question about olympus lenses

[Kofman13]

I have been using an OM olympus 50 mm f 1.8 lens for a few months and i love it except in situations where i need to take many pictures quickly, manual focus is just annoying the hell out of me and its just not practical sometimes. The reason i got OM lens is because i cant afford digital at the moment. But i have been looking around and maybe im not looking right or the something is wrong in the world. I cant find an olympus digital 50 mm f 1.8 lens. i only found 50 mm 2.8 macro that was a $400... or a pancake lens 25 mm f 2.8 thats around $220. is there no 50 mm 1.8 lens?

 

[Dao]

Would it be since the Digital SLR camera of Olympus has the crop factor of 2x, so they make the 25mm lens instead. Not sure why not F/1.8 instead of F/2.8. As for the 50mm macro, it is equivalent to the popular 100mm macro lens like other manufacturers in term of field of view.

 

[Kofman13]

sorry for the noob talk but would the 25mm 2.8 pancake get me same results as a canon 50 mm 1.8 for example?

 

[Dao]

It will not. What that means is if someone use the 50mm lens shoot with a Olympus 35mm film camera, the field of view will be the same if you use the 25mm lens on your Olympus digital camera.

For example, you are trying to take a picture of a elephant at the zoo. When you use a 35mm film camera with a 50mm lens, you find that the elephant is perfectly fit the picture. Now when you try to use the same 50mm lens with your DSLR, you will noticed that the elephant (assume it did not move) now is much bigger in the viewfinder, so you need to step back in order to compose the photo so that the elephant will be perfectly fit in the photo.

Or, you can change the lens to 25mm and go back to the original position. Now you should find that the elephant is perfectly fit the photo again.

What happened was the sensor size of your DSLR is smaller than a 35mm film. So the sensor can only capture part of the image (center region) that casted by the lens.

See here for more about crop factor

Crop factor - Wikipedia, the free encyclopedia

 

[Kofman13]

thats very informative thanks. ok so 25mm is just the way your eye sees it. but in terms of 2.8 vs 1.8 is there alot of difference? also my OM 50 mm /1,8 is so fast. is the olympus pancake lens that fast?

 

[Dao]

Well, F/1.8 and F/2.8, it does not seem a huge different. But it is a little more than 1 stop of lights, so it some situation, it may be big different. 1 stop of light could means able to take photo with 1/125 vs 1/250 shutter speed to freeze a motion. Especially for cameras that do not have high ISO performance.

However, I still think lens with F/2.8 aperture is a pretty fast lens (not talking about the autofocus speed).

Besides Olympus made lens, Sigma do make a 30mm F/1.4 lens that maybe worth take a look at.
300107 Sigma 30mm f/1.4 EX DC HSM AutoFocus Standard Lens for Olympus Four Thirds mount Digital SLR Cameras

Review:
Sigma Lens: Primes - Sigma 30mm f/1.4 EX DC HSM (Tested) - SLRgear.com!

 

[Turbo]

The ZD 50mm f/2 macro is a fantastic lens. The 25mm f/2.8 pancake lens is a bit disappointing.

If you're looking for something faster, Sigma makes a 30mm and a 50mm f/1.4 lens. For something a little longer and faster, I believe Samyang is releasing a 85mm f/1.4 soon, though I think it may be manual focus only.

If you want to focus faster with your OM 50mm 1.8, get a good split image focusing screen for your camera. It's a lot better than squinting and hunting around to focus.