[Nass]

The K7 is more than capable of doing long exposures cleanly...

I had no problems with my stacked star trails....



This is 16 x 30sec exposures, now the important thing is TURN OFF slow shutter NR, this will effectively turn off DFS for exposures <30secs.

And keep the camera firing continuously.

Hello

I saw this piccie at First Star Trail Attempt on Flickr - Photo Sharing! as well

I note that you say that - Cable Release (I found interval timer inbuilt didn't work properly for some strange reason, I think because of the buffer limits)

In other words we're talking about 2 different things here? You're doing it manually with a r/c whereas I was after using the interval timer?

[Nass]

Ok. I have worked out what the problem is. The interval timer/intervalometer is the problem.

• The intervalometer is the gap between photographs regardless of the length, it is not the absolute time gap between photograph starts
  
• In other words, if you set an interval of 1 sec, the camera takes a pic, then when it's done it waits 1 sec, then takes another. So if the exposure time is .3 sec, this is the process:
  
  • 0-.3 taking pic
  • .3-1.3 interval
  • 1.3-1.6 taking pic
  • 1.6-2.6 interval
• 1 second is the minimum interval. Because you cannot set an interval of ZERO seconds, the camera never shoots another pic straightaway
  
• Ergo, completely shite camera for star trails using stacked images out of the intervalometer. There must always be gaps.
  
• But WAIT!!! In true Pentax tradition... it doesn't even end here!!! There is also a BUG in this piece of shit
  
  • If the interval is GREATER than the exposure time, then it works as described above
  • If the interval is LESS THAN or EQUAL to the exposure time, the camera seems to miss its timeslot and only takes ((N-1)/2) exposures, where N is the number of exposures originally put in via the interval timer interface.
  • This has been tested with 5,9 exposures
• Pretty shitty all round

This is how PENTAX would make astro people happy

• MAKE IT POSSIBLE TO TURN OFF DFS PERIOD
• IN A FIRMWARE UPDATE MAKE AN INTERVAL OF 0 POSSIBLE
• IN A FIRMWARE UPDATE FIX THAT BUG

Who the hell do Pentax listen to in their user groups? Why didn't they pick this sort of BASIC stuff up in their design phase? Good grief, is this a Mickey mouse company??? Honestly I feel like really slagging off Pentax online. The list of K-7 inadequacies is growing, I wouldn't recommend it anymore. I FEEL SO CONNED BY THIS CAMERA.

edit - added later: Look Ma, there's more! It turns out that PENTAX REMOTE ASSISTANT (free software that can be used to control the camera from a laptop) which fixes this for the older models HAS BEEN DISCONTINUED AND ISN'T FREAKING COMPATIBLE WITH THEIR NEW SHINY SO-CALLED TOP OF RANGE K-7... Genius! Remote assistant has a 'time delay' setting which allows shots seperated by time rather than by time intervals. Bleedin heck.

-Nass. Grumpy.

[Jonson PL]

I note that you say that - Cable Release (I found interval timer inbuilt didn't work properly for some strange reason, I think because of the buffer limits)

In other words we're talking about 2 different things here? You're doing it manually with a r/c whereas I was after using the interval timer?

This is the digital timer that Wim used in his startrail shot from Namibia:
Aputure Limited - Digital LCD Timer Remote

Re: Damaraland (Namibia): star trails (1 img): Pentax SLR Talk Forum: Digital Photography Review

Startrails: Pentax SLR Talk Forum: Digital Photography Review




I was recently reading a book about National Geography photographers :
Moonlight is a favorite source of illumination for space photographer Roger H. Ressmeyer, who also works with long exposures at night. “I feel I’m returning to photographers roots. Back in the early 1800s it could take minutes or even hours to take a picture by sunlight“

Ressmeyer’s photographs of science and technology are often grand productions. When possible, he plans everything precisely. He pays attention not only to the timing of an eclipse, for instance, but to the sky positions of galaxies and individual stars. “To cover my bases, I may set up ten or twelve cameras to take pictures simultaneously with different exposures. If I’m doing a two-hour shoot that ends with a moonrise, I can’t do it twice.”


And here are some other links regarding Astro :
https://www.pentaxforums.com/forums/689414-post18.html

Star Trails Tutorial - FM Forums

Re: 5.6 - thanks: Pentax SLR Talk Forum: Digital Photography Review



And some long exposure photos :
Re: Pentax won 1st place... 2 times!!: Pentax SLR Talk Forum: Digital Photography Review

[Nass]

Many thanks Jonsol PL, that's a terrific collection of information with some gorgeous work. I've ordered a unit similar to that one (tried to get in touch with these guys but their email address bounced, besides, better to get it in the same country so the VATman doesn't stop the delivery).

In fact, whilst I was driving into work this morning I was still fuming about this and I logicked that by attaching a remote, locking it onto constant firing and setting the camera onto continuous mode 30 sec exposures I could still achieve the uninterrupted trartrails I'm after. So that was what I was planning to test tonight.

I've logged the bug and requests with Pentax, according to the fella I spoke with it's likely the bug gets fixed but unlikely there will ever be a 0 seconds setting or possible to fire continuously for >30 secs because of processor imitations. Interesting though, he thought it very likely that Pentax would develop and release a free successor to remote assistant which will work with K-7. That'd be rather good news for all our studio friends if that were true... fingers crossed!

[Christopher M.W.T]

Hello

I saw this piccie at First Star Trail Attempt on Flickr - Photo Sharing! as well

I note that you say that - Cable Release (I found interval timer inbuilt didn't work properly for some strange reason, I think because of the buffer limits)

In other words we're talking about 2 different things here? You're doing it manually with a r/c whereas I was after using the interval timer?

Cheers well I did that shot with the interval timer, it was supposed to be like 40 but the intervalometer only took 16, I found it to be a bit untrustworthy most likely due to buffer limits.

Next time I'll just use my cable release and continuous shooting mode.

[Nass]

Cheers well I did that shot with the interval timer, it was supposed to be like 40 but the intervalometer only took 16, I found it to be a bit untrustworthy most likely due to buffer limits.

Yeah - I'm guessing it's the same bug as the thing I've come across, though where 16 comes from I dunno

Next time I'll just use my cable release and continuous shooting mode.

yeah - though thinking about it I could see this suffering from battery issues - I don't have it with me as I'm at work but from memory there isn't a way to tell the camera to go shoot 50 continuously one after the other and just stop at the end - the remote would keep it going... and going... and going... hopefully this gadget will sort this *crosses fingers*

[Christopher M.W.T]

Yeah - I'm guessing it's the same bug as the thing I've come across, though where 16 comes from I dunno



yeah - though thinking about it I could see this suffering from battery issues - I don't have it with me as I'm at work but from memory there isn't a way to tell the camera to go shoot 50 continuously one after the other and just stop at the end - the remote would keep it going... and going... and going... hopefully this gadget will sort this *crosses fingers*

I dont think its a bug but more just when the buffer overruns it will stop.

[Nass]

I dont think its a bug but more just when the buffer overruns it will stop.

Aye, could well be Anyhow when I explained it to the Pentax servicing dude on the phone he seemed to think it was weird/bad behaviour that should be fixable and it's been sent to japan as an issue to be looked at... We'll see I guess

[Jonson PL]

Hello,

I've never done any astrophotography before and I'm trying to do a few nice star trails. I'm failing miserably though, can anyone point me in the right direction please?

First, ideally I'd like to do several exposures and stack/merge them. I downloaded a freebie called deepskystacker but I'm having a little issue with my camera. When I set the thing to do interval shooting, every 30 seconds, with an exposure time of 30 seconds set manually, there seem to be gaps between the joined images. Is this because the camera is doing some processing in between and how would I avoid that please?

Secondly, I'd like to do this for exposures longer than 30 seconds but the in-camera limit seem to be 30 seconds. Is there any way around that?

many thanks in advance

Already in the film days, bulb was the way to go for long exposures. The Olympus E3 can do 60 seconds in camera, pretty much all other do max 30 seconds.

The Pentaxian Martin Zalba has done some outstanding work when it comes to startrails :
Nocturnas - a set on Flickr

Dale had the K20 sensor analysed by astrophotographer Gordon Goodsman :
“Because minimal sensor noise is critical to his area of interest, astrophotographer Gordon Goodsman has designed his own software to test camera noise levels by analysing RAW image file data. When the K20D came out engineer Oleg Volkov and Gordon set out to put it through its paces. Here in Gordon's words are what they came up with: “
The Pentax K20D: a RAW review, page 3

And here is a discussion of it :
Yet another K20D review [Page 1]: Pentax SLR Talk Forum: Digital Photography Review


Pro shooters working with astrophotography use CCD sensors over CMOS, as these are better at base Iso. They even use liquid nitrogen to avoid it heating. This is why the K10 is so good at this type of work. No crop DSLR on the market beats the K10 at base Iso. And there it even has better DR, than the granted older FF Eos 5D.
If you really wanna get into it astrophotography, you can probably find a cheap K10, K200 or Km.

Wim, the guy who took the startrail photo from Namibia that I linked to, stated in another thread :
“I took a 20 seconds Exposure today (granted, it was blank test picture) with the K-7 and there was no slow behavior AT ALL after the exposure.
Of course I did deactivate the corresponding Custom Function.
…
First of all, indeed, DFS is only activated in Bulb mode and if exposure is longer than 30 seconds. So, if you want to expose for several minutes, you have to deal with DFS.

One solution for astroshooters would be to use two bodies. If you set them to use the same exposure times, one of the two should always be available while the other is doing DFS. Of course setting them both up so that there are no parallax problems could be a problem in some cases, but I suspect with most astrophotography that is not a issue?”



Andy is doing some good astro work with the Pentax K-x :
https://www.pentaxforums.com/forums/809949-post26.html

[wildlifephotog]

Before taking Martin Zalba's work as gospel you may want to check out this thread.
https://www.pentaxforums.com/forums/everything-else/80582-ppg-possibly-showin...es-theirs.html

[Nass]

ok, tried a first effort just outside in the garden, by using 30 sec exposures and the remote on continuous. This is only about 10 minute's worth as clouds started bellowing in so gaps appear, ugly. I blended them using merge to hdr in photoshop which is slow. I need to find some proper software

Fun though

[wildlifephotog]

Do you have this one?

Startrails application

[Nass]

Do you have this one?

Startrails application

Yeah I _tried_ that one first, but it didn't really seem to like DNGs - worked a dream when I batch changed them to JPGs but with DNG it produced a tiny image

[vizjerei]

ISO 2000 + 14mm f2.8 + 1068 of 30sec exprosure = Awsome!

VLT and SCP from VST on Flickr - Photo Sharing!

[Nass]

Update for y'all

The aim of this whole exercise was to find a way to set my camera to take gapless pictures at a time of my choosing in the middle of the night, so that I could blend them together to make seamless star trails.

I already have a cheap and cheerful 3rd party infra-red remote control unit, and by setting the camera onto "Drive Mode Remote Continuous Shooting", custom menu 18 to 2 (slow shutter speed NR - off) and using a manual exposure of 30 seconds I can set the thing up, click the remote once and it'll keep shooting _without gaps_ endless 30 second exposures. Then I come back in an hr, click the IR again to stop the sequence.

Whilst this is fine for what it is, clearly it means I can't just go asleep and set the camera to do its thing when I want it to.

I went out and bought a Seculine twin1 ISR model iC - which works for Canon, Pentax & Samsung. You can see a pic of it at B&H - in the UK it cost me £50 or so.

[Note to B&H rep - you've currently have a booboo there. Your description describes it as "ISR (Infrared Shutter Release)", in fact it is not infrared at all . I have that exact model and it is a "ISR (Interval Shutter Release)" - I think you just got the acronym wrong. This does matter because I don't think there's an infra-red remote timer available for Pentax at all, sadly.]

Anyhow, so fiddling around with this thing means you can delay anything by any time interval and have intervals etc etc etc. BUT! Beware it's cabled. So you must remember not to use "remote continuous shooting" but instead use just plain old continuous shooting (Hi, Lo works fine too). I discovered this after a lot of trial and error so I hope that this saves someone else the hassle. For me it's working on:

M+30sec exposure. Gadget has 4 settings, delay, interval, number & duration: for me this works: any delay I want up to 99 hrs, 1 sec interval, 1 shot, 2 minutes duration. What happens when I use this is that the delay I program in is counted down and the thing starts its 1 shot (for 2 minutes duration). But what also happens, because I've set continuous as the camera's 1 shot, is the camera just keeps taking until the duration (2 minutes) is fully used up. So actually it gives me 4 30 second exposures with no DFS delay in there, they're taken one after the other.

It is a bit of a bodge job though - that last "duration" setting is supposed to be for bulb exposures which in fact it works for too. So yes I can set up the thing to start taking a B exposure for 2 hrs at 3 am if I want, which is nice. The fact that it's made the M setting work like this is also nice, the result I wanted. So I hope that helps someone in the same boat as me. The next mystery to figure out is why the K-7's 30 second setting actually seems to last for 32 real seconds, but that might be a story for another day.