DSLR Camera Question
 

In London, I purchased a DSLR camera: Sony alpha 350 and purchased two separate lenses: Sony 4.5-5.6/75-300 and 3.5-5.6/18-70.

The Sony 4.5-5.6/75-300 served me well as I was able to take photos from afar. Using this camera, I was able to capture scenes in pitch dark. For that, I am grateful.

However, my architectural pictures can be blurry. Anyone else with similar experience? Maybe I am not using this correctly?

I was told to replace my Sony lenses with other lens in order to obtain sharper focus. Insights and recommendations?

I'm not sure this is the right place for this question, and without seeing photos, with the Exif details it is hard to answer.

I am amazed you could get usable photos in pitch dark, without a tripod and long exposures.

I assume you were taking the architectural photos with the shorter lens - the 18-70, not the 75-300?
The main reasons for blurry photos are just being out of focus - ie the camera is focussing on something else in the picture, or not finding a focus point, or more commonly due to camera shake - caused by too long a time for a handheld an exposure.
The 350 does not have built in shake reduction I believe. Which means you have to learn to take photos at a speed which can be hand-held.
It is not worth spending more on lenses until you know how to use the camera to its best. Then think about what lenses you would like - you will be limited to Sony's more up market lenses, or third party lenses from Tamron and Sigma - some of which have shake reduction built into the lens. I am not sure if either do SR lenses for the Sony however.

I suggest you look online at the many fine photography sites there are and get some help with using the camera, or find a course locally to you to follow. dpreview has some fine forums, including one for Sony which may be a good starting point for you.
This is also a very friendly site full of good advice and an excellent Sony forum - www.ephotozine.com.

Try using aperature priority mode and manual focus. Auto focus requires that the focus point includes something with sharp contrasts.

The shake reduction mentioned by hetismij, called vibration reduction (VR) by Nikon, is a feature of the lens. If your Sony lens has this it might not work when the camera is on a tripod or in auto mode. That is the case with Nikon's VR lenses.

Also, if you were shooting in automatic mode your camera probably changed the ISO to 1,600. This produces grainy, a.k.a. noisy, photos. Set the ISO to 400 and shoot in manual.

Stop down to f/22 to increase sharpness. This forces a longer exposure time and may require you to use a tripod and timed or remote shutter release.

Run your pictures through Adobe Photoshop and use the sharpen filter. It works great for slightly blurry photos.

Automatic time exposures of a minute or more can bring in some amazing night images. My old Olympus OM-2 worked great at night with Tri-X film. My little Olympus XA produced even better results at night.

See my page at http://tinyurl.com/3a2u7ln for more information on digital photography, and a few tailers on film.

Spaarne, some cameras have shake reduction in the body, including the newer Sony models, when I believe it is called steady shot. The A350 is an older model I believe and doesn't have it.
This makes lenses cheaper (and lighter!) too. I had a quick look though and the Sigma lenses with OS (as Sigma call it!) do support the Sony/Minolta mount

F 22 is fine for landscapes, but most lenses are actually at their sharpest around F5.6-F8. f 22 would not give a good DOF which may be required with architecture.

Always choose the lowest possible ISO - 100 in normally the lowest, sometimes 200. Only increase it if the shutter time is too slow for hand held. If the camera is in auto mode it should indicate that flash is required if the shutter speed is too slow. Then you either open up the F stop, increase the shutter speed, or up the ISO. But even then it may just be too dark for a good photo without a long exposure and a tripod. Flash wouldn't work with architecture, certainly not the built in flash.

Have a look at this http://members.virtualtourist.com/m/tt/98f0f/ and his other lessons for more explanations.

Contrary to Nikon and Canon, the Sony shake reduction is built in the camera body and is independent of the lens. All Sony cameras have it (I have an alpha 700 - best camera I ever handled). Don't forget to turn it on, and remember that it is a useful support tool, not a magic that entirely removes any movement.

Always look at the exposure time. No shake reduction will make sharp pictures at handheld 1 s exposure. The rule of thumb says that the exposure should be well below the 1/(3 x focal length), meaning that, if you shoot at 50 mm your exposure should be under 1/150 s. The shake reduction will allow you reasonable pictures at 1/50 or possibly even 1/25 s but not much beyond that. I had good handheld pictures at 1/10 s when pressing my shoulder (of the camera arm) against a wall, and holding my camera with both hands.
Do not use LiveView in low light - with stretched hands you cannot hold the camera as steady as you would need.

>I was told to replace my Sony lenses with other lens in order to obtain sharper focus.

Nonsense. The Sony kit lenses are reasonable - not excellent photographer tools (for that, look at Carl Zeiss line of Sony lenses) but reasonable. You will pay MUCH more if you want to get better optics; everything you get for the same price from third parties is comparable or worse.

High quality lenses from third parties (Sigma, Tamron, especially Tokina) are cheaper than Sony lenses and often not worse, but they are still more much expensive than kit.

My mistake - you are right the 350 does have in camera stabilisation, I missed in in a quick look at the specs.

Maybe Hobbit can post a link to some photos, with the exif details so we can help further?

The newer DSLRs are apparently able to produce excellent, low-noise pictures even at higher ISOs. My Canon 5D - now several years old - is pretty good at least up to ISO 400 but the newer 5D Mark II is supposedly excellent at much higher ISOs. So low light photography without a tripod may be much more practical in the next few years. Of course, there are still artistic reasons to want to take longer exposures and thus still use a tripod...

hobbitthefoodlover, how are you focusing with your camera? The typical way to use auto focusis to compose your shot, hold the shutter button down half way, and wait until the camera picks a focus point. On my Canon, sometimes this is quick, sometimes it needs a second or two (the 5D is not known for its focusing abilities). There are also different focus modes you can put the camera in, in case it is getting confused by the composition of the shot (what should I focus on?). Of course, as suggested, sometimes you still need to do manual focus. You might consult the camera manual and play with different modes of focus.