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11-16-2009, 07:29 PM   #1
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what's this?

I stopped using my 50mm f1.4 in favour of my 70mm DA because of CA and pf but especially because of the effect that you can see in the attached 100% crop - the circles of light on the hair. Can anyone tell me what this is.

The image is jpg taken at f1.4, 1/90th - window light.

One the reasons I ask is because I looked through my photo's and realised that many times the softness at f1.4 is more about about focusing difficulties at such a shallow dof rather than the lens itself being too soft and when focused correctly in close up photography it certainly is not too soft. The point is I would like to start using it again.

So if anybody could tell me what the circles are it would be much appreciated. Also regarding CA . I have terrible difficulties removing CA with lightroom 2.4. Is there an easier way or a better software?

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PENTAX K10D  Photo 

Last edited by kiwao; 11-16-2009 at 07:32 PM. Reason: added jpg
11-16-2009, 08:04 PM   #2
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Hi Kiwao
The one thing I have noticed in some of my pics is the CA with the 50 1.4 also
but the speckle (if thats what we can call it) is light reflection. I am going to find a lens hood for my fifty as that should stop a lot of it I reckon that would have stopped it in this picture too

Taff
11-16-2009, 08:22 PM   #3
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Yes I agree. I'd guess there is a UV filter on the lens and no hood. Take off the UV filter and add a hood.
11-16-2009, 08:57 PM   #4
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Thanks for the replies.

I have a hood which is screw on hard plastic but the problem is that it is incredibly fiddly fitting the lens cap. Do you know of another kind?

" Take off the UV filter and add a hood."

Yes you guessed right but if I remove it isn't there a danger of scratching the lens???

11-16-2009, 09:12 PM   #5
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There are clip on types available at places like Ebay. Also Nikon makes some nice metal versions. So there are some easy to use hoods available. With the hood on, there's almost no chance of damaging the lens. Only time I use a filter is in either rain or a place where wind would blow around dust, like the beach.

Otherwise the filters make great lens caps.
11-16-2009, 09:37 PM   #6
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To piggy back on the OP's question, since the field of view is cropped for an APS sensor, could we use a hood for a ~75mm lens for a 50mm without vignetting?
11-16-2009, 09:52 PM   #7
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QuoteOriginally posted by kiwao Quote
" Take off the UV filter and add a hood."

Yes you guessed right but if I remove it isn't there a danger of scratching the lens???
Yes, and if you cross the street there is a danger of getting hit by a bus. So take reasonable care, but no reason to lose sleep over it.
11-16-2009, 10:24 PM   #8
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Yes I have a couple of the old clip on 85mm plastic Pentax hoods. They don't vignette. So you can use a hood that was originally designed for a longer lens.

11-17-2009, 01:03 AM   #9
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QuoteOriginally posted by kiwao Quote
Thanks for the replies.

I have a hood which is screw on hard plastic but the problem is that it is incredibly fiddly fitting the lens cap. Do you know of another kind?

Of cap? Yes.

Priorities. You can cover a hood with a stocking if you have to: a lens cap won't help your images.



QuoteQuote:
" Take off the UV filter and add a hood."

Yes you guessed right but if I remove it isn't there a danger of scratching the lens???

A nice deep hood that's always on there makes it harder than you might think for anything but a windy day at the beach to put harm anywhere near your lens. Really. I like to use neoprene 'hood hats' for my odder-shaped hoods like that, but honestly, my 50 usually rides face-down in a bag with nothing but hood on there.

UV filters can be like plastic covers on your couch: unless you intend to sell the thing, you'll want to start living there, sooner or later.

There are exceptions, in my book, generally lenses that are particularly vulnerable, namely wides, may get one.


You'd probably be surprised how rarely I clean lenses that live in nice deep hoods. My 50 is used about every day, has rarely even had a hood hat on, and I've cleaned it maybe once or twice in the year I've had it. Condtions vary, of course, but for perspective: you're more likely to scratch your lens, even, by fussing with caps than by just leaving the hood on there. Not that you can't keep a UV on things, (you can put the hood on that, too, if you'd like) but you needn't be stressed about it.

And, as Peter mentioned, yes, you can use a tighter hood on a APS-C sensor than usual. This is desirable, in fact, if you don't intend to use that lens for film.

Last edited by Ratmagiclady; 11-17-2009 at 01:11 AM.
11-17-2009, 02:41 AM   #10
Damn Brit
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Unless you're catholic, use a rubber hood.
11-17-2009, 02:48 AM   #11
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I could see you grinning as you typed that...
11-17-2009, 02:51 AM   #12
Damn Brit
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QuoteOriginally posted by Igilligan Quote
I could see you grinning as you typed that...
Are you kidding, I had to sit on the floor before I started typing it.
11-17-2009, 03:11 AM   #13
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QuoteOriginally posted by Damn Brit Quote
Unless you're catholic, use a rubber hood.
you owe me a new laptop screen...I was drinking soy milk when I read that one!

11-17-2009, 03:43 AM   #14
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QuoteOriginally posted by Damn Brit Quote
Unless you're catholic, use a rubber hood.
Wait till I wipe the tears from my eyes. --------------------------------

Where would the world be without these damn Brits?

Mickey
11-17-2009, 03:50 AM   #15
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QuoteOriginally posted by Damn Brit Quote
Unless you're catholic, use a rubber hood.
Of course there is something you need to remember here....just don't make it a....."habit"...


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