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Messages - MintMark

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1
Do you think you'd like to try a tracking mount? That, with image stacking, would allow you to do longer exposures and lower ISOs (or smaller apertures) for a less noisy result.


Can't see how that would work.  The camera needs to be fixed or the landscape foreground will move.  Longer exposures, including exposure stacking would give star trails, which would ruin this lovely photo.

A great shot, well composed with the foreground.  For my personal taste, I would reduce the exposure a little.  I use a Samyang 14/2.8 on my 5DII wide open for 30sec at ISO 3200 for Milky Way photos.

I was thinking of the milky way as the subject and willing to sacrifice the landscape in the foreground... it would get blurred away.

Sorry for the confusion... tell you what let's compromise, the OP could do a timelapse :)

2
Really interesting comparisons... thanks for posting them. Not many places compare lenses for coma in the corners.
Lenstip.com is the only one I know.

Do you think you'd like to try a tracking mount? That, with image stacking, would allow you to do longer exposures and lower ISOs (or smaller apertures) for a less noisy result.

Thanks again for all your effort... amazing skies!

  Mark

3

That got me thinking.

Stills lenses often suffer from focus breathing, while - so I've read - cinema lenses do not. Do Canon cinema lenses focus breath? Does Canon repack optics from EF lenses that do not focus breath? Does it fix the design to prevent focus breathing?

The press release says

Quote
The Canon line of Cinema prime lenses is precision-matched for consistent and solid optical performance throughout the line, and the inner focus mechanism helps minimize focus-induced changes in the angle of view.

4
Each light frame you take contains the scene, some hot pixels (fixed noise) and some random noise.
Each dark frame the camera takes has no scene (darkness), the same hot pixels and different random noise.
When the dark frame is subtracted the hot pixels are removed but the random noise gets worse because it is different in the light and dark frame, but the same 'strength'.

Astro photographers take many dark frames and average them together... this forms a master dark frame that has the hot pixels (that were in every dark frame) and much less random noise (it's variation reduces as you average more examples together). Now if you subtract the master dark frame from each light frame you can remove the hot pixels without adding much more random noise.

Hope that helps,

5
EOS Bodies / Re: 6D Autofocus not impressive
« on: March 26, 2013, 06:20:14 PM »

There still is no (zero, 0) full cross point at all @f2.8 (only @f4+), so precision with fast lenses esp. on moving objects should be very bad.


I think that's a little harsh. With a faster lens you do still have the centre cross point... it's just no more accurate than with a slower lens. However, I understand that it is designed to calculate focus to within one depth of field. Since depth of field is shallower it means the focussing is more accurate in absolute terms. Also, the 6d centre point does become more accurate in one direction, so if your scene accommodates that then you get focus to within a third of the depth of field.

6
Landscape / Re: Need some advice & guidance about night/astrophotography
« on: February 16, 2013, 09:42:53 AM »
Another good "sky simulator" is http://www.stellarium.org/... it can show you the constellations and the milky way (and loads of other objects) for any time of night at whatever location you put in, past, present and future.

You'll see that some parts of the milky way are brighter than others (brighter looking to the centre of the galaxy, near sagittarius), so if you can see that it's a good target. To capture a given view you have some flexibility... you can select a time of year and stay up until the right time of night or you can select a time of night and wait for the right time of year... whatever fits your schedule. You might also want it in a particular area of the sky... for example, away from a distant town's light glow, or overhead where's there's less atmosphere in the way. A little planning can help a lot. For me August is milky way time.

Everything that noisejammer said is true... and there's loads of information about on the web.

7
Thank you for replying. I have seen those comparisons before but I'm not sure I share the same conclusion.
Looking at the Siemens star in the centre of the dpreview scene at various ISOs, it's hard for me to see a difference in resolution between the 6D and the 5D3. Especially at high ISO, the colour blotches obscure the fine detail for both cameras. At low ISO they seem equivalent to me.

What makes you think Canon is applying noise reduction to the raw data?

8
I don't think that I ever said that you could "not tell anything about it".  I do question trying to make such a strong point that seems to contradict prevailing wisdom without more evidence to back it up...and I don't recall you ever actually quoting a source.

Well, you didn't ask for a source on any specific item yet :-) ... and sorry if I seemed to generalize your post, I was also commenting on various other past threads where the idea that you have to own something to be able to comment on it is often mentioned - so sorry for being too strong on this.


Can I ask about the 6D sharpness compared to the 5D3? Is it just the slightly higher pixel density of the 5D3 or do you think there is another factor in play?

Thanks,

  Mark

9
EOS Bodies / Re: Canon Confirms 70D; Future of Semi-Pro DSLR is FF
« on: February 01, 2013, 08:34:20 AM »
There is no reason not to have FF cameras except production cost. that will be solved in the future and hopefully all cameras will be FF. Tough i guess APS-C will still always be around. I mean "back in the days" everybody was fine with 35mm film also  :o

A good step Canon :P Just get 1.4TC for reach...

flawed logic.. you will always have more reach with a crop and a 1.4 TC. :)

and FF will always be more expensive to produce then APS-C, if the price difference matters is a different question.
but a FF sensors has a bigger surface.
so you could always produce more APS-C sensors then FF sensors on a wafer.

And you can always crop a larger image into a smaller image...

10
EOS Bodies / Re: Where are you EOS 70D?
« on: January 27, 2013, 11:08:57 AM »
Well, there's a 6D and a smartphone running EOS remote... but it's unwieldy if you're holding both of them.
Yeah...not to mention you lose the 1000-shot battery life advantage of having a DSLR.

I wonder... you will be using your wifi, but on the other hand your screen and its illumination will be off instead of on. I wonder which uses more energy and which contributes more heat and electrical noise inside the camera?

I like the thought that the screen on my 60D keeps the display hardware outside the body when I'm doing long exposure astro photos.

And speaking of weather sealing... what about the microphone holes?

11
EOS Bodies / Re: Where are you EOS 70D?
« on: January 26, 2013, 11:57:53 AM »
I dont care about how many pixels it has. Just improve high iso performance and dynamic range and I will buy it :)

You could get a full frame camera and crop the pictures to achieve that...

Very good comment... does any full frame camera have a swirvel screen?

Well, there's a 6D and a smartphone running EOS remote... but it's unwieldy if you're holding both of them.

12
EOS Bodies / Re: Where are you EOS 70D?
« on: January 24, 2013, 01:29:33 PM »
I dont care about how many pixels it has. Just improve high iso performance and dynamic range and I will buy it :)

You could get a full frame camera and crop the pictures to achieve that...

13
EOS Bodies - For Stills / Re: Thinking of downgrading my 5d3 system
« on: January 06, 2013, 04:55:59 AM »
Nobody else has suggested it yet... how about the 40mm pancake lens?

It's cheap, sharp and changes any DSLR into something more portable.

14
Lenses / Re: Educate me about why 70mm <> 70mm...
« on: January 06, 2013, 04:42:22 AM »
In both instances, the image on the lower pic is larger.  Did you measure from the focal plane of the camera?

This assumes some how that 70mm or any other focal length *must* have a certain framing...which may not be the case. The focal length designated might be just tied to the optical system...lets not forget these are multi lens designs.
So it may be perfectly ok to have slightly different FOV for a given focal length depending on the optical system.

As an anology, i am guessing (not certain) that  if one takes two refracting telescopes of exact same focal length but one scope has a larger objective say 100mm vs the other's 30 mm, in addition to their vastly different light gathering power, they may also frame the sky more or less, even though they have the same FL.

Hmmmm.... I think it's true that focal length, along with sensor size, is the very definition of angle of view (for a rectilinear lens)... http://en.wikipedia.org/wiki/Angle_of_view.

The other explanations seem more plausible to me.

15
Lenses / Re: Moving on from my 7D to 5D MK III 24-70mm, 24-105mm or prime
« on: December 30, 2012, 04:45:12 PM »
I believe the Tokina 11-16 will fit on a 5DIII and at 16mm it will not vignette. If you search you can find some images where people show how it works on full frame at each focal length.

OK... I just tried on my 6D, it works fine at 16mm. You have to take the lens hood off. It's very wide :)

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