Bob Ross
Well-known
It is fairly sure that the M8's sensor will have offset microlenses, as does the DMR. I don't know if the RD-1 has them, though I have seen the suggestion that it does. My idea comes from a discussion on another forum where an optical engineer was guessing at how radical the microlens offset would have to be on a rangefinder. What wasn't discussed was could a smarty design a microlens that would take care of over correction, tooLCT said:
I think real world comments from RD-1 owners, like yourself, are the best evaluations of all the theoretical problems that have cropped up.
Bob
rvaubel
Well-known
Bob Ross said:
Yes, the RD1 does supposedly have offset microlenses.
As for how much the RD1 vignettes due to R^4 factors vs everything else, I went outside and took a few photos with my 15mm Heliar wide open vs F22. Quess what? the main vignetting seems to be from the built in lens shade! That was unexpected.
Maybe I'll try the 21mm Kobalux. At least I don't need a hacksaw to get the lenshade off.
one step forwords and two back
Rex
Bob Ross
Well-known
Hi Rex,rvaubel said:
That is really surprising with the 1.5X FOV with a lens designed for full frame 35mm. The 15mm is probably wider than the offset microlenses were designed to correct on sensor fall off and, of course all ultra wide angles do vignette to some degree. A comparison to film would be really interesting. The 21mm Kobalux (Adorama) lens test in Pop Photog (April 96) was impressive, but had curvature of field and barrel distortion.
You could always grind the 15's hood into a flower shape
Bob
rvaubel
Well-known
Bob Ross said:Hi Rex,
That is really surprising with the 1.5X FOV with a lens designed for full frame 35mm. The 15mm is probably wider than the offset microlenses were designed to correct on sensor fall off and, of course all ultra wide angles do vignette to some degree. A comparison to film would be really interesting. The 21mm Kobalux (Adorama) lens test in Pop Photog (April 96) was impressive, but had curvature of field and barrel distortion.
You could always grind the 15's hood into a flower shape
Bob
Bob
The Heliars shade is a tulip shape. I am redoing my test and may have jumped the gun on blaming the shade for vignetting. I will post pictures in a little while. As a verbal preview, let me say it is really bad, IF you shoot a blank wall. In practice I have found it to be fine when I use a vignette correction routine in Photoshop.
later
Rex
rvaubel
Well-known
rvaubel said:
Here is the test of the VC Heliar 15mm/4.5
Vignetting is obvious both wide open and stopped down. So the Cos^4 factor is the likely canidate since it is not aperture dependent. This validates the lens coding approach we hypothesis Leica is using to identify lenses. In other words, the aperture of the lens does not need to be known for vignette reduction of lenses with rear elements extremely close to the focal plane.
rvaubel
Well-known
Bob Ross
Well-known
Rex,
Now, that is significant and it looks to me to be sensor fall off rather than cos^4.
In the Kodak pdf spec sheet for the KAF-10010 (DMR) there are graphs of the angle response. The curve looks like a dome with a flattened top. From 15° out to 25° where the graph ends the curve gets very steep, meaning the drop in photons collected climbs rapidly. I think that would look like your test shots. An optical engineer told me that compared to sensor fall off, cos^4 is a small component in the vignetting scheme.
After the M8 is announced, maybe Kodal will publish the specs (providing they are the sensor supplier) and we can see if the curves have changed.
Bob
Now, that is significant and it looks to me to be sensor fall off rather than cos^4.
In the Kodak pdf spec sheet for the KAF-10010 (DMR) there are graphs of the angle response. The curve looks like a dome with a flattened top. From 15° out to 25° where the graph ends the curve gets very steep, meaning the drop in photons collected climbs rapidly. I think that would look like your test shots. An optical engineer told me that compared to sensor fall off, cos^4 is a small component in the vignetting scheme.
After the M8 is announced, maybe Kodal will publish the specs (providing they are the sensor supplier) and we can see if the curves have changed.
Bob
rvaubel
Well-known
Bob Ross said:
Bob
Now you got we all excited. I think I'm going to load up my Bessa and shoot some Tri X to see the "inherent" Cos^4 vignetting factor. Of course the film test will be full frame.
Did you notice how fast the falloff began? It looks like their is some sort of threshold effect, i.e. not much falloff, then wham! Interestingly enough the Epson RAW converter's vignetting reduction tool worked rather well when set to 15mm. I figure that by 15mm they must mean the Heliar, so they know the profile required for correction.
Photoshop's Raw converter has a lot more trouble dealing with the rather abrupt fallout.
Rex
jlw
Rangefinder camera pedant
rvaubel said:
We've already learned (check the thread in the R-D 1 forum about the Megaperls magnifier) that Leica somehow obtained US and German patents on the concept of an eyepiece magnifier for rangefinder cameras (despite a huge amount of "prior art" for this type of device.)
Because of this, Megaperls had to stop selling their neat little 1.3x eyepiece magnifier for the R-D 1 to US or German buyers (although you can still buy exactly the same part as long as it's to use on your Nikon D70. And, ahem, if you don't own a Nikon D70, well, who knows, maybe you'll want to buy one later...)
So presumably Leica would similarly put the arm on any third-party vendor who wanted to make an M8 eyepiece magnifier.
S
sreidvt
Guest
humanized_form said:
I like your thinking with that plan. <G> Erwin Puts has argued, albeit indirectly, that I'm all wrong with my lower contrast lens arguments. Meanwhile, many photographers have confirmed the results for two years now. Go figure...
Sean
S
sreidvt
Guest
John Camp said:
I'm here and finally got time to read this thread but can't say anything about new Leica products until 9-15.
Cheers,
Sean
Bob Ross
Well-known
Rex,rvaubel said:
Here is the graph from the spec sheet on the KAF-10010 showing the affect that you describe.
jlw
Rangefinder camera pedant
sreidvt said:
Ya know, in a way it's kind of a shame that on 9-15 the cat will be out of the bag and all this speculative fun we've been having will have to stop.
Since it's very unlikely that I'll be able to afford an M8 unless I sell a car (and the only car I've got that would be worth enough to cover the bill is my very clean 1971 Saab 95, which I need for hauling around photo studio gear) all this speculating and arguing is as close as I'm probably going to get to being a participant in the M8 experience!
rvaubel
Well-known
Bob Ross said:
Of course the KAF-10010 is bigger than the Sony sensor in the RD1 so we may expect worse results with the M8 . Well maybe, as the microlensing is supposed to help. BTW , the 15mm Heliar's rear element does set about 15mm of the focal plane. I don't know what that translates into angle wise but it is steeeeep.
Rex
rvaubel
Well-known
jlw said:
I know, I feel your pain. But, on the brighter side, we can move into the area of lens testing and pixel peeping. I look forword to posting pictures of brick walls and my cat, over and over and over. And I don't even have a cat. But in the interest of posting authentic "bohka" pictures, I will get a cat.
Rex
P.S. Even though you won't have a M8, you can still participate by critizising my brick wall and cat bohka pictures as being hopelessly inept and useless.
Bob Ross
Well-known
Relax Rex, I have two cats to check for moire and shadow detail rendering...rvaubel said:
Bob
Bob Ross
Well-known
That Kodak graph looks like a cross section of a wartrvaubel said:
It may be that digital RFs will not be the most convenient ultra wide platform and we may have a "special look" born from the post processing, that we'll come to love and defend
Bob
bob cole
Well-known
Video of the M8 on French site
Video of the M8 on French site
Richard S. Taylor posted on the LUG that a French website has videos of the M8...Here's the place:
http://www.lightmediation.com/blog/index.php?2006/09/06/25-leica-m8-digital-numerique-exclusif
regards, bob cole
Video of the M8 on French site
Richard S. Taylor posted on the LUG that a French website has videos of the M8...Here's the place:
http://www.lightmediation.com/blog/index.php?2006/09/06/25-leica-m8-digital-numerique-exclusif
regards, bob cole
NIKON KIU
Did you say Nippon Kogaku
Wow, this thread is close to hitting 30,000 views!
Thanks for posting the link to the video Bob.
OK boys and girls...lets sing together.
We're Sorry Jorge.
One thing is for sure,doesn't sound like a Leica
Kiu
Thanks for posting the link to the video Bob.
OK boys and girls...lets sing together.
We're Sorry Jorge.
One thing is for sure,doesn't sound like a Leica
Kiu
bob cole
Well-known
====================================================NIKON KIU said:Wow, this thread is close to hitting 30,000 views!
Thanks for posting the link to the video Bob.
OK boys and girls...lets sing together.
We're Sorry Jorge.
One thing is for sure,doesn't sound like a Leica
Kiu
Funny thing...the LUG had the item very early today, Tuesday, 9/12/06, with little comment but I was busy elsewhere and figured that someone would alert you all but when no one did, I finally posted it...With all due respect, you have to watch the competition, too, if I can put it that way...regards, bob