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04-16-2018, 01:11 AM   #1
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Want to try Astrophotography

Hi All,

I wanted to try my hand at some basic astrophotography (stars & Milky Way), but am pretty clueless as to the technique. I have taken photos of the Northern lights in the past & was wondering if the same rules apply? Note that I am able to go to places with minimal light pollution.

Also, I don't own an astrotracer, but have mentioned my current rig below. What potential does the below equipment have with astrophotography? Does anyone have any examples of astrophotos they have taken with the below (or similar) equipment?

KP
HD 15mm F4
DA 200mm F2.8
DA 18-135mm F3.5-5.6
Tripod
Shutter remote

Thanks!

Ducky

04-16-2018, 03:42 AM   #3
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Thanks! I'll have a read through those.

Would still really like to see what kind of photos you could potentially get without an astrotracer & using the equipment I listed above (or similar).
04-16-2018, 03:49 AM - 1 Like   #4
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you might want to look at threads in this area of the forum while you wait for responses

Photographic Technique - PentaxForums.com

https://www.pentaxforums.com/forums/38-photographic-technique/357171-astro-a...ts-anyone.html

https://www.pentaxforums.com/forums/38-photographic-technique/330539-beginni...otography.html

and perhaps send a pm or two to anyone who appears to have the knowledge you seek

04-16-2018, 05:59 AM - 1 Like   #5
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From my limited experience, the longest shutter time you can achieve with the widest lens you have (15mm) is probably around 25 seconds, before you start to see noticeable star trails in the image, which you do not want for a milky way shot.
If you can get to a site with minimum light pollution, 25 seconds is definitely long enough for milky way shots, without an astrotracer. You might have to increase the ISO to 1600ish, since the DA15 is only at F/4. Play around with different ISO and shutter time to get the best results.


Good luck, and don't forget to post back your results
04-16-2018, 06:34 AM   #6
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Thanks! If I were to buy an astr tracer then what would a good option be without breaking the bank?
04-16-2018, 06:39 AM   #7
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QuoteOriginally posted by Ducky13 Quote
Thanks! If I were to buy an astr tracer then what would a good option be without breaking the bank?
again, let me say I have no practical experience to offer but have you checked out whether this might be of help?

" Pentax O-GPS1 GPS Unit
Introduction
The Pentax O-GPS1 unit is a small accessory unit that attaches to any K-01, K-5, K-r or 645D (or newer) camera flash hotshoe and provides geotagging of images (latitude, longitude, elevation), an electronic compass, and a simple navigator function. The GPS function also has the option of keeping the camera clock up-to-date. It was announced in June, 2011 and made available shortly thereafter.
On the K-5 & K-r, the unit also provides an Astrotracer function that allows the camera sensor to act as a simple equatorial mount for astrophotography. This allows for exposures of up to five minutes without incurring star trails on the photo.


Read more at: Pentax O-GPS1 GPS Unit Review - Introduction | PentaxForums.com Reviews

https://www.pentaxforums.com/accessoryreviews/pentax-o-gps1.html


I don't know if it would work as an astrotracker on your cameras or not

perhaps some member of the forum might have real world experience to help out on that

the other functions work well on my K 3 and my K 5 II when I had one

Last edited by Aslyfox; 04-16-2018 at 08:00 AM.
04-16-2018, 07:27 AM - 3 Likes   #8
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I am just starting astrophotography as well. So no real experience except what I have been reading. But this might make a nice "how to get started" thread.

A few things I have learned:
1) Astro can be several different things that require completely different techniques.
a) Star trails - many multiple exposures over several hours stacked together.
b) Milky Way or other images where you want minimal star movement - can be single or multiple exposure stacks but exposure time is restricted by star movement
c) Deep space - other galaxies or deep space objects - needs longer lens, multiple stacked images and usually some type of tracking mount.

2) You can do quite nice astro without an astrotracer - all the astrotracer does is extend the exposure time for a single image. You can do the same (and better) with a real tracking mount but that would be vastly more expensive and complicated. Something like this: iOptron SkyGuider Pro EQ Camera Mount 3550 B&H Photo Video

3) Since your KP has no GPS you have no astrotracer build in so you need to add the O-GPS1 unit. ASTROTRACER | GPS UNIT O-GPS1 | RICOH IMAGING But again this is not required for astro, just makes it a bit easier.

4) Best lenses are debated and differ depending on what you are shooting but usually: very low distortion, very wide, very fast. Here is a good article about the lenses: How to Pick a Lens for Milky Way Photography – Lonely Speck

5) Exposure times vary with intended subject. But you can use something called 'rule of 500'. Dividing 500 by the equivalent focal length of the lens gives you the maximum exposure time before movement is seen. So for your 15mm: 500/(15*1.5) = 22.50 seconds. But many sources suggest on digital that 500 is too big and that 300 should be used now. So 300/(15*1.5) = 13 seconds. This is without astrotracer.

6) Adding astrotracer for Milky Way shots increases the exposure time because the sensor 'tracks' the star movement. Pentax limits it to 5 minutes I believe which sounds amazing but many users report that staying below 2 minutes gives better results. This will vary with the lens focal length as well.

7) Stars move at different speeds. So when shooting very wide even using a conservative 2 minutes with the astrotracer might still show movement in some areas but other areas of the image might be fine. Finding the proper exposure length for each image can be some trial and error.

---------- Post added 04-16-18 at 07:31 AM ----------

QuoteOriginally posted by Ducky13 Quote
Thanks! If I were to buy an astr tracer then what would a good option be without breaking the bank?
The Astrotracer is a Pentax device that mounts on some cameras like your KP or is builtin on others like the K-3II or K-1. o-gps1 | B&H Photo Video

However, you can also buy a "tracking mount" which goes on your tripod and then you mount the camera on it. Performs roughly the same function but more expensive, and far more sophisticated: iOptron SkyGuider Pro EQ Camera Mount 3550 B&H Photo Video

04-16-2018, 08:10 AM - 3 Likes   #9
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My beginner advice

With what you have I would suggest sticking to the prime lenses, so the 15mm and 200mm lenses. The fact that you have dark skies close by is nice and will make up for a lot of othre issues like not having a tracking mount or not using astrotracer. I have gotten good results using an old screw mount Vivitar 135mm lens that doesn't have any ED or APO glass in it by taking a bunch of 1 second exposures and then stacking in Deep Sky Stacker. With those you should be able to get some good wide field shots as well as some good deep sky objects (DSOs).

For DSOs (mostly the Orion nebula/M42) I find that I can get pretty good results shooting with that 135mm lens at f/4, ISO6400, 1 second exposure. Experience has taught me that things work better if I recompose after about 2 minutes with that lens. Set the camera to 2 second mirror up delay to minimize the shake that the mirror introduces and always use the remote. Then it is just grab a bunch of shots (by a bunch I mean several hundred), stack, and post process. Also when stacking be sure to get some dark frames (lens cap on pictures shot at the same ISO and exposure time as your actual images) and bias frames (same iso as the other shots but at the fastest shutter speed) as those can really drive down noise and other artifacts in your shots when combined using Deep Sky Stacker.

Post processing is really the key here and is something that one needs to learn. I started off down the wrong path and thought I was making good progress and wanted a critique and got a education. Here is what I produced from that stack which doesn't look too bad but I quickly found out that my abilities in post processing were much lower than I thought they were:


Here is what someone who know what they are doing (Pete_XL) with post processing was able to do with the same stack I created

For exposure times without a tracking mount I would suggest following the rule of 200 which is:
Exposure Time in seconds =200 / lens focal length
As this really cuts down on the chance of getting star trails

For focusing use live view and manually focus. I would highly suggest using a focusing aide, either a Y mask, bahtinov mask, or just something to create diffraction spikes.

If you want some idea of what you could capture (you would likely need a tracking mount to get something like this) there is this post from Pete_XL where he used an old 200mm SMC M lens

Last week I took a class on astro photography and have some notes that I can hand off once I get home, as well as having some links on post processing and how to do it right (i'm still learning but am getting better). I will post what I can dredge up for that when I get home.

I recently got the O-GPS1 for my K-3 but as luck would have it every night that I could have gone out and shot has either been cloudy or stormy so I haven't been able to play with it yet beyond mastering getting it calibrated and shooting off my deck into the overly light polluted sky in my city where a star like Sirius is pretty dim. With astrotracer never go out near the suggested maximum exposure time as a number of people have reported issues but I would think you could get up to 20-30 seconds without much issue if you can get a good calibration, and do check the results for the first photo and if you have trails re-calibrate and try again until you get no trails and then begin your shooting session.

As always ask questions, post progress, and get some pointers on this topic over in the astrophotography group. Pete_XL, VoiceOfReason, DrawsACircle and others there are really helpful. Hopefully you can get pointed in the right direction form the start and not wander down the wrong path like I did.
04-16-2018, 08:12 AM - 1 Like   #10
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you folks got me curious

I am planning on being in Yellowstone National Park in mid May \

it is during a new moon, so there will be no moon light

any one have a suggestion as to what lens to use ? I will have a K 3 with the Pentax O-GPS1 unit or a K 3 II

I could use:

HD Pentax-DA 16-85mm F3.5-5.6 ED DC WR,

SMC Pentax-DA 21mm F3.2 Limited,

Kino Precision Japan Kiron 28mm F2 MC P/KA

SMC Pentax-DA 40mm F2.8 XS

SMC Pentax-DA F1.8 50 mm

HD Pentax-D FA* 70-200mm F2.8 ED DC AW

I am guessing I want the widest point of view and the one with the largest aperture

thanks for any help anyone can give
04-16-2018, 08:19 AM - 1 Like   #11
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The nice part about the newer digital cameras is that they can make really good time exposures which are part of a lot of astrophotos you may be taking. As suggested previously, I would invest in a lower cost equatorial-type camera drive which allows you to track the stars. Get one with a polar alignment scope as it makes setting up the tracker a lot easier. I would suggest the "Star Adventure" mount package by Sky-Watcher USA ($318US available through their website and others). The astrotracer is nice to have (I have it in my K-1) but it limits the length of time of exposures and very wide angle lenses will show mistracking at their edges which a tracking mount will overcome.

Start with what lenses you have and get some experience with setting up the mount, taking long exposures, and post-processing. Any lens that you use for regular photography will work though you may want some faster lenses for astro work when you get going.

Light pollution can be a problem so search out some more remote areas that have dark skies.

For planetary photography, a telescope is really needed. You need long focal length, a really good guide system, and excellent seeing conditions (steady air) to get those types of pictures. Just using what you have and a fair drive can get you some great pictures otherwise with galaxies and nebulae clearly showing. Unguided shots can be used to show star trails, etc.

Good luck with your efforts.

Sky-Watcher Star Adventurer Multi-Function Mount Photo Package - S20520

Last edited by Bob 256; 04-16-2018 at 05:33 PM.
04-16-2018, 08:22 AM - 1 Like   #12
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As noted, try taking some pictures with your existing equipment.

If you get hooked and want more information/help, you might try to to find a local astronomy club. It will be full of helpful folks, most of whom will fall over themselves to be helpful! Someone might even have an old polar tracking mount to sell.

QuoteOriginally posted by Ducky13 Quote
Thanks! If I were to buy an astr tracer then what would a good option be without breaking the bank?
Depending on your enthusiasm and budget, you might look into these tracking mounts, found in a quick search on Ebay using “telescope mount.” (The titles below were copied from the page listing the item.) Most of them appear to be mountable to a sturdy tripod. Some of these are offered by Adorama. (I have no connections to any of these sellers.) The last one looks kinda cute and the price may be right.

iOptron SkyTracker Pro Camera Mount, with Counterweight, and Ball Head: $350

Slik ECH-630 Astro Tracker Motorized Mount, 11 lbs Capacity (Flat) #618-803: $340

Sky-Watcher Star Adventurer Astro: $329

Sky-Watcher Star Adventurer Photo Package #S20520: $319

Sky-Watcher Star Adventurer Mini: $299

iOptron SkyTracker Pro Camera Mount with Polar Scope, Mount Only #3322: $279

Sightron Star Seeker New Nano.Tracker AS0005 NEW F/S JAPAN: $180


The biggest trick with all of these will be getting them aligned with the Earth’s polar axis, although this won’t be too critical as long as you stick with your wide-angle lens and limit exposure times to a few minutes. Your new friends from the astronomy club would be helpful here.

If you are mechanically-inclined, you might try making a “barn door” tracker. The simplest of these would extend your exposure times to 5 minutes or more. Do a search on “barn door tracker astrophotography” to see how to build one. Stick with a simple version for starters!

You will find your shutter remote to be very useful.

Have fun!!
04-16-2018, 08:37 AM - 1 Like   #13
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QuoteOriginally posted by Aslyfox Quote
you folks got me curious

I am planning on being in Yellowstone National Park in mid May \

it is during a new moon, so there will be no moon light

any one have a suggestion as to what lens to use ? I will have a K 3 with the Pentax O-GPS1 unit or a K 3 II

I could use:

HD Pentax-DA 16-85mm F3.5-5.6 ED DC WR,

SMC Pentax-DA 21mm F3.2 Limited,

Kino Precision Japan Kiron 28mm F2 MC P/KA

SMC Pentax-DA 40mm F2.8 XS

SMC Pentax-DA F1.8 50 mm

HD Pentax-D FA* 70-200mm F2.8 ED DC AW

I am guessing I want the widest point of view and the one with the largest aperture

thanks for any help anyone can give
QuoteOriginally posted by Aslyfox Quote
any one have a suggestion as to what lens to use ? I will have a K 3 with the Pentax O-GPS1 unit or a K 3 II
I'd take the 21mm F3.2, the 50mm F1.8, and the 70-200mm F2.8 and mostly shoot wide shots with some stunning Yellowstone feature in the foreground, or see if you can do a DSO with half dome in the picture.

That sounds like a fun trip, I'm digging out of snow and with how this spring is going may still be doing so come mid May.
04-16-2018, 08:40 AM - 1 Like   #14
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QuoteOriginally posted by MossyRocks Quote
I'd take the 21mm F3.2, the 50mm F1.8, and the 70-200mm F2.8 and mostly shoot wide shots with some stunning Yellowstone feature in the foreground, or see if you can do a DSO with half dome in the picture.

That sounds like a fun trip, I'm digging out of snow and with how this spring is going may still be doing so come mid May.
thanks

nice thing about that plan is how small the 21mm and the 50 mm are since I have to fit the photography gear into a carry on

the other was making the trip any way

what is DSO?
04-16-2018, 08:46 AM   #15
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QuoteOriginally posted by Aslyfox Quote
what is DSO?
Deep Space Objects

---------- Post added 04-16-18 at 04:47 PM ----------

Thank you all for your informative replies! Looks like I've got a fair bit of reading to do
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