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06-13-2017, 07:03 AM   #16
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The new Fuji GF 23mm f4 R LM WR Lens for the GFX is said to be equivalent FOV to 18mm on 35mm full frame.....so not that much 'better' than the 25mm Pentax DFA lens, which is approx. 19mm on FF 35mm?

06-13-2017, 07:34 AM   #17
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QuoteOriginally posted by Digitalis Quote
Nice work there Mike.
...
thanks Digitalis!

QuoteOriginally posted by Ed Hurst Quote
It's splendid![COLOR="Silver"]
...
thank you Ed!

QuoteOriginally posted by BostonUKshooter Quote
Thanks ....cool image....
thanks Ian!
06-14-2017, 02:03 AM   #18
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QuoteOriginally posted by BostonUKshooter Quote
The new Fuji GF 23mm f4 R LM WR Lens for the GFX is said to be equivalent FOV to 18mm on 35mm full frame.....so not that much 'better' than the 25mm Pentax DFA lens, which is approx. 19mm on FF 35mm?
As you get wider, each additional mm adds a more significant amount of FoV, so going from 25->23mm is a big difference. Of course the GFX is also a mirrorless camera, so it has the advantage when it comes to WA lenses, in terms of size, weight, ease of design, etc. Even if Pentax comes out with something to compete on a technical level (also a 23mm f/4 for example), it'll still end up being bigger and more expensive.
06-14-2017, 02:06 AM - 1 Like   #19
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QuoteOriginally posted by Kolor-Pikker Quote
it'll still end up being bigger and more expensive.
..But at least it won't be focusing by wire.

06-14-2017, 07:02 AM   #20
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Focus by Wire is indeed a problem. The 63mm for the GFX has engine problems when installing a simple 100mm Gradient filter with holder (Lee). The GFX gives an error and the lens no longer works. Manually focus is then also turned off because the focus is by wire. Gone stupid...

I use the D FA 25mm on the GFX. Together with a small Cambo Actus I can then also make Tilt / Shift and Swing (weight of Actus ca. ~ 1kg). Cambo can control 645 lenses without aperture ring. The adjustment paths with a full 645er lens are more than sufficient and I'm quite happy with it ...

Greeting Gerd
06-14-2017, 11:20 PM   #21
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QuoteOriginally posted by Digitalis Quote
..But at least it won't be focusing by wire.
Hi Digitalis.....interesting to read....I'm not a techie so don't understand 'focusing by wire'.....???? Thks, Ian
06-15-2017, 01:32 AM - 1 Like   #22
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QuoteOriginally posted by BostonUKshooter Quote
Hi Digitalis.....interesting to read....I'm not a techie so don't understand 'focusing by wire'.....???? Thks, Ian
It's when the focus ring is electronically coupled to the lens, so when you turn it, you move an encoder than sends a signal to the camera, which in turn makes the autofocus motor focus the lens. Depending on how it's implemented, focusing action may feel disconnected or floaty from the actual input, and of course you can't focus at all with the camera turned off, which presents an issue when you want to adapt the lens to another system that can't deliver power to the lens.

06-15-2017, 03:46 AM   #23
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Focussing by wire is the biggest issue I have with the Sony system. It's not as precise as a physical window with focus distances
06-15-2017, 04:56 AM   #24
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QuoteOriginally posted by itshimitis Quote
Focussing by wire is the biggest issue I have with the Sony system. It's not as precise as a physical window with focus distances
I doubt that such behaviour can be generalized. My Pentax DA55-300PLM also works with electonic manual focusing / quick shift. Never realized an issue with it. When using it I in opposite always think how nice this works!
06-15-2017, 10:33 AM   #25
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QuoteOriginally posted by Kolor-Pikker Quote
It's when the focus ring is electronically coupled to the lens, so when you turn it, you move an encoder than sends a signal to the camera, which in turn makes the autofocus motor focus the lens. Depending on how it's implemented, focusing action may feel disconnected or floaty from the actual input, and of course you can't focus at all with the camera turned off, which presents an issue when you want to adapt the lens to another system that can't deliver power to the lens.
Thanks.
i'm glad someone explained this.
wth?
06-15-2017, 06:14 PM   #26
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QuoteOriginally posted by Kolor-Pikker Quote
It's when the focus ring is electronically coupled to the lens
Thanks for picking up on that Kolor. Focus by-wire may also be seen as a way to prevent users from adapting lenses entirely, one step further than the proprietary limitations imposed by lens mounts.

Some Canon lenses focus by wire like the EF85mm f/1.2 L - personally I use an adapted Leica Summiluix-R 80mm f/1.4 on my Canon camera bodies due to the poor manual focus feel from the 85L.
06-15-2017, 11:08 PM   #27
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QuoteOriginally posted by Digitalis Quote
Thanks for picking up on that Kolor. Focus by-wire may also be seen as a way to prevent users from adapting lenses entirely, one step further than the proprietary limitations imposed by lens mounts.

Some Canon lenses focus by wire like the EF85mm f/1.2 L - personally I use an adapted Leica Summiluix-R 80mm f/1.4 on my Canon camera bodies due to the poor manual focus feel from the 85L.
OK...thanks all....Ian
07-05-2017, 04:25 PM - 1 Like   #28
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In my experience testing out multiple samples of each of these two fine lenses, this has been my observations regarding optical performance. Of course I am pixel peeping at 100%.

Most samples of the 28-45 simply outperform the 25mm (both DA and D-FA), especially in the corners up to f9-f11. In the central part of the image, I found the 25mm actually is sharper from the get go and also when stopped down (contrary from what has often been posted), but the differences are not overly dramatic (in central part of the image) The differences though between the two lenses are fairly dramatic in the corners, with the 28-45 having the distinct advantage. This corner performance difference narrows if you shoot the 25mm at f11 and f13, where it becomes much closer.

One of the reasons for this is the 25mm has extreme field curvature, which is small, but increases as it approaches infinity focus. The same thing can be readily seen in the older FA 35mm f3.5 645 lens but not in the newer HF D FA 35mm f3.5 645 lens, which appears to have a redesigned aspherical element.

What I also noticed as has another well known reviewer, is many samples of the 25mm , must be AF fine tuned on the body, otherwise many samples of the 25mm lens doesn't quite reach infinity focus. This can be seen in live view and even on the lens barrel, where it falls short of the infinity mark on the focusing scale...sometimes by a good margin, when focusing at a subject that's definitely at infinity. In other words, the lens fronts focus at infinity. Some samples though don't need much if any AF fine tuning for this. It all depends and this extreme variability in sample to sample performance is another reason why pentax discontinued production.

Still lenses is smaller and lighter than the 28-45 and of course wider, so if used at f11-f13, it may be the preferable choice, especially for hiking or travel. For ultimate performance, especially at something wider than f11-f13, the 28-45 may be the preferable choice.

Dave (D&A)

Last edited by DandA; 07-05-2017 at 04:42 PM.
07-15-2017, 12:40 PM   #29
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There's a 28-45mm on eBay now for a Buy It Now price of $2,550 (with a Best Offer, too!) Absolute steal! I missed out on the seller's 645Z but I got good messages from her and she seemed a genuine seller.
07-15-2017, 11:27 PM   #30
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QuoteOriginally posted by Sarnian Quote
There's a 28-45mm on eBay now for a Buy It Now price of $2,550 (with a Best Offer, too!) Absolute steal! I missed out on the seller's 645Z but I got good messages from her and she seemed a genuine seller.
Looks like its been corrected to $3550!...
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