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Messages - Marsu42

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1951
I suspect what Marsu42 is referring to is the decrease apparent aperture, the light loss you get as magnification increases.

Indeed, but it's not "apparent" but for real, unlike Nikon Canon just chose to hide the fact that a f2.8 lens @1:1 doesn't get f2.8 light through anymore... that's why the shutter speed gets longer like by black magic. I just read up about it again, it's called "effective f-stop": http://www.cambridgeincolour.com/tutorials/macro-lenses.htm

There's no 'magic number' for that, there's no 'macro mechanism'

Imho there is, it's the "extension" that only a real macro lens has.

At 0.2x mag you lose ~0.67-stops of light, at 0.5x mag you lose ~1.33-stops, and at 1x you lose ~2-stops.

Ah, thanks, that were exactly the numbers I was looking for. Now I'd only need to calculate how much effective f-stop difference there is for crop vs. ff for some scenes, but what you wrote indicates ff still has a slight advantage, though to a much smaller degree than at non-macro distances. But *plus* you still need a smaller aperture to get a usable dof, so that means even higher iso on ff for the same framing.

That, the dr loss at the higher iso for ff, the working distance & swivel screen still make me use the 60d :-)

1952
EOS Bodies - For Stills / Re: 7D vs. 70D: Which has better image quality?
« on: February 26, 2014, 01:17:08 AM »
Do you think that keeping my Sigma back a little at the 400mm level and increasing the ISO ( like 400-800) and aperture to f8 or narrower will offer me better clarity on the 70D body?

Nope, the lens is already outresolved esp. on crop, the tiny sensor difference will be lost. You'll get 2mp more of blur though :-p ... face it - there are no good and inexpensive 400-500mm tele zooms, it's better to crop a good 300mm. Btw all I can look at are the charts, and I don't see any reasons why the conclusion shouldn't be valid.

1953
People that think a crop camera gives you anything for free are sadly mistaken. You don't get "free" reach, dof, noise, or any other quantifiable image metric from using a crop camera.

I'd disagree in one select special case, and that happens to be a macro situation... but please correct me if I'm getting it wrong:

If you have the same framing on crop and ff, the ff nears to the subject (the famed working distance). If the crop is still outside the macro distance and can use the full aperture, and the ff is inside it (meaning the usable aperture drops to rock bottom) the ff needs to use a *higher* iso setting to get the *same* exposure - that's how macro lenses work if you increase magnification and the macro mechanism is engaged.

This effect means that depending on the lens-object distance, the crop camera has less noise disadvantage than usual, or it might even have an advantage - the latter is my personal, subjective experience and part of the reason why I'd prefer to shoot fireflies with crop.

1954
That's exactly what I'm saying - with the same focal length, aperture and subject distance, a crop sensor will have a shallower depth of field.  The 'deeper DoF with a crop sensor' applies only when considering the same framing

Good we have that sorted out :-) ... and I'm no way intervening between you and good ol' CarlTN, but I'd like to add that the thread title and op makes most sense when considering the same framing, i.e. /me shooting a live firefly with my 100L and getting the vf to match on 6d and 60d. In that case, I'd pick the 60d.

1955
EOS Bodies - For Stills / Re: 7D vs. 70D: Which has better image quality?
« on: February 25, 2014, 04:46:08 AM »
I'm just wondering if I should sell the Sigma to fund other lenses

Right, as you were talking of the long end (just read your post again) I have to correct myself: it doesn't look like the wide end is outresolved if stopped down to f8 and could be a *slight* improvement on 70d.

http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=683&Camera=453&Sample=0&FLI=0&API=0&LensComp=683&CameraComp=453&SampleComp=0&FLIComp=0&APIComp=2

But tbh the long end at 500m is extremely ultra-crappy, and an upgrade to 70d won't benefit you at all - so if you actually use it for tele shooting, do yourself a favor and buy a 70-300L, keeping your 550d.

http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=683&Camera=453&Sample=0&FLI=3&API=0&LensComp=738&CameraComp=453&SampleComp=1&FLIComp=4&APIComp=2

1956
EOS Bodies - For Stills / Re: 7D vs. 70D: Which has better image quality?
« on: February 25, 2014, 03:39:07 AM »
Just wondering if the very knowledgeable folks on here think that the new technology in the 70D would improve the lenses capabilities.

Yes, a bit, the 70d has a bit more resolution, a bit less weaker aa filter (= more sharpness) and a bit less iso noise (= more detail after noise reduction). But make no mistake, basically it's a wash, the 18mp sensor of your 550d isn't much different from Canon's latest incarnation... the worth of the 70d is elsewhere (better usability than Rebel, phase & lv af system, more fps).

1957
What do you think, is really a crop sensor better than full frame for macro photography?

Owning the ff 6d and the crop 60d I do think the latter is better for macro for various reasons, this is my practical experience and I'll keep around the 60d if even for macro alone.

1. Working distance on 100mm lens: If using artificial light or taking shots of something tiny that tends to fly, crawl or jump away this focal length on ff is rather short, I guess that's why they also offer a 180mm... or you put a tc on the lens, but the Kenko has issues with the newer camera's afma and lowers iq a bit.

2. Swivel screen, though that wasn't the question: Only the 60d/70d/Rebels have it, it's invaluable for tripod macro work, esp. when paired with Magic Lantern's focus peaking.

3. Last not least dof (you mentioned it): If you do focus stacking you'll use the lens' best aperture setting before diffraction is an issue, which means many more shots required on ff. If using handheld, a deeper dof = smaller aperture means higher iso, i.e. the iso advantage of ff diminishes.

What might not have been mentioned yet: With ff, you are more likely to run into the macro zone where the usable aperture drops, or the problem is more severe, so that even more (over-)compensates for the iso advantage of ff... the only redeeming fact is that you can better noise-reduce recent ff shots than crop, but still higher iso = less dr. All of the above us for usual firefly to butterfly shooting distances, not for extreme 1:1 which I seldom really require.

With a good lens like the 100L and the current crop resolution, the iq of the lens on crop is about the same as on ff... but of course ff shots have more postprocessing elasticity if you need that.

Speaking of AF, I sometimes wish Canon did trap focus.  I wonder if ML has that feature?

Yes, it does - move the camera until the phase af point detects af lock, then the camera automatically takes the picture. Very handy if you slowly move the lens forward with a fixed focus setting.

1958
No official release date has been given to any of Sigma’s distributors as of yet.

Let's donate and put the author out of his misery of writing these [CR1] - with a software rumor generator!

It selects one of the most wanted products [7d2|Sigma50|35L2|100-400L2|...] and automatically ties it to some random month in the near future [March|April|...]. It also has a "Spec-o-matic" feature filling in various properties of said products like price, fps and sensor resolution. The whole thing will free up much needed resources for maintaining the forum - I'd like an option to (un)subscribe threads w/o writing a post into them :-)

1959
EOS Bodies / Re: Full Frame Vs Crop Sensor
« on: February 24, 2014, 02:51:39 PM »
Nope. Don't have to agree.

+1, I'd like to add that every image from a *d*slr is already postprocessed, or you would see the pattern of the bayer sensor to begin with, so the image already is processed and lens/ca/exposure-"corrected".

Most important: The camera freezes motion that is a blur to your bare eye, has a depth of field characteristic alien to us  and presses a dynamic range you cannot see with the human eye at one time into one image. So why is a jpeg out of camera suddenly sacred and exempt from further modification?

1960
EOS Bodies / Re: Full Frame Vs Crop Sensor
« on: February 24, 2014, 01:54:41 PM »
There are those who read a manual from cover to cover before flipping the "on" switch. Then there are those who once they find the "on" switch, just jump in learning as they go.

Interesting enough it seems men are said to be the "just turn it on, change all options and see if it still works" type, while women are more likely to rtfm - but as we don't have any (or very few) women on tech internet forums, we wouldn't know about the latter :-p

1961
EOS Bodies / Re: Full Frame Vs Crop Sensor
« on: February 24, 2014, 12:00:30 PM »
To learn photography properly, you must shoot JPG, use only a 50mm lens, and stand on your left foot.  Any other handicaps you'd like to dump on students of the art?

Reminds me of the time when I was studying chemistry - we had to do test series with ~60 year old equipment, the swastikas and imperial insignias (nearly :-p)) still on them. The front argument: You gotta know the basics even though you'll never ever use them again, only then can you learn modern methods. The real background: The people in charge did it in their time, hated it like everybody else, so why lift the burden? Also never touch a running system :->

Back to the subject: For me, digital photography is knowing what you can easily "fix" in postprocessing, and what more severe problems you can work around if in a pinch for select shots. That lets me concentrate on the issues I have to get right while shooting.

1962
Videography Technique / Re: Canon EOS 6D Moire and Aliasing issues?
« on: February 24, 2014, 11:40:47 AM »
Howevever, as I have tested the 6D for a day, I can say, that Moire is not a big issue for stills.
No, really, use search :-p
If I understand you correctly, you are saying, that the 6D suffers from Moire with stills a lot, too? Really? I only had it for one day, and didn't run into such problems, but it may depend heavily on the subject...

Oh my, you really want me to use search for you? http://www.canonrumors.com/forum/index.php?topic=18987.msg360151#msg360151

... also read Rock Kenwell on d800 vs d800e: http://kenrockwell.com/nikon/d800/vs-d800e.htm

1963
EOS Bodies / Re: Full Frame Vs Crop Sensor
« on: February 24, 2014, 11:09:49 AM »
I understand perfectly, I just don't agree that it's a worthwhile endeavor.
No, you don't. But I understand perfectly ...  ;D

Oh no, I'm too late to the thread, it's already page 3 and the mudslinging has already started :-p

1964
EOS Bodies / Re: Full Frame Vs Crop Sensor
« on: February 24, 2014, 09:45:43 AM »
What you see on the LCD is the JPEG preview anyway, regardless of what file type you shoot. Therefore you could argue that you are always shooting JPEG in a sense.

Not quite, if you use Magic Lantern you get a real raw histogram + (even automatic) ettr to minimize noise.

Pretty much everything else can be regarded as minor or for pixel peepers only. If you're not making very large prints you can ignore lots of info :-)

I'd like to add one fact I completely missed before moving to ff, something that cannot be seen in sample images or charts: the bigger pixels of the current ff sensors provide more postprocessing elasticity, i.e. you can do much more with the shot before it falls apart like changing individual colors and also pushing shadows (esp. on 6d). Sharpening and nr also benefit a lot from the latest sensors (5d3/6d), I didn't try 70d for that though.

1965
Videography Technique / Re: Canon EOS 6D Moire and Aliasing issues?
« on: February 24, 2014, 07:52:48 AM »
Do you have a link or reference regarding the AA filter you mention?

Use search, there is a recent thread about this.

Howevever, as I have teste the 6D for a day, I can say, that Moire is not a big issue for stills.

No, really, use search :-p

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