better on DSLRs because optics work on the center of it, where regularly has more resolution and all tough metal.

[tibbitts]

"I prefer VR lenses - quiet, highly accurate and quick to focus compared to Pentax noisy focus motor..."

With my K-r I use:
Pentax 50mm f1.4
Pentax 50mm f1.7
Pentax 55mm f1.8
Pentax 28mm f3.5
Pentax 18-55mm kit lens
Pentax 35mm f2.4
Pentax 135mm f2.5
Carl Zeiss Planar 50mm f1.7 MM (US70)
Sigma 18-200mm f3.5-6.3
Vivitar 70-210mm f2.8-4.0
Samyang 18-28mm f4-4.5
And also M42 lens Posibility

If you are a miliionaire you can buy all this lens I have, and all of them work great, on Nikons VR system. Maybe 2 VRs good ones.


Don't be taken in by the 'you can use all the old lenses on Pentax' story. This is no real advantage. None of the older lenses suit me - they are made to odd FL's - modern lenses are lighter as well. SR on Pentax is overrated compared to Nikon or Sigma built in VR systems.

Modern lens are lighter because they are all plastic, and with time you´ll feel how they start to get loose missing accurancy. Old lens work even better on DSLRs because optics work on the center of it, where regularly has more resolution and all tough metal.

You might want to redo the quoting on this post, because it's hard to figure out who's making what point.

Paul

[aleonx3]

You might want to redo the quoting on this post, because it's hard to figure out who's making what point.

Paul

Took me a while and still didn't quite get that..

[pinholecam]

Would I be disappointed in the K-r coming from a D5100? When I bought my Nikon I was on the fence trying to decide which camera to buy. There weren't any dealers around me who carry Pentax so I was kind of nervous about purchasing a camera I could not touch. Now I find myself really wanting IBSR and focus motor. I like my D5100 but never really use the video function. I don't know what but something keeps drawing me to the K-r...

Yes, the IBSR and focus motor would be the 2 key things the Kr will have over the D5100.
Others being preview of WB and picture styles and saving last shot photo in the selected style; 3 frame on-camera HDR (D5100 does a not very generous 2 frame HDR)
If I were to choose Nikon today, it would be D7K and no less because of the AF-S and non AF-S mess they have for 'lower end models'


But at this point, I guess you have to evaluate if jumping ship would mean loosing too much money.
Both cameras are easily capable of great photos.