Sunday, September 1, 2013

The Sony Alpha a58 - Cropping the sensor

Most digital cameras these days have the ability to digitally zoom by cropping the sensor - meaning a portion of the sensor is only used when utilizing this feature.  I am a proponent of using your feet or lens to zoom and NEVER this feature...except when you have no choice or want to show others how good or bad it is.  

Before I begin, I want to quickly describe crop factor.  A full frame camera like the Sony Alpha a99 or the Canon 5D MarkIII will exhibit a 50mm frame of view when they slap on a 50mm lens.  Because the a58 has a smaller sensor, it will have a different frame of view if we place that same lens on this camera.  It is listed to have a 1.5 crop factor, so the 50mm will have an effective focal length of 75mm.  When we digitally zoom the lens, we are effectively using a smaller portion of the sensor to get a longer reach.  There is a dedicated zoom button next to the shutter release that allows you to "zoom" or crop your sensor by 1.1 to 2 times. So the same 50mm lens will effectively be a 150mm lens if you apply the 2 times zoom/crop.  Please note that this can only be done in JPEG and not Raw.  Below are some sample shots taken with the 50mm lens - all taken at Disneyland's Tomorrowland Terrance - 80z All Stars

George as Devo

Todd McCool as...well, I'm not really sure

Devo George -A personal favorite from the night

Nigel - Lead Singer

More Devo

Nigel - It's nice having the option to digitally zoom when I can't physically move closer

The above photos were all taken in JPEG with normal noise reduction.  I personally think it is a bit over done, so I decided to set it to low.  The following shots display JPEG files with low noise reduction

Nathan Shrake as the Mad Hatter

Nathan Shrake as the Mad Hatter

Dan Franklin (Dormouse) and Jenny Kidd (Alice)  getting close and personal

The JPGs on the a58 aren't too bad, but given the option I would almost always shoot Raw.  Having that ability to pull out details in shadows/highlights and tweaking white balance is really helpful.  (see the following POST regarding why I shoot raw) Well, I hope this helps.  Please let me know if you have any questions.  Thanks for stopping by.

So say we all,


  1. Hi !
    With the experience that u have had with the A-58 what do u feel ....Is it a keeper ?:)

    1. Thanks for stopping by. I think it is a keeper for what I had paid for. I was able to get the kit lens plus a 50mm f1.8 for about $600. When compared to my Olympus OMD, it falls a bit short. However, as a back up camera, I am completely happy and intend on investing in future Alpha gear/glass. I plan on posting a long term user review after I've had some extensive use with it.

  2. Thanks for stopping by. Glad the post was helpful.