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Old 16-04-2012, 08:52 AM
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stardust steve (Steve)
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Canon 50mm 1.8 lens reflection/refraction

Hi everyone.
Just recently i have been noticing some annoying reflections/refraction going on with my 50mm lens. They seem to show up more when shooting bright objects such as the Moon. See attached picture.
Also the focus ring on the 50mm when in Manual focus is very loose and moves by itself after obtaining focus. Sometimes it will move all the way to the left (counter clockwise from looking from the viewfinder end). This is also very frustrating when trying to get a series of images to stack only to find focus has shifted and if not discovered, many frames wasted.
Is it possible to open the lens myself and try to tighten the ring or am i now looking at a nifty fifty paperweight
Thanks.
Steve.
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  #2  
Old 16-04-2012, 09:20 AM
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jjjnettie (Jeanette)
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The internal flare is par for the course.
Stopping down the lens may help, but I'm not sure, I've never bothered about it.
As for the sloppy focus ring, a tiny wad of Blue Tack, rolled into a sausage, and spread to cover both the edge of the focus ring and the lens body should help. Make sure the lens is set to infinity before applying it so it doesn't get over stretched.
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  #3  
Old 16-04-2012, 09:27 AM
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stardust steve (Steve)
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Quote:
Originally Posted by jjjnettie View Post
The internal flare is par for the course.
Stopping down the lens may help, but I'm not sure, I've never bothered about it.
As for the sloppy focus ring, a tiny wad of Blue Tack, rolled into a sausage, and spread to cover both the edge of the focus ring and the lens body should help. Make sure the lens is set to infinity before applying it so it doesn't get over stretched.
Great idea, thanks for the tip
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Old 16-04-2012, 09:34 AM
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CapturingTheNight (Greg)
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Hi Steve,
Are you using a UV/protection filter on the plastic fantastic? I used to get reflections like that all the time until I stopped using a filter on it. At $100 or so for the lens i'm not worried about damage to the little guy. It's as close to a dispossable lens as you will get. You will still get reflections if you push the exposure too much even without a filter on objects like the moon but it shouldn't happen as often. Not sure about the focus ring issue. Mine works fine. It's obviously not the firmest focus ring on the market but I have never had it shift like you describe. In fact I was using it last night for some widefield tracked shots and it didn't move at all over the two hours or so of exposures. Maybe try a piece of tape to hold it in place once you have focused?
Cheers
Greg
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Old 16-04-2012, 10:44 AM
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Octane (Humayun)
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This lens makes a great cap for a DSLR body.

As others have said, it's pretty much a throwaway lens, which just happens to be remarkably sharp for the price paid.

Your next step would be to move to the 50mm f/1.4 USM or the 50mm f/2.5 USM macro. They are of a far sturdier construction with more lens elements. The 50mm f/2.5 USM macro is a very, very slow focusing lens. But, most of the time, we're hooking up our cameras to computers to do astrophotography, anyway, so, it should be a no brainer to fire up EOS Utility, go into Remote LiveView and control the focusing from within EOS Utility itself: set lens to AF, load EOS Utility, select Remote LiveView/Shooting, click the 200% box, press the buttons for focus/fine focus until the star is in focus (typically, this means being on either side of red/blue chromatic aberration). Once the star is in focus, ensure you switch back to MF on the lens so you don't inadvertantly shift the focus from the computer.

Happy shooting.

H
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Old 16-04-2012, 10:55 AM
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ZeroID (Brent)
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I reduced ( note, reduced ) flare on my tele lens by making a new longer front light sheild with a matted internal surface. It's not the whole answer but it knocked off some of the side light intrusion and reflected glare that was also adding to the general mess. Sprayed flat black paint ( Hi Temp exhaust enamel I just happened to have ) inside.

Removing the UV filter is a good idea as well as already suggested.

Also worked wonders on my old 12 x 50 bins, couple of 50mm long lightsheilds made from a Xerox toner cartridge body cut that just happened to be the right diameter to squeeze fit on the front.

Every little bit helps.
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Old 16-04-2012, 11:23 AM
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Quote:
Originally Posted by obsidianphotos View Post
Hi Steve,
Are you using a UV/protection filter on the plastic fantastic? I used to get reflections like that all the time until I stopped using a filter on it. At $100 or so for the lens i'm not worried about damage to the little guy. It's as close to a dispossable lens as you will get. You will still get reflections if you push the exposure too much even without a filter on objects like the moon but it shouldn't happen as often. Not sure about the focus ring issue. Mine works fine. It's obviously not the firmest focus ring on the market but I have never had it shift like you describe. In fact I was using it last night for some widefield tracked shots and it didn't move at all over the two hours or so of exposures. Maybe try a piece of tape to hold it in place once you have focused?
Cheers
Greg
Hi Greg. There was no UV protection filter on at that time. Im thinking of the exposure issue as well could be one of the problems. Thanks for the reply.I cant wait to do some widefield tracked stuff, i hope they turned out well for you.
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Old 16-04-2012, 11:31 AM
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Quote:
Originally Posted by Octane View Post
This lens makes a great cap for a DSLR body.

As others have said, it's pretty much a throwaway lens, which just happens to be remarkably sharp for the price paid.

Your next step would be to move to the 50mm f/1.4 USM or the 50mm f/2.5 USM macro. They are of a far sturdier construction with more lens elements. The 50mm f/2.5 USM macro is a very, very slow focusing lens. But, most of the time, we're hooking up our cameras to computers to do astrophotography, anyway, so, it should be a no brainer to fire up EOS Utility, go into Remote LiveView and control the focusing from within EOS Utility itself: set lens to AF, load EOS Utility, select Remote LiveView/Shooting, click the 200% box, press the buttons for focus/fine focus until the star is in focus (typically, this means being on either side of red/blue chromatic aberration). Once the star is in focus, ensure you switch back to MF on the lens so you don't inadvertantly shift the focus from the computer.

Happy shooting.

H
Thanks H. I know but i love this little lens it has been very good to me(till now) and has opened up a whole new world of fun. I am certainly getting some bang for my buck with it. I know there will come the time when i have to part with it or use it as a cap but for now i am trying to grow the astro budget. Problem is i keep seeing all these wonderful things i want. Thanks for the great info on EOS Utility. I have used it a little bit but was not aware of the fine focus buttons and switching to AF. This knowledge will be extremely beneficial to me. Maybe the 50mm f2.5 Macro might be heading my wish list.
Thanks for the reply.
Steve.
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  #9  
Old 16-04-2012, 12:15 PM
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stardust steve (Steve)
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Quote:
Originally Posted by ZeroID View Post
I reduced ( note, reduced ) flare on my tele lens by making a new longer front light sheild with a matted internal surface. It's not the whole answer but it knocked off some of the side light intrusion and reflected glare that was also adding to the general mess. Sprayed flat black paint ( Hi Temp exhaust enamel I just happened to have ) inside.

Removing the UV filter is a good idea as well as already suggested.

Also worked wonders on my old 12 x 50 bins, couple of 50mm long lightsheilds made from a Xerox toner cartridge body cut that just happened to be the right diameter to squeeze fit on the front.

Every little bit helps.
Thanks Brent. I love a bit of DIY. I will have a hunt around and see what i can find.
All these great tips have helped lots.
Cheers
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  #10  
Old 16-04-2012, 04:48 PM
Danack (Dan Ackroyd)
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Quote:
Originally Posted by stardust steve View Post
Also the focus ring on the 50mm when in Manual focus is very loose and moves by itself after obtaining focus.
This can be fixed pretty easily be focusing in manual focus mode and then changing to AF focus mode, if you set the camera to back button focus.

http://www.learn.usa.canon.com/resou..._article.shtml

Back button focus separates the taking of the picture with the focusing of a picture - and is generally awesome.
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Old 16-04-2012, 05:37 PM
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Octane (Humayun)
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+1: AF-On is a gift.

H
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Old 16-04-2012, 06:20 PM
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jjjnettie (Jeanette)
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Thanks for the tip on back focus. Excellent!
I'll be able to put that function to good use.
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Old 16-04-2012, 08:17 PM
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stardust steve (Steve)
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Quote:
Originally Posted by Danack View Post
This can be fixed pretty easily be focusing in manual focus mode and then changing to AF focus mode, if you set the camera to back button focus.

http://www.learn.usa.canon.com/resou..._article.shtml

Back button focus separates the taking of the picture with the focusing of a picture - and is generally awesome.
Thanks Dan, What a great tip that was. I never knew my camera had that function. Wow i have learnt a lot today.
I just tested it now in the lounge room, AND its generally awesome!!!

Thanks for the tips everyone.
Steve.
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