Letus Extreme Resolution Chart

Luis Caffesse

Luis Caffesse

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Thanks to the graciousness of a DVXUser member, I was able to borrow a LetusExtreme yesterday for testing
(to see if I wanted to rent it for a project I have coming up).

Only having it for 24 hours, and it being rainy here, my options on what to shoot were a bit limited.
First thing I did when I got home was shoot some standard backyard footage, dogs running around, then some interiors of my housel.
I have to say, the stuff looked great.

After doing a decent amount of shooting - I figured I would do something for my own curiousity that I hadn't seen posted here before -
and that was shoot a res chart.

So here it is:

Stock HVX Chart
Letus Extreme Chart

(These grabs are about 2mb each)

Shot using a Zeiss 50mm f1.4
The HVX was left at the same zoom setting and moved to frame the chart.
Personally, I think the Letus held up pretty damn well.


EDITED TO ADD:
Oh yeah - and I have to be honest, I completely expected this thing to lose alot more light than what has been mentioned online... mainly because I didn't think it was possible that it would lose less than 1 stop.
Well, it is possible... I would estimate the light loss somewhere around 3/4 of a stop, maybe a little bit more.
Not having a light meter, I just used the exposure on the HVX w/ zebras.

I should be able to also get a RR and possibly a Brevis for testing sometime soon.
Too bad I couldn't get all 3 at once.
 
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With the LEX it seems pretty soft or out of focus.. is that just how much softer it is using a 35mm adapter?
 
It's in focus - double and triple checked it - and in fact shot it multiple times just to make sure.

Given that by their very nature adapters diffuse the image, a certain amount of softness is to be expected.
If they didn't diffuse the image, there wouldn't be an image on the ground glass to record.

Personally I think the Letus held up really well.
A little soft in the corners, which I'd be willing to bet we'll see on all adapters...but the center is crisper than I thought it would be.

Of course none of this really matters much - the footage looked great.
While stock HVX footage might be sharper, I can't possibly look at my side by side footage and say that I think the stock HVX footage looks better to my eye.

Everything we do is a compromise - and I just shot this chart to see what exactly I would be compromising to get shallower depth of field. When you weigh the softness against the image you get - I think its a compromise that is well worth it.
I honestly thought I'd see more of a hit in resolution loss.
 
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Zeiss 50mm at f1.4

I suppose had I set it to 2.8 you might see it being slightly sharper.
But I'm pretty sure the softness we're seeing is the diffusion from the GG, not a lack of sharpness from the lens itself.

I'd do it again at various Fstops but I literally just got home from dropping the whole rig back off to its rightful owner.
Well, that and I don't know that its really worth the trouble.
:)
 
Sorry Zeiss, yes.

If you get a chance to do it again can ya do it at different stops by chance? I'm wondering if that Planar lens is even worth it. It honestly looks like lens softness to me but you're probably right.
 
I won't get another chance until January sometime - if I wind up renting this same kit to shoot with. If I get it, then I'll go ahead and do that.

This is exactly what makes it so tough to properly test these things...
In an ideal world I'd have some sort of Nikon mount adapter on my HVX - so I could shoot through the Zeiss without the adapter and take that factor out of the equation.

Of course, that would be ridiculous....but it would make for a more controlled test.
 
if someone gets a chance to do a rez chart with the canon a1 please do so.it seems that the canon a1 and letus ex makes a pretty substancial sharper image,so much so that when i would use a nikon 105mm i've found myself dialing back the detail on my canon a1 just to soften it a bit.personaly i want my image a tad softer but at the same time i'd like to have the detail to start out with,and with the a1 and letus ex you have more than enough to play with.
 
The f-stop of the lens makes a big difference; most reviews of the Zeiss ZF series say that the 50mm needs to be stopped down to at least f/2 before it starts to really shine, and by the time you get to 2.8 or 4 it excels. If you want to test the sharpness of the adapter you have to do so with the lens performing optimally -- i.e., you have to remove the variable of lens performance so that you isolate your tested scenario to only one element, the adapter itself.
 
Well, unfortunately we'll never be able to completely remove the variable of the lens - but shooting at the given lens' peak performance setting woudl have definitely been the best approach.

Like I said, if I get my hands on that setup again I'll do it at f2.8 and f4.

Either way - I thought the Letus performed rather well.
I'm still surprised that it lost less than a stop of light, and the footage looks good.
 
I'd say the performance of the Letus is excellent! The Zeiss is a pretty good lens, but sharpness is going to suffer wide open--especially at the corners. Take a look at the following MTF chart and you can see that the resolution improves a lot by f/2.8.

http://www.photozone.de/8Reviews/lenses/zeiss_zf_50_14/index.htm

So the Letus is doing a superb job, considering you're placing a second optical system in front of the lens and shooting wide open. The biggest differnce is in the corners and I'd predict much of that is due to resolution loss by the Zeiss 50 @ 1.4.
 
Thanks for that link Barry, that's some great information
Looks like f4 is the stop to shoot for if I get a chance to do this again.

Though honestly, I don't see a reason to ... but, if I get a chance I'll do it.
 
Thanks for doing the test Luis. Your grabs confirm the progress that's been made in these adapters. Taken in context, I think the chart shows that the resolution loss from the adapter itself is minor.
 
Barry_S said:
Thanks for doing the test Luis. Your grabs confirm the progress that's been made in these adapters. Taken in context, I think the chart shows that the resolution loss from the adapter itself is minor.
Click to expand...

And again (i know i sound like a broken record) not only is the resolution loss minor, but the light loss, while obviously there, is something that can easily be dealt with. No longer the 2 stops or so these adapters had in the beginning (meaning past adapters from various manufacturers, not the Letus specifically).

No doubt, these adapters have come a long way in a short time.
 
I'm not the expert here by any means (yet!) but those Letus images look seriously soft around the edges. The numbers "16:9" in each corner are wicked blurry. It's much better in the center, but for me, unacceptable at the corners.

I too wonder about the Zeiss's f-stop. Wide open might be contributing a lot to the problem.
 
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I get the feeling that we're still going to see future improvements, but they'll be very incremental--at least in terms of image quality.
 
Ted Spencer said:
I too wonder about the Zeiss's f-stop. Wide open might be contributing a lot to the problem.
Click to expand...

Read Barry's post at the top of the page, and check out the link.
I think much of that is the lens.

I'll tell you this by the way, everything I shot yesterday (most of which was done at f1.4) was not only usable to my eye, but looked better than my stock HVX footage, no contest. What might look unacceptable on a res chart was not even noticable in a moving image.
 
While the lens is going to be sharper at f4, the test Luis did is a better PRACTICAL test, because if you're using the adapter, you're going for shallow DOF, and you're going to want to shoot wide open. It would be nice to confirm that it's sharper at f4 (and I'm sure it is), but these tests show what you can expect under REAL use conditions. You might use the Zeiss f1.4 at f2.0, but many other lenses that people use aren't going be that fast, and I'd guess that *most* adapter stuff is/will be shot wide open, so you can expect a little edge softness with most lenses--but I think, other than with a rez chart, it's not going be detectable 99% of the time.
 
Dan Vance said:
While the lens is going to be sharper at f4, the test Luis did is a better PRACTICAL test, because if you're using the adapter, you're going for shallow DOF, and you're going to want to shoot wide open. It would be nice to confirm that it's sharper at f4 (and I'm sure it is), but these tests show what you can expect under REAL use conditions. You might use the Zeiss f1.4 at f2.0, but many other lenses that people use aren't going be that fast, and I'd guess that *most* adapter stuff is/will be shot wide open, so you can expect a little edge softness with most lenses--but I think, other than with a rez chart, it's not going be detectable 99% of the time.
Click to expand...

I'm not sure if shooting wide open is practical in a situation where you can control it. F4 is STILL shallow enough to achieve a great amount of selective focus.

From what's been told around this section of the forum, most of us are using lenses at 2.8 and up. That's probably the most common stop.
 
Dan Vance said:
While the lens is going to be sharper at f4, the test Luis did is a better PRACTICAL test, because if you're using the adapter, you're going for shallow DOF, and you're going to want to shoot wide open. It would be nice to confirm that it's sharper at f4 (and I'm sure it is), but these tests show what you can expect under REAL use conditions. You might use the Zeiss f1.4 at f2.0, but many other lenses that people use aren't going be that fast, and I'd guess that *most* adapter stuff is/will be shot wide open, so you can expect a little edge softness with most lenses--but I think, other than with a rez chart, it's not going be detectable 99% of the time.
Click to expand...


..i have to disagree with this. while people do use adaptors to get 35mm film DOF that does not mean that they should or do shoot wide open all the time to get the shallowest DOF at any possible moment. if you really want good 35mm images your going to shoot at the optimal settings for lense sharpness and clarity while getting decent exposure, just like everyone shooting 35mm film does. the DOF just falls where it does naturally unless you have some real reason to manipulate it further one way or the other, and lense length/reframe would be my first choice to shallow it up or deepen it naturally rather than losing image sharpness by opening the lense up more, or losing natural DOF by closing the lense more. of course a little bit of either is fine as long as expoasure is still good, but shooting wide open all the time really isnt "real" conditions unless you want unusually soft backgrounds/forgrounds and subjects that fall in and out of focus. in my opinion thats mostly just a newb to 35mm thing because they are so concerned with getting the shallowest possible DOF thinking that somehow its going to look more filmic when in fact it just results in "artistically" super shallow DOF shots that are not any more "filmic" then the super crisp wide panoramas they could acheive without an adaptor.
 
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