To start with, I looked up the average size of an adult male’s hand and checked several sources for confirmation. It’s about 19cm (7.5″) from wrist to tip of middle finger. Thus my hands are actually normal size, and not gigantic as so many of the tiny devices in our lives today have led me to believe. This doesn’t really change things, though.
Over-all, ‘handling’ is a highly subjective criterion. Gripping the camera easily is surely the main part, and secondary to that would be the controls falling into place where those most frequently needing changing would be readily accessible. This is somewhat (but not very much) standardized across camera makes and models these days, with only the occasional “gotcha!” cropping up to ruin the experience. Your actual mileage may vary, as the saying goes. So let’s look at me gripping my cameras and discuss some other minor details.

I generally have no trouble holding this camera or operating its controls (except when they stop working). The grip area measures about 4″, which is a little shy of accommodating the whole hand but does take up more than half. I’m pretty comfortable with it. My major complaint about the controls is that ISO is buried in the menu settings instead of being a dedicated knob or at least easily-accessed adjustment. There may be some way of programming that, but even if so I’d never remember where it is. I don’t like “programmable” buttons for that reason. If you only have one camera or multiples of exactly the same camera you might remember which button is set to do what, but … not me.

As you can see it’s a little smaller handful than the Nikon, despite having a larger sensor and generally being about the same body size. The ‘finger grip’ in front simply doesn’t stick out as far. Still very usable, and some of the small controls are more sensible on this camera. Of course there’s no zoom control because of the detachable lenses. The ‘PASM’ dial, which also serves as the on/off switch, on top is fine. The ISO access button on the back is okay. Adjusting shutter speed or aperture when in the respective ‘preferred’ mode is also okay with the thumb dial, but I do prefer actual dedicated controls.

I like using this camera. It has the build and ‘feel’ of a 35mm SLR. But holding it is something of a challenge. There’s almost no ‘finger grip’ and the body is small (and lightweight). Most of the controls are well-placed, and it has a door on the side for memory cards (in this case CF or xD: no SD card) where it should be. Yeah putting them under the same access as the battery is a cost-saving measure, not a better design. The settings access for ISO, shutter, and aperture could definitely be better than it is. I still like using it. Too bad the battery is failing and only lasts about 20 shots at best. Also the auto focus is abysmally slow. Then again it’s an old (by digital standards) camera, dating from 2007.

This one is problematic in the extreme. I can practically encompass half the camera in my hand, and its utter lack of front ‘finger grip’ means my palm hits buttons on the back changing settings when I don’t want to. This can make it really annoying to use. Paradoxically, it has ‘handy’ knurled wheels for adjusting settings which are right where you can change them with your thumb – albeit sometimes you do so accidentally. Other than those problems, which are significant, it’s a good camera that takes good pictures. In some ways it’s the best I’ve got, such as the speed of autofocus and ease of adapting vintage lenses. It’s a dust magnet though, and the handling really is problematic. Oh I said that already. Did I mention the handling is problematic?
I will take a moment here to talk about lens rings. I like them. I want one for focus, one for zoom, and one for aperture out there in front like a film camera would have. None of my cameras meet that spec, although zoom and focus rings are present on some of the DSLR lenses. The Lumix has a ‘pseudo’ lens ring which can be assigned different functions such as zoom or focus or program adjustment, but it is not dedicated and sorting through the menu to find the adjustment is frustrating. The Sony’s kit lens has both a zoom button and a zoom ring which is redundant and annoying. Duplication of controls is never helpful. Using manual lenses eliminates a lot of this, but also eliminates autofocus and exposure. I see many Fujifilm professional cameras have very ‘film-like’ controls and so I envy Fuji users that. I certainly can not afford one though.
Now let’s step over the edge of the cliff into the realm of the sublimely ridiculous:

Right. Same hand, different camera. No argument about a “too small” body here! It would be great – if it didn’t weigh in at over 1.5 kilograms (more than 3 lbs.) and did have a 1500mm lens – which it would need to be because it’s a full-frame camera. Only 11MP, but great for low-light photography like night skies or infrared work because of that ‘low resolution’ in combination with the sensor size. Fairly impractical for daily shooting, though. Of all my cameras this one has the worst controls for convenience of access. Nothing is straightforward or dedicated about them, and a lot of ‘double pushing’ is needed to change things (hold one button down while advancing settings with another).

Yes if the lens were retracted I could hide that one in my hand. There are smaller cameras than this, but they do not take as good pictures. Again the viewfinder issue (it hasn’t got one) and focal length limit. But you can carry it anywhere. Besides that it’s the only one that automatically shifts resolution to get a better picture. That EXR function is quite a thing: so good that I never take the camera off automatic. This one is point-and-shoot heaven.
Is there a winner here? Yes, and it’s the *cough* Nikon P610. Were you surprised? One of the things against the P950 and the P1000 is that they are physically larger (and heavier), but offer no advantage from that increased size: they have the same tiny sensor as the P610 inside. Mostly the bodies got bigger to hold the larger lenses which at 83X and 125X respectively are probably best described as “overkill”. Or maybe “clunky”. I guess the thinking was “half an improvement is better than none”? The P610 aside, the next best in my collection for handling is the Canon T100. It is the most modern as well, with an 18MP sensor that allows some reasonable cropping (the 24MP Sony a6000 is actually an older design).
I don’t know how a Canon SX70 or Panasonic FZ80 handles and it’s unlikely I’ll find out. There are no camera stores near me and the closest is over 2 hours’ drive away, with no guarantee they’d have what I want to look at.
Even if I could afford it.
Addendum: adding a picture of the Pentax K100Ds. As you can see it fits my hand as well as the Nikon does, and indeed is a very nice-to-handle camera. It has a few faults, though: it’s only 6MP which I find too low for my usual photography (even though the images get shrunk way down before presenting), I’ve only got one auto lens for it and any new one costs as much as a lens for the Canon or Sony, and the pentamirror is desilvered to the point where not only are there large black spots in view but the light transmission is lower than normal for a DSLR. But it is a nice camera. I would have had the slightly newer K200 but ego-Bay killed me before the sale was complete. Another thing to ‘thank’ them for.
