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Discussion in 'Open Discussion' started by Phocal, Oct 29, 2015.
For what it's worth, there are 600mm f/8 lenses. Very lightweight and compact, clearly.
I think, realistically, the best system to compare to the E-M1 for telephoto would not be FF, but rather APS-C with the 7D II, which is weather sealed and retains the crop factor advantages.
So you'd be looking at:
7D II + grip + 400mm/f5.6 = $3000, 2.6 kg
E-M1 + grip + 300mm/f4 = ~$3500, 1.9kg
Given the sensor performance of the 7D II, you'd probably be behind in terms of equivalence vs. the faster E-M1. But you'd probably be ahead in terms of AF performance with the Canon, and the rest of the performance like burst rates are directly comparable. You will get slightly better resolution with the Canon, though it entirely depends on the aspect ratio of your final image. If you like 4:3, you're at 17.7MP, so the difference is totally negligible there.
So really, you're trading a moderate amount of money (17%) for a fairly significant weight savings (37%).
And for what it's worth, I strongly agree about stopping down telephoto lenses. I frequently shoot my 300mm lenses at f8-f11 on M4/3 to get better DoF.
I posted the 600/f8 with my tongue firmly in my cheek, just trying to lighten the mood a bit. It's some old Vivitar or Noflexar or something. I think it weighs about 2500 kg by itself, and in fact is not even a telephoto, strictly speaking, as it's a full 580mm long!
In any case, I agree with you on this. APS-C offers very little benefit in terms of image quality over M4/3, and in my personal view, you need to be something of a masochist to use long tele lenses on Full Frame. That, or you'd better hope that someone is paying you to break your back in order to justify it. But then again, I think all bird-in-flight photographers are masochists in the first place...
The reason FF and APS-C tend to be used interchangeably in these arguments is because they use lenses and mounts interchangeably with full functionality, that's all. Obviously the image quality benefits are nowhere near as large with APS-C, which is only modestly larger than M4/3. In Canon's case, their 1.6 crop sensor is 47% larger, and only 29% larger when cropped to a 4:3 aspect ratio...
Let's not forget the FZ300 from Panasonic.
691 grams. Weather-proof. 25-600mm equiv zoom. Constant f/2.8. Plenty of DOF. $600.
Maybe a slight trade off in IQ, but way easier to crawl through a swamp with to shoot those frogs and gators.
It is a pretty interesting comparison, really.
I wouldn't want to put the ISO anything above 400 on it, though. Some quick Sunny 16 math means you're at 1/800s (necessary for the long focal length) for ISO 400 and f/11 on a bright day, so for f2.8 you've got 4 stops of room to play with to deal with changing conditions. You might be able to shoot in overcast or some time after dawn/dusk, but it would be pretty dicey. And of course you're limited in resolution, especially if you need to crop at all.
How good is that lens when it's wide open?
The lens is the strength of the camera. I have not really seen a need to stop it down.
My post was half in jest, at least, but of course it really comes down to what you are doing with your images. If you are a pro or intend to print large then I think you need to use a different tool. But if pics are for fun, conditions are good from a light perspective, and you will mostly post on line or print smallish a superzoom can certainly be an option. I think the 4K photo setting would be interesting for wildlife as well.
I have that beast!
From what I have found out, it was made by Tokina and was sold as a Tele-Tokina and Vivitar. That is about all I have found online.
Equivalency debate centers around "FEAR" and it has been going on for ages. Fear from change and you will have militant people who would do anything to forcefully impose their will upon you and the masses. They do this because they are themselves fearful of their own insecurity in their own personal photography. In the old days, only view camera and medium format are "AUTHORIZED" by the landscape luddities to make landscape photos because of tradition (Ansel Adams made his mark with a 4x5 and fear). Anything less than tradition meant you sacrifice image quality. Then Galen Rowell came along and broke that tradition. Same with Vincent Versace when he started to represent Nikon when Nikon was just a small booth (the size of Olympus today) against the behemoth industry of medium format cameras like Rolleiflex, Hassy and the rest. Galen and Vincent and others who chose 135mm film and SLR bodies all had one thing in common. They all want to have a portable travel friendly system and 35mm SLR is much smaller and lighter than a Rolleiflex. And the lenses are much smaller compared to medium format. The debate then was no different than they are today -- aperture and light but revolves around film and lenses. It was just as nasty then as it is today. Well today, the debate takes on a new incumbent. Full frame vs APS/m43 and cell phones. The fear is still the same.
Every camera is a tool and the photographer chooses the tool based on what he or she needs to achieve whether it is a 300 f/4 lens or a 600 f/4, but the key is if you can achieve that with your equipment. Most of us who are deeply invested in m43 understood the balance m43 can deliver. But it is those who are not deeply committed into m43 and aren't sure of their own personal photography journey are the ones who are easily swayed by fear. They upgrade, then downgrade and go sideways.
I'm still not a fan of using crop factor on aperture measures, and it's especially pointless on a super tele lens.
Multiplying aperture by crop factor is a decent way to compare depth of field between systems, but it does not apply to exposure. With a super tele lens like a 300mm, creating shallow depth of field is neither (a) difficult, nor (b) especially desirable. It's light gathering that really matters at 300mm (or 600mm FF equivalent), as you need fast shutter speeds to negate vibration magnified that highly. And in this measure, f/4 is f/4.
Don't forget how much National Geographic photographers used 35mm. If it weren't for 35mm and Kodachrome, that mag wouldn't have been the same.
Wasn't it 10x8?
I think it's a reasonable approach if you concede that the FF camera will have zero improvement in image quality (and often a penalty). It just assumes that you're quadrupling ISO to compensate in the exposure.
In the real world, the very, very best FF sensors (A7r II and D750) have signal-to-noise performance about 1 2/3 stops better than M4/3. The average FF sensor is maybe 1 1/2 stops. The A7 II is perhaps even slightly less than that. So assuming a 2 stop improvement due to size is overly optimistic.
Equivalent apertures are an easy shorthand to get you in the right ballpark for estimation, but they don't tell anywhere near the full story.
To approximately match image quality and depth of field, you would need to use these settings for equivalence (as an example).
M4/3: f1.4 @ ISO 800
APS-C: f1.8 @ ISO 1250
FF: f2.8 @ ISO 3200
That's based on equivalence theory by surface area.
In reality with real sensors and cameras, you can only squeeze out ISO 2000-2500 on FF to match the image quality of ISO 800 on M4/3.
Yeah, IMHO, this is where crop factor goes far beyond usefulness and ventures into the realm of pointless squabbling. Crop factor is very useful for understanding field of view. Beyond that, I'm out.
I disagree completely.
I think that it's only pointless squabbling if people feel they have something to prove or they think that pointing out the value of another format / brand decreases the value of their preferred format / brand. All formats have different strengths, and none are unequivocally better than others. For those of us that use different formats, it's a useful shorthand. I find I end up defending both formats against different people depending on the discussion...
Understanding the relationship with image quality can also let you recognize when it simply doesn't make sense to try and use a larger format. If I need to stop down my 85mm/1.8 to f4 to get acceptable DoF, then why wouldn't I just take an M4/3 camera and shoot with a 45mm/1.8 wide open and shoot at 2 stops less ISO for the exact same image quality? By contrast, if I'm shooting environmental work and DoF isn't a limiting factor, then a 50mm/1.4 on FF can net me valuable noise and DR improvements over a 25mm/1.4 on M4/3.
With my film cameras, the math is a little bit trickier, since I think I can probably hand-hold my 6x7 leaf-shutter rangefinder at half the speed without getting mirror slap compared to my 35mm SLR, so the f3.5 maximum aperture isn't as huge a disadvantage, and the giant negative means that I can shoot with film that's twice the ISO and still have better quality. Like a rangefinder or a leaf-shutter, IBIS is a similarly disruptive technology that can change the math on what circumstances merit which format.
But anyway, I'm an industrial designer, so my art brain dances hand-in-hand with my engineering brain, and I'm actually interested in evaluating this stuff practically and objectively. If this isn't something that actually interests you, I heartily recommending just picking whichever camera makes you happy and shooting. It's the best policy.
To be clear, I think not that it's pointless to understand the differences between formats, but that using crop factor to get there is beyond the usefulness of crop factor.
RE: Depth of field, it's simpler to understand that depth of field is a product of focal length + aperture + distance to subject. And that a 25mm f/1.4 lens on Micro 4/3 won't give the same shallow depth of field as a 50mm f/1.4 lens on full frame because the focal length is shorter -- not because of the sensor size. Depth of field is an attribute of a lens, not a sensor, whereas field of view is a combination of lens + sensor.
RE: ISO noise, it's not an absolute value. ISO 400 is ISO 400 as far as exposure is concerned -- but the noise that you get from that ISO is a non-absolute metric that varies as technology improves, and as cameras trade priorities (e.g. resolution, price). The Sony A7s is a good example of why crop factor math on ISO noise is a sloppy metric. At high ISOs, it produces a better result than other cameras of the same format. And if Olympus / Panasonic don't move sensor technology forward, the gap gets wider than a 2x multiplication will calculate.
I get that using crop factor on aperture + ISO is a shortcut to roughly understanding differences between formats, but it's (1) at best imprecise, (2) suggests an effect on exposure calculations which is inaccurate, and (3) injects sensor size into calculations where sensor size is not actually a factor. If you're doing back-of-the-napkin math, sure, but it's not an accurate understanding of the components that contribute to a result.
I use an a7r2 and have used many m43 cameras in the past. Currently I only have an em5 with the 100-300 panasonic lens in order to have a nice compact tele kit. Equivalence is a good thing to understand but something that is being left out of the discussion is resolution.
M43 used to be about the same size file as my a7 or 5d3 but now with the a7r2 I can crop so much that it is negating the benefits of m43. I can use a 300f4 on my a7r2 and crop it to the equivalence of 600mm and still have as much resolution as m43 (possibly more).