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Messages - faustino

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1
7.  A third wheel.  In manual mode, this would let you control exposure time, ISO, and aperture.  In the mode you described, this would control exposure time, aperture, and exposure compensation.  And so on.
Thanks for sharing your ideas.

A third wheel would be really useful I believe; the puzzle for Canon would be to review controls layout keeping current usability also when wearing gloves; anyhow, I believe they could make it.

I have seen that Sony is putting four wheels on their a7 and a7r cameras; one is dedicated to exposure compensation. Such wheel, and the low camera weight are the reasons I was considering buying an a7.

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Lenses / Re: cheap AF-S 55-250 STM sharper than L series AF 70-300 USM
« on: March 03, 2014, 03:51:10 PM »
For the most part, telephoto designs do not benefit from a smaller image circle (note that the 50-250 is not a true telephoto lens design).
Thank you! This is the information I was looking for. I still don't understand why telephoto designs do not benefit from a smaller image circle, but most probably such understanding would require too much technical know how in optics (maybe it is due to the fact that, for telephoto lenses, front elements are the "optical bottleneck").

Also, note that the combination of a the L lens with a FF body is much sharper.

Yes it is clear. The reasons for this are also quite easy to understand.
Thanks.

3
Lenses / Re: cheap AF-S 55-250 STM sharper than L series AF 70-300 USM
« on: March 03, 2014, 08:15:54 AM »
How sharp is it at f/4?  F/2.8?
Do you really think we didn't thought about that?
 8)


The comparison is between the 70-300 L and the 55-250. I believe it is surprising that the 55-250 is sharper at equal apertures and focal length, I really would like to understand why it is the case. Do you know why the 70-300 L is not as sharp as the lightweight 55-250 STM?

4
Lenses / Re: cheap AF-S 55-250 STM sharper than L series AF 70-300 USM
« on: March 02, 2014, 12:44:06 PM »
http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=856&Camera=736&FLI=4&API=1&LensComp=687&Sample=0&SampleComp=0&CameraComp=736&FLIComp=0&APIComp=0

The only problem with the comparison above is that it is not at the same aperture. The 55-250 is at f/5.6, while the 70-200 is at f2.8. Closing the 70-200 to f5.6, the image seems to get sharper than the 55-250, but just a little bit.

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Lenses / Re: cheap AF-S 55-250 STM sharper than L series AF 70-300 USM
« on: March 02, 2014, 12:30:25 PM »
It seems that, by designing lenses that cover a smaller image circle, just sufficient for APS-C sensors, Canon was able to increase sharpness.
I am wandering if they could further improve sharpness by designing pro APS-C lenses in super-telephoto focal length range (lets say 200-400mm).

I know the "reach advantage" of APS-C bodies is a myth based on wrong understandings. Anyhow, if Canon could further increase sharpness designing pro APS-C dedicated lenses, then the "reach advantage" could actually take a real life; don't you think so?

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Lenses / cheap AF-S 55-250 STM sharper than L series AF 70-300 USM
« on: March 01, 2014, 11:27:11 AM »
It seems, from the eyes of a 18 megapixel crop sensor, that cheap lenses designed for crop sensor are sharper than L series lenses designed for full frame cameras; I am getting to such a conclusion looking a the comparison from the link below:

http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=856&Camera=736&Sample=0&FLI=4&API=1&LensComp=738&CameraComp=736&SampleComp=0&FLIComp=3&APIComp=2

I understand there are other lens characteristics beside sharpness; in this specific case, on vignetting and distortion fields, the full frame lens wins hands down. Without mentioning flare, transmission, and the focus motor. If the plastic lens has a motor that can focus, in proportion, the USM lens has a motor that could move a truck.

Anyhow, it seems that to a crop sensor body, I would better couple an sf-s lens, rather than the full frame lens I already own. I would both reduce my bag weight, and get "better" image quality (somewhat).

7
Often I read about the fact that Canon is not innovating their cameras, despite Canon being listed among the most innovating companies out there.

From such readings, I start wandering about how could Canon actually improve the EOS line, and would like to ask your opinion. What would you suggest to change, especially in EOS pro bodies (and maybe pro lenses)?

I am asking the question mainly for curiosity, and also because I have my own wish list of new features, twists and new products; maybe you can explain why my personal wishes actually won’t work.

The changes I would love to be implemented are, for instance:

1. Firmware changes (low implementation cost):
I would like a mode where I could set Aperture and Time - essentially a manual mode, and, instead of ISO, I would like to set exposure compensation; the camera should be able to set automatically the ISO in order to over or under expose according to my setting.
In such a special mode, I would change Aperture with the main dial, Time with the main dial keeping pressed the SET button on the rear dial, and exposure compensation with the rear dial (permutation of functions may be also possible).

2. Physical changes (medium implementation cost):
From the 5d line, I would disintegrate the mode dial. I would change modes by keeping pressed a button while turning the dial. I would also display the mode in the viewfinder (I know I am asking too much here, mode visible in the viewfinder is a feature differentiating the 1 series).

3. New product (high implementation cost and risky):
I would make a special version of one pro body and some selected lenses: I would use structural aerospace grade carbon fiber composites (impregnated fiber or pre-preg) for lenses and camera body chassis. The internal optical formula and the electronics would remain the same, as in the “low cost” version. We would have a 600mm f4 “low cost” at 10k€, and a 600mm f4 CFC at ??k€. I am sure Nasa would seriously give a hard look at such gears for their next shipment to the ISS. I know some who would buy a 10k€ 1dxCarbon and a 20k€ 600mmf4Carbon.
What do you think? Is really Canon not innovating enough?

Thanks!

8
==> The advantage of crop camera would be only in pixel count, which is a questionable advantage.

Questionable how?  Not from the standpoint of putting pixels on the subject.  50MP vs. 22 is quite a difference.

I agree, it is not that much questionable. I changed my mind about this specific point, and changed my previous post accordingly.

There is only one consideration about pixel count that I believe should be taken in account:
at higher ISO, considering current sensor technology, lower pixel count sensors produce better images than higher pixel count sensors.

True, but we're talking about macro here where tripods and low ISO are the order of the day. At ISO 100 I'm very happy with the IQ of the 15MPx covering the subject from my 50D at 100mm, and the extra working distance compared to my 6D is extremely helpful when shooting critters and flowers.

I agree about low ISO being the order of the day, also because, most probably, flashes are engaged beside good tripods.

My understanding is that the advantage of todays camera crop sensors is only pixel density (beside price, weight, and swivel screens). Right?

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==> The advantage of crop camera would be only in pixel count, which is a questionable advantage.

Questionable how?  Not from the standpoint of putting pixels on the subject.  50MP vs. 22 is quite a difference.

I agree, it is not that much questionable. I changed my mind about this specific point, and changed my previous post accordingly.

There is only one consideration about pixel count that I believe should be taken in account:
at higher ISO, considering current sensor technology, lower pixel count sensors produce better images than higher pixel count sensors.

10
I would like to thank you all for your replies.

At this point I feel the duty to summarize my learnings from your posts:

For macro photography, there are two meaningful ways to compare crop vs. full frame sensors:

1)
The comparison can be made trying to achieve the same image in terms of perspective and depth of field.
* In order to get the same image in terms of perspective (related to distance) and framing, the smaller sensor shall be coupled with a shorter lens. If we put a 100mm lens on the full frame, something in the range of 60mm lens should be mounted on the crop sensor camera (assuming a 1.6 crop factor).
* In order to get the same depth of field, the aperture on the full frame camera shall be roughly one stop smaller. The smaller aperture would loose one stop of light, that would be compensated by the "one stop higher" light gathering capacity of full frame sensors.
* Identical framing is achieved with the same distance to the subject.
==> In such first comparison the output from the two setup is theoretically very similar. Anyhow, in practice, as pointed out by Neuro and proved by Mackguyver, the image from the full frame sensor would be visibly sharper. Since there is a proof, I would say this conclusion is incontrovertible.

2)
The comparison can be made keeping the same lens on both full frame and crop camera.
In this case the distance to the subject can be either be selected to be the same (2.1), or we can move the crop camera further away (2.2) to get some sort of "same composition" (will never be the same composition because perspective would be different)

2.1) keeping the same distance:
The crop sensor would capture exactly the same image that would be obtained from the full frame sensor cropping in post production.
==> The advantage of crop camera would be in pixel count, allowing more latitude for further cropping (if ISO is not pushed up too much) - as Neuro was writing elsewhere, the subject image is captured with more pixels.
==> The advantage of the full frame would be a larger angle of view, which is potentially important for multiple reasons (e.g. easiness of composition)

2.2) moving the crop camera further away from the subject.
Such scenario would could be considered less important; a full frame owner could move his camera further away as well, then crop in post production, and get the same image that could be obtained by an APS-C camera owner (except from pixel count).

In this latter scenario (2.1 and 2.2), the crop camera have actually the advantage of capturing the same cropped image that a full frame camera can capture, but with more pixels (usually it is the case with current cameras, may not be true with future cameras). This is unquestionable an advantage, if the ISO is "low". It is not and advantage, and can be a disadvantage, if the ISO needs to be pushed up.

Besides the above, there are some advantages of current crop cameras that I am not considering, e.g. swivel screen, weight, and some sort of better autofocus (7d coupled with 100mm f2.8L IS USM).

12
What about the previous comparison I was suggesting?

Which setup would give a better image?
- Crop sensor setup: EOS 7d + EF-S 60mm f2.8 Macro USM @f/8 aperture shooting from 10cm
- Full frame sensor setup: EOS 1dx + EF 100mm f/2.8L Macro IS USM @f/11 aperture shooting from 10 cm

Or would it be a tie? My understanding is that it would more or less be a tie.

Thanks,
Fausto

13
Take the argument to the extreme and consider something like and iphone 5s. It has a tiny sensor so everything is always in focus. But it still has an f2 lens in terms of light transition. So sometimes I can get a better macro shot in low light on my 5s than I could on my 5d mk iii. Because to get an equivalent depth of field I'd have to stop down to f18 which would push up the ISO to extreme.

Well... I have seen people taking better pictures with their iPhone than I with my 5dmk3 + a bunch of L series lenses. Though, I have to candidly admit, the problem was not in the reflex; rather, it was located few centimeters behind the viewfinder.
 :-[

14
Thank you for your super quick replies.
I have only one additional question, probably redundant, to be sure my understanding is correct:

Shooting the same subject at the same distance with the following setups, Will I get the same image in terms of quality, perspective, and DoF (more or less)?
- Crop sensor setup: EOS 7d + EF-S 60mm f2.8 Macro USM @f/8 aperture
- Full frame sensor setup: EOS 1dx + EF 100mm f/2.8L Macro IS USM @f/11 aperture

If yes, then there would be no technical advantage of one setup over the other, except weight in favor of the crop setup, and flexibility in favor of the full frame setup (e.g. 1dx + 100mm used @f2.8 for portrait, combination that would not give the same result with the crop setup).



15
Many people claim that cropped sensors are actually better than full frame and larger sensors for macro applications.
Here is an example:
http://www.43rumors.com/micro-four-thirds-and-macro-photography-by-eugene-kitsios/

Their argument is that for macro photography DoF is the limiting factor. They say that to get the same DoF, the larger the sensor, the smaller the aperture needs to be, which would offsett the light gathering capacity of larger sensors.

As an example, if we compare full frame vs. 4/3 sensors:
- full frame is roughly four times larger than 4/3 (measuring the surface), thus has virtually a two stop advantage in terms of light gathering capacity;
- anyhow, if with four thirds sensor we need to close the aperture to f/8, then on a full frame sensor we would need to close the aperture at f16 to get the same DoF, thus loosing two stop of light (offsetting completely the larger sensor advantage).
I am not sure if the second point is correct. The comparison shall be done considering different lenses on the two systems:
- if we use a 50mm macro on the 4/3 sensor, for correct comparison (to get the same angle of view), a 100mm lens should be used on the full frame (I know there would be slight differences in the final image due to the different aspect ratio).

I am skeptical about the above argument, anyhow I am unable to tell why it would be wrong.
What do you think, is really a crop sensor better than full frame for macro photography? Or is the full frame better? In the latter case, can you explain why?

Thanks!
Fausto

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