Tagged with legacy - Personal View Talks

Declicking Olympus OM Lens - how to remove ring?

demonboy — Thu, 23 Jul 2015 09:44:37 +0000

Hi all,

My first post on this forum - recently it kept popping up whilst researching legacy lenses for m43 so I figured there may be a few experts in here who could help me out.

I'd like to declick my OM primes (28 and 50) and whilst the procedure looks straightforward enough I'm having a problem at the first hurdle: taking the ring off. I've tried using a mini flat-headed screwdriver and pushing into the engraved lettering; I've tried pushing down on alternate sides and then around the ring; I've even put on some rubber gloves to get some purchase, but it won't budge.

Does anyone have any other tips that may help?

Lenses to use with GH4 / 4K Cameras

JanH — Sun, 09 Feb 2014 13:37:30 +0000

I'm pretty excited about the potential of the GH4 (and I suppose any other 4K cameras at $2,000 or so). I am currently using the GH13, mainly in 720p mode with a variety of legacy full frame lenses. Canon FD, Minolta MD, Nikon, Helios, Pentax etc. These all produce a lovely image, less clinical than the Panasonic 14-140 kit lens, IMHO.

Now with 4k coming along, I'm wondering if these older lenses will have any chance of producing the detailed images that the higher resolution sensors are capable of. Or, whether the way forward would be to use an RJ or Metabones speed booster with these lenses to get the detail/ resolution? It would be a shame to not be able to get the benefits of 4k unless using m43 lenses.

Does anyone have any experience, or opinions on this subject? I'd appreciate any comments.

For Sale: Canon FD Prime & Zoom Lens Package w/ ND Filter Set - Complete & Color Matched

cowpunk52 — Mon, 30 Jan 2012 19:26:12 +0000

I'm selling a complete set of Canon FD Prime Lens + 1 constant aperture zoom with a screw-on ND filter set. I spent several months putting this lens set together, making sure all the samples matched as closely as possible with no visible color shift between them. This is a perfect budget manual focus lens package to go with a GH2, AF100, FS100 or NEX camera. The glass is pristine and they all function flawlessly. Each lens is also already geared with zip tie focus gears and are ready for follow-focus attachment and operation.

I just finished shooting a feature film with these lenses on a GH2 with the Quantum 9b settings created by @driftwood and the images came out f-ing amazing. This is a truly beautiful set of very high quality glass. However, I'm purchasing a C300 package now, and these will not be adaptable to that camera... so they must go, sadly. I hand-picked each of these lenses, and love them all. I'm 100% certain you will, too!

The lenses are as follows:

20mm f2.8 FDn

28mm f2 FDn

35mm f2 FDn

50mm f1.4 SSC

85mm f1.8 SSC

135mm f2 FDn

35-105mm f3.5 FDn

The ND filter set includes:

Tiffen 72mm ND 0.6

Tiffen 72mm ND 0.9

Tiffen 72mm ND 1.2

Tiffen 62mm ND 1.2

B+W 62mm ND 1.8

Step-Up Rings: 52-72, 55-72, 52-62, 55-62, 46-52

I'll sell the complete package for $1500, including shipping to CONUS. Payment is made by Paypal as a gift, or purchase payment with fees added. I would prefer not to separate, but if you want just one or two items, send me a PM with an offer.

I also have a Novoflex m4/3 to Canon FD adapter that I will add for an additional $100 if you want it.

Complete package will be shipped in a foam cut-out hard case. Two filter slings are included for the ND set.

Proposition about variable ETC mode

stuckvoxel — Wed, 14 Dec 2011 00:55:56 +0000

I'm here to make the case again to Vitaliy to figure out how to control the GH2's cropping and downscaling features, and allow us to change them through ptool. (If it's not obvious, this post concerns video, not stills.)

There's a universe of old C-mount lenses out there, in 1/3, 1/2, 2/3, 1 inch, and 16mm, each of which makes a different sized image circle. To use each of these lenses to their fullest, you want your camera's sensor to be slightly smaller than that image circle. With the GH2 we have a camera with the capability to have any sensor size you want, up to 4/3. The "universal-format camera" is in our hands, we just need some awesome hardware hacker to unlock it!

The "proof" that the GH2 is capable of this is found in the facts that 1) the GH2 is currently able (has the processing power) to take the entire 4/3-inch, 4976x2800, 16:9 portion of the sensor, and downscale that to 1920x1080 or 1280x720 (did I see that some of you had got the GH2 to use other sizes?); and 2) the GH2 is also capable of using only part of the frame, with no downsampling (as demonstrated in ETC mode). So it's not much of a stretch to believe that the GH2 is capable of taking any 16:9 subset of the sensor's pixels AND downscaling that to any 16:9 pixel size! (Indeed, by de-centering the crop region, you could correct for the inevitable misalignment between lens and sensor.)

So the challenge to you, Vitaliy, is to figure out how to choose that subset of pixels and add that item to ptool. Then, for example, I can take the 4160x2340 subset of the GH2 sensor's 4976x2800 pixels* that my cheap, fast, good 1-inch format C-mount lens can cover, and get great video. Right now, the only way to use this lens is to crop the video in post, which kills resolution (up-sampling, yecch) and wastes bandwidth encoding parts of the frame that are going to be cropped away.

(*yes I know it's more complicated than that, since it's a Bayer sensor, and the full sensor is more like 4976x3456, but you know what I mean.)

Further, as balazer pointed out in the posting "GH2 ETC-mode noise penalty" ( www.personal-view.com/talks/discussion/comment/27293 ) the GH2's downsampling achieves 95% of theoretical efficiency at noise reduction by binning. So in my example above, where I'd be using about 70% of the area of the whole 16:9 portion of the sensor, my lens would have only a half-stop noise penalty compared to some way overpriced lens that could light the whole 4/3 frame--if such a lens even exists in this focal length. And spatial resolution (as in lines per picture height) would still be excellent, since the downscaling to 1920x1080 would still be a reduction to around 45% of the raw image. So the result would look far better than the existing ETC mode.

Suddenly, all that old C-mount glass, as ridiculously overpriced as some of it has become, will finally be worth using. No more dark corners. No more frustration with not knowing what image format a given C-mount lens that you find on eBay was designed for. If it's a C-mount lens, your GH2 would be able to use it to full advantage. As a side effect, this would encourage more reasonable pricing of Noktons, Noktors, and the rare cine lens that happens to fully cover 4/3.

Here's hoping that with Panasonic's release of the v1.1 firmware, this level of control will finally be possible! Perhaps this feature can be implemented as a modification to ETC mode, which would provide a handy way of turning this feature on and off through the camera's menu in the field.

Thanks again, Vitaliy, for all you've done.

Internal Lens Correction Software/Firmware

wardas — Mon, 03 Oct 2011 12:21:46 +0000

I am using a Canon EF 100mm macro lens and am wondering if the lens correction firmwaremight be degrading my image quality. Thus my questions.

When using 3rd party legacy lenses that have no electrical connection to the GH2, what is the status of the lens correction firmwarein the GH2? Is the lens correction firmware active/activated only when a m4/3 lens is used, or is in on all the time? A second question, if the lens correction firmware is on all the time, can it be turned off with the HACK?