[Rondec]

The difference between crop and full formats looks pretty real to me. One is distinctly larger than the other. Artificial, you say ...

You keep forgetting that this started with a consideration of the question of modern lenses in the context of steadily improving AF on APS-C. Something tells me that most APS-C customers are unlikely to buy the DFA 70-200mm as their go-to telephoto on crop format, unless they wanted lumbago and and had a pocket book of large proportions. No one questions its top-drawer quality but isn't the point. The DA* 55mm was designed as a portrait lens. It has a high price, a long focus throw and by modern standards an out-of-date motor. My guess is that it would not be many people's first choice of walkaround lens on a crop-format Pentax with AF to the standard of a D500. What they'd be more likely to prefer would be around 35mm f1.8 on FF (50mm on APS-C) with a fast motor. But there isn't one. Looking forward to its release over here.

There is a 35 f2.4 and a 31 f1.8 for Pentax. The DA *55 is a portrait lens. It compares pretty decently to a lens like the Canon 50 f1.2 which also has pretty slow focusing.

As to the new DFA lenses, I have no idea who, if anyone is purchasing these lenses, but I have a feeling that in general, full frame lenses are purchased by APS-C photographers -- either to hedge against the possibility of their getting a full frame camera down the road, or just because they like the focal lengths.

Currently, Pentax has the 18-50, 20-40, 16-85, and 18-135, not to mention the rebadged Tamron 18-270 as APS-C walk around lenses. To me, the main thing currently missing from the APS-C line up is a weather sealed version of the DA 12-24.

[Kunzite]

Let's stop guessing: the number of FF lens produced is very close to half of that for the smaller formats, according to CIPA:
http://www.cipa.jp/stats/documents/e/s-201607_e.pdf
This, while all but one mirrorless system don't have a FF option (m4/3, Fujifilm X, EOS-M, Nikon 1, Pentax Q). So, unless FF users are buying way many more lenses than APS-C users...

APS-C users using FF lenses is normal/natural with Canon and Nikon - the market leaders in DSLRs. I can see two major reasons to do it with Pentax, too:
- for many lenses, making them APS-C only would not significantly decrease the cost/size.
- users might benefit from it, if they later decide to go FF.
What's left? Those lenses where there is a clear benefit of making them APS-C. But I see no problem with most of the lenses being D FAs.

[RonHendriks1966]

Let's stop guessing: the number of FF lens produced is very close to half of that for the smaller formats, according to CIPA:
http://www.cipa.jp/stats/documents/e/s-201607_e.pdf
This, while all but one mirrorless system don't have a FF option (m4/3, Fujifilm X, EOS-M, Nikon 1, Pentax Q). So, unless FF users are buying way many more lenses than APS-C users...

APS-C users using FF lenses is normal/natural with Canon and Nikon - the market leaders in DSLRs. I can see two major reasons to do it with Pentax, too:
- for many lenses, making them APS-C only would not significantly decrease the cost/size.
- users might benefit from it, if they later decide to go FF.
What's left? Those lenses where there is a clear benefit of making them APS-C. But I see no problem with most of the lenses being D FAs.

Absolutely true, but weight and price for lenses do make a difference. Lenses for ff are on average 2,68x as expensive as for smaller sensors. It is more common to buy a 999 euro sigma ff lens for your Nikon aps-c then buy a 2000 euro Pentax FF lens for your aps-c.

[Barry Pearson]

APS-C users using FF lenses is normal/natural with Canon and Nikon - the market leaders in DSLRs. I can see two major reasons to do it with Pentax, too:
- for many lenses, making them APS-C only would not significantly decrease the cost/size.
- users might benefit from it, if they later decide to go FF.
What's left? Those lenses where there is a clear benefit of making them APS-C. But I see no problem with most of the lenses being D FAs.

Absolutely true, but weight and price for lenses do make a difference. Lenses for ff are on average 2,68x as expensive as for smaller sensors. It is more common to buy a 999 euro sigma ff lens for your Nikon aps-c then buy a 2000 euro Pentax FF lens for your aps-c.

A few years ago I tested various DA lenses on a Pentax Z-1P film camera. More recently I've tried various lenses on a K-1.

A somewhat simplistic observation (from limited samples) is that FF lenses tend to have better corner-to-corner coverage of the APS-C image circle than APS-C lenses do. Both in terms of image quality and distortions. (I got some surprises, for example when looking at the corner-to-corner sharpness of the APS-C crop of the wonderful DA* 60-250mm at the wide end anywhere near full aperture).

I'm not saying this is universally true. Some APS-C lenses really are good to the corners of an APS-C sensor. Some problems get better when stopping down. And some distortions and aberrations can easily be fixed by lens-profiles in post-processing.

But it is worth keeping in mind when choosing a lens to be used (for example) for landscapes on an APS-C camera.

[Kunzite]

Absolutely true, but weight and price for lenses do make a difference. Lenses for ff are on average 2,68x as expensive as for smaller sensors. It is more common to buy a 999 euro sigma ff lens for your Nikon aps-c then buy a 2000 euro Pentax FF lens for your aps-c.

Are they? I'm not sure we can do direct comparisons and generalize on that - as, for example, there's no modern APS-C DA 70-200 f/2.8 to compare the D FA with.

Perhaps it's the other way around, and the better and thus, more expensive lenses tend to be FF?

[RonHendriks1966]

I wasn't talking about performance of lenses, but how much money you have to spend on them. Some people are limited to a certain budget.

[Kunzite]

My post above also covers price; of course, you can compare prices only on products of similar quality.

[RonHendriks1966]

My post above also covers price; of course, you can compare prices only on products of similar quality.

Products that are more expensive then thè existing budget don't get into the mix for comparison. It doesn't matter how great they are, they are then for those potential customers to expensive.

[Barry Pearson]

Are they? I'm not sure we can do direct comparisons and generalize on that - as, for example, there's no modern APS-C DA 70-200 f/2.8 to compare the D FA with.

Perhaps it's the other way around, and the better and thus, more expensive lenses tend to be FF?

I wasn't talking about performance of lenses, but how much money you have to spend on them. Some people are limited to a certain budget.

My post above also covers price; of course, you can compare prices only on products of similar quality.

Products that are more expensive then thè existing budget don't get into the mix for comparison. It doesn't matter how great they are, they are then for those potential customers to expensive.

For some time I've been saying here that what Ricoh should do as high priority is to add two "affordable" high-image-quality, smallish/lightish, FF zooms: one either side of the D FA 28-105mm zoom. I've been advocating these primarily for the sake of both existing and potential K-1 users (as companions for the 28-105mm lens)

But it occurs to me that this could result in a 3-lens set that would be attractive for many APS-C camera users too. Imagine: perhaps "D FA 18-30mm (or 18-36mm) variable-maximum-aperture", and "D FA 100-300mm variable-maximum-aperture". (Or whatever zoom-range could be made cheaply).

I would buy those two lenses even though I already have the recent FF zooms, because they would be useful on the K-1. But I would also consider them for (say) a round-the-world-trip with a K-3II or other APS-C camera. They would have high image quality right to the corners of an APS-C sensor, would be FF-ready in case the users decides to add an FF camera later, or be useful for someone with both FF and APS-C now. I think they would sell like hot cakes!

[mecrox]

Products that are more expensive then thè existing budget don't get into the mix for comparison. It doesn't matter how great they are, they are then for those potential customers to expensive.

There's an interesting article by Kevin Raber just out (it may be behind a paywall, though) about visiting bears in Alaska with a Sony A6300 (among other things). He said he used it with the the big Sony 70-400mm telephoto lens with an adapter but otherwise has the Sony 16-70mm crop-format zoom for use at home. This seems to me to be a sensible way to do things. You get a modern crop-format camera with very good AF indeed yet it is small and not too expensive, paired with a combo of APS-C lens (or lenses) and one big telephoto lens for wildlifing. I don't imagine one wants to get too close to hungry beasts in Alaska. You come home with some great images and no need to visit a joint specialist. OK it's Sony, which isn't my cup of tea at all, but one gets the idea.

My guess is that the key to the future of APS-C compared to FF is Canon. They seem to be on a roll at the moment and are introducing some kick-ass new ideas such as dual-pixel. If Canon develop the M mirrorless series to the point of signalling that smaller formats = mirrorless and larger formats = DSLR (predominantly though not exclusively in either case), then everything will start to change. I guess we'll know over the next couple of years. If you believe some commentators, Canon are well on the way to taking the #2 spot in mirrorless after Sony and I'm sure their target would be #1 if they are serious about it. Either way, the notion of "they can buy FF or they can eat cake" from the big DSLR companies when it comes to pairing modern APS-C lenses with sophisticated AF on smaller, APS-C cameras doesn't strike me as having a lot of mileage left in it. Earlier this year Thom Hogan estimated that more than 80 per cent of Nikon's DSLR sales were for "consumer DX", and yet he pointed out that Nikon's lens programme was largely ignoring these customers, four-fifths of their userbase. Perhaps it's easy to overlook how much FF anything is a minority interest, for budgetary reasons if no other.

[D1N0]

For some time I've been saying here that what Ricoh should do as high priority is to add two "affordable" high-image-quality, smallish/lightish, FF zooms: one either side of the D FA 28-105mm zoom. I've been advocating these primarily for the sake of both existing and potential K-1 users (as companions for the 28-105mm lens)

They should have made the new DAF4.5-6.3 ED PLM WR REfull frame instead of aps-c.

[Barry Pearson]

They should have made the new DAF4.5-6.3 ED PLM WR REfull frame instead of aps-c.

That would have made it more expensive. Perhaps Ricoh wanted to extend their range of affordable APS-C lenses.

Also, it has a long focal-length range; 55-300mm (5.45x). My observation is that when sensors are small, it is easier/cheaper to have a long range. (It appears only to be small-sensor cameras that have super-zoom lenses).

Then as sensors get larger, zoom ranges tend to become smaller. It just appears to take a lot of largish glass, (hence heavier and more expensive glass), to have zoom ranges as large as we might want.

The DA 16-85mm and D FA 28-105mm are very roughly equivalent on their respective sensors, and similarish in weight and cost, but one has a zoom range of 5.3x while the other has a zoom range of 3.75x.

[Kunzite]

Products that are more expensive then thè existing budget don't get into the mix for comparison. It doesn't matter how great they are, they are then for those potential customers to expensive.

My point is that you cannot compare - let's say - a 50-200 f3.5-5.6 with a D FA* 70-200 f/2.8 and claim that the FF lens is so much larger and outrageously expensive. In order to support your point, you'd have to find a DA 70-200 f/2.8 of similar quality to the D FA. Or, find a D FA (50)70-200 f/3.5-5.6 and make the comparison at the lower end.
In order to generalize, you'd have to find out quite a few similar examples.

[pres589]

A Pentax take on the old full-frame Sigma 17-35 2.8-4.0 would overlap really nicely with the 28-105. A 16-35 2.8-40 would be even better, and as an APS-C person I think that'd be an awesome walk-about lens.

As for a FF 55-300 retractable, I wonder how much the lens would have grown to move up from APS-C. it's an interesting idea at least.

[D1N0]

That would have made it more expensive. Perhaps Ricoh wanted to extend their range of affordable APS-C lenses.

Also, it has a long focal-length range; 55-300mm (5.45x). My observation is that when sensors are small, it is easier/cheaper to have a long range. (It appears only to be small-sensor cameras that have super-zoom lenses).

Then as sensors get larger, zoom ranges tend to become smaller. It just appears to take a lot of largish glass, (hence heavier and more expensive glass), to have zoom ranges as large as we might want.

The DA 16-85mm and D FA 28-105mm are very roughly equivalent on their respective sensors, and similarish in weight and cost, but one has a zoom range of 5.3x while the other has a zoom range of 3.75x.

The Sigma and Tamron 70-300 lenses are full frame and not that big and heavy. On full frame their aberrations will be less obvious...