Nice, that's a bevy of 75's. I'll be interested to see if that test comes to fruition and to see what the results are. We need an image thread for well-loved but imperfect M mount lenses...
genji wrote:
TBH, I haven't used the CV 75/2.5 much recently. It was relegated to reserve grade (or the minors, as Americans might say) once I got a great copy of the Summarit-M 75/2.5 from forum member DavidBM. But there's a plan for David and I to do a portrait distance test with my Leica for Phillip Reeve's 75/1.5 review and it wouldn't be too much trouble to do a couple of portrait pics with the 75/2.5 then.
As I mentioned in a previous post, I tested my copy of the CV 75/1.5 on an infinity scene with my Leica M10-P and found it has essentially a flat field. Using the Leica Visoflex 020 external EVF, I focused on the center of the scene (which was at the hard infinity stop) and took exposures at f/1.5, f2.0, and f/2.8.
I then moved the focus point left to the mid-zone and then as close to the left edge as possible, making another three exposures each time. Since, at each of these locations, the sharpest focus was also at the hard stop, there is no point showing images to demonstrate subtle changes in focus since there were none.
What I've done instead is shown the results for the three different apertures to illustrate how the resulting images sharpen as the lens is stopped down. I hope this is useful.
genji wrote:
As I mentioned in a previous post, I tested my copy of the CV 75/1.5 on an infinity scene with my Leica M10-P and found it has essentially a flat field. Using the Leica Visoflex 020 external EVF, I focused on the center of the scene (which was at the hard infinity stop) and took exposures at f/1.5, f2.0, and f/2.8.
I then moved the focus point left to the mid-zone and then as close to the left edge as possible, making another three exposures each time. Since, at each of these locations, the sharpest focus was also at the hard stop, there is no point showing images to demonstrate subtle changes in focus since there were none.
The edge, though, is still midfield (the corner of course gives the outer field). While it doesn’t matter in practice, it might be our fir the pixel peepers to know if FC shows up in the corners..
The edge, though, is still midfield (the corner of course gives the outer field). While it doesn’t matter in practice, it might be our fir the pixel peepers to know if FC shows up in the corners..
Ah, excellent point! That should have been obvious to me given that Fred and the Phillip Reeve team always use a Dutch angle for their infinity test shots. Looking back at the city from a vantage point somewhere in Pyrmont would have made that framing possible.
Actually, all I needed to do was pan a little to the right and I would have had the crane in the upper left corner!
What is the benefit of the Dutch angle for corner test shots? I noticed Fred recommended the same in his decentering test at or near infinity. I apply as prescribed, but why the Dutch angle ?
Aug 14, 2019 at 08:34 AM
Steve Spencer Offline • • • • • • • Upload & Sell: On
LBJ2 wrote:
What is the benefit of the Dutch angle for corner test shots? I noticed Fred recommended the same in his decentering test at or near infinity. I apply as prescribed, but why the Dutch angle ?
I think the benefit it just that you have something in the corners, which is the farthest from the center to examine the performance of the lens at the extreme of the image circle.
Aug 14, 2019 at 08:45 AM
Steve Spencer Offline • • • • • • • Upload & Sell: On
genji wrote:
Ah, excellent point! That should have been obvious to me given that Fred and the Phillip Reeve team always use a Dutch angle for their infinity test shots. Looking back at the city from a vantage point somewhere in Pyrmont would have made that framing possible.
Actually, all I needed to do was pan a little to the right and I would have had the crane in the upper left corner!
Given that the wide edge is 16mm from the centre, and the corner is just 21.6mm from the center, the test you did is still very informative. We don't know the performance in that last 5mm or so into the corner, but I think that is exactly the part of an image in evaluating a lens that is often overemphasized. In a huge percentage of my shots, there isn't anything meaningful in that area. I see it as being a bit beyond mid-field, which I think of as about 12mm from the centre, and a very important part of the image.
I'm seeing CA wide open but it looks like 2.8 it goes away. Have to check on computer. This would be normal for a lens like this. Remember this word Summilux
So couple quick thoughts I see CA until 2.8 than goes away on its own. I could probably eliminate that sooner in processing. As I thought if you want pixel peeping corners go to F5.6 but F4 is quite good. Really reminds me of a Leica Summilux in its look.
On center and I will post this but here is my thought you want that nice glow with people look go 1.5 but if you want sharp on center F2 is the answer and that's just ducky for me. I get two looks in one lens
I will get back to this . Need to go to hospital and do a breathing test. But my news yesterday was pretty positive.
GMPhotography wrote:
I'm seeing CA wide open but it looks like 2.8 it goes away. Have to check on computer. This would be normal for a lens like this. Remember this word Summilux
Aside from the FL and aperture, I don’t see much of a draw similarity with the Lux 75. The CV 75 1.5 has smoother bokeh, smoother transitions, is sharper wide open with less SA, sharper across more of the frame, has higher micro contrast, much better flare resistance, CV sunstars and better CA correction, especially of Lateral CA. The Leica has has a warmer palate as well it seems.
I like this lens and I’ll pick one up and shoot it against my Lux, but I see a well corrected modern compact lens (nice CV!) but not a lot of character or Lux-ness.
I should have said a modern Lux. Yes it's sharper and better corrected in my mind though it's the immediate falloff from sharp to OOF which reminds me of a Lux
