First, please let me apologize for my lack of proper vocabulary. 😃
I have a Canon EOS R50 with the stock 18 to 45 lens.
I need a stronger telephoto capability, to take bird pictures, the moon, get that lone oak tree out in a field etc. There are devices that one can place between the lens and the body to <<telephoto more>>, right? Would it be better to get one of these or to buy another whole lens? I am assuming the adapter would be less expensive. Money is a factor. (isn’t it always?)
The word you were looking for is “teleconverter”. There are inherent issues with those which you might want to avoid here… not the least of them is that they only work on some lenses and usually does not include the kit lenses. They cause the lens to let in less light so it’s also going to make it harder to shoot in darker situations. They can limit the functionality of the autofocus as well.
If you’re just getting into photography, as it seems, you might want to look into something like a zoom telephoto lens that would cover a reasonable range of focal lengths. A good all around lens will be 70-300mm or something very similar (IDK what the RF offerings are but you can get an RF to EF adapter and EF has tons of options). I would stick to some of the more known brands. Canon limits who can make RF mount lenses but again that EF adapter might be a good option. Brands I would look at would be sigma or tamron for budget or midrange prices. Sigma lenses are really good though. Often better than canon. Watch or read reviews for the specific lens you’re interested in once you find some.
Lastly I would suggest you consider used gear. There are some places that are very reputable and will warranty the stuff you buy and you will save a lot doing they. IDK what geolocation you are in but I would suggest checking out MPB, UsedPhotoPro , and KEH. They all check out used stuff before selling and give you a fairly reliable rating on every listing as well as warranties on most stuff of 6-12 months.
There are some really good sites and YouTube channels talking about cameras and photography that can give you some insights as well. If you aren’t on a deadline then it might be good to research a little bit and get a feel for the options available to you.
So TL;DR… I would consider a used 70-300mm as a good starting lens for getting into more range. It will get you used to what you’re looking to do and give some flexibility. You will likely be buying more lenses to cover other use cases if you really get into it. Common ranges for birds are 100-400mm or 150-600mm. Those will be more expensive and far heavier to carry which is why I wouldn’t recommend them from the start and you lose some of the closer flexibility.
—edit— While the R50 should be able to adapt to EF glass there is a chance you can lose some functionality like auto focus. So research the adapter AND and lens before going that route. It will be a case by case basis afaik.
Lastly I would suggest you consider used gear.
I second this, buy used. Out of the 10 ish lenses I own, I’ve only bought two of them new. I almost only use my second hand gear 😅 I also bought my current camera body used, as well as my camera sling bag! There’s so much money to be saved by looking at the second hand marked you wouldn’t believe it.
Only certain mirrorless lenses ate compatible with teleconverters, and that one isn’t. Teleconverters are also surprisingly expensive. RF mount is also expensive because Canon banned third party lenses entirely until recently and continues to heavily restrict them.
I believe there are only manual-focus adapters and adapters for additional lenses that don’t already attach to the R50. I also have one, but I haven’t seen any actual telephoto converters for it yet. So, you’d still need to buy additional lenses because there wouldn’t be any actual telephoto properties in the adapters.
If money is a factor, bird and moon photography isn’t the right hobby. 😆