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A night with the Micro Four Thirds cameras

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#26 chasing photons

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Posted 07 February 2014 - 09:03 AM

ccs_hello,

Interesting spreadsheet you have there. Could you run the numbers for the following configurations?

Telescope: ED refractor
110mm aperture
660mm focal length
f/6 focal ratio

Image sensor: Micro Four Thirds
17.3mm x 13mm
21.6mm diagonal
16 megapixels (4610 x 3450)
Pixel size: 3.7um


Reducer:
0.5x, 0.66x and 0.8x

Your findings would be much appreciated. Thank you.

#27 mpgxsvcd

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Posted 07 February 2014 - 11:37 AM

Travis,

Any other micro4/3 cameras out there worth considering? I too am a Panasonic fan, but I know some of the other companies like Samsung haven't been standing still either.


I have only used Olympus and Panasonic Micro Four Thirds for AP so I can’t comment on how the other Mirrorless cameras do. However, I couldn’t imagine anything being better than a modified GH3 for any type of deep space images or observing. Well, that is until the GH4 is available.

The GH3 is rumored to take a $200 price cut soon. If that happens then it will be right around $800 brand new without a lens. The GH4 is a BEAST though. Especially considering it records 4K(4096x2160) @ 30 FPS video for just under $2000. It can also output 4K @ 30 FPS 4:2:2 10 bit over HDMI. That would be really sick when combined with an Image Intensifier.

Panasonic GH4 4K Pro hybrid stills and video camera

http://www.amazon.co...2_1?pf_rd_m=...

#28 RichardHC

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Posted 07 February 2014 - 07:11 PM

]

All Olympus cameras since the E-PM2 have had live bulb and live time. This feature is exactly what the Mallincam does. It allows you to set the refresh rate of the live view while the image is being captured. For instance if I take a 2 minute exposure I can have the camera refresh every 15 seconds and show me what it has captured so far.

The previous image will remain on the screen until the next frame updates.

There are some limitations to it though. ISO is limited to 1600 or less and the number of refreshes is limited to no more than 9 at ISO 1600. Therefore, you have to take the length of the exposure and divide it by 9 to determine what refresh rate to use. [/quote]

That looks very useful but is there any degradation of the captured image when you use live-time? (It seems clear that it's using up to 9 frame stacking rather than a single exposure here, which means another lot of read-out noise every time an image is read out for viewing). Hopefully read-out noise is so low that you don't notice it.

#29 ccs_hello

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Posted 07 February 2014 - 08:41 PM

Todd,

I used the following estimated parameters (3 different lens designs):

0.8x F.R. is a 38mm clear aperture, fl=280mm (ATR design)
110% fully illuminated on a m43 imager.

0.66x F.R. is a 40mm clear aperture, fl=130mm (possible design)
108% fully illuminated on a m43 imager.

0.5x F.R. is a 41mm clear aperture, fl=110mm (my own bino design)
76% fully illuminated on a m43 imager.

Clear Skies!

ccs_hello

#30 jdbastro

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Posted 07 February 2014 - 09:06 PM

The GH4 is a BEAST though. Especially considering it records 4K(4096x2160) @ 30 FPS video for just under $2000. It can also output 4K @ 30 FPS 4:2:2 10 bit over HDMI. That would be really sick when combined with an Image Intensifier.


Based on my experience, I think that using 4K video (aka UHD) on an image intensifier could be resolution overkill. I would say that HD resolution 1920x1080 is sufficient. Now on my GH3, I usually record video using the 1920x1080/60p .mov format (per your earlier recommendation) which has a data rate of 50Mbps. The GH4 will do this same resolution at a higher data rate of 200Mbps (which requires a new, faster memory card, BTW). That's a 4X reduction in compression. Sounds good.

I wonder if that reduced compression makes a difference when posting video to YouTube, though. Would it?

The other plus in going from a GH3 to GH4 is that the GH4's new sensor is advertized to produce less noise and therefore the max ISO (for stills) has been bumped up one notch from 12800 to 25600. On the GH3, the max available ISO for video is 6400, so it could mean that on the GH4 the max ISO for video will go up to 12800, maybe. This feature has not yet been confirmed, however.

So what do you think? Is there a good reason to move up from a GH3 to a GH4 with the intent of getting better video low-light response (aka better low-light sensitivity)? I will admit, that I am drooling somewhat.

Thanks.

#31 chasing photons

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Posted 07 February 2014 - 10:26 PM

ccs_hello,

Thank you very much for running the numbers on those three reducers. I really appreciate it. It is good to gain insight on what I can expect for potential vignetting.

Now I need to find some fast refractor users that have experience with this level of reduction while imaging with Four Thirds or larger chips to determine the typical level of optical distortion around the edge of the image circle. I wonder if field flatteners perform well in conjunction with more aggressive focal reducers. Apparently the Astro-Tech 0.8x reducer/flattener does a good job with f/6 refractors.

Now to pick a Micro Four Thirds camera that performs well for near real time viewing and has all of the features that I want for every day photography!

#32 mpgxsvcd

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Posted 07 February 2014 - 11:51 PM

[quote name="RichardHC"]]

All Olympus cameras since the E-PM2 have had live bulb and live time. This feature is exactly what the Mallincam does. It allows you to set the refresh rate of the live view while the image is being captured. For instance if I take a 2 minute exposure I can have the camera refresh every 15 seconds and show me what it has captured so far.

The previous image will remain on the screen until the next frame updates.

There are some limitations to it though. ISO is limited to 1600 or less and the number of refreshes is limited to no more than 9 at ISO 1600. Therefore, you have to take the length of the exposure and divide it by 9 to determine what refresh rate to use. [/quote]

That looks very useful but is there any degradation of the captured image when you use live-time? (It seems clear that it's using up to 9 frame stacking rather than a single exposure here, which means another lot of read-out noise every time an image is read out for viewing). Hopefully read-out noise is so low that you don't notice it. [/quote]

It looks identical to not using the Live Bulb or Live Time feature. I can only assume that the ISO limitations are what makes the difference unnoticeable. I would love for it to be ISO 6400 or ISO 12,800 for this feature. However, it stills works at ISO 1600.

#33 mpgxsvcd

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Posted 07 February 2014 - 11:58 PM

Now to pick a Micro Four Thirds camera that performs well for near real time viewing and has all of the features that I want for every day photography!


All Olympus cameras since the E-PM2 have used the same sensor or virtually the same sensor. Some of the cameras have had 5 axis image stabilization which is great for everyday picture but not useful for AP.

The Panasonic GH3 is still ahead of all other Panasonic cameras and on Par with the Olympus models. The other Panasonic cameras are probably a little behind the GH3.

#34 mpgxsvcd

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Posted 08 February 2014 - 12:06 AM

The GH4 is a BEAST though. Especially considering it records 4K(4096x2160) @ 30 FPS video for just under $2000. It can also output 4K @ 30 FPS 4:2:2 10 bit over HDMI. That would be really sick when combined with an Image Intensifier.


Based on my experience, I think that using 4K video (aka UHD) on an image intensifier could be resolution overkill. I would say that HD resolution 1920x1080 is sufficient. Now on my GH3, I usually record video using the 1920x1080/60p .mov format (per your earlier recommendation) which has a data rate of 50Mbps. The GH4 will do this same resolution at a higher data rate of 200Mbps (which requires a new, faster memory card, BTW). That's a 4X reduction in compression. Sounds good.

I wonder if that reduced compression makes a difference when posting video to YouTube, though. Would it?

The other plus in going from a GH3 to GH4 is that the GH4's new sensor is advertized to produce less noise and therefore the max ISO (for stills) has been bumped up one notch from 12800 to 25600. On the GH3, the max available ISO for video is 6400, so it could mean that on the GH4 the max ISO for video will go up to 12800, maybe. This feature has not yet been confirmed, however.

So what do you think? Is there a good reason to move up from a GH3 to a GH4 with the intent of getting better video low-light response (aka better low-light sensitivity)? I will admit, that I am drooling somewhat.

Thanks.


This is a tough one. I really don’t know the answer. 4K video will show the noise more. The binning in 1080p video from a 16 megapixel sensor reduces the noise. That being said the 4K video will allow a lot more cropping. Then focal reducers might work well even with fast scopes.

I don’t think it will be any worse but I am not sure if it will be better or not. Only way to find out is to buy one. The current rumor is $1600. If so then it is a steal. I will buy one for sure.

#35 ccs_hello

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Posted 08 February 2014 - 07:52 AM

Live Time needs two clicks. First click starts the image acquisition process and the second one stops it. Live Bulb is almost the same except that pushing the shutter release button all the way down starts it and release the button stops it.

Either one will only show on the LCD screen the frame stacked (up to 9 frames) immediately after the new image is acquired. But you can continue for more frames, you just can't see additional improvement on he screen, the result will still be written into the SD memory card.

But Live Time/Live Bulb's ISO1600 limit is the problem.

Clear Skies!

ccs_hello

#36 ccs_hello

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Posted 08 February 2014 - 07:56 AM

Comments on sensor used in Panny and Oly

Both are marketing machines and set up tiers for different camera models. Low-end/cheaper models get the "proper" parts to match the tier.

Clear Skies!

ccs_hello

#37 ippiu

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Posted 08 February 2014 - 08:43 AM

I'm so interested in this topic because i have the omd em-5 for 2 years (wonderful camera).

But i have a question: as i use a meade LS 8" i certainly need a focal reducer. Now, with Watec 120 N+, i use a normal focal reducer because everything is easy due to small watec sensor. But with a micro 43 camera, what focal reducer could i use on my meade lightswitch 8"??

And what maximum focal ratio could i reach using micro 43 camera?

Thanks and sorry for my bad english, but i'm italian...:)

#38 chasing photons

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Posted 08 February 2014 - 10:55 AM

If the GH3 had focus peaking, in-camera time lapse and stop motion video file creation, and dipped below $800, I would be holding one right now. The E-M10 has Wi-Fi and HDMI, but I suppose the HDMI doesn't do Live View out. Are you sure they have not improved on the ISO and time limitations with the E-M10 Live Bulb/Time modes? Or is that a hardware issue that firmware cannot address? And would the new Live Composite mode have any value for near real time viewing?

#39 mpgxsvcd

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Posted 08 February 2014 - 02:21 PM

If the GH3 had focus peaking, in-camera time lapse and stop motion video file creation, and dipped below $800, I would be holding one right now. The E-M10 has Wi-Fi and HDMI, but I suppose the HDMI doesn't do Live View out. Are you sure they have not improved on the ISO and time limitations with the E-M10 Live Bulb/Time modes? Or is that a hardware issue that firmware cannot address? And would the new Live Composite mode have any value for near real time viewing?


You need to go ahead and buy the GH3 then. Those things are not an issue for the GH3.

Focus peaking is not affective for AP. Things like coma and aberrations will prevent the camera from being able to get very accurate focus automatically. The 10x and 14x lossless magnification modes are best for focusing.

The GH3 has time lapse in camera. A remote is always another option for the Panasonic cameras that don't do time lapse. Why do you need stop motion video? Just take 2 FPS videos or use the speed up video mode.

The GH3 is the only one that can do HDMI live view. However, the RCA output will work just as well as it will on the Mallincam. Wireless is the best option here though.

I believe that the bulb and live time is always limited to ISO 1600 on all Olympus cameras. It isn't a big deal though. For shorter exposures you don't need it to update because you don't have to wait that long anyway. For longer exposures you wouldn't be able to use the higher ISOs with a fast scope.

Like I have said before the key to near real time viewing is focal ratio. If you have a fast focal scope most of the newer m4/3s cameras will work great for near real time viewing. However, a modified Panasonic GH3 is the best option right now in my opinion.

#40 mpgxsvcd

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Posted 08 February 2014 - 02:27 PM

I'm so interested in this topic because i have the omd em-5 for 2 years (wonderful camera).

But i have a question: as i use a meade LS 8" i certainly need a focal reducer. Now, with Watec 120 N+, i use a normal focal reducer because everything is easy due to small watec sensor. But with a micro 43 camera, what focal reducer could i use on my meade lightswitch 8"??

And what maximum focal ratio could i reach using micro 43 camera?

Thanks and sorry for my bad english, but i'm italian...:)


I have not found a focal reducer that will work with micro four thirds in its native size with my 8" F4.0 scope. Now that is a fast focal ratio scope so it might be different with slower focal ratio scopes. You can use the in camera 2x lossless crop mode to eliminate most of the coma with a focal reducer. That is a pretty narrow field of view though.

#41 ippiu

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Posted 08 February 2014 - 03:36 PM

So do you use your micro 43 camera diretcly attached to your scope? What adaptor do you use? Yeah, you have an f4 scope and everything is fast. But if you had an f10 scope, how do you behave? Do you think a focal reducer is necessary? I think yes! Expecially for the largest deepsky obiects...

#42 mpgxsvcd

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Posted 08 February 2014 - 09:35 PM

So do you use your micro 43 camera diretcly attached to your scope? What adaptor do you use? Yeah, you have an f4 scope and everything is fast. But if you had an f10 scope, how do you behave? Do you think a focal reducer is necessary? I think yes! Expecially for the largest deepsky obiects...


Yes I use the adapter below to attache the camera directly to the scope. It will be difficult to do with an F10 scope no matter what camera you have. The advantage that smaller chip cameras have is that you can use focal reducers even in a stacked configuration to get a fast focal ratio without a lot of aberrations.

With Micro four thirds and larger sensor cameras you need a fast native focal ratio scope with a coma corrector.

#43 SJTill

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Posted 09 February 2014 - 02:54 AM

Wow, this is a real eye-opener for me as a total noob in AP.
I had no idea one could do near-real-time imaging like this with M4/3 cameras. I have two: an E-M5 and an E-P2--the latter unfortunately appears not to have live bulb/live time functions.
I'm leery of converting the E-M5 at this point since it's my main general photography camera. Tempting to buy an E-PM2 body and have it converted just to give it a try.

I have 2 F/7 refractors and a TV 0.8 reducer, so it looks like I would be getting a lot of vignetting with an M4/3 sensor.

In any case I look forward to learning more from you!

#44 chasing photons

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Posted 10 February 2014 - 05:28 PM

Concerning image sensors in Pana and Oly m43 cameras. I just ran across this rumor and have no idea if it is true. The new 'flagship' Olympus E-M1 supposedly has a Panasonic image sensor rather than a Sony sensor found on other Olympus cameras. People are now saying that is why The E-M1 is performing slightly worse than the E-M5?

Here is the link...

http://www.43rumors....nasonic-sensor/

#45 mpgxsvcd

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Posted 10 February 2014 - 07:48 PM

Yes I have seen that report as well. However, I don't believe the E-M1 performs worse than any other m4/3s camera. It is one of the best selling micro four thirds cameras ever despite being one of the most expensive. All of the test results say that it produces the exact same image as the other Olympus cameras and the Panasonic GH3.

Panasonic has never admitted that the GH3 has the same sensor as the Olympus E-M5 yet they produce the exact same image.

Really it doesn't matter who makes the sensor. It only matters what the results are. I can tell you from experience that the Panasonic GH3 and the Olympus E-PM2 produce identical results. It doesn't matter which one has the Sony sensor and which one has a Panasonic sensor. They both are tremendous for all AP once they are modified. Even not modified they are good for galaxies.

DXOMark comparison
http://www.dxomark.c...E-M1-versus-...

#46 iam1ru12

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Posted 13 February 2014 - 10:12 PM

I was at the observing session where Travis share these live views, it was extremely amazing to see this!

Travis, thanks for sharing!
-Mike

#47 mpgxsvcd

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Posted 13 February 2014 - 11:26 PM

I was at the observing session where Travis share these live views, it was extremely amazing to see this!

Travis, thanks for sharing!
-Mike


Thanks Mike. Would love to try the petite E-PM2 with the hyperstar sometime. Does the camera connect to the hyperstar with a t-mount adapter?

#48 ScottAz

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Posted 14 February 2014 - 06:53 AM

Wow! I had entirely missed this thread after being VERY busy at school for several days… Please keep posting cool ideas for micro 4/3 cameras! I ordered a GH3 after reading many of Travis's posts in previous threads (and on several sites) but have yet to get outside with it and a telescope because of the very cold weather here in Wisconsin. :coldday:

Can't wait for Spring! :fingerscrossed:

#49 Raginar

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Posted 14 February 2014 - 08:29 PM

Travis,

So, can you detail your setup? How do you have it plugged into your scope? You've modd'd the camera so that it doesn't have it's glass similar to a DSLR for AP right?

Can you compensate for a 'not fast' telescope by just increasing the exposure? Or are the cameras limited to certain exposures? I don't mind guiding. Is the limitation on using a focal reducer based primarily on the spot size versus the huge chip in these cameras?

Can you stream the live view? You mention an electronic bulb, what software is required? Is there a model that will operate via WIFI or is this put together with an HDMI cable/USB cable? Can you power it via an AC adapter?

#50 mpgxsvcd

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Posted 15 February 2014 - 10:25 AM

I will try to sum it up as best I can. I wish I could finally finish the video tutorial that I have been working on but I just have too many other things going on right now.

I have an Astro Tech 8 inch 800mm F4.0 scope with the Astro Tech coma corrector/field flattener. It has a 2 inch to t-mount adapter ring that came with the coma corrector. I put enough t-ring spacers in there to give me exactly 1 and 7/8 of an inch spacing between the shoulder of the t-mount adapter to the flange of the camera lens housing. If you need the exact dimensions of the spacers I can try to provide them later.

Then I use a thin t-mount adapter to micro four thirds adapter that I got off amazon for about $30 to attach the camera.

That is the setup I use when I am at a dark site. I don’t need filters there so I can just attach directly to the coma corrector. This gives me the least amount of coma and simplifies the collimation process.

When I image in my backyard I put the Orion 5 slot 1.25 inch filter wheel set in the imaging chain instead of the t-mount spacers. I have to adjust the total distance back a bit because the filters do affect the coma some.

I use 5 Baader filters including the UV/IR cut, UHC-S, OIII, 7nm Ha, and 30 nm Ha. Since I had Brent Oliver modify the E-PM2 to visible + Ha it works very well with all of the filters.

The GH3 and the Olympus cameras can be controlled by the Pixel wireless remote timer. There is no way to currently control the cameras by hooking them up to a computer with a wire. However, there is a program in development that will allow remote control of the GH3 via a wireless network. I have not tried that yet since I personally like the remote controls better. I hate bringing a laptop out there with me. It causes too much light pollution, the battery doesn’t last long enough, and it is just cumbersome to deal with.

I don’t guide normally. Since I have a fast F4.0 scope I can just take higher ISO images in 1 minute or less. The GH3 is only good for ISO 6400 and below since everything above that is not a true electrical gain. The new GH4 will go to at least ISO 12800 with a true electrical gain. However, that camera will be almost $1700. I will probably get mine late next month.

The GH3 will transmit the live view via wireless with a slight(1-2 second delay). The live view is good up to 8 second exposures. You can trigger the camera with a phone or ipad including in bulb mode. However, you can’t explicitly define what duration you are going to use with the wireless connection. I still use my wireless remote even when I am using the phone or Ipad for my live view.

The Olympus E-PM2 will do a true electrical gain all the way to ISO 25,600. I usually only use as much as ISO 12,800 though. 1 minute at ISO 12,800 with an F4.0 scope is a TON of exposure. You will blow out most bright objects with that exposure. From my testing ISO 12,800 is the equivalent of what the Mallincams I have tried will do. Canon A-PSC cameras cannot go above ISO 1600 effectively so that is why most people think you can’t use an interchangeable lens camera for near real time viewing.

I don’t get any vignetting and minimal coma when I don’t use the filters. I couldn’t afford the 2” filters so I do get a little vignetting when I use the 1.25” filters. I have tried aggressive(.5x) focal reducers and they produce massive coma with micro four thirds. That is one advantage a smaller chip camera like the Mallincams have.

That is much as I can say about it right now. The GH3 is a great camera for this. I just wish I could afford to have mine modified. That really does make a huge difference with a lot of great objects. I am excited for the GH4 though. It is supposed to have much better heat dissipation than even the GH3 has.

I might have my GH3 modified once I get my GH4. Gotta love the 4K @ 30 FPS video the GH4 will do!
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