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10-16-2012, 07:29 AM   #1
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Quick lens hood question

Hi guys,

I recently bought a Pentax 50mm 2.8 Macro lens and it came withe the standard PH-RBC lens hood. This however, does not have the little slot through which you can adjust your CPL filter. I'd rather not put my hands in the hood to adjust the CPL filter, so I searched around a bit.

My eye fell on the PH-RBD lens hood, used on the 50-200mm WR, which does seem to have the slot. Can anyone confirm it does have one? Both the PH-RBC and PH-RBD are 49mm, so I assume they'd both fit my 50mm 2.8 macro?

Thanks in advance!

10-16-2012, 07:49 AM   #2
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Hi, welcome to the forums. I have no definitive answer to your question, but beware! Sharing a diameter does not necessarily mean they use the same hood thread... I know, you'd think it would, right?
10-16-2012, 08:05 AM   #3
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My wild guess, is that the 50-200's hood is meant to cover the wide end (50mm), but also meant to cover the slower aperture (F4), and may vignette slightly on your 50mm macro at F2.8.

Won't affect the macro though.
10-16-2012, 12:56 PM   #4
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lens hoods cannot simply be "assumed" interchangeable just because the focal length is the same.

The defining requirements of a hood include the setback of the front element, as well as the mounting points for the hood. even if the mounting is the same, if the setback of the front element is different then the hood could be either too short (non ideal for shooting into the sun) or too long (causing vignetting)

Note that just because maximum aperture is different between the lenses is not a reason to assume vignetting would occur because it is the field of view of the lens, not aperture that impacts vignetting.

10-16-2012, 01:25 PM   #5
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Too, also
APS-C changes the situation.
10-16-2012, 01:47 PM   #6
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Most macro lenses have the front element recessed quite deep; a lens hood may not be necessary.

In many cases, you can use a step-down adapter ring as a hood. It's compact and provides protection for the lens.

When I need to use a filter, I put it between the lens and the "hood".

10-16-2012, 02:48 PM   #7
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Thanks for the replies so far guys!

This mainly concerns using a CPL filter on my lens, as I previously mentioned. So, assuming from the comments you guys would recommend me to either shoot
without a lens hood when using the CPL filter, to take it off every time you want to adjust the filter or to reach into the hood to adjust the filter, am I correct in thinking these are my options?

If I stop by my local camera store and try the PH-RBD hood on the lens and it does actually fit, would you still discourage me to use it on my 50mm 2.8 macro?

Thanks
10-17-2012, 12:10 AM   #8
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Well if you have the possibility to try it, you'll be able to make a more informed decision than everything we said! So, if it fits and it doesn't vignette, go for it...
Though there are other options:
- as Soldbear said use a stepdown ring above the CPL (this might take some trial and error too);
- or cut yourself a small window in the original hood. And then you can use some tape to close it when you don't use a CPL.
I'm sure there are other possibilities, be creative!

10-18-2012, 09:42 AM   #9
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If you have a screw in hood, put the CPL filter between the lens and the hood and rotate the filter and hood together. You only need the window on bayonet mounted hoods.

Last edited by Timd; 10-21-2012 at 10:26 AM. Reason: meant rotate filter with hood, not lens with hood
10-19-2012, 11:31 AM   #10
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QuoteOriginally posted by Timd Quote
If you have a screw in hood, put the CPL filter between the lens and the hood and rotate the lens and hood together. You only need the window on bayonet mounted hoods.
That's a good one, there: if you intend to use that CPL a lot with just that lens, you can actually leave one hood on that filter, (The stepdown kind would be nice and flat to carry as a combination: if you give it is own little case, pocket-size. ) and just swap the filter+hood with the bayonet mounted hood when you want to switch back and forth. (Less screwing and unscrewing every time, that way.)
10-19-2012, 06:41 PM   #11
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Well... It appears my comment of your other thread is completely redundant...

:-)
10-23-2012, 12:44 AM   #12
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QuoteOriginally posted by Gavin Jr. Quote
... to take it off every time you want to adjust the filter ...
This is my usual process when I don't have the finger slot. It forces me to slow down and think about the shot and the amount of polarization I want. 100% is not always best. It just takes a second to put it back on.

I'd be cautious about rotating the entire hood with the CPL. Those curved petals are engineered to provide just the right amount of shading at the angle designed. Rotating it might change that a bit. It will probably work, just check for vignetting or extra flare. Obviously, a strait edged, round hood doesn't have this problem.
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