Suitability of the Sony SEL200600G Lens for Astrophotography

[joerg]

A year ago now, I started using my super telephoto zoom lens, originally purchased for wildlife photography, for astrophotography. Here I would like to share my experiences, but also go into some limitations that the Sony lens has in my opinion.

In the first section, I will report on my experience using the SEL200600G lens in combination with a Sony SEL20TC 2xteleconverter and a Sony A6000 APS-C camera on a simple aluminum tripod. Although the construction is rather shaky and finding the objects and also focusing is difficult, exposure times up to about 1/8s (@ 1800mm focal length 35mm equivalent) can be achieved and so some bright objects of our solar system can be photographed.

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Lunar photography

To photograph the moon with its apparent diameter of about 30' format-filling the setup is almost ideal, the moon fills about 75% of the horizontal image area. Also the sharpness is sufficient to see some nice details.

Moon, 10.8 days old, F13 ISO-100 1/60s

Crop of the so called golden handle

 

Solar photography

Since the sun has almost the same apparent diameter as the moon, the same applies to solar photography as just mentioned, except that a suitable solar filter (in my case a Baader 5.0) must be used!

Sun with several sun spots, F19 ISO-800 1/1500s

 

Planetary photography

Bright planets can also be photographed with this equipment. However, the lens with its 95mm diameter is not fast enough and the achievable focal length of 1800mm is not long enough to see details.

Jupiter, F13 1/30s ISO-100

Saturn, F13 1/15s ISO-400

Venus 270 days old, F13 ISO-400 1/1000s

 

Edited April 14, 2021 by joerg

[joerg]

In the second section I would like to discuss the possibility of photographing deep sky objects.

To achieve exposure times of a few seconds the earth's rotation has to be compensated, in my case by the equatorial mount CEM25P from iOptron. With the possibility of autoguiding, here by the MGEN3 from Lacerta in combination with a 50mm finder scope, exposure times of several minutes can be achieved. Seemingly small things are also important in my opinion, like a heating tape to avoid humidity condensation and the use of a dummy battery adapter to be able to run the camera constantly for several hours.

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Emission and reflection nebulae

With the possibility to select the focal length almost arbitrarily between 200 and 1800mm, very many objects can be photographed with the SEL200600G. For emission nebulae with a primary emission at hydrogen-alpha and 656nm the use of an astromodified camera is recommended (replacement of the IR cut filter by clear glass). In my case I took a Sony A7R bought used at E-Bay and let it astromodify.

Orion nebula M42 Composit 10x10s and 30x180s ISO-800 F6.3 600mm 7xDarks 15xFlats 15xBias Optolong L-Pro Filter

Plejades M45 28x120s ISO-800 F6.3 600mm 5xDarks 26xFlats 20xBias

 

Galaxies

The same applies analogously to galaxies as to planetary photography. It is possible to photograph single galaxies. However, the optic is not fast and not long-wavelength enough for very detailed images.

Markajan chain 102x240s ISO-800 600mm F6.3 6xDarks 15xFlats 15xBias

M51 110x120s ISO-1600 1200mm F13 7xDarks 15xFlats 15xBias

Edited April 14, 2021 by joerg
typo

[LiveShots]

That is cool !

[photocowb0y]

On 4/14/2021 at 9:54 AM, joerg said:

A year ago now, I started using my super telephoto zoom lens, originally purchased for wildlife photography, for astrophotography. Here I would like to share my experiences, but also go into some limitations that the Sony lens has in my opinion.

In the first section, I will report on my experience using the SEL200600G lens in combination with a Sony SEL20TC 2xteleconverter and a Sony A6000 APS-C camera on a simple aluminum tripod. Although the construction is rather shaky and finding the objects and also focusing is difficult, exposure times up to about 1/8s (@ 1800mm focal length 35mm equivalent) can be achieved and so some bright objects of our solar system can be photographed.

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

 

Lunar photography

To photograph the moon with its apparent diameter of about 30' format-filling the setup is almost ideal, the moon fills about 75% of the horizontal image area. Also the sharpness is sufficient to see some nice details.

Moon, 10.8 days old, F13 ISO-100 1/60s

Crop of the so called golden handle

 

Solar photography

Since the sun has almost the same apparent diameter as the moon, the same applies to solar photography as just mentioned, except that a suitable solar filter (in my case a Baader 5.0) must be used!

Sun with several sun spots, F19 ISO-800 1/1500s

 

Planetary photography

Bright planets can also be photographed with this equipment. However, the lens with its 95mm diameter is not fast enough and the achievable focal length of 1800mm is not long enough to see details.

Jupiter, F13 1/30s ISO-100

Saturn, F13 1/15s ISO-400

Venus 270 days old, F13 ISO-400 1/1000s

 

Thank you so much for sharing this interesting post, and especially for the great images you took and showed us.

[AntDX316]

Where are you shooting to get such a dark non light polluted sky?

[joerg]

In my backyard (officially Bortle class 4, but I guess it is worse).

The nearest streetlight is only about 10 metres away. I just gave it an extra cardboard lampshade so that it doesn't shine fully into my optics. ?

Fortunately, there was almost no gradient in the shots. You can live very well with homogeneous background lighting in post-processing, but I can't cope with gradients at all... ?

Edited April 26, 2021 by joerg

[alasdairmac]

Thanks for posting this Joerg. Very interesting. Astro is not something that I've tried but I do have a 150-600mm and a 2x teleconverter in my camera bag and so you have got me thinking that I might do some experimenting.  

[thebeardedgroundsman]

Interesting post.

I'm experimenting with astro - moon and star trails at the moment- from my back garden. I live in a Bortle class 7 area and have found my Haida MC Clear Night filter cleans up the image really well.

 

[joerg]

Taking a cue from "Lucky Imaging", I have reworked my approach to photographing bright celestial objects (namely the Moon, Jupiter, Saturn, Mars and Venus) with my Sony equipment:

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Jupiter Sony A7R iii 100x1/60s ISO-400 1200mm F13

Hardware used:

- Sony A7R iii (full frame camera)

- Sony SEL200600G (SEL 200-600mm F5.6-6.3 E-mount telephoto zoom lens)

- Sony SEL20TC (2x teleconverter)

- Sony RMT-P1BT Bluetooth remote control unit

- Sturdy tripod

- Bahtinov mask

Software used (all freeware):

- PIPP

- AutoStakkert 3

- RegiStax 6

Take pictures:

- Centre object in frame (helpful to zoom to 200mm first and find the object, then move to 600mm).

- Focus using the Bahtinov mask (alternatively, focus manually using the focus magnifier)

- Take approx. 100-700 pictures in continuous shooting mode (high speed) (manual mode with exposure time much shorter than 1/10s)

Post-process the images:

- Convert the RAW images into an AVI film in PIPP

- Stack the images in AutoStakkert

- Sharpen in RegiStax

- Further post-processing, e.g. in Adobe Photoshop, is possible, but not really necessary.

For those interested, the workflow in PIPP:

- Open RAW images in the Source Files tab, pre-select "Planetary"" for all planets (not moon!) (object must contain 25 pixels, image will be cropped to 448x448 pixels),

- Output Options - here you can set the data format and the output directory, but it should fit (AVI into the same directory as the RAWs).

- Do Processing - Start Processing

in AutoStakkert:

- Open generated AVI file ( 1) Open)

- Image Stabilization - "Planet (COG)" and "Dynamic Background" remain activated.

- Select the size of the alignment points (e.g. 24 or 48, rather not more than 100) and create a grid with "Place AP Grid", approx. 20-50 blue frames should be created in the analysis image.

- 2) Analysis - a "Quality graph" (grey graph of single images, sorted in green descending order) is generated.

- Use the green slider to select a limit (e.g. the best 10%, 20% or 35%). Then enter this in the first field on the left at "Frame Percentage to Stack".

- The other 4 options can be/remain activated.

- 3) Stack

 and in RegiStax:

- Open stacked image

- Possibly more contrast and less brightness, if there are bright areas without inner structure you have overdone it.

- Sharpen - the sliders sharpen larger and larger details from top to bottom. Pull them to the right in this order. This creates artefacts, which can be removed by increasing the

- denoise (whereby the denoise box above the first sharpness control with e.g. 0.4 is often sufficient).

- The goal is an image with many clearly defined details without traces of noise or grain.