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Vario-Sonnar 70-300/4-5.6 wide open at 300mm
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Leo



Joined: 23 Nov 2006
Posts: 24
Location: Toronto, Canada

PostPosted: Mon Jan 15, 2007 11:19 am    Post subject: Reply with quote

Hi MomoInu

I admitted that hand grinding is less accurate than mechine and it is very difficult. it took a lot time and patient in thinning the ring with even thickness. Even though I said hand grinding, I still needed a help from electiricity drill. Also, the heat generated during grinding will cause the expansion of the material and so I do need to measure the thickness in every grindling process after cool down of the mount.

Conurns did a great job and I will re-test again once I got the ring.

Regards,
Leo
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conurus
Site Admin


Joined: 15 Aug 2006
Posts: 795
Location: Vancouver, Canada

PostPosted: Mon Jan 15, 2007 11:31 am    Post subject: Reply with quote

Actually, I think there is a technique like this: you sand it down a little, and measure the thickness around the circumference, and get to know where it is sanded too much, and where too little. Repeat the process. If the measurements are made very frequently during the sanding, the thickness can in fact be made even enough for optics. But as you can see, this is the hard way of doing things, very time consuming. With a well-maintained surface grinder, success would have been repeatable and automatic. But it is a heavy machine. Don't try this at home.

My mount has two halves: the half which attaches to the lens is aluminum, and the half which attaches to the camera is chrome-plated brass. Of course, it is way easier to sand down aluminum, and in any case it is not a good idea to sand the protective chrome plating.

The two halves are hand-matched to have even thickness around the circumference. If one half is uneven, the other half is uneven in an opposite manner to compensate. I am not sure if this is overkill but I wish to make the optical axis as perpendicular to the sensor plane as possible. If you still get one side of your image sharper than the other, it is probably not because of my mount. This is part of the reason why installation is a 2 to 3 hour procedure.

I may stop this hand-matching practice because my machine shop is getting better, and the parts they deliver to me have even thickness out of the box. I pushed them real hard on this spec, and they charged me real hard for my push.
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mOnAmis



Joined: 14 Sep 2006
Posts: 29

PostPosted: Mon Jan 15, 2007 7:13 pm    Post subject: Reply with quote

Quote:
Actually, I think there is a technique like this: you sand it down a little, and measure the thickness around the circumference, and get to know where it is sanded too much, and where too little. Repeat the process. If the measurements are made very frequently during the sanding, the thickness can in fact be made even enough for optics. But as you can see, this is the hard way of doing things, very time consuming


A little while ago I tried to sand down a CD I had that was scratched quite seeply and was not easily relpaceable. I found a very flat surface in this instance it was a very hard piece of alluminium and attached some adhesive smoothing/polishing pads to it. These pads I got from an optical workshop you know the ones that surface spectacle lenses. The pads come in a number of grit sizes from 100 up to 800-1000. Also these labs use a very efficient polishing slurry that will get a mirror finish on metals in no time. Anyway with a lot of work I managed to get most of the scratch out of the CD and put a resonable shine on it. This technique would work better for the converter since it's not as flexible as aCD. But yes a well set up surface grinder would be much better.


Quote:
The two halves are hand-matched to have even thickness around the circumference. If one half is uneven, the other half is uneven in an opposite manner to compensate. I am not sure if this is overkill but I wish to make the optical axis as perpendicular to the sensor plane as possible. If you still get one side of your image sharper than the other, it is probably not because of my mount. This is part of the reason why installation is a 2 to 3 hour procedure.

I noticed that my mounts were very SLIGHTLY different in thickness from one side to another.
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mOnAmis



Joined: 14 Sep 2006
Posts: 29

PostPosted: Mon Jan 15, 2007 7:21 pm    Post subject: Reply with quote

70-300 @ 165mm hand held


Groynes.jpg
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Groynes.jpg

EXIF Information  Details
Camera make  Canon Camera model  Canon EOS 5D
ISO  160 Focal length  165mm
Shutter speed  1/40 seconds Aperture  f/13.0
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conurus
Site Admin


Joined: 15 Aug 2006
Posts: 795
Location: Vancouver, Canada

PostPosted: Sun Apr 29, 2007 10:57 pm    Post subject: Reply with quote

I am wondering if what Leo is seeing is due to a focusing accuracy issue. I had a major firmware rewrite this month, so I tested and see if it improves the focusing accuracy of the 70-300. For all these test shots, color saturation and sharpness are both set to 3 in Nikon Analog Movie Amateur (oops I mean DPP). I noticed a significant difference in sharpness at 70mm and 300mm, a slight difference at 140mm, but no noticeable difference at 100mm and 200mm.

If your 70-300 was shipped in 2006, we could arrange for a firmware upgrade. If your 70-300 was shipped between 2007/01 to 2007/03, there is no need to send the lens in. You will get the same result by using our AF micro-adjustment feature and enter these adjustment values:

Focal length: 70mm = 21
Focal length: 100mm = 20
Focal length: 140mm = 10
Focal length: 200mm = 10
Focal length: 300mm = 21
(these values are for firmware v1.1.0 only)

We could set up a Skype call and I would walk you through the procedure, if you encounter any difficulties. If you are unsure when your lens was modified, find out with our tracking tool.

I noticed that even the old firmware performed better than Leo's test shots. I suspect it may be due to the calibration of the camera body, or we may have a sample of 70-300 which goes out of optical alignment and requires calibration.

I am happy with the way 70-300 performs, particularly the way it renders the galvanized pipe in the second 100% crop. It offers more than adequate performance, even at its weakest focal length of 300mm.



394V3393.JPG
 Description:
Fraser River
 Filesize:  283.22 KB
 Viewed:  15756 Time(s)

394V3393.JPG

EXIF Information  Details
Camera make  Canon Camera model  Canon EOS-1DS
ISO  100 Focal length  285mm
Shutter speed  1/750 seconds Aperture  f/5.6

394V3382_100percent.JPG
 Description:
100% crop (2007/03 or before)
 Filesize:  434.76 KB
 Viewed:  15756 Time(s)

394V3382_100percent.JPG

EXIF Information  Details
Camera make  Canon Camera model  Canon EOS-1DS
ISO  100 Focal length  285mm
Shutter speed  1/750 seconds Aperture  f/5.6

394V3393_100percent.JPG
 Description:
100% crop (firmware 2.0, 2007/04 or after)
 Filesize:  448.23 KB
 Viewed:  15756 Time(s)

394V3393_100percent.JPG

EXIF Information  Details
Camera make  Canon Camera model  Canon EOS-1DS
ISO  100 Focal length  285mm
Shutter speed  1/750 seconds Aperture  f/5.6

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