BMCC M43 - There *is* a reduction in crop factor after all

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rick.lang

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Re: BMCC M43 - There *is* a reduction in crop factor after a

PostFri Sep 14, 2012 11:11 pm

claimsfour wrote:.
.
They repeatedly talk about this, especially at the 6 minute mark (it's worth watching the entire video)



In essence: The shorter the mount, the less the crop. The M43 BMCC camera means
you might not have to buy an 8mm fisheye after all to get a basic wide angle shot.


The Blackmagic rep alludes to the focal length being 'natural' and not 'doubling' which is what
you'd get with the EF model. My guess is he's meaning: 24mm is 24mm, 50mm is 50mm?

Camera EF/M43 lens tests please.


At the risk of being an idiot, I'm not sure that Stuart Ashton of BMD meant there was no longer the 2.3x crop factor. I think he was trying to say, the mount adapters from MTF were not causing any change compared to the EF lenses on the BMCC EF since they mount adapter essentially brought the lens to the same position it would be on the BMCC EF. He mentions the adapter on the BMCC MFT creates the same distance the long flange has on the BMCC EF. As you say, let's see a test comparing the two cameras using the same lens but with the adapter added to the BMCC MFT. The image FOV will be identical.
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Nick Smith

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Re: BMCC M43 - There *is* a reduction in crop factor after a

PostSat Sep 15, 2012 12:21 am

I'm gonna say that was a slip of the tongue on the part of the black magic guy. He meant that because the lens mount is smaller than the EF mount, putting an adapter on it brings the lens mount back to being about the same length; so you're not going to see much change between the 2 versions. The sensor is still the same so it'll still have the same crop factor. Any differences caused by slightly different lens mount lengths should be very minimal.
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John Brawley

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Re: BMCC M43 - There *is* a reduction in crop factor after a

PostSat Sep 15, 2012 2:46 am

Crop factor is very misunderstood.

This is exactly why I hate using the phrase.

Lens performance doesn't change with focal length. A 50mm lens is always a 50mm lens.

The sensor is exactly the same size between EF and mFT. There is NO difference.

So the crop factor COMPARED to 135 full frame cameras like the 5dmk2 is still 2.3x no matter what mount the BMCC uses. This would only change if they change the sensor size.

The mFT mount simply allows a wider range of lenses that are more optimised to the bmcc sensor size.

There would be NO DIFFERENCE in shot size between a 50mm lens on an EF BMCC and a mFT BMCC.

The topic of this thread is incorrect.
JB
Last edited by John Brawley on Sat Sep 15, 2012 3:30 am, edited 1 time in total.
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John Brawley

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Re: BMCC M43 - There *is* a reduction in crop factor after a

PostSat Sep 15, 2012 3:33 am

claimsfour wrote:Hi John,

The very best way to put an end to this is to simply see a test.

Can we agree that BM should do this? A basic/simple test where a prime lens (wide angle)
is attached to both cams/shooting the same thing (could be anything, a chart!)

It's really incumbent for BM to be upfront/clear as possible about what they are selling,
if there is a crop difference between cameras: People want to know.



There's no need for a test.

The sensor is the same. All BMD do is make the same camera and put a different mount on the front.

The mount is different. Lens focal lengths won't change. The crop factor doesn't change. It's basic physics.

A 50mm lens on m4/3 will be the same on EF.

jb
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Gabriele Turchi

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Re: BMCC M43 - There *is* a reduction in crop factor after a

PostSat Sep 15, 2012 12:36 pm

mtf mount allow mtf lenses to be mounted ,

mtf lenses are optically designed for smaller sensors , so you can have wide angles on this sensors ,

for instance a 15mm mtf lens will be a 15mm lens on the BMC camera ... (an not like the canon where a 15mm would be a 48mm lens )

than , if the MTF adaptor for canon will reduce a bit the canon full frame lens crop factor on the BMC camera .. that i am not sure (but let me think : why BMD would have designed an EF mount (on their EF version) that have higher crop factor than lower ???)

g
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Thomas Ko

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Re: BMCC M43 - There *is* a reduction in crop factor after a

PostSat Sep 15, 2012 3:06 pm

John Brawley is right. Focal length for lenses is the same regardless of the size of the sensor it's being used for. Only the 35mm equivalent will be calculated using the size of the sensor to determine the crop factor. Therefore, the crop factor is the same regardless of mounting system.

Gabriele, MFT lenses express focal length the same as lenses on any other system. To calculate the 35mm equivalent focal length you still need to multiply it by the crop factor. A 15mm focal length MFT lens on a GH2 has a 15mm focal length but it is the equivalent of a 30mm lens on a 35mm (135) body.
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Thomas Ko

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Re: BMCC M43 - There *is* a reduction in crop factor after a

PostSat Sep 15, 2012 3:35 pm

The MTF rep is correct. He states he doesn't know crop factor until he calculates based on sensor size. BM rep is simply wrong in the video about how focal length works. Both Rick Young and BM are on these forums and can answer directly if they want to. The only way the crop factor is different in the two cameras is if the sensor size is different.
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Kholi Hicks

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Re: BMCC M43 - There *is* a reduction in crop factor after a

PostSat Sep 15, 2012 4:24 pm

You don't have to wait.

Just have someone with a GH2 and EF mount, along with matching focal lengths for MFT glass, do the test.

35mm EF and a 28mm MFT lens.

There isn't a reduction in crop factor, though. AT all. It's the same no matter what mount you strap on.
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Brett Casadonte

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Re: BMCC M43 - There *is* a reduction in crop factor after a

PostSat Sep 15, 2012 5:16 pm

Hi Claimsfour,

The crop factor between the sensor in the BMCC camera and a 35mm equivalent sensor CAN NOT CHANGE unless the physical size of the sensor changes. "Crop Factor" simply refers to the ratio of the dimensions of one image sensor vs a reference size. Its a mathematical equation that measures the diagonal of one sensor vs another (Crop Factor= 35mm sensor diagonal / comparison sensor diagonal). In our case, the 'comparison' sensor is the BMCC sensor.

Please note that camera mount is not an element of the equation, and therefor CAN NOT impact Crop Factor.

Do the math and 100% of the time, when the BMCC sensor is compared to a 35mm sensor, the crop factor will be the same.

Brett Casadonte
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Re: BMCC M43 - There *is* a reduction in crop factor after a

PostSun Sep 16, 2012 1:33 am

The sensor size and the focal length are the only two variables in determining the field of view of a lens on a sensor.

The mFT has the same sensor with the same active sensor area as the EF model.

The lens mount has nothing to do with the focal length and sensor crop.

There's no conspiracy. This is what it is.
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Joel Graham

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Re: BMCC M43 - There *is* a reduction in crop factor after a

PostSun Sep 16, 2012 1:57 am

Hmm what an intresting turn of events for you claimsfour.

I was right in my initial evaluation because of basic physics. I appreciate others coming here to back up my point.

I'd ask that you don't go around these forums placing my stance out of context. It's rude and honestly shouldn't be allowed. My responses to your original thread still stands.

Brandon Graham

Re: BMCC M43 - There *is* a reduction in crop factor after a

PostSun Sep 16, 2012 2:08 am

I suggest that you fully understand how focal length, crop factor, flange distance, etc works before making definitive statements or believing others blindly. This is simply math and if you work it out yourself correctly you will find there is no difference in the mft or ef version of this camera.

Wanting a test doesn't change this fact but if it makes you feel better then more power to you. Those who understand what is going on don't need to see it and you will find little support for personal attacks, trolling and stubborn seemingly willful ignorance.

2+2=4 it's a fact. No one needs shoot a test video to prove that.

PS to BlackMagic.

Can we please enforce the use of real names in this forum. Thanks!

Brandon Graham

Re: BMCC M43 - There *is* a reduction in crop factor after a

PostSun Sep 16, 2012 3:04 am

My name is actually Brandon as it is stated on this forum. Also, my relation to Joel has nothing to do with anything. Your blatant misinterpretation of the facts in a public space demands correction for the betterment of the community as a whole. However, to answer your question.

Yes, he is my brother and yes we talk about film all the time. It's seems to work well.

We did the math, we worked it out and we know the facts. The EF and MFT cameras have the same crop factor.

Greenscreen doesn't interest us because it's not something we use in our productions. It may be terrible on the BMC but it's not a use case we plan for this camera so I haven't looked at what tests are out there and don't have the knowledge to talk about it with confidence.

Also, because it's greenscreen perfprance doesn't matter to me it's not something I take into account when considering the purchase of this camera. For you it may be and your calls for more tests are a valid concern if green screen is important to you. However, this thread is about EF vs MFT crop differences which has been established as non-existent.
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John Brawley

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Re: BMCC M43 - There *is* a reduction in crop factor after a

PostSun Sep 16, 2012 3:18 am

claimsfour wrote:

Brandon Graham wrote:2+2=4 it's a fact. No one needs shoot a test video to prove that.


Just like how we didn't need to 'see a test' over BM Green screen...and when we finally did,
we all had a collective gasp in horror.



Sorry ? Do you have a problem with the way keying works on this camera ? So far I can certainly seen some bad keys done with the footage out there. There's many things that contribute to getting a key right and more than the "magic" camera, you need to get a lot of other things right. No compression, 12 bit DNG's and high DR mean this camera will key beautifully. The only only caveat being rolling shutter, which is never good for high speed movement for any camera that keys. That includes RED and Alexa BTW.

Seems you've fabricated a scenario where the double digit of cameras out there with independent users are conspiring to not do green screen tests to your satisfaction. To which you conclude, a coverup.

The video you keep holding up as proof is flawed. You have an indepndent blogger, a "sales" guy from BMD (i know him so he won't mind me calling him that and actually he's a lot more than that but you get my idea) and a thrid party manufacturer who has nothing to do with BMD getting their terminology wrong. Pretty simple. And as I said, a lot of people misunderstand just exactly what crop factor means and when it applies. Which is why I DETEST it's use. Because you've latched onto something in the perhaps vain hope that the crop factor won't be as high.

So. Speaking as someone who actually works alongside the engineers at BMD and was a part of the discussion to offer m4/3 as an option on this camera.....

To reiterate.

The crop factor of the BMCC EF mount camera compared to 135 is 2.3x
The crop factor of the BMCC m4/3 mount camera compared to 135 is 2.3x

End of story.

Well make sure you come back here and refute this claim once people start pulling great keys from this camera and confirm for yourself the crop factor.

claimsfour wrote:
Hi, I'm Jimmy Graham. Pleased to meet you.


You need to change it in your account settings.

jb
Last edited by John Brawley on Sun Sep 16, 2012 5:11 am, edited 3 times in total.
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Kholi Hicks

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Re: BMCC M43 - There *is* a reduction in crop factor after a

PostSun Sep 16, 2012 5:05 am

claimsfour wrote:
Kholi wrote:You don't have to wait.

Just have someone with a GH2 and EF mount, along with matching focal lengths for MFT glass, do the test.

35mm EF and a 28mm MFT lens.

There isn't a reduction in crop factor, though. AT all. It's the same no matter what mount you strap on.


Y'know...what's even better than a GH2 is a BMCC EF & M43 camera testing wide angle lenses!

If what you're saying is true, then Rick Young would have flat out told me "No, such thing as crop"
yet himself and Mike Tapa both spoke in length about this (Crop differences between EF/M43)

I suggest you actually watch the video first before posting. If crop was not an issue, Rick Young/Mike
Tapa would not have mentioned it.

Don't hate the messenger.


I don't hate you... I'm just trying to help you. It's like... if I were to come across a small child that was somehow convinced that stepping closer to a painting makes the actual painting larger.

Just wouldn't want that kid to grow up thinking like that.

Cause then? He'd just be like "I want a larger house" and he would step forward, and then his entire world would come crashing down.

You can trust that no matter which camera you do the test on, the laws of physics will not change. If they do, though, let me know because I'd need to leave Earth pronto; just a sign of the end of times.

On Green Screen:

Don't mistake someone's quick test for a definitive answer. If you're talking about the green screen footage of the girl waving, well, I could list three to four things off the top of my head that makes it almost impossible to pull a solid key... none of them have anything to do with the camera itself.

I'm sure you know, though, so I won't actually list them.

Good luck, man.
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simonkn

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Re: BMCC M43 - There *is* a reduction in crop factor after a

PostSun Sep 16, 2012 9:02 am

claimsfour wrote:The crop factor is a huge deal for everyone,


No it's not... So please do not speak for me.
Messrs Brawley and Carr have shot the most beautiful, creative and dynamically different footage from the EF camera with it's "terrible" 2.3 crop factor. Those tiny 2 minute (ish) clips give me hope and faith that my films will indeed look better with useage of the BMCC.

I have no delusions of grandeur - my films will not be seen on a cinema screen. They are scripted for the small (well whatever you call a 50inch plasma these days!!) screen. Therefore my training with the BBC and independent study from some great filmmakers books tells me to shoot for the small scene - i.e., close ups... not wide screens. The Tokina 8mm will suffice for me. The ability to shoot 600mm from a fast glass 300mm lens is perfects for ME (my wildlife shoots) But my short film, weddings and corporate stuff - my money making, bill paying income from films will work just fine with a 2.3x crop.

I'm sorry but if the crop factor is REALLY so important that you NEED it to be more "natural" - enough so that an 8mm wide is ESSENTIAL and therefore you MUST put £5k lenses on a £2k camera.... Its does really sound like you ought to wander over to RED/ALEXA and firmly place your money on their counter.

Putting things into perspective, is it really BMD's job to provide tests on the camera? Surely you want the tests done to evaluate the products suitability for your use? Therefore speak to either the owners of the cameras or a supplier who has both units. There are none at present so once again, like the shipping channel, we have to wait!
But its in the suppliers/dealers interests to sell more units therefore do the test.. I have a sneaking suspicion that BMD will still sell the cameras... to idiots like me..

SK
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Re: BMCC M43 - There *is* a reduction in crop factor after a

PostSun Sep 16, 2012 9:02 am

In fact... look at the British Broadcasting Corporation as a perfect example.. They have a technical analysis and testing department! They dont TRUST the tests made by the manufacturers.

So please... wait... then approach your dealer to do the tests... offer to do them yourself or for a small fee.. Or even cough up the cash, buy both and represent the small group of people who "just-gotta-get-dem-tests"

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Hans Engstrom

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Re: BMCC M43 - There *is* a reduction in crop factor after a

PostSun Sep 16, 2012 10:41 am

Can someone edit the name of the thread and lock it as it spreads missinformation among people?

To Claimsfour - The only difference is that lenses in m4/3 mount aren´t made to cover a full format sensor and by that the "projection" of the lenses will be smaller compared to EF lenses made for 35mm. On m4/3 a larger percentage of the total projected image will be used by the sensor BUT even tough a lot of light miss the sensor when a full format lens is on the camera the image that hits the sensor will look the same. So you crop out a big part of the projected image when using a full format lens but it will still look the same as the m4/3 image.

Putting a s35 sized sensor inside the camera with a full format lens on would give a bigger "field of view", but a bigger sized sensor inside the camera with a m4/3 lens on it would show vignetting instead of displaying more "FOV".

It´s hard to describe technical things in a second language but I hope someone gets what I´m talking about.
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John Brawley

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Re: BMCC M43 - There *is* a reduction in crop factor after a

PostSun Sep 16, 2012 12:03 pm

claimsfour wrote:
Oh, you're in for a rude awakening.



Is there something you know ?

claimsfour wrote:
When it comes to camera tests: dpreview.com/Adam Wilt quickly come to mind as 'just the facts' sort
of reviewers who will push a camera to the very bitter end.

I frankly don't care about a 'reviewer' who uses lenses most of us will never have access to in our
natural lives...shooting basically 'demo reels' to pimp their blogs.

What I want to see are charts/acid tests. Not how 'great' a camera can shoot something,
but how it works under adverse situations (real world)



I'm not a reviewer. I'm a professional director of photography. I have a blog, that covers a wide range of topics from gear to philosophy. I have a separate website with my reel for those that want to see my work.

I like to share information. There's no advertisements on my blog. I'm not paid by BMD. I gain nothing from traffic to my blog from other cinematographers or potential customers of BMD as they aren't the ones that employ me. The people that employ me, generally aren't interested in the things I write about.

I've also published resolution charts and greenscreen demo footage. But the majority of my work IS in the real world. Whereas charts couldn't be any further than the real world.

Anyhow you have both available and claim to have seen neither. Seems to me you're just agitating now.

It's not like there's a conspiracy here to hide truth from you. The camera will be rigorously tested by all those whose opinion's you care about. Why the anger ? Why so disbelieving when every single responder here tells you that there is no difference in crop factor ?

What's more, you still refuse to use your real name, in disregard to the forum guidelines.

jb
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Martin Scanlan

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Re: BMCC M43 - There *is* a reduction in crop factor after a

PostSun Sep 16, 2012 1:07 pm

I once had a very long conversation with a very established Camera Operator about using S16 format lenses vs 35mm format lenses on Super 16. (Generally speaking on S16, you'd use 35mm format lenses above 25mm, but Super 16s for 9.5, 12, 16 and 25).

For some reason, the DP on this job had specified both S16 and 35mm format 25mm lenses. It was a commercial ...

I spent most of the conversation trying to persuade the Operator that the field of view of a 25mm S16 lens was the same as the field of view of a 25mm 35mm lens on a Super 16 camera. My argument basically consisted of me saying '25mm is 25mm' quite a lot.

He didn't believe me and dismissed what I was saying as I was only the Clapper Loader.

So I shot a test and eventually he shut up.
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simonkn

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Re: BMCC M43 - There *is* a reduction in crop factor after a

PostSun Sep 16, 2012 2:46 pm

claimsfour wrote:
simonkn wrote:But its in the suppliers/dealers interests to sell more units therefore do the test.. I have a sneaking suspicion that BMD will still sell the cameras... to idiots like me..
SK


When it comes to camera tests: dpreview.com/Adam Wilt quickly come to mind as 'just the facts' sort
of reviewers who will push a camera to the very bitter end.


As i don't know about dpreview.com... which camera manufacturer do they work for?


claimsfour wrote:oh...the Beeb...


I'm sorry but i find your above comment offensive. Why would you have distaste for the organisation that put moving images into homes back when your father was a small boy?
Please stop filling these pages with repetitive diatribe. WAIT for the camera to be widely available. Every Tom, Dick and Harry will have a review/test/theory. Pick one that suits you and decide if you want the camera.

Please stop telling everyone else what to do in order to satisfy your lust for knowledge.
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Re: BMCC M43 - There *is* a reduction in crop factor after a

PostSun Sep 16, 2012 3:17 pm

claimsfour wrote: Just like how we didn't need to 'see a test' over BM Green screen...and when we finally did,
we all had a collective gasp in horror.

did you gasp at how poorly it was shot, that it was out of focus, or how poor the key was?

explain again how it's incumbent on the *manufacturer* to provide tests that meet your requirements? And they're going to do this, and go out of their way, to sell you a $3K camera?

Here's how it works. They make the gear. You research the gear. If it's what you want, you buy the gear.

Hey BMD, aren't you glad you priced this camera so low? No good deed goes unpunished, eh?
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Re: BMCC M43 - There *is* a reduction in crop factor after a

PostSun Sep 16, 2012 5:34 pm

I just finish to listen at the video!
The bmc rep is clear : not double the angle!

So what i understand and what make sense for me
Is that mft lens are designed to smalk sensor

So a mft 24mm lens mounted on the bmcc
Will give me the same final image than
A 24mm full frame lens mounted on a 5d

I'm not talking about crop sensor because the sensor is the same size

Small rear lens give small images that fit for small sensor
Maybe i' completly off rhe track but this is what i understand in this video
And it's fit my way to wanting aps-c lens

I agree with those who want a simple test!!
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Mark Wilhelm

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Re: BMCC M43 - There *is* a reduction in crop factor after a

PostSun Sep 16, 2012 8:06 pm

Ladies and gentlemen, please. Let's keep this discussion civil until a developer drops in to clarify.

Also, folks not using their real name as their user name here should go fix that in their user control panel.
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Nick Bedford

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Re: BMCC M43 - There *is* a reduction in crop factor after a

PostSun Sep 16, 2012 10:10 pm

Repeat with me... There is no change in crop factor.

There is no change in crop factor.
The sensors are the same size.
The lenses are the same focal length.
The mounts are different to accommodate different lenses.
You are completely misguided to think you are somehow uncovering some conspiracy.

Focal length + sensor size = a field of view.
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Kristian Lam

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Re: BMCC M43 - There *is* a reduction in crop factor after a

PostSun Sep 16, 2012 10:12 pm

Hi,

There is no change in the active sensor imaging area between the EF version and the MFT version of the Blackmagic Cinema Camera so the crop factor still remains the same.

Also, let's have some civility in our discussions. I'm locking this thread as I have answered the question. Please free feel to start another topic if you have any further questions. Thanks.

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