I have three good camera's that I use:

1) Sony A900 (Full frame)
2) Sony A77 II (APSC)
3) Sony RX100M2 (smaller sensor yet)

Each of these camera's have their own advantages and charm. PhotoShop CS5.1 is only able to open the RAW files from my old A900. When I try to open a RAW file from the other two cameras I get the following message:

Could not complete your request because the file appears to be from a camera model which is not supported by the installed version of Camera Raw.
Please visit the Camera Raw help documentation for additional information.

Must I now pay to update to a new (cloud monthly payments version of PS) or is there another way to get Adobe's more modern RAW converter(s)?

I have work around solutions i.e. Aperture or DxO. I'm curious why Adobe PS is the only program giving me a problem with 2 of my 3 cameras?

Is there a way I can upgrade the RAW converter(s) to my current version of PS?

-----Edit-----
I contacted Adobe and asked this same question. Attached is part of the correspondence:

Once you understand the value inherent in the Adobe Photoshop/LR subscription, you'll see the benefit. This has been covered ad nauseum everywhere on the internet, but software maintenance is a standard in the industry. If you choose to rely on outdated software for your current needs, then you will always be in this situation where new hardware is not supported on old software. Aside from your specific situation, PS has added tons of new "stuff" to make it really worthwhile upgrading to. I was averse to subscribing at first, when it was $30 for a single application. But at $10/mo it really is a no-brainer. CS6 Extended costs $650, and LR is $75. Just quickly doing the math, it would take over 6 years before the cost of subscribing exceeds the purchase price of this software. And this does not include subsequent version upgrades to the perpetual licensed software, which are absolutely free. In fact, the subscription model has already been version updated twice since it's release, and the latest, CC2014, is a major rewrite to make it faster and include more capability.

It is not a get rich quick on your back - it is a very strategically good move that allows them to kick up the product cycle, deliver better product more often, and help them be more responsive to user needs. Downloading software as opposed to selling it on DVD's in little boxes in retail packaging to add to inventory on store shelves is a win for the buyer and for the company. And they pass the savings on to the consumer. Yes, subscription model is actually a win-win when it is done right. If you are not familiar, you can test drive it at no charge for a month - then you can see what you are missing out on, especially if you are using such an old version.

BTW, I use DXO as well, been a user since V5 and a strong advocate.

However, like ACR, LR and other Raw converters, DXO is a parametric editor - it can apply amazingly powerful adjustments to an image or group of images quickly and efficiently, much better than pixel editors like Photoshop. It is not a substitute for Photoshop, nor will it ever be. In general, parametric editors are not great at finishing images. If anyone tells you otherwise, they don't understand what goes into high quality photo finishing.

I love DXO 10 btw. Just upgraded to it last week and I am enjoying the speed. I use it in my LR-Photoshop workflow to do a few things that it does better/faster than LR.

To put things into a different perspective - the subscription model costs about the same as a six pack of a premium craft brewed beer, or 4 Latte Grandes at your favorite green-logo'd intenet coffee shop. :)

From my understanding, this is a photography forum, and a discussion that includes your political views whatever they may be is inappropriate.

I may well go for PS-cc in the near future. I would not call my old version CS 5.1 "worthless". It does everything I need it to do. I have yet to master all the features built into it. The only limitation I have experienced is CS 5.1's inability to convert raw files from some newer cameras. Other programs like DxO do that better that Adobe does. In fact I was totally unaware of this inability in PS CS5 until a visiting friend with a different work flow used my computer and pointed it out to me.

Only when I discover that newer versions of PS have a feature that I need or want, will I subscribe to CC version.