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Forum: Pentax News and Rumors 06-19-2020, 03:20 PM  
Development update regarding the HD PENTAX-D FA★50mmF1.4 SDM AW
Posted By RobA_Oz
Replies: 734
Views: 72,875
Given that this thread was about the development of the D FA*50, I wouldn’t feel constrained by it, at this stage.

Having said that, Norm’s comment about diffraction starting to affect the lens’s performance from f4 had me thinking about the conventional view, which is that you generally don’t need to worry about it until at f16 and above. My recollection of the basis for that was, as Norm says, that diffraction effects will fill the aperture at f16, so, if I’m correct, they’ll also affect the peripheral rays at any aperture setting, but increasingly so as the f-stop increases. So, given that the edge resolution of the D FA*50 starts to noticeably deteriorate firstly at f4, while the centre holds up, this seems consistent with that conclusion.

So, was that what you were contesting, or have I missed something?

Either way, the wide open performance of the D FA*50 is phenomenal, and even on its own suggests that it’s up there with the likes of Leitz or Zeiss lenses, which, if I remember correctly, were designed to perform like that, and previously unchallenged in that respect.
Forum: Pentax News and Rumors 06-27-2018, 05:23 AM  
Development update regarding the HD PENTAX-D FA★50mmF1.4 SDM AW
Posted By RobA_Oz
Replies: 734
Views: 72,875
I don't know why you put the word "unifocal" within single quotation marks – it's an accepted word for what many people call a "prime" when they're speaking about lenses, but "prime" in that sense means "the first" or "best", which could equally well be a zoom lens. I was referring to non-zoom lenses.

That aside, I wasn't implying that a single unifocal lens doesn't have limitations. My second SLR lens was a 28mm, for exactly the same reasons as you've indicated, but the Brenizer Method wasn't an option when you were shooting film and printing in a darkroom! Also, the few zooms that were available then were really used for convenience, not quality.

I use zoom lenses, too, and some of them are very good, but I also like unifocals for the other things they bring to the picture. Sometimes, what they bring is attention to things you'd miss, otherwise. When I'm travelling, I often put one lens like my FA31 on the camera, because it causes me to see differently. Other times, I'll use a zoom, particularly when I want to record a lot of different things that I'm seeing. Horses for courses.
Forum: Pentax News and Rumors 06-27-2018, 04:39 AM  
Development update regarding the HD PENTAX-D FA★50mmF1.4 SDM AW
Posted By RobA_Oz
Replies: 734
Views: 72,875
It's interesting how photographers' perspectives have changed over the years. For a long time, many who started in 35mm film photography only had a 50mm lens, because most SLR bodies came standard with one, and disposable income was less. It was the same with rangefinder bodies from the likes of Leica and Zeiss, of course. Nonetheless, it was a great learning experience, having to cope with the one focal length. As time went by, prices dropped and wages rose, so other focal lengths became affordable.

Short zooms became the standard before the start of the digital era, with greater general affluence, but quality gave way to convenience despite the steady improvement in zoom lenses, then. Now, we don't tend to think twice about using today's very good zoom lenses, except when we need the things that most don't provide, like control of shallow depth of field or ultimate resolution.

I think the concentration on unifocal lenses like the forthcoming D FA*50/1.4 is actually a good thing, partly because it provides a standard that other lenses in that range can be measured against, but also because it gives attention to the potential benefits of work with a unifocal lens, even for those who never buy one of these. I've got more than one lens in that range, so I'll probably remain in the latter category, because I don't need the lesson – I've had it in the past, but this has reminded me that I should revisit the 50s, now that I'm shooting mostly with my K-1.
Forum: Pentax News and Rumors 06-26-2018, 10:22 PM  
Development update regarding the HD PENTAX-D FA★50mmF1.4 SDM AW
Posted By RobA_Oz
Replies: 734
Views: 72,875
So, that makes Yoda an English-speaking European, I guess. Or American? Definitely not Australian.
Forum: Pentax News and Rumors 05-24-2018, 12:45 AM  
Development update regarding the HD PENTAX-D FA★50mmF1.4 SDM AW
Posted By RobA_Oz
Replies: 734
Views: 72,875
Sorry, but the gear train itself is only a part of the focussing process, and isn’t a major contributor to the problem you describe. The major problem with any given gear type is its propensity to backlash, which a worm drive can also exhibit. Removing or minimising the “hunting” motion (ie back and forth movement before settlling, if it does, at all) is the job of the control mechanism, which is almost always electronic, these days. Worm drives are mostly used where significant speed reductions are required (10 to 1 or greater), and gear trains or other forms take up too much space or produce too much backlash. They won’t solve a hunting issue, but the control process will.
Forum: Pentax News and Rumors 04-14-2018, 12:23 AM  
Development update regarding the HD PENTAX-D FA★50mmF1.4 SDM AW
Posted By RobA_Oz
Replies: 734
Views: 72,875
Indeed. It also needs to be as good as they can get it on release, because you can trust some reviewers to be more critical of it than they may be of others’. So, this small delay is welcome, if that’s the cause.
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