[texandrews]

Much more. Don't get me wrong, I love a sharp lens. But some lenses also have interesting characteristics that may trump sharpness alone---which can be clinical. And the K1 as a FF camera is a good unit to bring out the goodness of some of these older lenses. Others will say it will only bring out the flaws. I disagree.

And in terms of FF, the real benefits over APSC have to do with light gathering and better tonalities, just as DMF has those benefits over FF (even when they may be slower, in equivalence terms). So, try thinking about this more expansively, and just shoot a whole bunch with these lenses you've got and see what happens. You may be surprised.

[rumplestiltskin]

A big "thank you!" to all who have opined on this matter. My mention of pixel-peeping may have been an unintended head-fake; I was referring to how equally-framed photos (let's say 18mm on the K5IIs and 28mm on the K1) might appear to be a better quality on the K1 because, at whatever print size I chose, the photo taken with the K1 would be enlarged less (due to the K-1 having a sensor with 50% more pixels in each direction). (Shardulm referenced this "FOV" issue.) Am I thinking of this incorrectly?

Perhaps the IQ of the two "28-" Sigma zooms are so bad that just changing to the Pentax-branded 18-250 would make it much better quality than the Sigma "28-" zoom on the K-1?

Using a Lightroom tool (whose name escapes me at the moment but I think it's a free 3rd-party item), I was able to have it examine all of my photos' EXIF data. The vast majority of my photos are shot with focal lengths in the 18mm (28mmFF) range. I guess I "see" at that focal length. I'm sure you know what I'm talking about. The longest focal lengths were rarely used but those photos were mostly taken because I couldn't get closer and were almost exclusively hand-held so I knew I was sacrificing IQ.

The "28-" zooms on the K5IIs don't really interest me as I invariably am zooming out closer to the 18mm setting on the Sigma. Those two Sigmas were purchased when I first bought the K5IIs but, once I bought the 18-250 Sigma, the "28-" zooms stayed on the shelf.

Prior to my K5IIs, I had (and still own and use occasionally) two Fuji bridge cameras (S9100 and S100fs). I admit I have a soft spot for bridge cameras. If Pentax (or anyone) would make an APS-C 24-150mm bridge camera, I'd be all over it like a cheap suit; hence, my rationale for the K5IIs with the 18-250 Sigma. (Panasonic's LX100 is also in my "hmmm..." field but I've been waiting to see if the next version extends its zoom range a bit more. Its low-light capabilities and tiny size might make it an ideal coat-pocket camera for a vacation.)

Additional advice is always appreciated. Thanks!

[VoiceOfReason]

Based on what you said get the K1, because at the same print size and same FOV the K1 wins. You can make decisions about lenses after you get it. The Tamron 24-135 is pretty cheap and reasonably sharp stopped down a little, the Sigma 24-70 f/2.8 is awesome on the K1, if your Tamron is the 28-75 f/2.8 constant aperture lens then that would be an excellent lens and you wouldn't even need to buy anything, and if not and you want a good WR walk around package the Pentax DFA 28-105 will fit the bill and from what I see is pretty sharp.

[Rondec]

The K-1 is better than what you have in almost every respect. I would definitely look at improving your glass, as well. It doesn't have to be really expensive, but a minimum of the DFA 28-105 is probably in order while you sort out what are the best lenses to add to your stable of glass.

[shardulm]

My mention of pixel-peeping may have been an unintended head-fake; I was referring to how equally-framed photos (let's say 18mm on the K5IIs and 28mm on the K1) might appear to be a better quality on the K1 because, at whatever print size I chose, the photo taken with the K1 would be enlarged less (due to the K-1 having a sensor with 50% more pixels in each direction). (Shardulm referenced this "FOV" issue.) Am I thinking of this incorrectly?

You are exactly right on your math.
But with a bad lens when you pixel peep you are going to see 50% more unclean pixels in both directions on a K-1.

Also it sounds like you prefer to shoot widish angle and 18mm FL seems your favorite on Aps-c. Check out the Da15 club on this forum and indulge (rent or borrow) in this da15/f4. It will be a meaningful upgrade. You will instantly notice the difference of clean and unclean pixels with that lens at your preferred FL.

[rumplestiltskin]

Unfortunately, the Tamron zoom I have is the 28-80mm f3.5-5.6. This one, apparently:
Tamron 177D AF 28-80mm F/3.5-5.6 Aspherical Lens Reviews - Tamron Lenses - Pentax Lens Review Database
I think that was actually the first lens I bought for my K5IIs but I know I haven't used it since getting the 28-105 Sigma (only a few weeks later). Based upon the review, I might find it useful to disassemble it and maybe see if I can craft some sort of "soft-focus" beastie from it. Certainly using it as is on a good Pentax camera is an abomination.

What's that site? Will It Blend? | Presented by Blendtec of course.

[VoiceOfReason]

Keep an eye on the marketplace here. I've seen a Sigma 24-70 f/2.8 for just over 200 before. I've seen the Tamron 70-200 f/2.8 for 400 before. Both of those and a K1 would give you a heck of a good base to start from along with your 50 macro.

[normhead]

Without reading everything said up to this point, I'd add, if you depend on lenses like the 18-250, which I've owned, you shouldn't be thinking K-1 unless you do a lot of shooting over 1600 ISO. There just is not FF equivalent to such lenses. From my own perspective, the K-1 isn't useable without the DFA 28-105, and for an extreme zoom type user, it's just not workable. You'd be better off with a K-P and continuing with what you have.

For me it's all about the weight. Any full range kit with a K-1 is going to be heavy compared to your superzoom.

The K-1 is a very nice camera and great to use. But it really crimps your style if you are a largely superzoom user.

[funktionsfrei]

There just is not FF equivalent to such lenses

Achtually, there is - though being slightly shorter at the long end. That's Tamron's 28-300 lens, on the market since more than a decade.
Alas, that and other "super zoom" lenses' image quality does not come close to what the K-1 (or an APS-C camera with a higher pixelcount than, say, the Pentax *ist DS) can deliver.

A nice lens, and much better than the Tamron 24-135 mentioned some posts before is the old Pentax FA 24-90. That one, stopped down to f8 truly delivers and that even without any lens correction in Lightroom (which isn't available unless one creates a lens profile for that specific combination).

The Tamron in comparison is quite blurry and has rather noticeable color fringing.

[normhead]

Achtually, there is - though being slightly shorter at the long end. That's Tamron's 28-300 lens, on the market since more than a decade.
Alas, that and other "super zoom" lenses' image quality does not come close to what the K-1 (or an APS-C camera with a higher pixelcount than, say, the Pentax *ist DS) can deliver.

A nice lens, and much better than the Tamron 24-135 mentioned some posts before is the old Pentax FA 24-90. That one, stopped down to f8 truly delivers and that even without any lens correction in Lightroom (which isn't available unless one creates a lens profile for that specific combination).

The Tamron in comparison is quite blurry and has rather noticeable color fringing.

I also have a rebadged Tamron, Pentax FA 28-200 but I won't recommend it on a K-1. was actually discussing lenses I'd actually use. My FA 35-80 is also a very useful lens on a K-1 but, build quality and lack of WR are issues, as well as screw drive. It all depends on whether you want lenses that actually make use of all the features of the camera including WR and DC or SDM AF.

Personally I told myself I wasn't buying anything but my Tamron 300 2.8 for the K-1, but IMHO your use of the camera will suffer if you don't buy at least a DFA-28-105.

[rumplestiltskin]

Thanks again to all who have responded. I've been processing all the advice (here and from a few locals who have been using FF and actually switched to APS-C) and made a sort of decision. As much as the K-1 is lustworthy, I really can't justify it for my needs. I will sell some of my "lesser" lenses (keeping the 18-250 Sigma and 50mm Pentax FA macro) and maybe both of my Fuji bridge cameras.

One of the nice things about the K5IIs (and all the K cameras) is the ability to connect some really strange old lenses with the appropriate (and cheap) adapters. For example, I have a couple of old Spiratone Portragon (100mm F/4) lenses that produce nice portraits and flower shots; yep, soft, not sharp so why am I thinking about a K-1 (he says, as he dope-slaps himself)? I was given an old Spotmatic setup that a client had deposited in a drawer 30+ years ago. Of course, the camera is worthless but I just now checked the other lenses in the M42 database here in the forum and was quite surprised to find they're pretty good Super-Takumars: 28mmF3.5, 55mmF1.8, and 135mmF3.5. If I'm so damn interested in sharpness, I can get M42 adapters for just some pocket change, relatively speaking. The other M42 lens in the kit was really surprising as I would have thought a Spiratone lens was a POS. It's the 135mmF1.8.

So I guess I've got plenty of sharp lenses if I only take the time to connect them via adapters to the K5IIs and shoot. Certainly these lenses aren't going to go traveling with me to foreign lands as the tours we take require a bit more speed (so the 18-250 Sigma is the "one" lens for those trips).

Given the above, I'll wait for the successor to the Panasonic LX100 for a fairly pocketable camera that would be handy for our night-time tours through foreign cities. (But the 135mmF1.8 would be tempting for night excursions if I have the time to manually focus, eh?)

So let's close this thread with an additional thanks to all. It's been good to talk this through before dropping a crazy amount of money I'd regret later.

Barry

[BigMackCam]

So I guess I've got plenty of sharp lenses if I only take the time to connect them via adapters to the K5IIs and shoot. Certainly these lenses aren't going to go traveling with me to foreign lands as the tours we take require a bit more speed (so the 18-250 Sigma is the "one" lens for those trips).

I think you've made a wise choice, Barry. The only thing I'd say (and push home a little too hard, perhaps - but for good reason ), is this.... Don't stay too attached to that Sigma 18-250 If you really must use a super-zoom, take a look at the Sigma 18-300. It has many limitations, but it performs extremely well for a super-zoom, especially at the long end... Centre sharpness at 300mm is a good match for the HD DA 55-300 (I own both)

[kjphilippona]

I would purchase a DA*50-135 and use your K5IIs! Wish I had not given my K5II, DA*16-50 and DA*50-135 to my daughter.

[BigMackCam]

I would purchase a DA*50-135 and use your K5IIs! Wish I had not given my K5II, DA*16-50 and DA*50-135 to my daughter.

... and yet, what a wonderful gift Very little you can't do with that kind of setup...

[rumplestiltskin]

I think you've made a wise choice, Barry. The only thing I'd say (and push home a little too hard, perhaps - but for good reason ), is this.... Don't stay too attached to that Sigma 18-250 If you really must use a super-zoom, take a look at the Sigma 18-300. It has many limitations, but it performs extremely well for a super-zoom, especially at the long end... Centre sharpness at 300mm is a good match for the HD DA 55-300 (I own both)

I'm not married to the 18-250 Sigma. There was no 18-300 at the time I bought the other.