[leonine]

Hello everyone.

Can anyone please let me know how good or bad the autofocus speed of Pentax 645Z is compared to Fujifilm 50S, 50S ii and 100S? This is probably the only bit of information I need before making up my mind regarding the second camera I need for aerial photography using a helicopter.*

Thanking you in anticipation.*

[marco_gea]

Two quick comments from me, although my experience of shooting from a helicopter is extremely limited, and dates back over 10 years, so not really that relevant.

I would describe pentax 645 files as smooth,deep ,thick and luscious. I would describe Fuji 645 files as sharp crispy & crunchy.

I find this description absolutely 100% spot on. BUT, I don't think it's the camera at all. Rather, it's the lenses. I say so because I shoot P645 lenses on a Fuji GFX50R and notice the exact same difference.

New gear is good, but discipline, knowledge, practice and patience is far more important. Enjoy what you have and make the most of it:

Also 100% spot on.

Marco

---------- Post added 02-18-22 at 10:25 AM ----------

Indeed most of the aerial photography is with lens at infinity, preferably in manual (and taped to infinity) with mid wide to short telephoto lenses (say 35mm to 90mm on the 645Z).

If that's the case, consider that you can use manual focus Pentax lenses on an IBIS-equipped Fuji body, too. Just saying'

[leonine]

Pentax 645Z files are very nice to work on. I enjoy shooting with the camera. However, there are times while flying over a busy city, with landmarks bunched together and restrictions on flying height, no-fly zones etc, that you miss the composition by the time you focus or click the shot. I know it sounds crazy, but it is my experience that quicker Autofocus helps a lot even in aerial photography.

The problem with shooting at infinity in manual focus is one doesn't know where the exact infinity focus is. It is not at the hard stop at all times. Besides, there are times when you are focusing on buildings and structures which are close enough not to be at infinity.

[biz-engineer]

I know it sounds crazy, but it is my experience that quicker Autofocus helps a lot even in aerial photography.

It's not crazy, medium format systems are all slow to focus. And about Fuji GF being fast focus, it is fast compare to phase one, hasselblad , but totally lousy compared to full frame. The truth is (as opposed to market talk), is that the Fuji isn't capable to tracking action properly, it's not much different than Pentax 645 & FF. It's a decision to be made between trading the superior image quality of medium format for poor autofocus and lack of long lenses , or trading the lower image quality (yet very good) of full frame for the high-performance autofocus and broad range of lenses. Full frame 50Mp like A1, Z9, deliver the best autofocus, high-res., and lot of lens choice. Ultimately the choice depends on maximum print size, the perceived difference between prints at 200PPI and 300PPI is very small, so in order to appreciate more than 50Mp (e.g GFX100/S), you must print at least 30x40" (larger than 30x40"), otherwise the added pixel count isn't worth the drop in speed, autofocus performance and limited choice of lenses in medium format. But some photographers print 40x60", if so, medium format makes a significant difference.

How large will your prints be?

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Last edited by biz-engineer; 02-19-2022 at 03:48 AM.

[leonine]

It's not crazy, medium format systems are all slow to focus. And about Fuji GF being fast focus, it is fast compare to phase one, hasselblad , but totally lousy compared to full frame. The truth is (as opposed to market talk), is that the Fuji isn't capable to tracking action properly, it's not much different than Pentax 645 & FF. It's a decision to be made between trading the superior image quality of medium format for poor autofocus and lack of long lenses , or trading the lower image quality (yet very good) of full frame for the high-performance autofocus and broad range of lenses. Full frame 50Mp like A1, Z9, deliver the best autofocus, high-res., and lot of lens choice. Ultimately the choice depends on maximum print size, the perceived difference between prints at 200PPI and 300PPI is very small, so in order to appreciate more than 50Mp (e.g GFX100/S), you must print at least 30x40" (larger than 30x40"), otherwise the added pixel count isn't worth the drop in speed, autofocus performance and limited choice of lenses in medium format. But some photographers print 40x60", if so, medium format makes a significant difference.

How large will your prints be?

If the Fujifilm GFX autofocus is not "considerably" better than the Pentax 645Z, then I do not really need the Fujifilm except on occasions where I need the stabilisation of the camera-lens combo (say 50S with the 45-100 OSS or 50Sii/ 100S with any lens that can be mounted) to keep the ISO low. Since most of the flying is restricted to daylight hours, I end up shooting at say 1/1000 sec with f/5.6 at ISO 800 or so in the worst possible situations. I don't think ISO 800 is a problem with Pentax DNG files with some help from Topaz DeNoise etc. Not getting another Fujifilm saves me a lot of money as well as the hassle of learning and getting fully conversant with a new system. Handling even the 645Z and the K1 together itself is a pain in the air. You end up fumbling with buttons or controls or even the tactile feel of the differences in responsiveness of the two cameras.

This is a sage and practical advice by biz-engineer and I can't thank you enough for it. Indeed, while the OVF, the DR and the DNG files (which are a visual joy to work with) of the Z make the experience highly enjoyable, ultimately, if not missing a composition, achieving tack sharp focus consistently and reliably and yet not sacrificing image quality much are the prime considerations, then a fast mirrorless with adequate resolution and excellent buffer is the most useful camera at least over the cityscapes. Just disable all control buttons except the barest minimum, set up the shutter priority mode, have a fast lens with adequate zoom (24-105 with constant aperture is what will be good for 95% of the shots, a 28-75/ 24-70 for 85% of the shots), and the only thing you would do is get the composition in your head, zoom and compose in one quick action and shoot. No additional wasteful actions or waiting for the lens to focus. With the Sony A7 iii and Tamron 28-200, I missed not more than perhaps 2-3% of composition opportunities and whatever I shot, almost every image was sharp (no blur/ shake). They had to be at 1/1000 sec with a camera giving 5-stop IBIS.

Coming to the print size, well, we started with around 24x36 or 20x30. But I am kind of getting a bit greedy, in that I would like to have the option of blowing much bigger than this in future for the absolute best of these images (say upto 40x60). I was hoping that the Sony A7 iii aided by Topaz Gigapixel AI/ Adobe Super Resolution etc computational tools would be adequate for sizes bigger than 24x36 (say upto 40x60). Perhaps it is not good enough. I need to understand this aspect better. Now, since I am already quite used to the Sony, perhaps I should think of a Sony A7R iii/ A7R iv to start with or go for Sony A1 if finances allow. Since I also fancy myself doing a lot of wildlife photography in future, maybe the Sony A1 as the primary camera and Sony A7 iii as the secondary camera would be just the right kit for that purpose. Or what about the new Sony A7 iv as the primary camera for aerial photography? Good feature set.... 33 MP, practically unlimited buffer, fast AF, decent resolution, not too expensive...it ticks a lot of boxes, except that it won't allow you to crop much.

As an aside, I wish to inform that the Pentax Z with the 400mm is an absolutely phenomenal combination for environmental portraits of wildlife (lions, leopards, cheetahs, elephants lazing around in their habitat). Not for action, but then despite the blazing FPS and AF of the Sony monsters, how many great wildlife action pictures does one get to see regularly? Very few. The ones which appeal the most and are also frequently photographed are mostly animals in habitat.

In the end, if the aerial sortie allows a more languid pace, good weather, low winds, a cooperative pilot who also shows willingness to drop height to the extent feasible, then the Pentax Z with 55mm or a reportedly good zoom like 45-85 will still be a camera that I will be happy to use compared to any other camera system.

Every sortie gives a new lesson. I guess I will continue to evolve as a photographer as the project progresses. However, coming to the right equipment for the specific job, I guess I have got it mostly figured out, and I am grateful to the pentaxforums members to help me with their practical and timely advice. A big thanks to you all.