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01-26-2010, 09:24 AM   #1
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compensating for crop factor

Has anyone ever tried mounting a super wide angle converser lens to their 50mm slr lens to counteract the crop factor. I Have as SMC Pentax-m f1.4 lens, which is great, but the crop factor makes its usefulness somewhat limited. I've considered buying the Sigma 30mm f/1.4 EX DC HSM, because I've read it closely approximates the true 50mm field of view. However that lens is $400, not so high a price in the world of lenses, but high considering the K-x was only $550. Anyway I was thinking I'd just buy the wide angle converter lens for $50 and attach it to my smc 1.4. What I am wondering, is if any else has tried it and knows of any issues to consider. For instance, thread size. The stock lens on the K-x says it has a 52mm thread size. Am I to assume that my 50mm lens also has a 50mm thread size, or would it too have a 52mm thread? Most of the converters I've looked at have a 52mm thread and some come with adapters for larger sizes, but I've seen none that are 50.

01-26-2010, 09:29 AM   #2
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crap optics in front of good optics isn't a good idea. buy a wide angle manual focus like a 28mm/f2.8.
01-26-2010, 09:42 AM   #3
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QuoteOriginally posted by jeans Quote
The stock lens on the K-x says it has a 52mm thread size. Am I to assume that my 50mm lens also has a 50mm thread size, or would it too have a 52mm thread? Most of the converters I've looked at have a 52mm thread and some come with adapters for larger sizes, but I've seen none that are 50.
The thread (filter diameter) size of the M 50 1.4 should be 49 mm. Take a look at the front of the lens to confirm.

Tim
01-26-2010, 09:44 AM   #4
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QuoteOriginally posted by attack11 Quote
crap optics in front of good optics isn't a good idea. buy a wide angle manual focus like a 28mm/f2.8.
thumbs up here!

You have bought a very good camera and lens, though why throw away the quality, buying a crutch?

Ben

01-26-2010, 09:56 AM   #5
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I tried this once and it actually worked.
I just tried it for the kick of it and was surprised that it worked.
I had a Canon S3 IS before and played with the additional lens you can attach to these P&S since they have fixed lenses, because of this I bought a Raynox DCR-730 which was a wide converter (0.7x).
Raynox makes good glass so the image I got still seemed good and didn't deteriorate.
You might know Raynox as making the well known macro conversion lenses DCR-150 and DCR-250.
Here it is: DCR-730 Wideangle conversion lens 0.7X for Digital camera and High Definition camera
If you want to toy around with it, this is the lens to consider.
The 18mm kit (widest end) won't work with this though as it catches the edges of the kit lens and causes vignetting.
01-26-2010, 09:57 AM   #6
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QuoteOriginally posted by atupdate Quote
The thread (filter diameter) size of the M 50 1.4 should be 49 mm. Take a look at the front of the lens to confirm.

Tim
You can try a step up ring.
01-26-2010, 10:49 AM   #7
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Ok, I did some real quick tests for you.
I'm attaching shots taken with K100D super with Helios 44-M (52mm) wide open at f:2.
I didn't attach to a tripod but I was seated and never moved.
Only difference is that one is normal 58mm while the other one has attached Raynox DCR-730 wide conversion lens.
Last photo would be the Raynox DCR-730 attached to the Helios 44-M.
These are straight jpegs and just resized for uploading.
No additional PP.
Hope this helps!
Attached Images
     
01-26-2010, 10:58 AM   #8
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QuoteOriginally posted by atupdate Quote
The thread (filter diameter) size of the M 50 1.4 should be 49 mm. Take a look at the front of the lens to confirm.

Tim
Of course I did already look at the front of the lens, which says 50mm. I just wasn't sure that automatically meant thread size. Can this be confirmed?

01-26-2010, 11:12 AM   #9
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QuoteOriginally posted by Ben_Edict Quote
thumbs up here!

You have bought a very good camera and lens, though why throw away the quality, buying a crutch?

Ben
I don't think this is always the case as when you want to do some macro and attach the Raynox DCR-150 0r DCR-250.
A lot of people will attest to the quality of Raynox.
Just take a look at the Raynox Macro club: https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/74221-raynox-macro-club.html
01-26-2010, 11:13 AM   #10
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QuoteOriginally posted by jeans Quote
Of course I did already look at the front of the lens, which says 50mm. I just wasn't sure that automatically meant thread size. Can this be confirmed?
Focal length is 50mm but filter size is 49mm like the old Pentax-M, Pentax-A 50mm f:1.4/1.7/2.
01-26-2010, 11:20 AM   #11
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QuoteOriginally posted by jeans Quote
Has anyone ever tried mounting a super wide angle converser lens to their 50mm slr lens to counteract the crop factor. I Have as SMC Pentax-m f1.4 lens, which is great, but the crop factor makes its usefulness somewhat limited. I've considered buying the Sigma 30mm f/1.4 EX DC HSM, because I've read it closely approximates the true 50mm field of view. However that lens is $400, not so high a price in the world of lenses, but high considering the K-x was only $550. Anyway I was thinking I'd just buy the wide angle converter lens for $50 and attach it to my smc 1.4. What I am wondering, is if any else has tried it and knows of any issues to consider. For instance, thread size. The stock lens on the K-x says it has a 52mm thread size. Am I to assume that my 50mm lens also has a 50mm thread size, or would it too have a 52mm thread? Most of the converters I've looked at have a 52mm thread and some come with adapters for larger sizes, but I've seen none that are 50.
There is no such thing as crop factor.
01-26-2010, 11:24 AM   #12
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QuoteOriginally posted by Wheatfield Quote
There is no such thing as crop factor.
Then what do you call it?
01-26-2010, 11:35 AM   #13
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QuoteOriginally posted by jeans Quote
I Have as SMC Pentax-m f1.4 lens, which is great, but the crop factor makes its usefulness somewhat limited.
Can you explain what you mean by that? It seems to me you have started this thread based on something you think you know rather than something you actually know. Crop factor will NOT affect your photography and does not change the usefulness of lenses.

Last edited by Damn Brit; 01-26-2010 at 11:46 AM.
01-26-2010, 11:37 AM   #14
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QuoteOriginally posted by graphicgr8s Quote
Then what do you call it?
What do I call what?
01-26-2010, 11:37 AM   #15
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QuoteOriginally posted by Wheatfield Quote
What do I call what?
ZING!


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