7D+300mm F4L IS Filter Issue-- TEST SHOTS, as requested..

Started Apr 5, 2010 | Discussions
bellevilleguy
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7D+300mm F4L IS Filter Issue-- TEST SHOTS, as requested..
Apr 5, 2010

At the request of some interested members I have completed the following test shots with an old Bank Note taped to a cereal box, camera mounted onto tripod and with one shot focus selected, 2 sec timer delay, and image stabilizer turned off.

First shot is the 300mm F4L IS with the Hoya Super Multi Coat filter in place... Second shot is only the lens, with no filter. Third and forth shots are deeper crops.. The RAW files really scream the differences when viewed on DPP !!

The differences I see here in sharpness and contrast are exactly what I was seeing in my shots out in the field and mistook for a focusing issue with the lens... If you have followed my other thread, my shots this weekend with no filter have been like night and day... I would never tell anybody not to use filters, as they provide excellent protection, but just be fore warned, that yes they indeed can impact image quality... Many thanks to those who participated in the first thread, your input and links were most helpful... Original thread is here... http://forums.dpreview.com/forums/read.asp?forum=1019&message=34985371

300mm F4L IS with Hoya SMC Filter

300mm F4L IS with NO filter

Heavy Crop, With Hoya SMC Filter

Heavy Crop, with NO filter

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clknight
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So your conclusion is
In reply to bellevilleguy, Apr 5, 2010

that the filter itself is degrading the image? Seems clear enough to me.

Thanks for the follow up.
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Colin

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500mm f/4, 85mm f/1.8, 70-200mm f/4, 17-55mm f/2.8

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Kevin G.
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Re: 7D+300mm F4L IS Filter Issue-- TEST SHOTS, as requested..
In reply to bellevilleguy, Apr 5, 2010

Thanks! This, and other posts have convinced me there's no reason to cover an expensive piece of glass with a filter of any kind, for protection or any other reason.
Regards,
Kevin
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scottb
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Re: 7D+300mm F4L IS Filter Issue-- TEST SHOTS, as requested..
In reply to bellevilleguy, Apr 5, 2010

First - weird looking toonie - all flat and miscoloured You don't see many of the bills around anymore.

I have a Hoya HMC Super on my 7D's 18-135 and given your test and field experience I'm going to have to take a closer look and run a few tests of my own. I don't expect my results to be as pronounced given the quality differences between our lenses, but I'm still curious.

Has anyone else tried this? Have you tried with other lenses if you have any with the same width?

Thank you for posting this! I'll be bookmarking the thread.

Scott

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bellevilleguy
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Re: 7D+300mm F4L IS Filter Issue-- TEST SHOTS, as requested..
In reply to scottb, Apr 5, 2010

They don't make toonies like that anymore!! LOL!! I would also like to see if others see similar effects too!! Post to the thread if you do, by all means!!

Cheers!

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Hurricane Phil
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Re: 7D+300mm F4L IS Filter Issue-- TEST SHOTS, as requested..
In reply to bellevilleguy, Apr 5, 2010

Your test results definitely back up what you posted, earlier. I'm surprised at the huge difference. Do filters negatively affect your other lenses or just your 300mm?
Great job. Thanks.
Phil

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bellevilleguy
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Re: So your conclusion is
In reply to clknight, Apr 5, 2010

My conclusion is that yes, ifilter use can affect image quality... Even using good quality filters such as Hoya SMC's they can degrade your images... Another thing to keep in mind too, is that this is a controlled test, fixed on a tripod, with timer release fired.. In real life shooting it will never be that steady and from what I have seen out shooting, the results can be much worse when actually shooting. Which is why I thought it was some sort of focus issue... Thanks for your input along the way!
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bellevilleguy
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Thanks Phil !!
In reply to Hurricane Phil, Apr 5, 2010

I am going to test my other glass the same way as I did here, all of my lenses have Hoya SMC filters, and I guess are just as prone to image degradation as my 300mm. I hope this info. can help someone else, because top notch image quality is what we all strive for, and so far with my 300mm, that just is not possible with a filter... Thanks for tagging along Phil !
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bellevilleguy
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Re: 7D+300mm F4L IS Filter Issue-- TEST SHOTS, as requested..
In reply to Kevin G., Apr 5, 2010

I'll be removing all of my filters!! that is for sure!!
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gm1974
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Re: 7D+300mm F4L IS Filter Issue-- TEST SHOTS, as requested..
In reply to bellevilleguy, Apr 6, 2010

First off, glad you used non-destructive painter's tape on that bill, it's probably worth more than $2 right now Looks like it's pretty much mint condition too.

Second, I put a UV filter on my 24-105L for a day when I first got it, and promptly retired it due to image degradation. This was a B+W filter too, not some cheap $20 special.

I now shoot with a hood on at all times for extra piece of mind, but only use a filter for special things (i.e. a polarizer if needed for certain effects) and then it's back to a naked lens for me.

I think these front elements are designed to be pretty tough. Someone posted a YouTube video of some guy whacking the cr@p out of a nifty 50's front element and it looked like it can take a fair amount of abuse. If you are going to have something happen to a lens that's going to wreck the front element, then I'm guessing there will probably be some internal damage too

p.s. I spent a bunch of summers at the base in Trenton during my teens. Beautiful part of the province. I still try and get out to Sandbanks when I'm back in Ontario visiting family/friends.

Cheers
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Dietmar Fichter
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Re: Thanks Phil !!
In reply to bellevilleguy, Apr 6, 2010

Years ago on this forum, the filter issue came up in a heated discussion and is not new that degradation occurs when sticking a inferior piece of glass in front of superior quality glass. It's nice however to see some conclusive results.

Dietmar

bellevilleguy wrote:

I am going to test my other glass the same way as I did here, all of my lenses have Hoya SMC filters, and I guess are just as prone to image degradation as my 300mm. I hope this info. can help someone else, because top notch image quality is what we all strive for, and so far with my 300mm, that just is not possible with a filter... Thanks for tagging along Phil !
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bellevilleguy
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Re: 7D+300mm F4L IS Filter Issue-- TEST SHOTS, as requested..
In reply to gm1974, Apr 6, 2010

Ya, I've had that old $2 bill for years now!! LOL!! Nice to hear of other peoples issues with filters too!!

I love the Sandbanks provincial park! I usually get there at least a few times a year!! Nice place to go shooting too!

Thanks for chiming in!

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Peter 13
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Re: 7D+300mm F4L IS Filter Issue-- TEST SHOTS, as requested..
In reply to bellevilleguy, Apr 6, 2010

Repeat the test by taking the shots at an angle slightly different than 90 degrees. Look for misfocus. This way you will know whether the filiter causes AF problems or really degrades the image.

I have done many experiments with my 70-200 f/4 IS with and without an B+W filter. No difference at all. The only downside of the filter is flare under extreme conditions - a light source in the frame.

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clknight
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Sounds like a load off of your shoulders. Enjoy!! (NT)
In reply to bellevilleguy, Apr 6, 2010
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Colin

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500mm f/4, 85mm f/1.8, 70-200mm f/4, 17-55mm f/2.8

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guy schlacter
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Re: Sounds like a load off of your shoulders. Enjoy!! (NT)
In reply to clknight, Apr 6, 2010

Two things are needed to round out your test....

1. Since the Hoya Super HMC (and HMC) were top rated in a published test, and showed improved results and no image degradation, I suggest you try a second copy of the filter to determine whether you have a bad copy.

2. Take shot at Angle to determine AF issue (notate and use center spot AF) - determine whether some slight front / back focus issue occurring

IMHO, Your results seem too dramaticly different to simply say it is all HMC Hoya filters that degrade IQ.

-Guy

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clknight
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I think he's finished.
In reply to guy schlacter, Apr 6, 2010

guy schlacter wrote:

I suggest you try a second copy of the filter

No, really, I think he's done with filters. LOL

You may have a valid point, true enough. But something tells me.....yeah, he's done.

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rwbaron
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I think what would be worthwhile...
In reply to bellevilleguy, Apr 6, 2010

would be to shoot one series using the phase detect AF with and without the filter and another using contrast detect in liveview. This would tell you if the filter itself is screwing with the IQ or if the phase detect AF doesn't like the filter. There is an obvious difference that looks like a loss of contrast but lower contrast can be the result of slight misfocus too.

Bob
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mmullen
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Re: I think what would be worthwhile...
In reply to rwbaron, Apr 6, 2010

rwbaron wrote:

would be to shoot one series using the phase detect AF with and without the filter and another using contrast detect in liveview. This would tell you if the filter itself is screwing with the IQ or if the phase detect AF doesn't like the filter. There is an obvious difference that looks like a loss of contrast but lower contrast can be the result of slight misfocus too.

Yes, but it doesn't matter what is causing the problem, mis-focus caused by the filter or lack of contrast and sharpness caused by the filter, the net effect is the same - less than optimal images.

That's why I never use filters for "protection".

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Mike Mullen

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rwbaron
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Re: I think what would be worthwhile...
In reply to mmullen, Apr 6, 2010

mmullen wrote:

rwbaron wrote:

would be to shoot one series using the phase detect AF with and without the filter and another using contrast detect in liveview. This would tell you if the filter itself is screwing with the IQ or if the phase detect AF doesn't like the filter. There is an obvious difference that looks like a loss of contrast but lower contrast can be the result of slight misfocus too.

Yes, but it doesn't matter what is causing the problem, mis-focus caused by the filter or lack of contrast and sharpness caused by the filter, the net effect is the same - less than optimal images.

That's why I never use filters for "protection".

I've never seen this with any camera body or lens using B+W UV filters and I test extensively. I'd like to know what's causing this and if it's related to the 7D PD AF using the Hoya filter. None of my lenses long or short on my 7D have shown this issue with my filters.

Bob
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mmullen
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Re: I think what would be worthwhile...
In reply to rwbaron, Apr 6, 2010

rwbaron wrote:

I've never seen this with any camera body or lens using B+W UV filters and I test extensively. I'd like to know what's causing this and if it's related to the 7D PD AF using the Hoya filter. None of my lenses long or short on my 7D have shown this issue with my filters.

It's not specific to the 7D, lots of filter problems have been reported before the 7D was even available. But the higher resolution of the 7D is more likely to show filter issues because you can view the images at a higher magnification. That is not a problem but a benefit.

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Mike Mullen

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