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Forum: Pentax SLR Lens Discussion 07-20-2018, 02:56 PM  
Why would somebody buy the DFA28-105?
Posted By BigMackCam
Replies: 104
Views: 6,977
This has parallels for me with my experience of the HD DA20-40 Limited...

This is a lens I've owned for a few years now, and never really connected with. It's the only DA Limited that disappointed me (I've even stated this quite recently). My own experience suggests that it has really strong field curvature at the longer end, even when you stop down, such that it's very noticeable on distant flat-ish field subjects at, say, f/8. One of our members called it "runway style" field curvature, and that's a pretty good description, IMHO. Borders are in focus at much closer distances than the centre (at the longer end).

It has been more-or-less a "shelf queen" in my kit for the last couple of years. Recently, though, I've been forcing myself to use the lens more often, and I'm starting to find more value in it. Rather than expecting it to do what I want, I'm working with what I believe I understand about its optical properties and performance. And I'm getting some nice shots. That's not to say I'm much less frustrated by what I see as its limitations... It's just that I'm beginning to understand how I might use those "quirks" to my advantage.

The funny thing is, I've been taking that approach when shooting with my vintage Soviet lenses for quite a long time. Right from the outset, I accepted expected they'd have idiosyncrasies I'd need to work with. I guess I just never thought I'd have to take that approach with a modern lens. But now that I am, I'm feeling better about owning the 20-40. I'm not totally convinced yet, but far less critical than I originally was...
Forum: Pentax SLR Lens Discussion 07-19-2018, 01:20 PM  
Why would somebody buy the DFA28-105?
Posted By BigMackCam
Replies: 104
Views: 6,977
I'm glad you got some useful information out of the thread :)

The reason you got such "robust" responses from some of our members is that, with respect, you appeared to suggest that your choices made more sense, or resulted in better IQ, than a K-1 + D FA28-105. I'm sure that wasn't actually your intention, but subtleties can get lost in forum posts :o Hopefully, you now see there's a wide range of reasons why people shoot what they shoot - whatever the camera(s) and lens(es) may be - and their choices can make perfect sense for them, even though they may not work for you. "Better" and "worse" are almost always individual to the photographer, and highly subjective :)

I don't shoot the D FA28-105 on APS-C, but I do use other full-frame zooms including its old predecessor, the SMC Pentax-FA 28-105mm F3.2-4.5 AL [IF]. I don't shoot wider than 28mm on APS-C very often unless I go out specifically with that intention, in which case I might use the DA21 or very occasionally the DA15. I typically prefer the 28-80mm range, or thereabouts. My favourite walk-around lens on APS-C is actually the Tamron 28-75 f/2.8... that range is absolutely ideal for me, and f/2.8 is enough for most of my shots. Plus, I like the rendering (though perhaps it's not one for pixel peeping at 100% on a 4K monitor when shot at f/2.8 ;)). I have faster primes for some focal lengths, and frequently use those when I'm happy to work with fixed focal lengths :)
Forum: Pentax SLR Lens Discussion 07-19-2018, 08:16 AM  
Why would somebody buy the DFA28-105?
Posted By BigMackCam
Replies: 104
Views: 6,977
Yeah, it was the sharpness away from centre at the longer end that I was disappointed with.

The main reason for me trying the lens was to have something weather-resistant as a walk-around one lens solution when required. It definitely fills that role, but I didn't gel with it unfortunately. Having said that, I know you and many others get some great shots with it. I certainly wouldn't call it a bad lens... I just didn't take to it :o
Forum: Pentax SLR Lens Discussion 07-19-2018, 08:04 AM  
Why would somebody buy the DFA28-105?
Posted By BigMackCam
Replies: 104
Views: 6,977
Indeed. It's all good :) The take-away from this is, we're all different...



Now that's a lens that seems to polarise opinion. I've never shot with it, and if I did, I think I'd want to use it on full frame - where I suspect I'd love it, based on what I've seen and read. But there are plenty of people who tried it and didn't like it because it didn't meet their personal expectations.



And just a final comment... The 18-135 is loved by many here. I bought one, though, and simply didn't get on with it... primarily at the long end. For my purposes, it wasn't a great fit :o
Forum: Pentax SLR Lens Discussion 07-19-2018, 07:36 AM  
Why would somebody buy the DFA28-105?
Posted By BigMackCam
Replies: 104
Views: 6,977
Pretty much every lens limits the K-1 and K-1II, depending on how it's used. What's important is whether those limitations are acceptable given the other benefits of the lens in relation to your personal requirements.

The biggest limitations of the FA Limited primes compared to the D FA28-105 are that you have to keep changing lenses for different fields of view. In some situations, that's not a concern. For those situations, and others where you need faster apertures, the Limited primes are probably better. In situations where you prioritise versatility of focal length range (and perhaps weather-resistance) and can live with the creative and technical limitations of a slower variable aperture, the D FA28-105 is better. It doesn't matter how good the FA31 is, if you're going out shooting and don't know what focal length you'll need, or it's windy and/or raining, the D FA28-105 is going to walk all over it.

We're comparing apples and oranges here, really. The primes serve a different purpose to the zoom, though both can be used to take a cross-section of similar images, albeit with different rendering characteristics. Outside that cross-section, each lens has advantages and disadvantages. We can find situations where any single one of those lenses is the best or worst. By selecting a lens, we're always choosing one set of benefits and failings over a different set from another lens...
Forum: Pentax SLR Lens Discussion 07-19-2018, 07:08 AM  
Why would somebody buy the DFA28-105?
Posted By BigMackCam
Replies: 104
Views: 6,977
I believe I did... We just have different views on the matter :)



What expectations are you referring to, and from which groups of people other than fellow photographers? And to what ends are these expectations rising? Could it be, in many cases, just for the sake of it, rather than tangible differences to the end product as the viewer / consumer will appreciate it?

I mentioned in an earlier response, there are many different factors we can use to measure whether one lens is "better" than another... Resolution, distortion, chromatic aberrations, contrast, colour reproduction, out-of-focus rendering, etc. etc. A lens might have incredible resolution and low chromatic aberrations, great contrast and colour, but lifeless out-of-focus rendering. Another might have lower resolution, noticeable CA, but render out-of-focus areas and transitions beautifully. Which is better, according to the rising expectations? That's the problem... "better" is, to a large extent, dependent on your requirements. It's subjective.



I'd like to see the comparisons too, just out of curiosity. But, all I need to see is full screen images on my colour-profiled laptop and desktop monitors (non-4K, by the way). I'm looking for character of rendering and nothing more - those are where my expectations lie.

In your undoubtedly far more careful examination of images (whatever ends that may achieve), I'm going to take a guess that you might actually find the D FA28-105 sharper edge-to-edge than some of the FA Limited primes, at certain apertures and distances... especially the FA43, since those particular primes weren't designed with test chart brilliance in mind. Heck, they weren't even designed for digital sensors (as you'll see with CA)...
Forum: Pentax SLR Lens Discussion 07-19-2018, 05:06 AM  
Why would somebody buy the DFA28-105?
Posted By BigMackCam
Replies: 104
Views: 6,977
Sure. If we display a crop at large enough magnification, with high enough resolution on a premium monitor, and look closely enough for long enough, we'll find something wrong with any image from any lens. My point is, that's an obsession only us digital photographers are afflicted with, and a largely fruitless one IMHO, with very little relevance to the final output and how it will be viewed by other people.

But, each to his own. If critical sharpness at 100% reproduction in editing suite conditions is of primary importance to you, that's perfectly valid. It's not entirely unimportant to me, but it's much lower down my list of priorities. Gentle local contrast and sharpening adjustments can easily offset minor softness where necessary, so long as the detail has been recorded. My vintage Soviet lenses don't even come close to the resolution of high-performance modern lenses, but sharpness in the final image is rarely (if ever) a problem. If it is, that's usually a focusing error on my part.

In any case, I doubt you'd find the D FA28-105 unsharp... it has a very strong reputation in this regard, and the MTF charts bear this out. For those that like the versatility of a zoom lens, it is - by all accounts - an excellent choice. But if you prefer to work only with primes, that's fine too :)
Forum: Pentax SLR Lens Discussion 07-18-2018, 12:34 PM  
Why would somebody buy the DFA28-105?
Posted By BigMackCam
Replies: 104
Views: 6,977
If someone takes you up on that, I'll be as interested as you to see the results :)

However...

Who actually views a final image at 100% reproduction, 60cm from their computer screen? That's right, no-one but us photographers.

At normal reproduction sizes and viewing distances, the rendering of a lens is going to be far, far more important than critical sharpness at 100% reproduction. I mentioned in an earlier reply that my best lens overall is probably my Sony Zeiss 24-70 f/2.8... yet, there are times where the rendering of one of my lowly 1970s Helios-44-2 lenses will suit a shot better. And, at normal reproduction sizes, with relevant post-processing adjustments, you won't care about the difference in resolution between the two. You'll just find that you prefer one image to the other because it looks a bit nicer :)

While we're on that subject, what is it that you feel defines the performance of one lens being better than another? Because that's a very subjective thing. Is it resolution? Low distortion characteristics? Level of chromatic aberrations? Contrast? Colour reproduction? Out-of-focus rendering (and if so, what's your preference)?

If you answered resolution - i.e. MTF - then the D FA28-105, being a very modern and high performance lens designed to match the K-1 well, actually outclasses some of the classic primes at various apertures. It does awfully well on contrast, colour repro, and level of chromatic aberrations too - at least, if we believe the various reviews and the reports from our users. Where it may not perform so well is distortion... It's pretty much impossible to cover this sort of focal length range in one lens and not have some degree of distortion at one or both ends of that range, and possibly in between.

But perhaps the biggest difference you're likely to notice with lenses compared side-by-side, is the quality of out-of-focus rendering. It's one reason why primes such as the FA31, 43 and 77 are so revered. Related to that, all three of those lenses are much faster than the D FA28-105, so they'll produce greater subject to background separation. And that's a big benefit... but only if you need it. Some people don't, or they're prepared to trade that capability for the convenience of one nice, sharp lens that renders well, at a slower and variable set of apertures across a wide focal length range...
Forum: Pentax SLR Lens Discussion 07-17-2018, 03:25 AM  
Why would somebody buy the DFA28-105?
Posted By BigMackCam
Replies: 104
Views: 6,977
As with the lens, it's all down to a wide range of individual priorities, likes and dislikes. Sometimes, a K-1 will be the best camera for the job... I've seen some beautiful landscape photography from the K-1 plus D FA28-105, and that's a very manageable kit considering the incredible detail and overall image quality it provides. Other times, the K-1 might be overkill, but people will still shoot it because they enjoy doing so. For many of us, the enjoyment we get from using our cameras can be an important factor in encouraging us to get out there and shoot :)
Forum: Pentax SLR Lens Discussion 07-16-2018, 03:55 PM  
Why would somebody buy the DFA28-105?
Posted By BigMackCam
Replies: 104
Views: 6,977
I don't include myself in that group, of course. Heck, I'm the other end of the scale entirely :p :lol:
Forum: Pentax SLR Lens Discussion 07-16-2018, 03:12 PM  
Why would somebody buy the DFA28-105?
Posted By BigMackCam
Replies: 104
Views: 6,977
That's a valid view-point, but - importantly - it's yours... and certainly not everyone's :D

Although there are occasions where I take more than one body with me, it's usually for backup in case one fails. So, if I'm shooting with my K-3, I might take my K-3II as backup. Or, if I'm shooting my Hasselblad HV, I might take the A7 MkII plus LA-EA4 adapter as backup. In both cases, the lenses I carry are compatible and have the same field of view on both the main and backup bodies.

I can see why you might carry a different format body with you, but that means different lenses (if you want to replicate the same fields of view), different batteries, different battery grip, etc. If cost is the main consideration, then it might work out cheaper, though I doubt it. Most people, I think, only want to carry one camera and one set of compatible lenses for the majority of amateur photography situations...

EDIT: I will say, there are times when an entirely different format and lenses make an excellent addition or alternative to one's main kit. On numerous occasions, I'll carry my Pentax Q7 with one, two or three lenses instead of an APS-C or full-frame DSLR. That setup gives me similar fields of view and decent IQ in a very small package. But these situations are quite different, for a number of reasons, than those where I would happily carry and APS-C or FF DSLR / mirrorless setup...
Forum: Pentax SLR Lens Discussion 07-16-2018, 02:59 PM  
Why would somebody buy the DFA28-105?
Posted By BigMackCam
Replies: 104
Views: 6,977
Respectfully, Steve, I don't think the OP was trolling. But I do think it's sometimes rather easy to make assumptions that everyone has the same priorities and requirements from their gear, when the reality is wildly different. Hopefully, some of the answers in this thread, as well as the obvious popularity of the lens with K-1 & K-1II users, will demonstrate that :)
Forum: Pentax SLR Lens Discussion 07-16-2018, 12:59 PM  
Why would somebody buy the DFA28-105?
Posted By BigMackCam
Replies: 104
Views: 6,977
I'm neither a K-1 nor D FA28-105 owner, but I can hazard a few guesses here.

(1) Whilst the K-1 may be bigger and heavier than an APS-C camera such as the KP, that doesn't mean it'll never be used as a walk-around camera. In such situations, you probably don't wish to carry several lenses in a bag. The D FA28-105 offers a versatile range of focal lengths / fields of view, and great IQ considering that range.

(2) The D FA28-105's image quality is widely regarded as excellent. I would generally agree that a very good prime lens is typically better than a very good zoom lens. But that doesn't mean that a very good zoom lens can't produce fantastic quality images. I have many lenses of different types, including some lovely primes, and by far the best lens I own - if we use sharpness / detail, colour and rendering as measurement criteria - is my Sony Zeiss 24-70 f/2.8 zoom in A-mount. Decent zoom lenses these days can be extremely good, and everything I've seen and heard suggests the D FA28-105 falls into that category. Furthermore, shooting primes is all well and good until you come across a subject or scene where you need a completely different focal length. While you're fumbling in your bag for an 85mm lens to replace the 28mm currently fitted to your camera, the D FA28-105 owner is busy taking the photograph ;)

(3) I wouldn't say a full frame camera is for maximal image quality alone. That's just one possible reason for using it. Another is to get greater subject to background separation at the same field of view and aperture. Yet another is the ability to use old full-frame glass in the way it was intended. There are other reasons too. I shoot my Sony A7 MkII almost exclusively with vintage Soviet glass - some of which is remarkably capable, and some which isn't. But by using a full-frame body, I can enjoy the entire field of view those lenses were intended to provide. My point is, people have different primary reasons for shooting a full-frame camera like the K-1. For most of those people, a versatile lens that provides excellent IQ across a wide range of focal lengths is a very useful tool for the kit bag.

I could go on, but I think these points are a reasonable start :)

EDIT: To underline points 1 & 3 above, I bought a used Tamron 28-300 PZD which I occasionally use on my Sony-A99-based Hasselblad HV. It doesn't even come close to the IQ of my Sony Zeiss 24-70 f/2.8, but there are occasions where it's the most useful and appropriate lens I can take with me...
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