should i buy rf-s or ef and use my adapter?

Not buy RF-S for a fullframe camera. The picture will be cropped.

They are kit lenses developed from the ef-m lenses and should not be bought if You not get them at a very small extra when buying a new camera.

Use Ef or RF to get the best results.

questetheincubator wrote:

so i have an eos r and currently use an ef adapter with my older ef lenses because rf lenses are too expensive (i had to get a loan out for this camera i cant afford a lens that is the same price again or more) i want to get something in the range of 14-16mm maybe a telephoto like the 15-35 f2.8 but its again ott expensive so my question is would i be better off getting more EF lenses (the adapter is a little slow with one of my lenses but find with the other two so kinda hit or miss?)

Hmmm that doesn't sound possible, the adapter doesn't affect lens performance. Is it an old non-Canon lens with a possible compatibility issue?

or should i get one of the new rf-s lenses like the 18-45 4.5-6.3f stm or the18-150 3.5-6.3 is stm? and just accept that itll be cropped?

No, because as well as the loss of resolution, the crop means you won't have a 14-16mm field of view.

If your budget is tight, the best solution is EF lenses. They work really well with the adapter. The EF 16-35/4L IS is superb.

questetheincubator wrote:

so i have an eos r and currently use an ef adapter with my older ef lenses because rf lenses are too expensive (i had to get a loan out for this camera i cant afford a lens that is the same price again or more) i want to get something in the range of 14-16mm maybe a telephoto like the 15-35 f2.8 but its again ott expensive so my question is would i be better off getting more EF lenses (the adapter is a little slow with one of my lenses but find with the other two so kinda hit or miss?) or should i get one of the new rf-s lenses like the 18-45 4.5-6.3f stm or the18-150 3.5-6.3 is stm? and just accept that itll be cropped?

When you mount an EF-S or RF-S lens on an R system FF camera the image recorded is a APS-C sized crop of the FF sensor. This means you will lose nearly two thirds of your sensor's resolution for recording the image. There are a no wide angle benefits to using any crop lenses on a FF camera. There are only telephoto benefits.

Have you considered the RF 16mm f/2.8 prime? It is very affordable compared to the RF wide angle zooms.

Buy EF, or the RF 16mm if you want cheap and surprisingly good ultra-wide angle. The RF 100-400mm is a lot of money, but it's over two grand less than the 100-500mm, so it's really quite a bargain.

The RF-s 18-45 is a crop lens equivalent to a 28-70mm f/7.3-10 on your EOS R, and the 18-150 is equivalent to a 28-240mm f/5.6-10. They will be decent kit lenses for the R10 and R7 respectively, small, light, well finished, good IS and good if not spectacular performance, cheap and mostly plastic and glass. With the crop, they will both drop your camera's resolution to 11Mpx, so avoid them like the plague for your camera. Avoid any crop lenses at all for your camera, unless 4k video is your thing.

questetheincubator wrote:

so i have an eos r and currently use an ef adapter with my older ef lenses because rf lenses are too expensive (i had to get a loan out for this camera i cant afford a lens that is the same price again or more) i want to get something in the range of 14-16mm maybe a telephoto like the 15-35 f2.8 but its again ott expensive so my question is would i be better off getting more EF lenses (the adapter is a little slow with one of my lenses but find with the other two so kinda hit or miss?) or should i get one of the new rf-s lenses like the 18-45 4.5-6.3f stm or the18-150 3.5-6.3 is stm? and just accept that itll be cropped?

As long as you're ok with an 11.8 megapixel image.  Have you looked at 3rd party FF lenses for Canon EF and adapting them instead?

its a Tamron 28-300 3.5-6.3 xr di and it takes an age to focus and is a pain actually getting the right focus, an issue i never had on my old 5d iii. its one of the offical canon adapters ( the cheapest £200 one) and i use this lens on my panasonic m4/3 with a metabonz adapter with no issues hence assuming it was the adapter but maybe the camera just doenst like the lens idk

questetheincubator wrote:

its a Tamron 28-300 3.5-6.3 xr di and it takes an age to focus and is a pain actually getting the right focus, an issue i never had on my old 5d iii. its one of the offical canon adapters ( the cheapest £200 one) and i use this lens on my panasonic m4/3 with a metabonz adapter with no issues hence assuming it was the adapter but maybe the camera just doenst like the lens idk

You can check with Tamron and see if there's a firmware update available for the lens, but there's a chance it is not possible if the lens is old enough.