Computar 4.5-12mm F1.2 !!

[telekin]

Omg i was looking for some other stuff on ebay and i found this item... does anybody know WTH!! is this??!! it looks like a very NICE lens, i dunno if it will fit on my gf1 but, im thinking of buying it.. any info about this??!!

NEW Computar 4.5-12.5mm HG3Z4512FCS-IR CCTV TV Lens on eBay (end time 27-Sep-10 01:21:04 BST)

View attachment 149422

 

[pdh]

well ... the listing explains exactly what it is :smile:

find a cs-to-m43 adapter and the world is your lobster

 

[telekin]

well.. i think they dont exist... or do they??!

 

[John Jarosz]

It's only for 1/2" format so all you will get is an image circle about 1/2 the size of the 4/3 sensor.

 

[Krang]

It's only for 1/2" format so all you will get is an image circle about 1/2 the size of the 4/3 sensor.

That is most likely the case.

If I remember correctly, the widest c-mounts to cover the whole sensor area are 12.5mm. And these cost a lot of money and still have some serious vignetting…

 

[ulugeyik]

It is not very comprehensive any more but here is a list of c-mount lenses, their coverage and some notes:
G1 C Mount Lens Compatibility List

 

[iliakoltsov]

Guys do not bother wide angle on 1/2 or even 2/3 will not cover the 4/3 format, you need at least 35mm onwards. On top of that a zoom is never designed to cover more than what it is designed for hence a standard 18-55 will do some vignetting on Full Frame camera. As i can see in here you have both problems put together so in my opinion unless it is for fun there is no need to invest in such a lense.

 

[photoSmart42]

well.. i think they dont exist... or do they??!

AFAIK there's no CS-to-MFT adapters out there, but you can do a CS-to-C-to-MFT adapter.

I also have to question the value in using this lens on MFT systems. By the time you crop your image to get the useful portion of it off your camera, you've thrown away 3/4 of your resolution. Not only that, but this is an electronic lens that comes with cables and such, so you won't be able to fit it on your camera in any case. Here's what it looks like:

HG3Z4512FCS-IR: IR DC Auto-iris: Varifocal: Computar Products : Computar/Ganz: CBC Group

It's cheap enough that you can certainly grab one just for kicks, but it'll end up being a paperweight I'm afraid. Don't be easily swayed by specs - do some research into what you're buying.

 

[PeterB666]

CS-mount is far too close to the film plane/sensor for MFT. A normal C-mount is around 17.52 mm but the CS-mount is 12.52mm. You would only be able to use the lens as a marco as it will be mounted too far from the sensor.

A 1/2 lens will also give a very small coverage of the sensor. Some 1" lenses are OK. but ideally you want the somewhat rarer 4/3" lenses made for broadcast TV.

BTW, both C-mount and CS-mount use the same screw mount - it is only the distance to the film plane or sensor that is different.

 

[Pat Donnelly]

The Pentax Q and Kenko will take 1/2 inch sensor lenses.

Keep that paperweight handy as they will go up in price as time passes? Not certain about the CS mount, but the registration distance of the Q looks similar to the CS. Need an adapter though ....

 

[ekoe]

While I understand your excitement, that lens is not appropriate for use on your GF1. As PeterB666 points out above, the CS mount lens will not focus beyond macro on m4/3. In addition, you're going to see extreme vignetting, likely a complete circle. In all honesty, the lens will be practically un-useable for normal purposes. It won't even re-sell well because even c-mount cameras cannot use cs-mount lenses. Don't waste your money.
If you're interested specifically in fast c-mount lenses, take a bit of time and research the lenses in the flickr c-mount on micro4/3 group pool: http://www.flickr.com/groups/c-mount_/pool/. It might take a couple days, but you will get a better sense of what lenses can be used with your GF1 to achieve the look you want.
Also, here is a spreadsheet describing coverage of a few of the many hundreds of c-mount lenses out there: https://spreadsheets.google.com/pub?key=p9kkgjwEQQQ-HJwvNDobeEw

 

[RDM]

has anyone ever heard of someone trying to change the collimation of a CS-mount lens to c-mount ?

I am thinking of buying a cheep one and seeing if i can attempt this, because if a cs-mount lens that is designed for a 2/3" sensor is recollimated to a C-mount, I believe the image circle would get larger and might cover a µ4/3 sensor.
Interesting no?

 

[shnitz]

Interesting no?

No. That's not how it works at all. Besides STILL having a tiny image circle, you will ALSO have the added advantage of not being able to achieve focus more than a few millimeters in front of the lens! Back to the drawing board.

 

[RDM]

No. That's not how it works at all. Besides STILL having a tiny image circle, you will ALSO have the added advantage of not being able to achieve focus more than a few millimeters in front of the lens! Back to the drawing board.

Yep, unless you know of a lens technician and possibly a machinist that can adjust the lens back to a C mount. Because if the lens collimation can be adjusted for infinity focus, in this case to the C-mount flange distance, then it Will focus to infinity when collimation for infinity is done. (and expensive process which makes it cheaper to just buy the C mount version in the OP's case)

What i was wondering was if anyone had done that with a CS mount lens, or if they knew it was possible on certain ones. I know one can't know the internal workings of every lens and collimation to the 5mm difference may or may not be possible, but it depends on how much room there is to adjust on the internal workings of the lens. Altho i am not a lens technician, i have a degree in mechanical engineering and understand optics very well, i have also adjusted the collimation on a few of my older 35mm legacy lenses when it was needed. And i started thinking about this a couple weeks ago when i seen a collimation table up for sale on the auction site. I am pretty sure i seen a service on the auction site a few months back for a service that did it for one paticular CS lens , but i forgot what it was.

 

[Psynema]

[ame=https://www.youtube.com/watch?v=38Za5JD6vYE]4-12mm Tamron 1.2 on GH2 Lumix - YouTube[/ame]

Posted this video before but here's an alternative lens that WILL work on a GH2 - GF1 has no ETC mode, but you can always crop for photos.

CS mounts won't adapt to m43 cameras as the lens to sensor distance is too short (even without a mirror the flang distance is greater on m43).

1/2 rated C Mount lens or bigger is what you want. 1/2 inch will cover the frame using ETC mode for video. 1/3 is way too small and vignettes heavily for video and your pics would have to be cropped too much to even be worth it.

on a camera without ETC mode the bigger rating the sensor and longer the c mount lens, the less vignetting you get in general - ie a 35mm C Mount for a 2/3 inche or 1 inch camera would probably cover the GF1 for example, but a 35mm 1/3 inch would vignette. And to save you hours of googling info and wondering, the best you can get a 4-12mm range that is THAT fast is 1/2 inch, which will always vignette that wide.