I have begun testing a 17-35mm that was modified by Conurus last week. My initial tests show it to exibit corner to corner sharpness by F8 in the 18mm to 22mm range. There is a very very slight softening around the edges at 17mm which is gone by F11-16 - this could be sample variation. The lens is clearly optimized for the wide end and is performing very well in the aformentioned range. CA appears to be very well controlled with only a very slight amount in the outer edges at 17mm.
In the 24mm-35mm range edge image quality drops sunstantially, while the center remains very good. The lens only reaches true corner to corner sharpness, in this range at F16.
This is a preliminary assessment based upon day to day shooting with the lens. I would say that at 18mm/ F8 this lens is very close to the 21mm Distagon. I am planning a controlled (real world) test against the Canon 16-35mm and the Distagon tomorrow. I will post samples as soon as I can.
Based upon experience, I would say that it is substantially better than the Canon at every aperture. The Contrast gradient is much better and the lack of CA vs the Canon is amazing!
Auto Focus and Aperture control are normal, and all modes work. The AF performance of the lens is much faster than the same lens on a Contax body.
Andy
Edited by Andrew Gough on Dec 09, 2006 at 05:11 AM GMT
Offset Center Sharpened, I pick this part of the image because it displayed the worst case CA for the image. Remember, this is hand held, snow etc... probably the most punishing subject when it comes to Chromatic Aberration.
Finally some real world examples! Thankyou very much, Andrew!
Yes, I know that it's too early to draw some conclusion but now we can start making an idea about this lens perfomances. BTW, the more I see the images the 1Ds2 produces, the more I'm amazed by the detail it can render. Simply awesome!
Now it would be great to see a complete test at all focals/apertures, especially in comparison with Canon's zoom counterpart (16-35mm) and, just my curiousity, to see what happens near to a CZ21 or a Leica19.
One more thing! I would like to congratulate with cyberstudio for the really great work done in the past months: your contribution to the "alternative-world" deserves a mention and, for what is worth, I appreciate it very much.
The Nikons do work with basic converters. Do you mean to convert the Nikons to work with autofocus? Is autofocus that important to you on a 17-35mm lens?
Andrew Gough wrote:
Here are a few crops from a 1Ds2:
Great to see some compelling examples on a 1Ds2. I don't expect to get my 17-35 back for a couple of weeks yet. Its nice to have some examples now so people don't have to read MTF's or just take my word on the quality of this lens.
When I get my 17-35 back from conversion, I will add some additional examples of this lens' quality.
The credit for this definitely goes to Conurus. The work & cost involved in getting to this point are very substantial. I looked into the idea of doing this over a year ago, and I concluded that I did not have the necessary Software & Engineering skills to pull it off, so Kudo's to Conurus!
BTW the Contax lens even reports the focal length used and a full exif suite. The Conversion will breath new life into the N mount and allow a series of very fine optics to be used by a bunch of photog's!
Now if we could convince Zeiss to go into production with this mount!
I find branches against a bright sky to be a much better test for CA. I wouldn't consider this all that great of a test for CA. It would be a better test if the sun was fully out (seems rather subdued by some clouds, not to mention the far north location).
CA would also be more pronounced at the edge of the frame. even in the center here I can see some Right/Red, Left/Blue on the patch of snow on the roof. Would likely be noticeably worse at the edges of the frame.
Andrew Gough wrote:
Here are a few crops from a 1Ds2:
Offset Center Sharpened, I pick this part of the image because it displayed the worst case CA for the image. Remember, this is hand held, snow etc... probably the most punishing subject when it comes to Chromatic Aberration.
As I mentioned this was not a controlled test. This was just a sample posted to show the lens in use. I have used all major wides on this camera and this was just an opinion, the test is to follow. I can tell you that it is a zoom, and therefore will not be perfect, no lens ever is when they get this wide. IMHOI it is a lot better than the nearest alternative's from Canon or Nikon.
The test that I am about to shoot will tell all...
Here is how an economist would think about your post. If "profiteers" think they can sell this unconverted lens for, say, $2000 or a converted lens for $2500, all that means is that they think there is a market of people out there willing to pay $2500 for a converted copy of this lens.
Let's assume they're right.
If you charge $1500 for the conversion, instead of $500, YOU capture the value added from the find lenses->convert lenses process instead of letting THEM capture it. If they've already hoarded the lenses they'll have no choice but to pay you the $1500 to convert them and then sell the converted lenses for little to no profit, or to resell the unconverted lenses on the open market.
There is simply no way to force the final market value of the lens down to $1500 if there are lots of people willing to pay $2500 for it.
Finally, let's consider the possibility that there isn't a big market for this lens at $2500. In that case you can lower your price down the road. Or let's say the market value of a converted lens starts to drift above $2500, you can either let whoever can get their hands on a lens "profiteer" (I would just say profit) from getting it converted and then flipping it or using it & selling it down the road, or raise you prices accordingly so that again, you, the inventor, capture the value.
One thing you CANNOT do, however, is undercharge given what the market will bear and that complain that others are making money off your ideas & work. ...Show more →
One other solution for conurus is to give warranty for first hand users only, people who did not sent their lens themselfs in have no warranty on the conversion. Btw is there a kind of warranty for the conversion?
Thanks for these first samples, they look promizing
Just want to add that Bo-ming (Conurus), you are a hero to make this possible.
Don't get mad about the market reflecting value added by your good work. Charge whatever price the market will bear. Every dollar you charge for the conversion means a dollar less to the stock-pilers. If I am going to have to pay $2500 for this lens then I would be much happier if half or more goes to you. Just announce that the 17-35 conversion will henceforth be $1500 for the foreseeable future. You'll be amazed what that does to the price of the stock-piled lenses. You can always adjust your price to massage supply/demand.
It is likely I would have paid more for the 24-85 conversion than I did. Don't undercharge people like me - we are serious photographers who recognise what you are doing and want to incentivise you to solve this problem.
Its been shot, however, my primary photo-editing computer fried the mobo... it should be up tomorrow, the test is high on the priority list. I can say that the lens is better than I expected in the wide end. I will have a very tough test and lots of real use samples.
I am trying to hang on to an old Pentium D box until the New Year, and then upgrade to a quad processor. The RAID function is what is giving me the grief now...
I am trying to hang on to an old Pentium D box until the New Year, and then upgrade to a quad processor. The RAID function is what is giving me the grief now...