Hard to get decent lenses for the GH1?

Schmoe

Schmoe

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Complete newb to all this stuff, so go easy on me :beer:

I've been reading a bit, and from what I understand, a 25mm f1.2 lens placed on a GH1 is equal to a 50mm f2.4 on a full frame camera, as far as field of view and DOF.

So is it possible to get decent DOF on a GH1 without breaking the bank on a superfast wide? It seems that buying a superfast wide would cost as much as the camera itself...

And I don't suppose that there is ANY chance of getting decent DOF with the kit lens, since it only goes as high as F4. Or am I wrong here?
 
A superfast wide will cost an arm and a leg for any camera. There's some less expensive options like the sigma 14mm f/2.8 aspherical and the zenitar 16mm f/2.8 fisheye. There's also a sigma 20mm f/1.8.
 
Yes, but my point was that with the GH1, a superfast wide is a REQUIREMENT just to get the equivalent of a basic 50mm. So you may be paying the price for a superfast wide, but you're only getting the performance of a slower standard lens.

For example, that $570 Sigma 20mm f1.8 is only going to be a 40mm f3.6 on a GH1.

Can you even get decent shallow DOF with a 40mm f3.6?
 
well unless you're in a confined space you can stand back and your 20mm will look like a 20mm. the angle of view is the same it's just that the edges of the frame are cropped. full frame camera's have much a shallower depth of field than a 35mm movie camera does. there's plenty of shallow DOF examples on vimeo from the GH1, it's not a major issue.
 
That's true. And standing back is fine for outdoors shots, but what about stuff done inside? You can only move back so far until you back into a wall.

The shallow depth of field shots on Vimeo are all either taken outside, in long rooms, or they are close-up shots. The few that aren't are shot on an $1100 Summilux 25mm f1.4 lens, which in GH1 math means that you are paying $1100 for a 50mm f2.8 equivalent.

I'm not bashing the GH1 btw. It's an excellent camera and I would really like it to be MY next camera. But it's beginning to look like a decent 50mm equivalent for this camera will cost as much as the camera itself. Something to consider when making a purchase if someone doesn't already have a superfast wide.
 
MatzeB said:
that's wrong - or at least missleading.
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If I am being misleading, please tell me how.

It is my understanding that for DOF PURPOSES(as I mentioned in my first post) a 20mm lens on the GH1 gives the equivalent FOV of a 40mm lens on a full frame camera. I mean, if the edges are cropped...then they're not there for me to use regardless of what the "true angle of view" might be. And an f1.8 aperture gives the equivalent of an f3.6 aperture(as far as DOF is concerned.)

As I mentioned in my first post, I am a newbie to all this 4/3 stuff, so I may be completely mistaken on any/all of it. I'm not here to argue, only to get information. I'm more than happy for someone to point out where I am wrong and explain things correctly for me.
 
Well, the answer is that it really depends on what you're looking to get DOF-wise. Not everyone is looking to get the DOF that full-frame imaging solutions provide. So what one might consider to be "decent DOF" is highly subjective.

Consider this: The GH1's sensor in video mode provides a very similar horizontal field of view compared to the Academy film frame, which is the format in which most studio productions are shot. And the most common F-stops used in studio productions also happen to be F4.0 and F5.6, something that I read years ago (but correct me if I'm wrong). So with the stock lens wide open, the kind of DOF that you get should be close to what you see in the movies that you commonly see in theaters.

Movies are rarely shot with apertures larger than F2.8. For instance, The Godfather was shot at around F2.8. Ultra-wide lenses are hard to find at that aperture, but you can find a few inexpensive ones at F3.5 (half stop difference). For instance, Tamron made a very good Adaptall-2 17mm F3.5 lens that appears on eBay every once in a while.

The DOF question only matters if you're used to shooting full frame, either in still photography, or with 35mm adapters. If you don't have that kind of background or experience, then don't sweat it. The crop factor won't matter much to you at all.
 
there's a lot of fast/wide c-mount lenses around but it's hard to say if they will vignette on the 4/3 sensor but sometimes you can find them so cheap that it may be worth trying some out.
 
squig said:
there's a lot of fast/wide c-mount lenses around but it's hard to say if they will vignette on the 4/3 sensor but sometimes you can find them so cheap that it may be worth trying some out.
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Actually, users have found that pretty much any C-mount lens wider than 25mm will vignette.
 
as far I know the DOF depends on lens aperture, not the crop factor, this is, the sigma 20mm f1.8 gives 40mm f1.8 on a GH1, so you get a f1.8 DOF
 
No, DOF depends precisely on focal length and aperture. Image size or crop factor is an informal factor, since it alters field of view, which then affects the other two (real) factors.
 
Come to think of it, the ideal wide lens is the Tokina AT-X 116 PRO DX (11-16mm F2.8), which Kholi keeps pimping around here. It really is a fabulous lens, nothing else like it on the market from any other manufacturer. It's a must-have, IMO, if you're really serious about wide angles. Only $600.

Do you really need anything faster than F2.8? Nothing else exists that will work (since the wider C-mounts will vignette), AFAIK.
 
There is so much false information in this thread. First of all a 50mm lens is always a 50mm lens, no matter what camera it is used with, what changes is the FOV and not the focal length. The smaller the sensor the narrower the FOV (with a given lens).

ydgmdlu said:
No, DOF depends precisely on focal length and aperture. Image size or crop factor is an informal factor, since it alters field of view, which then affects the other two (real) factors.
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No, the aperture, the focal length, and lens to subject distance are the factors that influence DOF. A 50mm lens at f1.4 will give you about the same DOF on a GH1 as it does on a FF SLR Camera. (I use the word "about" because the enlargement factors when projecting the image are different, therefore, you might use a different value for the "circle confusion diameter limit".)
 
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cordvision said:
There is so much false information in this thread. First of all a 50mm lens is always a 50mm lens, no matter what camera it is used with, what changes is the FOV and not the focal length.



No, the aperture, the focal length, and lens to subject distance are the factors that influence DOF. A 50mm lens at f1.4 will give you about the same DOF on a GH1 as it does on a FF SLR Camera. (I use the word "about" because the enlargement factors when projecting the image are different, therefore, you might use a different value for the "circle confusion diameter limit".)
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I never said that crop factor "changes" focal length. I said that it "affects" the other two factors, and I apologize for not being clear about what I meant. The change in FOV "affects" focal length insofar as shorter focal lengths are required in order to achieve the same FOV. That's why I called the crop factor a "secondary factor." The aperture is affected insofar as its relation to focal length and lens choice. A shorter focal length means greater DOF for a given F-number, and wider lenses tend to be slower as well, limiting the aperture options.

Yes, actually there is the third factor of subject-to-camera distance that I can't believe I forgot.
 
cordvision said:
A 50mm lens at f1.4 will give you about the same DOF on a GH1 as it does on a FF SLR Camera.
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Thanks for the clarification. Just to make sure I understand-
For the same distance to shooting subject: A 25mm f1.8 lens on a GH1 will give the equivalent FOV and DOF as a 50mm f1.8 on a full frame. Is that correct?
 
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No, the DOF will not be the same because the shorter focal is responsible for greater DOF. As I've been saying, aperture is not the only factor.

A 25mm lens on Four Thirds will give the same FOV as a 50mm lens. That's all.
 
ydgmdlu said:
No, the DOF will not be the same because the shorter focal is responsible for greater DOF. As I've been saying, aperture is not the only factor.

A 25mm lens on Four Thirds will give the same FOV as a 50mm lens. That's all.
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I agree.
Sorry for misunderstanding you in the post above.
 
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