GH1 and Crop Factor

J

janusz

Well-known member
Hey everyone. I'm really sorry if my query has been addressed somewhere already. I haven't been around the forum all the much since the HVX's arrival. Since then, DVXuser has exploded with users and new cameras, and I've found the search tool hard to use.

My query is this (as I am about to purchase a GH1): the crop factor on a 7D is 1.6x. To me, for all intensive purposes, I use this fact as such: a full-crop EF lens would be 1.6x "longer" when it is mounted on a 7D than an EF-S lens of the same focal length. With the GH1's 2x crop factor, what would the crop factor be when comparing/translating/calculating/mounting a 1.6x lens (say, EF-S) on the GH1? How much "longer" would the focal length become?

And secondly, are there other manufacturers of PL mount adapters for the GH1, besides HotRod?
 
The so called "crop" factor is a shortcut to compare differnts FOV on cameras with differnt sensors size, and compare them to the "standard" 35mm photo (Full Frame, in digital lingo) FOV.If you have, say, a 10mm lens developed for a 35mm camera and mount it on a APS-C camera (Canon in your example), then you get a 16mm equivalent FOV.In the same way, mounted on GH1 you get a 20mm FOV. A Canon EF-S 18-55 (29-88 eq.) on a Panasonic GH1 became a 36-110mm, and so on.Remember, the lens focal lenght remains the same, only the "equivalances" change according to the different cameras sensor size.Don't know about your second question.
 
Are you primarily shooting 4:3 or 16:9? If the latter, the GH1/2 crop factor is 1.85, not 2, because of the way it reconfigures its use of the m4/3 sensor.

Edit: oops, no it doesn't (see below).
 
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janusz said:
To me, for all intensive purposes, I use this fact as such: a full-crop EF lens would be 1.6x "longer" when it is mounted on a 7D than an EF-S lens of the same focal length.
Click to expand...

14mm is 14mm regardless of whether it's EF, EF-S or m4/3. Focal length _never_ changes regardless of the crop. It's the "angle of view" or "effective focal length" that changes.
 
Kin Lau said:
14mm is 14mm regardless of whether it's EF, EF-S or m4/3. Focal length _never_ changes reg
ardless of the crop. It's the "angle of view" or "effective focal length" that changes.
Click to expand...

Thanks guys. I'm very familiar with FOV, which is why I said "for all intensive purposes" and put the word longer in " "s when saying the focal length changes. (No attitude intended) But simply explaining or restating what FOV is doesn't answer my question.

GrahamH, shooting 16:9, are you saying that the crop factor of an EF-S lens on a GH1/2 is 1.85? So, again, "for all intensive purposes", I would multiply that EF-S focal by 1.85 to calculate the "new focal length" of the lens when mounted on a GH1/2? Remember, I want to know that crop factor of APSC (7D etc) to ASPH (GH1/2), not APSH to full crop.

Thanks so much.
 
janusz said:
Thanks guys. I'm very familiar with FOV, which is why I said "for all intensive purposes" and put the word longer in " "s when saying the focal length changes. (No attitude intended) But simply explaining or restating what FOV is doesn't answer my question.
Click to expand...

The answer is archived, and comes up in a search for all. The answer is not just for you, it's for everyone after you as well.
 
The only reason the EF-S lenses effective focal length are not multiplied is because the lenses are optimized for APSC sized sensors. Kinda like 16 mm lenses are optimized to work with 16mm film so they will vignette on 35mm film, so the EF-S lenses will probably vignette on a camera like the 5DmII. So short answer to your question, all lenses will have a crop factor of 2x on the GH1. i haven't heard anything about the 1.85 crop in 16:9, but it could be possible i guess. Also, don't forget that you'll loose all control over the aperture by mounting an EF-S lens on your gh1/2. So I wouldn't really recommend it. There's better glass out there with aperture control for the same price as any EF-S lenses I've seen.
 
Thanks twotone.

I think I'll be using Nikons. I don't know why I used the EF-S specifically as an example. I suppose it was the easiest way for me to describe what I was after. Though easiest way to describe my query would have been this: what is the crop factor of APSC to ASPH? Crap, why didn't I just say that!?
 
Barry Green has a helpful chart here (for the AF100 but same should apply to the GH1/2): http://www.dvxuser.com/V6/showthread.php?227826-Relative-Focal-Length-Angle-of-View-and-CCF-Chart

Barry's chart is for 16:9 shooting, so my earlier post is incorrect - sorry.

The crop factor you are asking about will be 2.0/1.6 =1.25X. In other words, a 28mm lens on a GH1 will have approximately the same the FOV as a 35mm lens on an APS-C camera.

And yes, Kin Lau, obviously the actual physical focal length of the lens doesn't change - the "crop factor" is just a convenient shorthand for describing changes in FOV.
 
Yes, Ciecio7 on ebay, and MFT services, and Denz all make m43 PL mounts. I don't know if the Denz can work with the stills cameras, it may be only for the AF100; I'm sure it'd fit, but it might look a bit odd.
 
Thanks Barry.

I only see BNCR mounts for sale. Perhaps ciecio7 has no PL mounts listed at the moment?
 
Yeah, looks like his auction expired, but I'm sure he'll start another one soon.

Also found another manufacturer, Kipon, is ebay'ing a PL adapter.
 
Thanks for presenting these other manufacturers, Barry! But once again, I don't see (or can't find via search) the PL adapter, by Kipon. On their site or eBay.
 
I've got a Ciecio7, and while it does fit the PL lenses nice and securely, it doesn't provide for shimming and it's not perfectly collimated. As a result, my focus marks don't line up where they should. I'm looking to replace it with a HotRod, MFT, or Denz.
 
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