my first DSLR a T7 - ok to use a USM with bad focus motor?

[ROMzombi]

I'm coming off S95 (lens error) S100 (lens error) S110 and an SX620hs. This is my first DSLR. I went to a camera shop today that is going out of business and found a 50mm 1.4 USM for free. I took some pictures with it using manual focus and it seems to be ok other than no autofocus. It it ok to use with a broken focus motor? I don't like the kit lens it came with as the focus is so slow going in and out before it settles on focus in a semi dark room. Sometimes it won't even let me take a picture. The powershot cameras didn't care, they would take a picture no matter what. I'm very new with DSLR so maybe I'm not doing something right or some setting is off.

[jrhoffman75]

You won't harm the camera by using the lens for manual focus if that is what you are asking.

[ROMzombi]

There are step by step instructions on replacing the motor in this lens. It appears that this lens is prone to motor failure?  I'm wondering how hard it would be to do it myself. There are a lot of steps....

[ebiggs1]

Use it as is. DIY lens repair is not for the untrained. Just getting the right part may be a challenge. If the store gave it to you for free that should tell you something like it isn't worth repairing.

[Anonymous]

If you raise the flash on the camera, it will emit a burst of flashes to help the camera focus in low light.

[shadowsports]

Greetings,

Free is great.  My advice.

Using something broken with something that's working is not a recipe for success.  Will it work, yes.  How long and how well is anyone's guess.  If you are stuck between a rock and hard place, sure.  

The cost to repair the lens would practically exceed the cost to replace.

EF 50mm f1.4 USM new $399, Used Like new $240

EF 50mm f1.8 STM new $125, Used  Excellent $78

Side by side there is no appreciable different in IQ or bokeh between the f1.4 or f1.8. 

You are not going to notice any speed difference in AF (USM vs STM) in this case.    

Me, I'd replace it.  Decide using the information provided above and use it in MF focus until a working replacement can be acquired.  Photography should be about enjoying your camera and getting the most from your gear.   

[ROMzombi]

* edit - I should as if I need to turn off autofocus in the camera software when using manual focus?

The kit lens i'm not really impressed with. It seems like I can focus faster or at a similar speed, manually.

I do like the F1.4 as opposed to F3.5 because of the bokeh it produces and if I get used to manual focus and often use it, is it really broken?  As long as the switch is on manual it's disengaged from the motor assembly, if that could present a problem in the future.

What purpose or condition of use is there is a manual mode option included? I don't know how fast USM autofocus is as i've never owned one. 

I have another 18 - 55 kit lens, from the shop, with broken plastic that i'm going to take apart to determine what skill level is required to reassemble without breaking any ribbon wires.

I'll ask some of the guys, that are uploading youtube videos on this repair, where or how they got replacement motors.

Thank you all for your replies. I appreciate it.

[ROMzombi]

When I was using the S powershot cameras, I would always use manual and never used the flash. I used a tripod to take pictures at night.

[ROMzombi]

The store is going out of business. The owner wasn't even there - just some people hired to liquidate everything. The lens was from the leftover repairs that were abandoned, which was free.

[deebatman316]

What @5DIV is referring to is called an AF Assist Beam. Your semi dark room is too dark and lacks contrast for AF to work correctly. A DSLR camera relies on contrast not how bright something is. For instance the camera won't lock focus on a clear blue sky because it lacks contrast. The built in flash can provide quick strobe bursts of light to assist the camera's AF system. You can set to built in flash not to fire. Then have the built in flash providing AF Assist when the camera needs it. Some of Canon's speedlites project a red grid to assist the camera's AF system too. This method is faster and doesn't have any buzzing noises. Associated with Intermittent Flash Firing that the built in flash uses or some speedlites utilize.

AF Assist Beam projected from a speedlite. Note depending on how many AF points your camera has. The speedlite will project different AF Assist patterns.