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05-31-2011, 12:45 AM - 1 Like   #1
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k-r moon shots on tripod - too blurry?

Greetings gents!

Here are 2 shots of the moon (plain as possible, nothing fancy), 2nd one is a crop.

I made the shots with my k-r using a regular, no-name tripod but with a build quality well above most no-names.

My question is: Aren't these shots (i have several others, all of them with the same level of sharpness) too blurry, lacking a lot in sharpness?

Is this a normal output for a moon shot image with no extra post-processing?

Might this be because of the mirror-up vibration? Is there a way to avoid this?

I know for this kind of photography there are a lot of variables, residual city light, tripod vibration (isn't the case here, i've used 1/60 shutter speed), but, in the end, i guess i hoped for more sharpness.

Exif info:
Pentax k-r, on tripod, 2 sec. delay timer, no SR
55-300 mm DAL
300 mm focal distance
f/8, 1/80 sec
metering mode: pattern

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PENTAX K-r  Photo 

Last edited by Penumbra; 05-31-2011 at 12:47 AM. Reason: exif info
05-31-2011, 12:58 AM   #2
Ash
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There's significant chromatic aberration and some softness, not unusual for a heavy crop from this lens.
What else that could be causing the slight softness is focusing inaccuracies and wind slightly moving the camera during the exposure (1/80 sounds short, but lots can happen in that time )
05-31-2011, 01:24 AM   #3
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Keep in mind that the moon is also moving fairly fast up there, even if it doesn't seem apparent. I recommend shooting at 1/250s to 1/500s for best results. You shouldn't be wide-open, but F6.7 or F8 should probably get the job done.

One of my best shots was taken at 1/1000s, F4.5 (stopped down from 2.8), ISO 100, although it's not perfect. A slower shutter speed even with a teleconverter would have probably made this result even better:

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05-31-2011, 03:11 AM   #4
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Thank you, gentlemen!

I will do some more tests and see if i can get better results. I think i had some shots with manual focus as well, those shots were taken some 1 month ago and didn't keep them all.

Side question regarding this: In photo magazine with tests of various lenses i see better resolutions of the image with manual focus than those with autofocus (sometimes by a considerable margin 10-15-20%). I hope this isn't a naive question but i thought that (aside from low light or difficult contrast/shapes), when it is achieved, autofocus should be at least the same as manual in terms of resolution. How come the resolution is different?

On the other hand, is there a noticeable blur caused by the mirror going up vibration on tripod shots when the SR is turned off?

I remember reading about some DSLRs that have a mirror up followed by a latency to allow vibrations to settle, but i don't think the k-r has this (or it has it, only in bulb mode? - haven't used bulb yet)

Would one, in these delicate situations, see better results with a remote control than with, let's say, the 12 sec delay shutter?

Adam, your photo of the moon, bw nicer contrast aside, looks much crisper, i don't know if you remember having any sharpness adjustments settings in camera for it? +1, +2 or more maybe?

Lastly, there was no wind, the picture was taken with the tripod on my desk, in my room, through the open window. Hmm, first thing i'll try next is a faster shutter speed, see if anything changes!

Many thanks for your answers!

05-31-2011, 08:21 AM   #5
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I did this one handheld (1/320), but i pushed the iso a little.
Anyway, my copy of 55-300 get his maximun sharpness at f9 / f11, try that.


05-31-2011, 08:27 AM   #6
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QuoteOriginally posted by Penumbra Quote
Greetings gents!

Here are 2 shots of the moon (plain as possible, nothing fancy), 2nd one is a crop.

I made the shots with my k-r using a regular, no-name tripod but with a build quality well above most no-names.

My question is: Aren't these shots (i have several others, all of them with the same level of sharpness) too blurry, lacking a lot in sharpness?

Is this a normal output for a moon shot image with no extra post-processing?

Might this be because of the mirror-up vibration? Is there a way to avoid this?

I know for this kind of photography there are a lot of variables, residual city light, tripod vibration (isn't the case here, i've used 1/60 shutter speed), but, in the end, i guess i hoped for more sharpness.

Exif info:
Pentax k-r, on tripod, 2 sec. delay timer, no SR
55-300 mm DAL
300 mm focal distance
f/8, 1/80 sec
metering mode: pattern
You have some really clear craters in that crop which doesn't indicate there is much movement. To me, it looks a little underexposed.
05-31-2011, 11:02 AM   #7
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I got this one handheld with the DA L 55-300. 1/200s, 300mm. Not great, but I was happy with it. A pretty solid testament to the K-r's shake reduction. Adam's suggestions should help a lot.

05-31-2011, 11:57 AM   #8
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QuoteOriginally posted by Penumbra Quote
Side question regarding this: In photo magazine with tests of various lenses i see better resolutions of the image with manual focus than those with autofocus (sometimes by a considerable margin 10-15-20%).
Which magazine have you seen that posts side=by-comparisons with AF and MF on any sort of regular basis? And do they tell precisely on what spot they focused? I don't think I've ever seen a comparison that would allow anyone to draw any kind of conclusion about this.

But overall, MF gives you more control over exactly where the focus is. Not relevant in a moon shot, maybe, but in a portrait, if you want the eye versus the nose, or in a landscape, this branch versus that branch, etc.

On the other hand, is there a noticeable blur caused by the mirror going up vibration on tripod shots when the SR is turned off?

QuoteQuote:
I remember reading about some DSLRs that have a mirror up followed by a latency to allow vibrations to settle, but i don't think the k-r has this (or it has it, only in bulb mode? - haven't used bulb yet)
It does this in the timer mode. Definitely recommended.

06-01-2011, 12:58 PM - 1 Like   #9
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It is a myth that the moon moves so fast that you will need very short exposure times: The movement of the Moon relative to a point on the Earth is roughly 350 degrees per 24 hours. (Earth rotates 360 degrees in 24 hours and the Moon makes one turn around the Earth in opposite direction in 28 days).

Give and take a little adjustment for the Moon's position above or below the celestial equator, this relative movement corresponds to 0.004 degrees per second. With 300 mm FL that would "stretch" the image of the Moon by 0.02 mm each second on your sensor = a meager 4 pixels on a K-r sensor!

So, here you have a picture of the Moon taken with a K200D + Tamron 350 mm catadiotpric lens + two 2 X teleconverters in series. The whole setup was indeed mounted on a fairly flimsy tripod and the combination required exposure times longer than 1/15 sec. (We'll come to the details later):



The big difference here in sharpness is due to STACKING (here in Registax) of 8 images at 1/6 and 10 images at 1/15 sec. Too often, people do not take the atmospheric conditions into consideration. The air may look clear and transparent, but any turbulence will cause detail to smear out during exposure.

In that sense, shorter exposure times are better but for longer focal lenghts there is no real substitute to stacking. And preferrably a clear, calm sky. It may well be a bit windy, but not turbulent. Alas, I rarely have that and it was not the case for this image.

And finally and by all means: Do use delayed exposure with mirror lock-up. The vibrations caused by the mirror must die out first with these relatively long exposure times.
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