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Messages - heptagon

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121
The lens is fairly new, I love it.  These are difficult shots due to the distance.
Reported Settings.  These are what is recorded in EXIF and, in the case of stacked TC's the f stop is wrong.  I used AV setting of f/11, but the aperture of the lens would have varied according to the TC with it being stopped down more without a TC
Also, it was a winter day and the light varied from shot to shot so the shutter speeds varied according to available light.
No TC  - 1/2500 sec f/11, ISO 800
1.4X - 1/3200 sec f/11 ISO 800
2X   - 1/3200 sec f/11 ISO 800
1.4 + 2X - 1/2000 sec f/11 ISO 800 (not the actual equivalent aperture)
It might be interesting to redo them with my 1D MK IV, but in our near 100 degree weather, the air is too turbulent, and the 1D MK IV is going to be sold soon.

Another thing is: Did you scale the images made with the TC or change the focal length? Comparing the length of the tower by hand doesn't give a magnification of 2x or 2.8x compared to the 1.4x (maybe this is also done on the webpage). I ask this because scaling images is also often problematic and there is quite some discussion on how you should scale the images in order to provide a "fair" comparison.

What we can conclude however is that taking images with a TC is much more complicated than using the bare lens.

122
Here are some images of Mount Spokane from my back deck for a comparison of my 100-400mmL at 400mm with 1D MK III and Canon TC mk II's.  I've cropped them all to the same view.  With no TC, thats 100% so the image is smaller. They have no post processing other than my lightroom defaults, so obviously they can be improved.

I feel that the 1.4X TC provided the best image, I tried to avoid any motion and used a heavy tripod with underweight, however, with the long TC's, there may have been some vibration, particularly with the 2X.  The top of the mountain is several miles away, so there is a lot of distortion coming from 7 miles of air.

Nice comparison. Could you also post the f-stops used or do you have a stopped down image of the 2x? In my experience the 2x "wide open" doesn't work very well.

Also i have the 2nd hand impression that there are old and new 100-400mm lenses which perform differently. So if you have an old one it wouldn't work as well.

123
2: you lose f-stops if you put on the TC. (The light gets distributed on an area 2 or 4 times as big, leading to 1 or 2 f-stops loss of light density on the sensor.)
Light density, yes, but not total light, so it's not so bad. For this reason, you can improve signal to noise and dynamic range with a TC compared to cropping since you can collect more photons from the same scene without saturating. (you could of course also take multiple exposures with the same result with the crop)
You can only win here if you increase the exposure time. In total you have more noise compared to cropping or using a camera with smaller pixels, but you also have more photons if you increase the exposure time to overcompensate for that and increase DR and SNR after downscaling.

124
Lenses / Re: Canon super tele choices!!!
« on: August 13, 2012, 03:46:19 AM »
Mainly for hockey, football, basketball and soccer. I already have the 70-200mm f2.8 so yea. Body I will be using will probably be a 1D IV I will use my 1Ds III if I have to...... ;)

How about an 1.4x extender to your 200mm and a 7D body for a start? Being able to carry the lens without Major Pain sitting on your shoulders is a big benefit in the field.

125
Hi,

I did a test once with my 70-200 4.0 L IS and a Canon EF 1.4x II converter. At 200mm, the image quality cropped (to approx. the same field of view) was better than the one with the converter. So no converter for me :)

Ray
Did you stop down to f/8 for taking the images? I have a 2x III extender on a 70-200mm L IS II and it is ok (not great but ok) when stepped down. However with increased focal length the exposure time also has to be shorter in order to avoid blur due to shake or movement of the object.

I heard a lot of diverging impressions from people using extenders. You definitely lose resolution and contrast when zoomed to 100% but you still usually gain in detail of a small subject and if you can't carry an additional long lens, the extender is better than cropping. Maybe the differing impressions are from people not adjusting for the longer focal length or due to manufacturing variations of the lenses which become obvious with the additional magnification.

126
1: your lens needs to outresolve the sensor at the longest focal range. If it doesn't you won't gain anything.

2: you lose f-stops if you put on the TC. (The light gets distributed on an area 2 or 4 times as big, leading to 1 or 2 f-stops loss of light density on the sensor.)

3: Your lens needs to be wide enough to still reach f/5.6 for autofocus. (Autofocus also gets slower with extender due to less light on the focusing mechanism. Low light performance is worse.)

4: you may want to stop down further to f/8 because that usually improves the image quality and resolution.

5: you may need a tripod because 800 mm focal length are hard to hand-hold.

Since you write about the 100-400mm lens on a 22MP FF-body, i assume that it would go well with the 1.4x extender since then the resolution matches a crop body with 18MP without extender. The 2x extender would most likely result in blurred images which don't provide more detail. Also the overall image quality reduces severely with 2x extenders. It's not just resolution but also contrast CA vignetting distortion etc.

What you could try is to use MF and shoot at F/8 without extender and if you can work with that, go for the 1.4x extender (or better yet get a used crop body, which equals to about 1.5x extension but with working AF and no f-stop loss).

EDIT: I may have misunderstood you. Decreasing the sensor size is always better than a TC. So a crop body with all other things equal will always be better. Unfortunately you also have to consider price, weight, different performance of different bodies, different noise characteristics etc... I for myself use a crop body + TC.

127
Third Party Manufacturers / Re: A Small Sigma 180 f/2.8 OS Macro Issue
« on: August 12, 2012, 04:48:36 PM »
As far as i know, some (all) lenses aren't identified in the EXIF-Data of the image by lens-ID but by parameters like aperture and focal length ranges. Programs have to sort out which lens it actually is from that data. This might be one of the causes for the problem and i don't know how it is done for new lenses.

128
Third Party Manufacturers / Re: A Small Sigma 180 f/2.8 OS Macro Issue
« on: August 12, 2012, 11:19:50 AM »
IMHO, the best solution for Canon would be to set aside a block of IDs for lenses by companies that reversed engineer the mount protocols, and not doing any lens specific processing for lenses that use an ID in that block.
This would be a very good idea for a start.

129
Third Party Manufacturers / Re: A Small Sigma 180 f/2.8 OS Macro Issue
« on: August 12, 2012, 06:42:20 AM »
So can we conclude that Canon lenses should be protected like printer ink (more expensive than blood). This can be done with a little security chip built into the lens which identifies it as a genuine Canon. From a certain date on e.g. 1/1/2014 all other lenses will be disabled or set to full manual (no aperture control). It's about time for Canon to step up to these product pirates!

130
Third Party Manufacturers / Re: A Small Sigma 180 f/2.8 OS Macro Issue
« on: August 11, 2012, 09:59:17 AM »
typicall for sigma.
you wonder if they have a quality management at all.

how can such an issue not be noticed and fixed when developing a lens?

This is NOT a Sigma problem.

It is a Canon problem.
You are very unfair and I totally disagree.

Canon's business is too sell Canon products, not Sigma or Tamron or any other brands.
When Sigma sells 1 lens, Canon does not receive any yen/dollar for that. Why should they care about them? Sigma should already feel happy that Canon doesn't try to definitely inactivate their reverse tech and making their products unusable --> end of business.

Does that then mean that you should buy Canon tripods, Canon monopods, Canon camera bags, etc?
Where do you draw the line?

Canon need to realise that it is the ecosystem around their products that keeps them alive.
If Canon makes a good lens, it will sell. If the competitor is better, Canon needs to "protect their market". If they fall behind not only in the Sensor development but also with the lenses, Canon will have a big problem, because then there's little reason to buy a Canon camera. The lens prices are still up and it's a good time to sell now.

131
Third Party Manufacturers / Re: A Small Sigma 180 f/2.8 OS Macro Issue
« on: August 11, 2012, 05:26:39 AM »
typicall for sigma.
you wonder if they have a quality management at all.

how can such an issue not be noticed and fixed when developing a lens?
Maybe because it is Canon who broke the compatibility?

132
Third Party Manufacturers / Re: A Small Sigma 180 f/2.8 OS Macro Issue
« on: August 11, 2012, 03:14:08 AM »
So Canon doesn't provide a proper way for other manufacturers to make EF lenses without paying horrendous licensing fees. Then it purpously breaks compatibility with existing 3rd party lenses with new bodies. That doesn't sound good to me. All Canon would have to provide would be a proper way to ID the lenses. A simple manufacturer ID + item ID would be sufficient.

133
Third Party Manufacturers / Re: A Small Sigma 180 f/2.8 OS Macro Issue
« on: August 10, 2012, 07:04:09 PM »
Why the heck are the new top line Canon cameras so broken?

134
Imagine a D800 with an EF lens mount released by Canon and called 8D. What would you think about it?

135

Generally speaking, if you want to criticise someone else's results of a scientific method then you do so by doing your own experiments that prove your point. And yes, I'm willing to bet that the method DxO use to generate the raw numbers that goes into those calculations and the method of arriving at the calculations in that table is a lot more scientific than the process of saying "That 0.0 is wrong and because that 0.0 is wrong all other results lack credibility."

A wrong answer on one calls every answer into question.  That is how a engineer views it.  And, I have done plenty of scientific reports for NASA.
The difference is that my reports were checked by a person, not just something kicked out by a formula in a spread sheet.  If the spread sheet calculated one wrong, its not up to me to verify all of them.
Yet the other datapoints LOOK good. Can we verify at least two cameras 5D3 and D800? Getting second opinions on them would be good.

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