Confused about the new Olympus 300 PRO lens

Started Jan 30, 2016 | Discussions thread
EcoPix
EcoPix Regular Member • Posts: 317
Re: Old lenses and sacred kingfishers
2

The attached image was made last Sunday with much less expensive gear than Oly's, but it's an example of a 1980's lens, and action subjects irrelevant to image stabilisation (I know you have some fantastic examples of this, Danny).

What's needed in this work is speed - lens speed, ISO speed, and primarily, shutter speed. It was made at 1/2500th of a second at f3.5 with a 400mm lens on an APS-c format camera (Sony NEX-7) set to 800 ISO, and is heavily cropped. Close scrutiny shows it would have benefitted by 1/4000th of a second, which, under the lighting, would have required about 1250 ISO. Shutter speed is the limitation on detail here, not lens resolution.

It could have been made with the rig under discussion, but the f4 lens would have needed another half a stop - about 1800 ISO (if light transmissions are the same). The projected image of the bird by the 400mm lens was 5.7mm, laid on a sensor with close to the pixel density of a 16mp 4/3 sensor. The projected image from a 300mm lens would have been about 4.2mm, necessitating more enlargement and therefore a bit more grain in the raw file. Probably nothing careful noise reduction in post couldn't equalise acceptably.

Whether the image would be acceptable to you, made on a 4.2mm portion of your camera's sensor at 1800 ISO is for you to judge. To get better quality, one would need denser pixel density (provided the lens/shutter speed gave the extra detail) or a longer lens, or to get closer, of course, without disturbing the bird.

If a longer lens or closer working distance, a larger format would be needed, simply because it would be difficult to keep the rapidly moving subject in such a tight frame (or a 'sports' style viewfinder that shows more than the captured area, which no SLR or Mirrorless camera maker does these days). But the pixel density would need to be the same.

In any event, there is no question of focal length equivalency, because that only relates to the frame, and the whole frame isn't being used anyway. It's about actual focal length, and the size of the image of the subject projected onto the pixels at the pixel density in use. When 4/3rds cameras get to the same megapixel count as larger formats, you can start talking about focal length 'equivalents', for this type of telephoto work.

PS Why do people marvel at manual focus? Mirrorless cameras are made for manual focus. They are far superior in ease and accuracy of focussing to the film SLRs that these old lenses were designed for.

Sacred kingfisher at termitarium nest, Sth Queensland. 400mm F3.5 @ 1/2500th, 800iso, cropped.

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