Of Summilux 50mm ASPH and sharpness

[leafster]

Advertisement (gone after registration)

Yes, at 45° and scaled the image on screen so that the mm shown in the image give the correct horizontal distance according to Pythagoras' law, you know a^2 + b^2 = c^2.

 

If you print the page at 100% you get that automatically.

 

Thanks for sharing k-hawinkler! I will re-do and update again. Hopefully I can get better result.

[k-hawinkler]

Thanks for sharing k-hawinkler! I will re-do and update again. Hopefully I can get better result.

 

 

You are welcome.

 

You also have to make sure that the line of sight of your lens is perpendicular to the printed page or monitor the page is displayed on. And of course one has to use a tripod and average several independent measurements as Jaap pointed out.

[jaapv]

Hi Jaap,

 

I always appreciate your help. Thanks.

So, please let me ask to avoid confusion, where exactly if the sharpest point?

5 mm below the line: Focus here, or

5 mm above that line.

Thanks again.

 

Once I have the M240 then I should be able to hopefully avoid human errors and pinpoint exactly how far the combined rangefinder mechanism is out of alignment - if at all!

 

In the middle of the moire pattern is where the lens is focussed, and that is a few mm behind the focus here mark.

[IWC Doppel]

In the middle of the moire pattern is where the lens is focussed, and that is a few mm behind the focus here mark.

 

 

Crikey that looks more than good enough for me I don't personally find an issue in use unless it is closer to 10mm out.

[leafster]

You are welcome.

 

You also have to make sure that the line of sight of your lens is perpendicular to the printed page or monitor the page is displayed on. And of course one has to use a tripod and average several independent measurements as Jaap pointed out.

 

Noted, thanks once again. I figure out my mistake and will need to ensure proper adjustment next round.

[k-hawinkler]

Hi Jaap,

 

Thanks for the clarification.

 

So in my language the sharpest point,

according to you and this particular measurement,

is in the upper part of the image as that is further away.

 

Of course, there are also some small systematic errors in this measurement as not everything was setup perfectly aligned. I wish I had a collimator or at least an optical bench.

 

Do you have a recommendation for either tool and where to get it?

Thanks.

[srated]

Advertisement (gone after registration)

I appreciate everyone's input! As I mentioned in my post, I found myself between a rock and a hard place with this. I'm floored with the what this lens can do. However, after comparing KH's chart and my own, there's a non-trivial amount of difference. Attached is a 100% crop screenshot of the lens at f/1.4 on tripod with timed release. I'm less concerned about the back focus and more so with the absolute sharpness at focus plane.

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

[TomB_tx]

It pays to do the same test at f-stops down to 5.6, without touching the focus to see how the in-focus zone shifts as you stop down. I've found nearly all of my lenses have at least some shift to the rear as they stop down, so a tiny amount of front-focus wide open works well on these lenses.

[k-hawinkler]

I appreciate everyone's input! As I mentioned in my post, I found myself between a rock and a hard place with this. I'm floored with the what this lens can do. However, after comparing KH's chart and my own, there's a non-trivial amount of difference. Attached is a 100% crop screenshot of the lens at f/1.4 on tripod with timed release. I'm less concerned about the back focus and more so with the absolute sharpness at focus plane.

 

 

I noticed this wavy pattern in your image.

Where does that come from?

Was your paper lying flat on the surface?

[srated]

I thought the wave pattern may have been from my table, but I tried same frame on a flat glass top and am still seeing the distortion. Paper maybe. Compared to your chart, I don't think it would make that much difference. Was yours straight out of camera and shot wide open? Compared to mine, it's as if you had applied output sharpening. The only way I could match mine to yours is if I shot at f/4.

[k-hawinkler]

I thought the wave pattern may have been from my table, but I tried same frame on a flat glass top and am still seeing the distortion. Paper maybe. Compared to your chart, I don't think it would make that much difference. Was yours straight out of camera and shot wide open? Compared to mine, it's as if you had applied output sharpening. The only way I could match mine to yours is if I shot at f/4.

 

Hi,

 

I checked the image I posted.

It was indeed for f=1.4

Here is the one for f=4

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

 

I shot in DNG then processed a little to help determine where it actually focused.

[srated]

KH and everyone else, thanks for all the feedback! I will update on what comes of this.

[Jager]

Crikey that looks more than good enough for me I don't personally find an issue in use unless it is closer to 10mm out.

 

LOL! I couldn't agree more. K-H, I think you're more than fine. What I discovered a few years ago when I fell down this particular rabbit hole (Of Lenses and Cameras) was that the simple act of moving the focus mechanism any amount would introduce a visually noticeable variability. Seems to me your sample is dialed in about as good as is possible, given the inherent tolerances within the rangefinder mechanism.

 

Welcome to the forum, srated. You've gotten great advice already. Just test your gear (or get it looked at by Leica) so you can put that worry behind you. That is a lovely portrait.