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07-07-2018, 06:48 AM   #1
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Hi there...

Hi All,

what do you usually say in a introduction thread? ASL? I'm from Germany, I got a PhD in Biology, I worked with a lot of different high-end microscopes, image analysis, etc. over the last decade or so and am currently employed by a manufacturer of laboratory equipment as an application specialist for imaging.

I own a super-zoom Bridge Camera (HS10) which I occasionally still use (e.g. for high-speed video) but recently purchased a Pentax KP. Why an interchangeable lens camera (APS-C) and why Pentax? My wife recently got a new 1" point-and-shoot which is so much better than my bridge (10 years of sensor technology improvements and a bigger sensor on top)... we tried to shoot long exposures of a meteor shower with my camera (and didn't get good results) and just on a whim used her camera on the tripod and it was a revelation. I tried some of the recent 1" super-zoom bridge cameras (which perform nicely but not that much better than my wifes compact) and thought about full frame (but too expensive and heavy glass repelled me). So I ended up in the APS-C micro-cosmos and among the medium- to high-end choices Pentax stood out because it had all the "nerd" features I always wondered why nobody would implement. Pixel-shifting the sensor to improve resolution? We do that in microscopy, why doesn't anybody... wait, Pentax does that. And the use it to compensate for the earths movement, too? Brilliant! Why buy an 50 interval timer if it's a simple task for the camera electronics? Strike, point Pentax... I feel I am a bit limited with 3rd party lenses (and availability of used glass) but I feel I made a good choice feature wise with the bodies.

I already own for my Pentax KP:

"Sigma 18-300mm f/3.5-6.3 DC MACRO HSM"
Don't use it for macro work, but there is some perspectives you can't compensate for by walking (and I hate walking and it's a nice every day lens I use when walking the park, a city, etc. It's goof enough for some close ups, portrait, architecture and has a good maximum reach for wildlife... as long as the light is good. I also used it with a 2x converter for bright night sky objects like the Moon or Saturn (yes, 6.3 with a 2x converter is very, very dark but Saturn is very, very bright but small, need the extra mm badly)

"Sigma 70mm F/2.8 EX DG Macro"
Love that one for things that aren't moving too much like pottet plants, my millipedes and I recently used it for biometric portrait shots for a new passport, too.

"Sigma 10-20mm f/3.5 EX DC HSM"
For Landscape and Panorama shots where I don't want to employ stitching or don't have the time to take 20 shots from a tripod. Those extra 8mm compared to the 18mm are fantastic.

All bought used and yes, despite I'd like a weather resistant objective, somehow no Pentax glass has made it onto my camera... strange but that's how it is for now.

Currently thinking about:
Samyang 24mm 1.4 ED AS UMC or Irix 15mm 2.4 Blackstone or just using my 10-20mm f3.5 with O-GPS? For Panoramic shots of the milky way with some landscape included. Will probably open a discussion thread for that?

Let me know if you have any questions about image enhancement (wide-field de-convolution) or panorama stitching with focus stacking, have done that for thousands of microscopy images, will do that for some photos soon...

07-07-2018, 07:35 AM   #2
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Welcome to Pentax Forum, TheoRK. Looking fprward to your many contributions to this very active and helpful forum. Share some pictures when you get a chance.
07-07-2018, 12:29 PM   #3
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QuoteOriginally posted by TheoRK Quote
application specialist for imaging
Welcome to the forum, sounds like you could be our "go to guy" for high end macro stuff questions.
07-08-2018, 12:50 AM   #4
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QuoteOriginally posted by Kerrowdown Quote
Welcome to the forum, sounds like you could be our "go to guy" for high end macro stuff questions.
Well, If you want to focus-stack and stitch a mosaic of image stacks into an enhanced depth panorama (or keep the stacks and stitch them so you have a panorama where you can adjust focus) I have a nice workflow with free software. However, it will take some time for me to get used to all the different naming conventions (NA vs f/ and so on) and the whole post-processing thing is new to me. Sure, enhancing detail, choosing the right dynamic range, but I feel a little helpless right now removing orange glow from my astro images and have to read into that...

07-08-2018, 03:44 AM   #5
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welcome to the forum!
07-08-2018, 04:45 AM   #6
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Welcome to the forum.
Kind regards,
(New Zealand)
07-09-2018, 12:22 AM   #7
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Hi from Australia.
07-29-2018, 01:16 PM   #8
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The baby-twins are keeping me kind of busy at the moment, so ne stacked-mosaic images yet (I have shot some nice material) but a couple of examples what I've shot so far:
TheoRK's Album: First year with my KP -

07-30-2018, 07:48 AM   #9
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Pretty interesting stuff, I would like to learn about your stacking technics.
Regarding the Milky-way, have you considered the Samyang 10mm f2. 8?
07-31-2018, 08:16 AM   #10
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Thanks it's a bit limited what you can upload here and what resolution you can use... yes, I might consider donating.

About the milkey way, my 10-20mm f/3.5 Sigma is well... giving ok results with AstroTrace but a faster, less distorting lense would certainly be more useful. The 70mm f/2.8 macro from Sigma is giving near perfect results (still not very much light collected, but nice shape stars into the corners and nice colour), but the field of view is rather limited.

I've calculated that I can do a 3x5 mosaic with something like the Sigma 35mm 1.4 Art or 35mm 1.4 Samyang to get the same field of view as my 10mm, much higher resolution and much more light collected with less distortion. Both lenses seem between good and briliant for the task, I am undecided if the auto-focus (which will make the lense a lot more useful everyday) is worth double price... also having a look at vintage 300/4 and 500/5.6 glass now for planets and deep sky stuff. Certainly something like 400/2.8 would be nicer, but I feel I would need a car to mount it on instead of a tripod - while at the same time having to sell my car to afford one...

About the stiching, I can do a write-up some time soon. I use free software like Fiji to stich stacks of microscopy images. Currently struggling with background subtraction in astro images, as my usual approaches also remove all the nebula... lol.

Last edited by TheoRK; 07-31-2018 at 08:23 AM.
08-01-2018, 04:04 PM   #11
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Hello welcome aboard

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