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07-27-2018, 03:49 AM   #1
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K70 Astro lens advice

Hi guys, my first post and new to photography after an accident ended my career & I find myself retired and seeking new adventures..!!

Looking for some advice on lens’ for the K70 ( a present 2 get my head out my #$$ & back in the great outdoors, hence the need for weather sealing and stabilised body) in the following genres please..

Wildlife /action..birds in flight (we live rurally and out with the dogs see plenty of deer, buzzards/kites.. couple miles away is a bird of prey center. I also have awesome coastline with puffin colony's within hours drive)

Motorsport (regularly frequent track days)

Astro &landscape ( have a caravan sited on Dumfries & Galloway coastline, so now I can blast the tarmac anymore, thinking I’ll take advantage of the beautiful landscape @ a much slower pace, very keen2 try Astro photography while up in the dark sky forest)

So my question, as a newbie.. which lens’ should I get?
Budget.. I go second hand as this is early days and I might well find it’s not for me, but I’m loving the learning curve and being out with a camera so far. 🤩

Any advice greatly appreciated
Regards
Don

07-27-2018, 05:15 AM   #2
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Well, for the track days, you're going to want something with some flexibility so consider a zoom. As weather sealed zooms go on a budget, I would strongly recommend a good used copy of the DA 18-135WR. I just got one earlier this year and it's a terrific walk-around lens with decent reach, while still backing out wide enough to get the whole scene if you need to. I suspect it's not enough zoom for moon shots, but it should be good for full sky shots when opened up to 18. A quality used copy is going to run you somewhere around $200-ish, maybe as much as $250 if they are scarce when you go looking.

For the moon, I think you need more zoom, so I'd suggest a DA 55-300. The HD version is good, but the new PLM version is better. It's going to run you $350-400, unless you catch a sale. You could do the job with an older F or FA lens (either a long prime or a zoom with that kind of reach) for $50-100, but image quality will be somewhat less sharp and you won't have weather sealing.

I'm just an amateur at this, myself, so others may come along and correct my thoughts.
07-27-2018, 05:41 AM - 1 Like   #3
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Hi Don, welcome to the Pentax Forum!
When you mention wildlife, action, birds in flight and motorsport, I can think of only one lens: the 55-300mm PLM, lightweight, fast autofocus, good IQ check out the reviews here: HD Pentax-DA 55-300mm F4.5-6.3 ED PLM WR RE Reviews - DA Zoom Lenses - Pentax Lens Reviews & Lens Database
Pictures taken with the 55-300mm PLM: HD Pentax-DA 55-300mm F4.5-6.3 ED PLM WR RE - Show us what it can do, what it CAN'T! - PentaxForums.com
SRS Microsystems has it for 369£, you get a 45£ discount until beginning of August: Pentax HD Pentax DA 55-300mm F4.5-6.3ED PLM WR RE Lens - Pentax Lenses - Lenses
For astrophotography, consider some of the older A/M/K manual lenses, the lens review section is a must read if you're looking for some older glass: Pentax Lenses - Pentax Lens Reviews & Lens Database
A couple of lenses to consider for astrophotography/landscape could be the DA 35mm f2.4 or the DA 50mm f1.8, they are both offer good value for money (110/115£ at SRS Microsystems)
The DA18-135WR is also a lens to consider, DA 18-135 WR, Show us what it can do - PentaxForums.com
Apart from the DA35 I have them all in my bag next to my K-70.


SRS Microsystems also offers refurbished/used lenses: Used Pentax Fit Camera Lenses | SRS Microsystems
07-27-2018, 05:46 AM   #4
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For astro (if you aim at starscapes rather than nebulae) some old second hand and cheap lenses can do - I use SMC Pentax-M 28/2.8, but SMC Pentax-A 28/2.8 should be more convenient. Wider (less mm), faster (smaller f-number) lens, like 16/2 , is better, but this is a good starting point - just set lens to infinity keep it wide-open, set exposure time around 15 seconds and experiment with the ISO (sensivity) setting.


Last edited by Piotrek K; 07-27-2018 at 07:45 AM.
07-27-2018, 06:08 AM   #5
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Thank you, “ dubyam” “DrawsACircle” & “Piotrek K”... some reading for me to do on those previous reviews, cheers.

Luckily for me the K70 came with the afore mentioned 18-135mm DA lens which I’m using mainly @ moment.. ( also have been gifted the 50mm 1:1.8 DA lens, but not clipped it on yet)..!!?

Cheers
Don
07-27-2018, 06:49 AM   #6
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Sounds like you only need a longer zoom, and you're all set! Enjoy!
07-27-2018, 06:53 AM - 1 Like   #7
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For astro on APS-C my advice is as follows:
1. For the moon get as big of a telephoto as you can find. Even with a 300mm the moon doesn't fill much space. For example on my k-3 a moon photo taken with my 300mm is something like 600-800 pixels across (I should probably measure it). So if you want a moon photo with the moon the primary subject I suggest bigger.
2. For constellations I find that a 50mm works great and you can pretty much fit any of them in the frame. A fast old good 50 or 55 is cheap so just buy one.
3. For Deep Sky Objects (DSOs) you want something big, bright, and ideally with ED glass. DSOs are pretty faint in general so you want a pretty fast lens, add in that many are pretty small you need a big lens. A 135mm is the smallest I have used for DSOs and gotten reasonable results from but if you have a fast 200 or larger it would be better. You will need to stop the lens down 1 or 2 stops in almost all cases to help with chroma because DSO photography seems to be exceptionally punishing on lenses. That said if things are done right one can get some really impressive results even with old small lenses. Also for DSOs you will need to learn how to stack photos and do post processing because otherwise you will just get faint items just above the noise floor of the image.
4. For Milky Way and star trail pics go wide and stick something in the foreground. I have used by 28mm f/3.5 SMC Takumar and 17mm f/4 SMC fisheye takumar for these and have really liked the wide view from that 17mm fisheye.

Also with astro photography if you don't have a tracking mount you will need to remember the rule of 500. Basically to avoid star trails from being visable keep the shutter speed under 500/(focal length). This works best for constelations and milky way photos. For DSOs I will use the rule of 200 as this typically keep the object from moving even a couple of pixels so things stay sharp.
For the moon use the looney 11 rule, always use this as it gets you close enough that post processing can easily handle the rest.
If you are using astrotracer as your tracking get the astro object you want centered in the frame and keep the exposure under 1/4 of the max it recommends. This will help a lot with the errors that accumulate in tracking and also since astrotracer doesn't do rotation this will keep the trails at the edge of the image to a minimum.

My other advice for astrophotography is get a heavy stable tripod, cable release, use the 2 second mirror up delay, and finally get a focusing aid (a bahtinov mask is the preferred solution it sounds like) as auto focus really doesn't work all the well if at all when doing astrophotography.

---------- Post added 07-27-18 at 07:13 AM ----------

QuoteOriginally posted by Piotrek K Quote
just set lens to infinity keep it wide-open, set exposure time around 1/15 and experiment with the ISO (sensivity) setting
Have you tried extending the exposure, even with a 28mm lens on a tripod that is a very short exposure for star fields or any wide field astro pics. I've done DSOs with a 135mm and 1.5s exposure with good results using the rule of 200 and not gotten trails. I've done constellations with a 50mm and 4 seconds of exposure without trails so with a 28mm you should be able to shoot pretty close to 10 second exposures without getting egg shaped stars. If you use the rule of 500 you should be able to shoot pretty close to 20 seconds with that 28mm lens giving you about 8 extra stops to work with. So maybe put 1 or 2 stops into the f/stop to sharpen things up some more and the rest into a lower ISO or more exposure to bring out the details.
07-27-2018, 06:54 AM   #8
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QuoteOriginally posted by dubyam Quote
sounds like you only need a longer zoom, and you're all set! Enjoy!
��������

07-27-2018, 07:22 AM   #9
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QuoteOriginally posted by Bodie450 Quote
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Based on the lenses you have, and the various recommendations you've received here, you have just about every focal length covered except something in a longer zoom (250-300mm focal length or longer) to cover the uses you've specified. You have the 18-135, and a nice 50mm prime, so all you need now is a longer zoom.
07-27-2018, 07:44 AM   #10
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QuoteOriginally posted by MossyRocks Quote
For astro on APS-C my advice is as follows:
1. For the moon get as big of a telephoto as you can find. Even with a 300mm the moon doesn't fill much space. For example on my k-3 a moon photo taken with my 300mm is something like 600-800 pixels across (I should probably measure it). So if you want a moon photo with the moon the primary subject I suggest bigger.
2. For constellations I find that a 50mm works great and you can pretty much fit any of them in the frame. A fast old good 50 or 55 is cheap so just buy one.
3. For Deep Sky Objects (DSOs) you want something big, bright, and ideally with ED glass. DSOs are pretty faint in general so you want a pretty fast lens, add in that many are pretty small you need a big lens. A 135mm is the smallest I have used for DSOs and gotten reasonable results from but if you have a fast 200 or larger it would be better. You will need to stop the lens down 1 or 2 stops in almost all cases to help with chroma because DSO photography seems to be exceptionally punishing on lenses. That said if things are done right one can get some really impressive results even with old small lenses. Also for DSOs you will need to learn how to stack photos and do post processing because otherwise you will just get faint items just above the noise floor of the image.
4. For Milky Way and star trail pics go wide and stick something in the foreground. I have used by 28mm f/3.5 SMC Takumar and 17mm f/4 SMC fisheye takumar for these and have really liked the wide view from that 17mm fisheye.

Also with astro photography if you don't have a tracking mount you will need to remember the rule of 500. Basically to avoid star trails from being visable keep the shutter speed under 500/(focal length). This works best for constelations and milky way photos. For DSOs I will use the rule of 200 as this typically keep the object from moving even a couple of pixels so things stay sharp.
For the moon use the looney 11 rule, always use this as it gets you close enough that post processing can easily handle the rest.
If you are using astrotracer as your tracking get the astro object you want centered in the frame and keep the exposure under 1/4 of the max it recommends. This will help a lot with the errors that accumulate in tracking and also since astrotracer doesn't do rotation this will keep the trails at the edge of the image to a minimum.

My other advice for astrophotography is get a heavy stable tripod, cable release, use the 2 second mirror up delay, and finally get a focusing aid (a bahtinov mask is the preferred solution it sounds like) as auto focus really doesn't work all the well if at all when doing astrophotography.

---------- Post added 07-27-18 at 07:13 AM ----------



Have you tried extending the exposure, even with a 28mm lens on a tripod that is a very short exposure for star fields or any wide field astro pics. I've done DSOs with a 135mm and 1.5s exposure with good results using the rule of 200 and not gotten trails. I've done constellations with a 50mm and 4 seconds of exposure without trails so with a 28mm you should be able to shoot pretty close to 10 second exposures without getting egg shaped stars. If you use the rule of 500 you should be able to shoot pretty close to 20 seconds with that 28mm lens giving you about 8 extra stops to work with. So maybe put 1 or 2 stops into the f/stop to sharpen things up some more and the rest into a lower ISO or more exposure to bring out the details.
I meant 15seconds. I will correct my previous post. 15 was clearly better for me compared to 20 sec. when looking at 100% crops. Thank you!
07-27-2018, 08:24 AM   #11
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“Rule of 500” is for full frame, APS-C is more a “rule of 300”
07-27-2018, 10:50 AM   #12
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QuoteOriginally posted by Piotrek K Quote
I meant 15seconds. I will correct my previous post. 15 was clearly better for me compared to 20 sec. when looking at 100% crops. Thank you!
That makes more sense and is much more inline with what I have been advised. With the limited amount of light when shooting at night I just didn't want them to start off on the wrong foot. I usually try to stick to the rule of 200 when I shoot stars so with a 28mm I would be at 7 or 8 seconds depending on where I have the camera pointed. Then I just take as many frames as I can shooting what ever object I can until I have to leave, it falls below the trees, or I am too tired to continue.
07-27-2018, 11:02 AM   #13
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Another vote for a 55-300 - the latest PLM version if you can afford it.
This a great zoom range to cover motorsport unless you are track side when your existing 18-135 is fine.
I recently visited Le Mans Classic with those two lenses and never felt the need for any others -- just a need for better technique.
07-27-2018, 11:44 AM   #14
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I agree with those voting for the 55-300mm PLM (much faster and quieter AF compared to the old equivalent). I also have the 50mm prime and the 18-135mm, and although I'm not into astro, with those three lenses, you've got a lot of bases covered.


Congrats on the new K-70, and have fun!
07-27-2018, 02:27 PM   #15
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Thanks to everyone one for the advice and experiences, plenty for me to digest..!
���� Don
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