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11-11-2010, 03:09 PM   #61
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Don't get to fall asleep =) DFS doubles the time of the exposure +/-.
Have a great time.


Last edited by Kenn100D; 11-11-2010 at 03:10 PM. Reason: spelling
11-11-2010, 03:21 PM   #62
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Please record your position long & lat and direction of camera. I would use about F8 for an hour exposure. Also I would recommend taking an equivalent 4min exposure at 1600 ISO*, so you can a, record the star field and b, check for high cloud which may not be obvious to the eye but could reduce the maximum exposure possible.

* based on an hour @ 100 ISO (couldn't find an online calculator that 80 ISO)
11-11-2010, 04:37 PM   #63
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QuoteOriginally posted by Col Quote
Please record your position long & lat and direction of camera. I would use about F8 for an hour exposure. Also I would recommend taking an equivalent 4min exposure at 1600 ISO*, so you can a, record the star field and b, check for high cloud which may not be obvious to the eye but could reduce the maximum exposure possible.

* based on an hour @ 100 ISO (couldn't find an online calculator that 80 ISO)
Doesn't quite work that way for stars - unless ISO is boosted equally to the amount of stopping down.
Time of exposure is *not* the determining factor for exposure of the stars - they move. So whether you have a 5 minute or a 5 hour exposure, as long as the rest of the scene has next to no light, the star trails will work out well exposed with the right aperture and sensitivity settings.

I have gotten consistently good exposures of star trails at f/5.6 ISO 200-250 on a *ist D/K10D.
11-11-2010, 04:47 PM   #64
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I'm not too concerned about the OPs successful recording of trials. But frequently you've not detected that there is a haze, which can limit the exposure duration. Hence, I normally take a shorter high ISO shot to "test the sky".

11-11-2010, 05:35 PM   #65
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I get what you mean Col.
I do that too, particularly for scenes I'm not sure will register too hot/cold on the final exposure from stray ambient lighting in the distance.
11-11-2010, 06:46 PM   #66
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QuoteOriginally posted by Raylon Quote
I am hoping someone can get some good shots of Jupiter with the K-5, just to see it's cropping power and IQ.
This is one of the first things i'm planning to do with my K-5 when i eventually buy it!

A few comments:

Firstly, is it true that the camera must be powered down to switch between grip and internal battery? If so, this won't help for long exposures!

Secondly, when you use the "long exposure NR" in-camera DFS, does it save the dark frame, or does it only put them together in-camera and give you a single output file? If so, wouldn't you be better off to take two exposures manually, so you can do the DFS in post-processing?

Finally, if you did want to make your own dark frame, would the lens cap really block out ALL the light? I know on some other cameras i've owned, the lens cap doesn't block out quite all the light. Multiply that by 100 minutes and you could get quite a spurious result!
11-11-2010, 07:36 PM   #67
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QuoteOriginally posted by Col Quote
Please record your position long & lat and direction of camera. I would use about F8 for an hour exposure. Also I would recommend taking an equivalent 4min exposure at 1600 ISO*,
I'd rather like to see the exact same parameters, just DFS enabled now.

BTW, the common wisdom no longer applies for the K-5. ISO 80 may be the new starry night setup. Because stars (especially if you compensate for earth's rotation) will always blow the highlights and the higher DR is highly welcome. The darker parts can probably still be boosted almost like at a higher iso setting. Of course, stacking still gives the ultimate DR anyway.

---------- Post added 11-12-10 at 04:38 AM ----------

QuoteOriginally posted by Raylon Quote
I am hoping someone can get some good shots of Jupiter with the K-5, just to see it's cropping power and IQ.
You know that Jupiter is best shot with a webcam, don't you? Serious comment.
11-11-2010, 07:50 PM   #68
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QuoteOriginally posted by falconeye Quote
You know that Jupiter is best shot with a webcam, don't you? Serious comment.
Webcam Astrophotography Tutorial for Planets

Interesting. But i don't have a telescope handy. I want to see what can be done with just a normal SLR telephoto lens..

QuoteOriginally posted by falconeye Quote
I'd rather like to see the exact same parameters, just DFS enabled now.
That is why i asked about whether in-camera DFS saves the dark frame separately. If the dark frame is done manually and subtraction is done in PP, we will be able to see an exact comparison between the original and the subtracted image - and be able to play with the subtraction process manually!

11-11-2010, 08:21 PM   #69
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QuoteOriginally posted by secateurs Quote
That is why i asked about whether in-camera DFS saves the dark frame separately. If the dark frame is done manually and subtraction is done in PP, we will be able to see an exact comparison between the original and the subtracted image - and be able to play with the subtraction process manually!
In-camera DFS doesn't save (or even cache) the dark frame.

But first we would have to verify that subtraction is all it does.
BTW, I noticed with the K-7 that the dark frame exposure time is slightly less than the prior exposure.
11-11-2010, 09:05 PM   #70
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Ok. Tonight was not a real success. I set the camera and took the exposure for an hour then stopped the exposure and the camera started a countdown doing it's DF thing. This lasted 90 minutes then the camera returned to normal. All I had on the card were 2 totally dark pictures.

A bit disappointing, so I reset and took a shorter exposure of half an hour, again the camera did it's DF thing and this time I did get an image, I think that the Df did not complete before the batteries ran out. So I am unsure about this image. I will go back to exactly the original setup tomorrow night or the next clear night.

Here is the image, for some reason the star trails have a double image, not sure why.

Last edited by telfish; 01-30-2011 at 10:17 AM.
11-11-2010, 09:27 PM   #71
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BTW I notice the same smudge across the frame as last night. I am certain there was no moisture on the lens so this must be the milky way.
11-11-2010, 11:24 PM   #72
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Can't see any EXIF on this image, but it's overcooked and OOF.
11-12-2010, 12:11 AM   #73
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QuoteOriginally posted by telfish Quote
Ok. Tonight was not a real success. I set the camera and took the exposure for an hour then stopped the exposure and the camera started a countdown doing it's DF thing. This lasted 90 minutes then the camera returned to normal. All I had on the card were 2 totally dark pictures.

A bit disappointing, so I reset and took a shorter exposure of half an hour, again the camera did it's DF thing and this time I did get an image, I think that the Df did not complete before the batteries ran out. So I am unsure about this image. I will go back to exactly the original setup tomorrow night or the next clear night.

Here is the image, for some reason the star trails have a double image, not sure why.
Yuk! Things just don't seem to be adding up here. You are exposing what the so-called reviewers have blissfully ignored.

1. The K-5 obviously screwed up big time on the first, and the 2 dark result speaks of that. A broke DFS here maybe?

2. On the second it seems to have coughed out another mess, would that be DFS blending misalignment that caused the double vision?

Yes, please carry on with your interesting tests to eliminate any possible PEBKAC. Will be nice to see if the all singing and dancing new model actually can do it reliably and repeatably.


Btw; has anyone given K-5 in-cam HDR a decent road test yet? Samples of one or two that I've seen to date don't really qualify.
Even seem sparse on Flickr so far too.
Pentax K-5 HDR - Flickr: Search
..and Long Exposure only picks up 2 as of 2010-11-12 AESDT.
Pentax K-5 Long exposure - Flickr: Search

.R.
11-12-2010, 04:27 AM   #74
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Unlucky - quite a useful thing to do is to take a high ISO shot before the sequence/exposure just to doublecheck focus.
11-12-2010, 04:50 AM   #75
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I think the latest photo was not focused on infinity.
There's a clue - the building (?) in the far lower left looks sharper than the star-trails or the tree-tops.

Just too bad.
The DFS producing two totally dark pictures is intriguing. I've never met such a problem before.
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