Pentax Kx anyone?

[Welrod50]

Hello all,

I'm after some advice folks please. I've put a similar thread on the camera forum, but don't seem to be getting any responses. I guess not enough folks are visiting there? Anyway....

Does anyone here use a Pentax K-x DSLR for astro imaging and if so what might I need to attach it to my SW Explorer 130 ??

I've been into stargazing since I was a child and having recaptured the fascination lately with the new 'scope, I am now conversant with it, but I am utterly clueless about taking photos through a telescope (although I do own and use DSLR's and know my way around photography quite a bit).

I understand I will need a T adapter, but will the SW 130 take the weight and if so, is there anything else I might need besides? What kind of exposures could I expect? I imagine I will be looking at a number of seconds. I have the EQ2 mount for the scope and although I can track planets and DSO's quite capably manually, this will not be accurate enough for long exposure work

Any advice would be greatly appreciated. I saw Saturn properly for the first time last night and the bug is biting !!

Thanks all.

Scott

[Marki]

Hi Scott.

I use a K-X - nice camera in my opinion (always been a pentax fan ).

So far only used it for afocal and prime focus in my Equinox 80 Apo and my Starwave 102 ED - moon only so far. For prime focus I just got the t-ring adaptor and nose piece from FLO First Light Optics - FLO 1.25-inch T mount camera adapter.

I also use a infrared remote (pentax brand, off Amazon) to take the shots, as even on my EQ5 I found the shutter causes some shake.

Anyway, sure some proper astro-imagers will be along soon and will able to advise you better!

[Welrod50]

Thanks Mark for quick reply. I bought the Kx specifically for low noise/high ISO capability. It is a brill unit.

With your scope, how do you focus? I take it that the EP effectively replaces the lens, so in live view you can focus the EP and the camera takes the picture directly through this?!

I will be using a Skywatcher 130 Newtonian.

Thanks again!

[Probablynot]

Me too, I've got a K-x. I've bought a T-ring for it, so some time soon I hope I'll be able to attach it t my scope and get some sensible imaging done with it.

But I've also got a webcam. And blimey, I only got myself caught up in astrology - oops I mean astronomy! - three months ago! [i'm renewing an obsession that I used to have back when I was a teenager, far too many decades ago than I dare to admit to!]

So far, the webcam is being uber-interesting! Partly because I had to mod it myself! But I do mean to attach the Pentax K-x to my 'scope sometime soon (when the clouds roll back a bit!), and I'm rewally hoping for some good results.

[Marki]

Well, all I do is effectively use my scope as really long lens (wthout any specific ep) with the camera body attached directly to the scope(or diagonal - not sure if this is the right way to do it) via the t-ring/nose piece, and focus with the scope itself, or manual focus in live view. As I use refractors, I really have no idea how it'd work with the 130 - sorry Scott!

I am considering buying a variable projection camera adaptor, so I can try this with eps in front of the camera body - something like the one here. T-Adaptors for connecting Cameras to Telescopes

Anyway good luck! By the way you might want to get this book...First Light Optics - Making Every Photon Count - Steve Richards

pretty much everyone says this is essential reading for the budding astrophotographer, although it is perhaps weighted more to imaging DSOs.

Good luck!

[Welrod50]

Ah, yes I see what you're saying. A refractor will act as a long lens, but having a Newt, I need an EP to act as the lens. (Do I?!)

As for the book, I will source a copy and see what it can tell me. Thanks Mark.

Anyone here use Newts with DSLR's who can also assist

Scott.

[Welrod50]

Oh and Brian,

Just saw your post too. Have you tried attaching the Kx to your scope yet?

Does it need to go via an EP or will the scope itself work as a lens which lets you manually focus the camera, effectively replacing the EP??

Cheers

[Eastridge]

Another k-x owner here so will be watching this threa with interest. Hubby wants to try a little photographing ( just moon & maybe a planet out of curiosity but not full stuff or we would not have bought have bought a dob) so bought T adapter from FLO.

SW say that the 250 Skyliner allows direct to OTA. Haven't worked out how yet as T is hidden away pending his birthday.

Also got a T adapter for the Hyperion.

[Probablynot]

OK Eastridge, Welrod, here's what I've done with the K-x so far. No actual astro imaging done yet, due partly to lousy weather and partly to my low position on the CG-5 GoTo learning curve.

The T-ring attaches to the camera in place of the lens.

I think FLO sells an adapter that screws into the T-ring and goes into the focuser, but I didn't need it. The Barlow that came with the scope has a thread that fits the T-ring, and the lens part of the Barlow can be unscrewed if it's not required. [Actually I did remove it at first, but I found I couldn't get any image without it so I put it back on.]

Turn on camera, switch to the lcd view.

Try to focus. Fail. Realise the camera is actually far too heavy for the Explorer 150p's focuser, so it's going to be a pain to focus! You have to support the camera with one hand while you try to get in focus with the other.

For the purpose of this initial test I set the 'scope to look at some fence posts on the hilltop about a mile away. Camera was on fully automatic; very low ISO (sigh! Something else to learn about!). But here's what I got. Hope it helps.

[Welrod50]

I have spoken to a very helpful chap named Martin at FLO today. Apparently, the SW 130's focus tube is not long enough to use a DSLR with it and it will not achieve prime focus. However, it is possible to use an extender or special EP that the T ring will screw onto. Baader being one such EP it seems. Here are the links that FLO sent me:

First Light Optics - Baader Hyperion 68 degree eyepiece

First Light Optics - T Rings

First Light Optics - Baader Hyperion eyepiece T-Adaptor (M43-T)

Interesting to know.

Of course, if anyone else has had any success, hopefully it can be shared. Seems like there are one or two of us who own Kx's and these are good high ISO cameras which would allow faster shutter speeds, so would seem to me to be ideal for those of us without tracking mounts etc.

Scott.

[Welrod50]

Brian,

just a thought - what about rotating the scope in its mount so the focus tube and camera are vertical. It will ease the weight hanging on the assembly.

Also, put the camera on manual and high ISO. The image you've posted looks to me like its slightly misfocused and suffering from camera shake. High ISO and faster shutter speed will rectify this.

Good luck and if you have further success, please share it

Scott.

[Marki]

Those baader hyperions look nice! I have the hyperion 8-24mm clickstop zoom and thats nice too :-).

Be interested to see how you get on if you get the kit, Scott. Martin is indeed very helpful, as are all the FLO crew - always had sound advice and good service from them.

[Probablynot]

Thanks Scott. I did try rotating the scope so that the focus tube was vertical, but [a] the K-x is still too heavy, and you need to be 8ft tall to look at the lcd screen!

Yes, my image is out of focus, and I took it by pressing the button instead of getting my little remote control out of its bag. I expect the RC battery is dead anyway.

And yes, I do realise I need to learn to actually USE the features I paid for when I bought my K-x! The pic was taken in a hurry, through my back doorway, about 3 minutes before I posted it here! I just wanted to check the practicalities of using the dslr in combination with my scope.

I wonder if the 2-speed Crayford focuser is a more robust bit of kit than the standard SW one?

[Welrod50]

Mmmm, yes I see your point, and the Kx is one of the lighter DSLR's available too. I've just been fiddling with my scope and trying to envisage what the Kx would look like on and its weight. The tripod will not go down far enough to allow this rotation unless you stand on a box or something to see the LCD.

That said, better to have that weight vertically held, rather than hanging off the scope to the side.

I think if you have a bit more time, you'll nail the focus and exposure!! Although I wonder if there is some way of bracing the focus tube, as you could use the self timer on the camera, as it locks the mirror lock up when you use this function anyhow. Just need to be rid of the shake from holding it then.

Or, attach the camera to a tripod and rotate the scope a little to then allow the camera to be used, whilst having the tripod take the weight as though you were just taking a posed portrait?!

It would be a lot of messing about, but well worth it if you had a sharp shot of Saturn or Jupiter.

I'm going to see about either getting a barlow with T mount or an extension tube and go from there.

I did also look at compact camera mounts last night online as I have a Panasonic TZ8. However, if I'm going to do it, I want to do it right. The Kx is far, far superior in low noise/high ISO and the image quality is far better than the Panny will manage, especially in low light with long exposures.

I feel a bit of a challenge coming on. Will keep all posted on progress when I get the kit and give it a whirl.

As I say Brian, please show any pics you get in the meantime...if this darned cloud actually goes away though!!

Scott

[Probablynot]

I think for now I'll probably concentrate on webcam pics. Because I can, and because it won't overstretch the kit that I've got.

Up until four months ago my over-riding obsession was kite-flying, not astronomy. Believe it or not, my kites have mopped up about a six month's supply of State Retirement pension in the past two years!

I do still fly my kites, so I can't yet put them on ebay and recoup enough cash to invest in an industrial-grade focuser! (plus some decent eps, of course!)

However, I can confirm that I have bought a new battery for the Pentax remote control!

[sgazer]

I've been looking for camera's recently after selling my 1000d with some of my astro kit and also looked at the Pentax cameras. The k-x gets good reviews and has pretty good noise levels. I went with a Canon 450d as I've always had Canons, already had lenses, low noise and accepts the EOS clip filters internally.

As FLO said, you probably won't be able to obtain focus once you attached the camera directly to the focuser tube. (Actually I think you're scope will be too long, ie. not enough inward travel on the focuser to achieve focus).

I think the 130p focuser is 1.25" too, but could be wrong. The DSLR adapters are generally 2".

I've not tried the Hyperion lens method of attaching the camera, but most people try to do prime focus without anything lenses, so purely using the scope as the lens of the camera.

Skywatcher introduced a range of reflectors that were slightly shorter called the 'pds' range, these allow DSLRs to come to focus. I highly recommend this one;

First Light Optics - Skywatcher Explorer 150P DS OTA

as it's compact, light weight, big enough for visual, fast enough (F5) for imaging, allows focus, great optics, dual speed focuser.

[Probablynot]

I'm intrigued, sgazer.

'Hyperion lens method'. Is that the same as using a Barlow? (please excuse my newbie ignorance). So if I had left the Barlow lens off when I did my little bit of experimenting earlier this evening, and if I could only have got my focuser to travel a bit further inwards, you're saying I might have achieved focus?

[sgazer]

I have spoken to a very helpful chap named Martin at FLO today. Apparently, the SW 130's focus tube is not long enough to use a DSLR with it and it will not achieve prime focus. However, it is possible to use an extender or special EP that the T ring will screw onto. Baader being one such EP it seems. Here are the links that FLO sent me:

First Light Optics - Baader Hyperion 68 degree eyepiece

First Light Optics - T Rings

First Light Optics - Baader Hyperion eyepiece T-Adaptor (M43-T)

Scott.

@probablynot; referring to the suggestion from FLO above; appears that the hyperion eyepieces have an adapter that allows a DSLR to be attached to them. I've read about it before, but never tried it.

[RikM]

How far back in the camera body is the sensor set in the Pentax cameras as compared to the Canon EOS cameras?

The EOS range WILL reach focus on a standard single speed 150P and won't reach focus on the older blue tube 130P scopes. If the Pentax has a deeper body than Canon you might struggle.

There are lots of reason for NOT wanting to use a barlow lens with a DSLR, the main one for deep sky images is that by taking the scope form f/5 to f/10 you need 4 times the exposure time. So think 20min subs instead of 5min.

As regards DSLR cameras for astrophotography, none of them are optimised for AP properly (not even the Canon Da models, they just have a different filter and the same can be had from Astronomiser far more cost effectively). They all do pretty much the same job and will give about the same results if used properly. The best DSLR images seem to come from 350D, 450D, 1000D, and 1100D cameras and very fast optical scopes f/4 or lower. (I've used all these except the 450D and prefer the 1000D personally)

[Eastridge]

@probablynot; referring to the suggestion from FLO above; appears that the hyperion eyepieces have an adapter that allows a DSLR to be attached to them. I've read about it before, but never tried it.

This set up is what I have waiting for hubby, his birthday 3rd May so should be able to report how this works (albeit not with a Exp 130) after then.

Yes Hyp eyepice has a thread under the rubber eyecup, Hyperion adapter screws onto that, then t ring adapter mounted on KX in place of lens screws into that. Main concern is how heavy that will make the viewing end of the scope. Suspect that both camera body and OTA will need support to stay in place. Happily there are 2 of us.

[marshy123]

Sorry to join this debate so late on, only just logged in. I have a Pentax k-x and Skywatcher 130M (900mm) reflector. I have my K-x mounted with a t-ring and t-adaptor going into the stock x2 barlow that came with my 130M. I have achieved focus with this setup and managed some Lunar shots. I found that while the weight of the camera and bits was considerable I could get it balanced nicely and I could still focus OK; I found that even with the remote I was getting shutter shake so I opted for some nice 720p video from which I extracted some frames in VirtualDub which were stitched together in photoshop. Should have stacked instead really but it was only a first attempt and it came out OK.

cheers

Chris

[Welrod50]

OK folks, more info.....

Rik & Chris - I can't say how far back the sensor is in Kx compared to the canon as I've not used a Canon SLR and have nothing to compare with therefore. However, Martin at FLO reliably informs me that the SW 130 tube is indeed too long so it will not achieve prime focus. My scope is a black SW 130 900mm f8 (newer but not parabolic) scope.

It is also possible to use a x2 Barlow with T adapter, although having looked at both systems, I think the Baader EP with adapter set up (earlier post) is going to be my preferred choise simply because i reckon I could get closer and have slightly better quality end image.

For the benefit of everyone else, I asked FLO about an adapter to fit a compact out of interest, and martin gave me this link :

First Light Optics - Skywatcher Universal Camera Adapter

It seems a bit fiddly, but a lot less pricey.

That said, I reckon the end result would justify the cost. So I'm going down the Baader route.

Just need to decide now on 10mm or 13mm EP. The 10mm will get me closer to outer planets and nebulae, but may well be that bit less sharp than the 13mm.

I will also get a neodymium filter too, as I will need to limit the streetlamp pollution as much as I can.

Anyone else have any input or ideas. We're doing well so far!

Scott

[RikM]

If you are sticking to planetary imaging, you won't need the Neodymim filter. Planets are bright and you will be using exposures much less than a second. Does the Pentax have video out? That might be the way to go, otherwise a little webcam will wipe the floor with a DSLR for planetary images.

The key to good planetary images is lots and lots...like thousands...of very short exposure images, normally taken as an avi file. Then compiled into a single composite using Registax or Avistack software.

[Welrod50]

Was thinking of doing some DSO imaging too aswell as planetary, although this will be my main objective. I have read many times of folks stacking individual frames froma webcam, and I did consider this but two things have put me off:

1. Webcam must surely be far less resolution and IQ than a 12 mp DSLR.

2. A single image I can process in Photoshop from a RAW file and not have to faff about stacking frames.

Or am I way off?? I'll take your advice here Rik, as you've used webcam. What do you reckon??

Scott.

[RikM]

The thing is that a planet (even with a barlow) will only cover few hundred pixels in the centre of the chip. Pentax Kx has 5.5µm pixels, a Philips webcam has 5.6µm pixels, so not so much difference in native resolution if you take a single image. Also remember that the atmosphere is not stable, so most of your single image will be blurred because of the atmosphere (the seeing). When you take a few hundred images, Registax compares them and stacks only the sharpest parts from each frame so you get much more detail. With the webcam at 10-15 frames per second a 3min video clip will give you a couple of thousand images from which the software can extract the sharpest bits.

Please don't just take my word for it (webcam imaging doesn't float my boat). Make a web search for planetary images taken with a DSLR and then make a search for images taken with a Phillips SPC900NC or flashed SPC880NC (or similar CCD based web cam. Then a search for planetary images with an Imaging Source DMK type camera.

Eyepiece projection using a Baader 8mm or similar might be different, I have no experience there.

For deep sky imaging, you would probably do better to piggyback your DSLR on the back of the 130 and just use camera lenses rather than image through the scope. You can get very nice widefield images that way.