I headed off to the Great Falls park last Saturday (02/02/08) to hike along the river and photograph the falls. It was beautiful out there… about 50 degrees – perfect hiking weather, although the trails and towpath were still muddy. I was carrying my Sony Alpha 700 and 2 lenses – a Sigma AF 28-80mm and the Tamron 70-300mm. The Tamron was for closeup views of the raging waters. The Sigma is a recent acquisition, and I was trying it out.

It’s still early in February, and we’ve already had a lot of rain in Montgomery county – the average rainfall for February is about 2.85 inches here, and by the 2nd, we already had about 3 inches… which means, every stream in the county is overflowing and that the Potomac is running full already. Normally, we’d have to wait until the Spring thaws.

Since my intent was to photograph the falls, I did not mind lugging along the heavy Tamron, but on my way over there, I was thinking about the most desirable characteristics for a hiking lens – good zoom range, rugged, light, cheap, close up capability etc. At the same time, the optical characteristics of the lens should be good enough that you don’t regret the quality of the pictures when you get back.

The more I thought about it, the Sigma I was carrying seemed to be the perfect fit. After all, it had a zoom range of 28-80mm, which is a 42-120mm on the Sony A700. Besides, it has a plastic body, which makes it lightweight. Great optical quality with multicoated aspherical lenses, very cheap so it would not matter if it was damaged or lost – and it has a 1:2 Macro capability, for those occasional very close-up shots of interesting grass or moss or little critters that I might come across.

I would have liked at least 35mm at the wide-angle, but I’ve found that in the open woodlands and hilly areas of Maryland , even a 50mm is sufficiently wide, since one can always step back a few paces to include more of the scene. The Sigma 28-80mm definitely qualified as a Cheap Awesome Lens. Some may complain about the “cheap” build quality – it’s plasticky – but one can’t fault it optically for the price.

The 1:2 macro capability is only at 80mm f/5.6 (120mm f/5.6 on the Sony Alpha 700) and is is a matter of moving a switch on the lens from Normal to Macro position to lock it. Now, f/5.8 is pretty slow, I was able to get decent images even at 100 ISO. I’m not complaining, since I can always increase the ISO to compensate. However, in Winter, with no overhead tree canopy and bright sunlight, it beats carrying an extra lens for the rare occasion one might want to take a real close up.
Here are some of the pictures at the Falls and along the Towpath. The river is very impressive this week.


The Tamron is a beast on the Sony Alpha 700 – it’s equivalent to 105mm-450mm and fairly fast for such a large focal length f/3.5 at the shorter end, and f/5.6 at the 450mm end. Fast enough to handhold at 100 ISO on a bright day. It’s a macro lens as well, and goes to 1:4 along the entire focal length range, which is pretty impressive. This is another Cheap Awesome Lens.Tamron 70-300mm– Potomac River and Towpath.


Potomac River

Potomac River
Potomac River
Potomac River
Potomac River
Potomac River
Potomac River
Potomac River
Potomac River
Potomac River
Potomac River
Potomac River
Potomac River
Potomac River
Potomac River

Potomac River 1/5 sec exposure
Potomac River
Potomac River
Potomac River
Potomac River
Potomac River

Sigma 28-80mm – Potomac River

Potomac River
Potomac River
Potomac River
Potomac River 1/5 second
Potomac River 1/5 second
Potomac River
Potomac River
Potomac River

Sigma 28-80mm Canal and Towpath

Canal and Towpath
Canal and Towpath
Canal and Towpath
Canal and Towpath
Canal and Towpath
Canal and Towpath – macro
Canal and Towpath
Canal and Towpath

Sigma 28-80mm Great Falls Tavern

Tavern
Tavern
Tavern
Tavern
Tavern
Tavern
Gate at Widewater
Great Falls

Sigma 28-80mm – Great Falls Tavern

Great Falls Tavern
Great Falls Tavern
Great Falls Tavern
Great Falls Tavern
Great Falls Tavern
Great Falls Tavern
Great Falls Tavern
Great Falls Tavern
Great Falls Tavern
Great Falls Tavern
Great Falls Tavern
Great Falls Tavern
Great Falls Tavern
Great Falls Tavern
Great Falls Tavern

Sigma 28-80mm – Canal and Towpath

Canal and Towpath
Canal and Towpath
Canal and Towpath
Canal and Towpath
Canal and Towpath
Canal and Towpath
Canal and Towpath

Sigma 28-80mm Macro Photos (approx 8-10 inches)

Sigma 28-80mm macro
Sigma 28-80mm macro
Sigma 28-80mm macro
Sigma 28-80mm macro
Sigma 28-80mm macro

Tamron 70-300mm


Great Falls
Great Falls
Great Falls
Great Falls
Great Falls
Great Falls
Great Falls
Great Falls
Great Falls
Great Falls
Great Falls
Great Falls

Tamron – Wildlife

Wildlife
Wildlife
Wildlife

Tamron

Lichens on Rock
Lichens
Wildlife

Photographed with a Sony Alpha 700, Sigma 28-80mm f/3.5-f/5.6 Aspherical Macro 1:2 and Tamron 70-300mm f/3.9-f5.6, ISO 100, Circular Polarizer.



Creative Commons License
olympus/zuiko by Ajoy Muralidhar is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 United States License.
text and images © 2008 ajoy muralidhar. all names, websites, brands and technical data referenced are the copyright or trademark of their respective owners. thank you for visiting olympus/zuiko.

There’s a lot of confusion when it comes to using lenses designed for 35mm cameras on the current crop of Digital SLRS. Many photographers have sizeable investments in 35mm lenses for their film cameras, and for the most part their lens investments drive them towards a particular digital camera body, whether it’s Nikon, Canon, Minolta (Sony), Pentax or Olympus.

Luckily, all the manufacturers retained their old AF mounts, except for Olympus, which uses the newly designed Four-Thirds mount. Sony retained the Minolta ‘A’ autofocus bayonet mount for the Alpha series cameras, allowing all the fine 35mm lenses out there since 1986 to be used. The same goes for Nikon and others.

However, due to cost constraints at the present time, most digital SLRs use a sensor that is smaller than the 35mm format size of 36mm x 24mm. This smaller format is 22.7mm x 15.1mm, and is known as the APS-C format. Sony and Nikon (and others) use a sensor size that is approximately the APS-C format size. As can be seen, the APS-C size provides a much smaller image area, 342.77 square millimeters versus 864 square millimeters for the standard 35mm format.

When a 35mm lens is used on the current crop of digital cameras, the smaller sensor size means that the 35mm lens will now have a narrower angle of view (also called FOV or field of view) than when used on a 35mm film camera body. This is due to the fact that the 35mm lens creates an image on the film (or sensor plane) that is is sufficiently large enough to cover the 36x24mm frame it is designed for.

When used in a Digital SLR that has a smaller sensor (and thus image size), the image formed by the 35mm lens is still the exact same size as before, but the smaller sensor can only use a portion of it. In effect, this constitutes an “in-camera” crop. This cropping is determined by the ratio of the sensor size to the 35mm format size, distance of the image plane from the front of the lens etc.

In most of the cameras using APS-C size sensors, the ‘cropping’ is equivalent to using a lens that has a narrower angle of view (telephoto effect). This Crop Factor (also known as Focal Length Multiplier) is around 1.5x (Sony Alpha) 1.6x (Nikon). In some cameras, Canon uses a sensor size that is slightly larger, which gives a 1.3x factor (this is the APS-H format). The Four-Thirds system used by Olympus and Lumix (Panasonic) has a 2x factor.

The focal length does not really change, of course. The smaller sensor’s ability to register only a portion of the total image causes an APPARENT increase in focal length due to the cropping. This has the effect of using a lens with a narrower angle of view, the same as using a telephoto lens. (Luckily, the sweet center portion has the sharpest part of the image).

The image edges which may not be sharp, or have aberrations are cropped in-camera. For the user, it’s easier to remember by multiplying the focal length of the lens they are using with the factor for that particular body, and that gives us the APPARENT focal length.

A lot of the confusion can be eliminated by using the term APPARENT rather than EQUIVALENT. for example, on my Sony Alpha 700 (which has a 1.5x multiplier for 35mm lenses), it would be more accurate to say that my Minolta 50mm lens has an APPARENT focal length of 75mm, rather than saying my Minolta 50mm is EQUIVALENT to 75mm.

This apparent increase in focal length does not affect the aperture, so the APPARENT focal length of 75mm is still at a fast f/1.7. This will serve as an excellent portrait lens, since it can frame head and shoulders perfectly, but you’ll find yourself having to move back when you want to include more of the scene.

For most wildlife photographers, birdwatchers and even landscape photographers, the apparent increase in focal length can be a unexpected blessing – they get more ‘bang’ for the buck from their existing lenses. When coupled with the higher ISO capabilities of DSLR cameras and in-camera image stabilization that will let them handhold the camera in situations that would have required them to lug along a heavy tripod.

If you’re using a MACRO lens, such as, for example my Sigma 50mm f/2.8 (a very sharp lens with a true 1:1 macro capability) the apparent increase in focal length permits the macro subject to be fill the frame without moving in as close. Since the stand-off distance is greater, more light can reach the subject. The increased distance also helps when photographing skittish subjects that are likely to fly or hop away if approached too closely.

When the subject is framed in the Sony Digital SLR, it is seen that the Depth of Field is greater for the same magnification when compared to using the lens on a 35mm film camera like my Minolta Dynax 800si. This is a great advantage for macro-photography where depth of field and subject lighting are always problematic.

The whole situation is different when it comes to wide angle lenses. This is where most photographers are ready to burst into tears. The 1.5x or 1.6x multiplier effect holds good on the wide angles too, and this means that a normal wide angle like 24mm lens which would give a 74 degree field of view on a 35mm format camera will now only provide a FOV of 62 degrees or so, approximately that of a 35mm lens. In the same way, an ultra-wide 16mm becomes an apparent 24mm a 28mm is an apparent 42mm and a 35mm lens behaves like a 52.5mm normal lens.

Given the fact that most wide angle lenses are EXPENSIVE, no photographer would like to see his investment reduced to a moderate wide-angle or a normal lens. However, such is life. You win some, you lose some. To get a true wide angle on the Sony Alpha 700, I would have to invest in a 18mm to get 27mm (luckily, that’s included in the zoom range of my Sony 18-200mm lens that I bought with the camera). Since the 18-70mm is bundled as a kit lens, most owners will have at least a 27mm wide angle, albeit a slow one).

To get the 24mm, we’d have to invest in the very expensive Sony 16-105mm Zeiss coated zoom lens (apparent focal length 24- 157.5mm). Buying a faster wide-angle prime lens would be prohibitively expensive for any amateur, and even professionals would hesitate.

My advice? If you really need to shoot wide angle, just use your film camera. You can still buy a fine Sigma 24mm f/2.8 AF at a reasonable price. The Sigma 24mm is a good deal, since it had a matte black Zen finish that tended to flake off, giving the lens a “very used” appearance and usually marked down. This is just cosmetic, and does not affect the lens performance in any way.

The same Sigma lens was re-badged and sold by Ritz as their house-brand Quantaray lens, but with a different, more durable finish – but it’s still the same lens. Don’t be fooled by the appearance of either lens – this is a very high quality lens. Besides, you can always use the Sigma on the digital SLR as an apparent 35mm f/2.8 prime lens in place of a ‘Normal’ lens. You’d pay hundreds more to get a similar “designed for digital” Nikon, Sony or Canon lens.

Of course, all this talk about crop factors and multiplication factors will become moot when Full Frame digital SLRs become common. Canon already has one, and Nikon and Sony will follow shortly. In fact, I would not be surprised if the Sony Alpha 900 was not released in a few more months. When that happens, lenses will behave as they were designed and there will be no more confusion.

As for me, I rather like the fact that my Tamron 70-300mm now behaves like a 105mm-450mm super-zoom. With the Image stabilization turned on, I can actually hold that baby steady enough to use hand-held.



Creative Commons License
This work by Ajoy Muralidhar is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 United States License.
text and images © 2008 ajoy muralidhar. all names, websites, brands and technical data referenced are the copyright or trademark of their respective owners. thank you for visiting olympuszuiko.

This old farmhouse and barn sits just outside of Westminster, a couple of miles north of the town. I usually drive that route when I want to take a more scenic way into the town, instead of taking MD Rte 97 south from work. This is a very accessible site, just off the road, with easy parking… there aren’t many vehicles around that road (except on Mondays, when a nearby auction house is holding their occasional outdoor and barn auction). I’ve photographed this barn many times over the past year. The pond, well and barn always stop me dead in my tracks., and I pull over for a couple of minutes just savoring the view.

OM-2, Vivitar 24mm 1/500 at f/16, Fuji 400
OM-2, Vivitar 24mm, 1/500 at f/16, Fuji 400
OM-2, Sigma 35-105mm f/1.8, 35mm 1/500 at f/16, Fuji 400
OM-2, Zuiko 50mm, 1/500 at f/16, Fuji 400
OM-1, 50mm f/1.8, Fuji 200
Ricoh 500G, 1/250 at f/16 Fuji 200
Ricoh 500G, 1/250 at f/16, Fuji 200

Photographed with an OM-2, (Vivitar 24mm, Sigma 35-105mm, Zuiko 50mm f/1.8) OM-1 (50mm f/1.8) and Ricoh 500G


text and images © 2007 ajoy muralidhar. all names, websites, brands and technical data referenced are the copyright or trademark of their respective owners.
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