Today was my second day shooting with the Pentax 645D. We’re still getting to know eachother. I found out the electronic level is not level (as I suspected the first day already). Since I’m not the only Pentax user experiencing this it probably is behaviour by design, I’ll just put my bubble level in my back pack.
After these few extra hours of usage I’m thinking that the Pentax might actually be a bit easier to focus than my old Canon 1Ds II. When focusing quite close the big viewfinder helps, the few portraits I shot were all tack sharp on the closest eye (@ f/2.8). With greater distances or flat surfaces that are harder to focus some detail that is there seems to “pop” in and out of focus more clearly than I was used to with the Canon.
But what I really wanted to find out was this ISO 100 versus ISO 200 business, so I shot three series of four test shots: first a correct exposure at ISO 200, then I set the camera to ISO 100 and halved the shutterspeed for the second photo (shutter stays open twice as long, should yield the same exposure). Then I shot two more on ISO 100 increasing the shutterspeed by 1/3rd stop each, trying to find out whether it actually was ISO 125 or ISO 160. Here’s one, all four photos taken at f/10:
ISO 200 1/100
ISO 100 1/50
ISO 100 1/60
ISO 100 1/80
In my book a shutterspeed of 1/100 on ISO 200 is the same as 1/50 on ISO 100 exposure wise, all else being equal. This is clearly not the case, in stead the exposures look about the same with 1/60 for the ISO 100, which indicates it is actually ISO 125. All three series pointed to ISO 125. Good to know.
I couldn’t find any obvious evidence of reduced dynamic range in ISO 100. It might be there but with my eyes using photoshop at 200% inspecting the lightest and the darkest parts I couldn’t see it. Looking at noise: ISO 200 seems to have slightly more (I had thought there would be no difference for ISO 100 is part of the extended range).
It is an absolute pleasure to take photographs with the Pentax and to review them at home on the computer. The sharpness is stunning. This is hard to show. I have looked at countless photographs with some detail shown bigger and still didn’t think the photographs would be _this_ sharp. But here’s mine.
The past nine years I have been shooting with Canon gear. Starting with a 350D, then two of them, building a business, until shooting weddings with a pair of 5D’s (the then current model) in 2008. After that, I decided I wanted to take a different turn and got rid of most of my gear, leaving just one 1Ds II (bought second hand) and four lenses. Over the following years I grew very accustomed to the 1Ds II and its quirks, trying to get the best possible image quality from it. Last monday I sold it.
Today was my first day out and about with my new camera: the Pentax 645D. I wanted to concentrate on handling the machine and experimenting with ISO 100 and 200 (100 is part of the “extended” range).
1) The 645D is a joy to work with, after a slight (inevitable) learning curve (I read the manual before going to sleep yesterday). Buttons are very well placed, the whole interface makes sense.
2) The mirror up switch is a godsend (goodbye fiddling with the menu).
3) Manual focusing with the Pentax is not harder than with the Canon. At first I thought it was easier, but because it is more critical, even at f/4 and f/5.6 (hello big sensor), I had about the same amount of keepers due to focus as I would have had with the 1Ds II.
4) There’s obvious chromatic aberration, both with the 55 and the 90 mm, in high contrast areas. This was a slight dissapointment.
5) The 55 has some very noticeable barrel distortion which I hoped it hadn’t.
6) ISO 100 seems more like 125 or 160 and / or has less headroom / dynamic range. This needs to be investigated further but for now I think ISO 200 will do fine.
7) ISO can be changed without taking your eye from the viewfinder, like I was used to with the 5D’s. Really happy with that, this is a must for fast paced environments like weddings.
Sharpness and image quality will be judged with large high quality prints, which I don’t have yet. So I will refrain from going into that, but on the screen it looks very promising.
I made some changes to the default setup of the 645D:
1) Moved AF from half-press of the shutter button to only the AF button on the back. Since I mostly MF and the 55 and 90 are FTM I can now MF without the focus changing when I press the shutter and still AF with one push of a button.
2) Turned the level indicator in the viewfinder on, this moves the under / overexposure indicator to the right where normally the ISO is. The ISO can still be changed (and seen in the viewfinder) when pushing the ISO button.
3) Expanded ISO on (pending investigation).
4) All noise reduction off (pending investigation).
5) Auto image rotation off, I can rotate the camera myself, thank you. (It still saves the orientation of the image to be picked up by ACR.)
Here’s some shots from the day (unedited, except the last one is a slight crop). Note the fringing in the first one (this is the 90 mm), and the barrel distortion in the last (55 mm).