Stargazing Level of details in prime focus vs eyepiece images

[sophiecentaur]

Is there an adapter that can fit a monochrome atsronomy camera to DSLR lenses directly?

A camera lens can obviously be adapted for any image sensor but going too far down that road is of questionable worth. Look around the suppliers; if there's a need for it then there must be something on the market.

A telescope OTA, is little more than a lens, a tube and a focus arrangement. The optical requirements are based on Astrophotography and not on general photography. A camera lens has an (auto) iris and a focussing arrangement (an internal motor perhaps) that is not intended for five minute exposures. Long lenses use telephoto optics which keep them short but involve several more elements. You are paying for stuff you don't need and you are not getting some of the things a regular scope can give you.

However, the quality of many good camera lenses (cheap and on the second hand market) will be a lot better than many entry level scopes.

One needs to ask oneself why nearly all the best astro images tend to be taken with scopes with large apertures and very simple lenses.

 

[PhysicoRaj]

A camera lens can obviously be adapted for any image sensor but going too far down that road is of questionable worth. Look around the suppliers; if there's a need for it then there must be something on the market.

A telescope OTA, is little more than a lens, a tube and a focus arrangement. The optical requirements are based on Astrophotography and not on general photography. A camera lens has an (auto) iris and a focussing arrangement (an internal motor perhaps) that is not intended for five minute exposures. Long lenses use telephoto optics which keep them short but involve several more elements. You are paying for stuff you don't need and you are not getting some of the things a regular scope can give you.

However, the quality of many good camera lenses (cheap and on the second hand market) will be a lot better than many entry level scopes.

One needs to ask oneself why nearly all the best astro images tend to be taken with scopes with large apertures and very simple lenses.

I agree. Was simply trying to think through avoiding having multiple DSLR 'bodies' for simultaneous narrowband exposures.

 

[sophiecentaur]

I agree. Was simply trying to think through avoiding having multiple DSLR 'bodies' for simultaneous narrowband exposures.

Horses for courses again. A DSLR will do loads of things that are not needed of Astro work and the sensor has the colour filters built in. Spending sever hundred quid will get you a very good sensor which you can buy to suit your planned subject and you can COOL it too. All the brains have to be supplied by your computer control but you can expect to be using a laptop out there in any case.

I can see that you are fully committed to a multiple camera solution. That is something you will have to learn about. Three DSLR systems, sharing a mount would need to be driven carefully- they can only be operated in sync because you can't poke around on one camera when another is making its exposure. That builds in a fair amount of necessary down-time; you won't get three times the exposure time.

BTW, have you read anywhere of anyone else who has operated a three camera system successfully? Do you have any links to other similar work or opinions about your system?

 

[Devin-M]

I doubt you can get 3 full-frame 36 megapixel astro-cameras for less than 3 second-hand dslr bodies. The D800’s were $3000 USD brand new but I picked up 2 averaging about $700 each…

“At the time of its release, the Nikon D800 became the Dxomark image sensor leader, replacing the Nikon D4 in the top position.[7]”

https://en.m.wikipedia.org/wiki/Nikon_D800

 

[sophiecentaur]

I doubt you can get 3 full-frame 36 megapixel astro-cameras for less than 3 second-hand dslr bodies. The D800’s were $3000 USD brand new but I picked up 2 averaging about $700 each…

“At the time of its release, the Nikon D800 became the Dxomark image sensor leader, replacing the Nikon D4 in the top position.[7]”

https://en.m.wikipedia.org/wiki/Nikon_D800

Are you comparing like with like here? I have to agree that there will be a premium on top end astro cameras but there will be a huge difference in the specs of the two different types of sensor involved. A high res monochrome astro camera does what it says on the tin whereas a colour DSLR camera is designed with different targets in mind.

People are free to make whatever choices they want, of course but unlike with HiFi equipment, there are many astro experts who can produce reliable numerical data to back up their choices of approach. I'd be inclined to read around a lot before committing to spending a lot on any astrophotography system.

Nevertheless, a standard colour camera can produce some really stunning images. It's all in the post processing.

 

[Devin-M]

I don’t need a laptop, I do everything on my phone from polar alignment (finding the right aim point), to visually locating the target with mobile stellarium, to confirming aim by transferring images from camera to phone and then mobile uploading http://nova.astrometry.net/upload for plate solving.

 

[Devin-M]

In my case one camera works decently enough for my needs, but taking a Hubble palette image would take excessive time, so for me 3 cameras is the solution till I run out of targets and want something even higher quality. The cameras aren’t a complete waste… I could even use them on upgraded OTAs in the future.

 

[Devin-M]

Last night I caught an ISS flyover and did a nightscape animation… (with only 1 camera, still waiting on tripods to use the goldman array)

14mm f/4 6min 100iso full frame sensor
https://www.speakev.com/attachments/img-4506-gif.150765/

14mm f/2.8 2min 400iso full frame sensor
https://www.speakev.com/attachments/img-4509-gif.150766/

On the left side of this animation you can see what light pollution looks like when looking from a bortle 4 back towards a bortle 6. The brightest “star” is the planet Jupiter. Saturn is the second brightest to the right and slightly below Jupiter. The core of the Milky Way is visible on the right. Whiskeytown Lake in California, USA is in the foreground.

 

[Devin-M]

I'm pretty impressed that the currently $675 used Nikon D800 DSLR's from 2012 have better image quality than the currently $3820 used Sony A9 II mirrorless from 2019 for less than 1/5th the price, or a currently $5839 used Canon EOS-1D X Mark III DSLR from 2016 for less than 1/8th the price according to:

https://www.dxomark.com/Cameras/

I seriously doubt you could find a used version of one of the other cameras that's higher on the camera sensor quality list for less than the $675 a used D800 currently costs. The D800 from 2012 currently ranks 23rd in all time sensor quality according to the list... better even than a Phase One IQ 180 Digital Back (medium format) with 80 megapixels from 2011 that costed $42490 new (currently $6619 used), according to the list.

 

[PhysicoRaj]

I can see that you are fully committed to a multiple camera solution.

Not fully committed, but I'll see when I can make that method cheap. The 3 camera setup is a bit bulky for me since my astro stuff is usually during hiking and travel. Especially because of 3 tripods and 3 trackers (!), not the 3 DSLRs themselves. But for now my single DSLR rgb should be more than enough.

In the future I will probably setup multiple narrowband working simultaneously and to get the most of it I'll use the cooled astrocams, but having to have 3 separate mounts still irks me a bit.

BTW, have you read anywhere of anyone else who has operated a three camera system successfully? Do you have any links to other similar work or opinions about your system?

Nope, Devin-M is the only inspiration. The video in post #100 caught me a bit (3 of them can be cheaper), but that's it.

 

[Devin-M]

I’m even more shocked there is no Canon camera on the list with a better image sensor than the Nikon D800 from 2012 (currently going for $675 used) except for the Canon EOS R5 from 2020 which is currently selling used for $3.6k USD… over 5x the price…

https://www.dxomark.com/Cameras/

 

[sophiecentaur]

having to have 3 separate mounts still irks me a bit.

There's no need for three separate mounts. People (with domes) frequently keep two or more scopes on one mount but the various scopes are for different purposes, usually.

 

[Devin-M]

The Star Adventurer 2i (currently $425) actually allows for 2 cameras if you add a separately sold ball head.

See pictograms on the manual cover & page 12 figures 11 & 12…

https://inter-static.skywatcher.com/downloads/StarAdv_manual_150722V2_updateds.pdf

Essentially you’d be using the second camera in place of a counterweight.

 

[Devin-M]

While it’s possible to do it I’d hesitate to implement 2 cameras on the mount, mainly because you’ll have quite a time trying to get the thing balanced with 2 cameras (I had to buy a macro-focusing rail just to get one camera balanced in both the declination axis and right ascension axis), and as I think was previously mentioned you don’t want to be messing around with one camera while the other is shooting if they’re both attached to the same mount & if the mirror flips on one of the cameras it will ruin the picture the other one is taking…

 

[sophiecentaur]

you’ll have quite a time trying to get the thing balanced with 2 cameras

I've not tried it but, for a PF member, I'd have thought you could use the cameras to balance each other, to some extent. It always strikes me that the standard 'weights on a stick' solution is heavier, in total than it need be. The weight of the optics always seems a long way (high up) from the polar axis and requires a lot to balance it. Two OTAs slung low (like the anhedral on some aircraft), on either side of the dovetail base could have their CM right on the polar axis. I guess, if the payload is too wide, you might find it fouls the tripod.

But this is a bit of a digression. I shall have to go out in the garden an try an alternative to the standard system which could possibly be a bit 'legacy' and was invented long before multiple scopes and computer guiding was introduced. There could be a lot of money in it for someone . . . . .

 

[Devin-M]

You could get both cameras perfectly balanced on the right ascension axis with both pointing in the exact same direction, but as soon as one of the two cameras swivels on a ball-head, they will be out of balance because you're essentially changing the distance from the fulcrum of one of the cameras, so it will either have more or less leverage on the right ascension axis (from gravity) than the other camera after you finish pointing it.

 

[Devin-M]

I should add that when you use the fine-tune declination adjuster instead of ball head with a single camera & counterweight, you can get it perfectly balanced on the right ascension axis pointing at, say, the north star, but as soon as you swivel the camera on the declination axis, it will be out of balance for essentially the same reason as in the last post... (unless you use something like a macro focusing rail that I mentioned earlier to finely balance the camera+lens on the declination axis.)

 

[sophiecentaur]

You are right but the errors are second order. Unlike most ‘balance’ systems, what I propose (easy for me with arm waving) remains balanced for all mount directions, once set up, if the scopes point parallel.

but now you will introduce the problem of wind.

 

[sophiecentaur]

I found this. An expensive mount, if I'm not mistaken.
See here.

 

[Devin-M]

At least with the Star Adventurer 2i setup polar aligned and balanced as pictured below, I think they will be significantly out of balance in most cases, even if you have them pointing at the same target. Suppose both cameras are “front heavy” on the mounting points due to the lenses. Suppose you want to aim to a target somewhat to the left of the North Star from the initial position. When you point the camera on the left towards the left, the heavy lens will be further from the fulcrum and the lens on the right will be closer to the fulcrum. The camera on the left will pull downwards with greater force ie out of balance. You can slide the central dovetail to compensate but it will be a huge hassle, and the ball joints can also slowly slip especially with heavy cameras mounted sideways.

 

[Devin-M]

I present to you…

“…the goldman array…”

 

[PhysicoRaj]

I present to you…

View attachment 290358
“…the goldman array…”

View attachment 290359

Waiting for the first light from this! Are all 3 stock?

The Star Adventurer 2i (currently $425) actually allows for 2 cameras if you add a separately sold ball head.

That's great. Though I understood there could be some issues.

I see a lot of people compositing images over multiple nights. Have you tried it? Will imaging 3 narrowbands over 3 different nights work?

 

[Devin-M]

Waiting for the first light from this!

It’s too cloudy the next 2 days and after that the moon will be up for the following 2 weeks so it will be that long before I test. I’ve found it isn’t worth trying to shoot when the moon is up. If you’re in a bortle 2 & the moon is up you’re basically in a bortle 7 at that point.

I see a lot of people compositing images over multiple nights. Have you tried it? Will imaging 3 narrowbands over 3 different nights work?

Yes you can composite from a single camera over multiple nights, I just won’t have patience for that.

 

[Devin-M]

Are all 3 stock?

They are all stock Sky Watcher Star Adventurer 2i Pro Pack mounts but I have macro focusing rails in between each camera and mount so I can balance each camera on the declination axis which is important because otherwise it will become out of balance on the motorized right ascension axis when you swivel to the target from the initially balanced position.

https://optcorp.com/products/sky-wa...GD81VmjiJTU9j1-8wL9nUM70nGhUxT5BoClI0QAvD_BwE

 

[Devin-M]

It’s too cloudy the next 2 days and after that the moon will be up for the following 2 weeks so it will be that long before I test.

On second thought, maybe I’ll have a go tomorrow night. Should be clear and the moon will be down after 9pm onwards.

I took these a couple of nights ago with some handheld 10 second exposures on an iPhone…

 

[Devin-M]

I think tonight went well. I got RGB as well as narrowband Hydrogen, Oxygen and Sulfur data of an emission nebula at 600mm f/9 with 3 cameras running concurrently in a single session. I was on site at about 7:45pm had all 3 narrowband cameras up and running by around 11:30p and let them run until 3am, so that’s over 9 hours of narrowband data in just over 3 hours. I set up one camera with no narrowband filter first to capture rgb, and once this was up and running I got the 2 other cameras capturing narrowband. Once those two were up and running I reconfigured the RGB camera for Hydrogen Alpha and as I mentioned from 11:30p til 3am all 3 cameras were capturing narrowband. I left the cameras running dark frames on the way home and will continue to let the cameras capture more dark frames while I sleep. The settings I chose were pretty extreme on the narrowband… 10 minutes per exposure at 6400iso for the hydrogen and oxygen filters and a full 20 minutes of open shutter per exposure on the sulphur filter. Haven’t had a chance to look at the data but I do know they were in pretty decent focus as I used a bahtinov mask to focus every camera, and again after switching from RGB to Ha. The most troublesome thing that happened was I had very slow internet on my phone for plate solving to confirm aim. Also one of my USB batteries powering the mounts kept shutting off so I ended up running 2 mounts off a single USB battery pack (fortunately it had 2 output ports). Also next time I’ll remember to switch camera batteries when switching from RGB to Ha as I think the Ha session may have ended a little early from the camera battery running out of juice at some point. All in all I deem the mission a success (having not yet seen the actual data). Will begin processing data tomorrow…

 

[Devin-M]

…getting dark frames while I catch some zzz’s…

 

[Devin-M]

https://www.speakev.com/attachments/dsc_8781-median-2-2_blended-2-final-gif.151007/

 

[PhysicoRaj]

I took these a couple of nights ago with some handheld 10 second exposures on an iPhone…

You have some serious steady hands... And btw 10s exposure in a little light pollution makes night look like day! I see why NB is the way to pursue this hobby in difficult skies. But there's no solution for clouds :(

They are all stock Sky Watcher Star Adventurer 2i Pro Pack mounts...

Was asking about the DSLRs - two others you bought. Isn't a full spectrum modified camera going to give amazing results for Hubble palette?

 

[Devin-M]

All 3 DSLR’s are standard unmodified D800’s. I don’t have any experience with the modified cameras except clipping in narrowband filters.

I ended up with about 48x 60s RGB shots (2880s) @ 3200iso 600mm f/9, 19x 600s Ha shots (11400s) @ 6400iso, 28x 600s OIII shots (16800s) @ 6400iso and I think around 10x 1200s SII shots (12000s) @ 6400iso or about 12 hours of data total. I was physically there for about 7 hours and did about 4 hours of work in one chunk at the beginning of the session.

 

[Devin-M]

 

[Devin-M]

 

[PhysicoRaj]

Great Shots. What were the shutter actuation counts on the used Nikons?

 

[Devin-M]

My original Nikon which I’ve had since it was new has 186259 shutter actuations. The two I bought used have 29895 and 14358 actuations respectively.

 

[Devin-M]

Here's each of the 4 bands (stacked with some minimal histogram stretching). I subsequently removed the stars from each of the SII, Ha, OIII images after blending with the RGB...

RGB:

Ha:

OIII:

SII:

RGB-SII-Ha-OIII Composite:

 

[Devin-M]

A couple quick tips that could save one from a ruined evening of astrophotography...

Some or all of the Star Adventurer 2i mounts have what I would call a slight software bug that could have you tearing your hair out if you don't know about it. Essentially what happens is this...

The Star Adventurer 2i mounts have an "app" mode that let's you connect to your phone through WiFi, which is useful because you can potentially use the tracker as also an intervalometer that controls your camera exposure times, shutter releases, shot counts, etc (and control it all from your phone -- potentially eliminating the standalone intervalometer)...

Where the "bug" comes into play is this. On at least some Star Adventurer 2i mounts (& I have tested this), suppose you set up an exposure campaign in the "app mode" that shoots suppose 10x 60s shots totaling 10 minutes of exposure time and you run this exposure campaign. So far so good. But suppose several weeks later, you get an external intervalometer, and you don't use the mount in "App" mode but rather just "plain old" star tracker mode... You carefully point and aim the camera, set the exposure and program the external intervalometer to run for 2 hours then you go in your car to get warm... You'll find that low and behold, somehow the "App mode" setting for a 10 minute campaign from weeks ago has turned off the tracking function of the mount after 10 minutes in the "regular old" star tracking mode. The solution is, whenever you expect to be running star tracker ("non-app") mode, make sure the last exposure campaign in "app" mode is set to something like 40 hours, that way when you go to regular old star tracker mode, the motor will be "programmed" to run for at least 40 hours. Probably 16 hours would be enough for any given evening but on second thought, maybe not if you're in Alaska... 6 months??

The other one is quality settings on your camera. Obviously you'll want to be shooting in RAW mode... but if you're doing plate solving through your phone and you have slow internet in the middle of nowhere, you don't want to be fiddling around with RAW files, so at least on my camera I set it up to record both the RAW file and a "small" size jpg (there's also medium and large). So instead of trying to fiddle around with converting and uploading a raw file on your phone, you transfer the small JPG and use that for plate solving ( http://nova.astrometry.net/upload ) while you also retain the RAW file for later processing.

 

[PhysicoRaj]

A couple quick tips that could save one from a ruined evening of astrophotography...

Some or all of the Star Adventurer 2i mounts have what I would call a slight software bug that could have you tearing your hair out if you don't know about it. Essentially what happens is this...

The Star Adventurer 2i mounts have an "app" mode that let's you connect to your phone through WiFi, which is useful because you can potentially use the tracker as also an intervalometer that controls your camera exposure times, shutter releases, shot counts, etc (and control it all from your phone -- potentially eliminating the standalone intervalometer)...

Where the "bug" comes into play is this. On at least some Star Adventurer 2i mounts (& I have tested this), suppose you set up an exposure campaign in the "app mode" that shoots suppose 10x 60s shots totaling 10 minutes of exposure time and you run this exposure campaign. So far so good. But suppose several weeks later, you get an external intervalometer, and you don't use the mount in "App" mode but rather just "plain old" star tracker mode... You carefully point and aim the camera, set the exposure and program the external intervalometer to run for 2 hours then you go in your car to get warm... You'll find that low and behold, somehow the "App mode" setting for a 10 minute campaign from weeks ago has turned off the tracking function of the mount after 10 minutes in the "regular old" star tracking mode. The solution is, whenever you expect to be running star tracker ("non-app") mode, make sure the last exposure campaign in "app" mode is set to something like 40 hours, that way when you go to regular old star tracker mode, the motor will be "programmed" to run for at least 40 hours. Probably 16 hours would be enough for any given evening but on second thought, maybe not if you're in Alaska... 6 months??

Yikes. Will write this down for the future me. I already have an intervalo so probably not going to mess with any tracker mode other than - just track.

The other one is quality settings on your camera. Obviously you'll want to be shooting in RAW mode... but if you're doing plate solving through your phone and you have slow internet in the middle of nowhere, you don't want to be fiddling around with RAW files, so at least on my camera I set it up to record both the RAW file and a "small" size jpg (there's also medium and large). So instead of trying to fiddle around with converting and uploading a raw file on your phone, you transfer the small JPG and use that for plate solving ( http://nova.astrometry.net/upload ) while you also retain the RAW file for later processing.

Good point.

 

[Devin-M]

The moon probably won't be down long enough for me to shoot again til around the evening of 10/31-11/1 so here's a few more lens/OTA tests on the local bird population... two Anna's Hummingbirds and a Lesser Goldfinch... An interesting fact about the Anna's Hummingbird is they are the fastest vertebrate on Earth for their length... faster than a fighter jet relative to length and to sustain this flight they flap their wings 50-60 times per second or more... they can also hover, fly backwards & even upside down…

"The cheetah, the fastest land mammal, scores at only 16 body lengths per second,[5] while Anna's hummingbird has the highest known length-specific velocity attained by any vertebrate."

https://en.wikipedia.org/wiki/Fastest_animals

https://www.speakev.com/cdn-cgi/image/format=auto,onerror=redirect,width=1920,height=1920,fit=scale-down/https://www.speakev.com/attachments/dsc_8674-jpg.151290/

https://www.speakev.com/cdn-cgi/image/format=auto,onerror=redirect,width=1920,height=1920,fit=scale-down/https://www.speakev.com/attachments/dsc_8758-jpg.151291/

https://www.speakev.com/cdn-cgi/image/format=auto,onerror=redirect,width=1920,height=1920,fit=scale-down/https://www.speakev.com/attachments/dsc_8735-jpg.151292/

 

[Devin-M]

It’s predicted that Fri Nov 5th will be the 1st time since Oct 10th that the moon will be down til at least 3am and no cloud… fingers crossed… I’ve also realized there’s only about 1 week a month where the moon is down from early evening until 3am.

 

[PhysicoRaj]

Caught some signal from Saturn. I definitely can improve over this, because this is my first planetary image and there was a layer of clouds / haze that I shot through, which will have certainly pushed the quality down. I believe I can get the gap between the rings and the planet clearly next time.

 

[sophiecentaur]

Planetary images are best with very long lenses (2,000mm) to fill more of the sensor.

 

[PhysicoRaj]

Planetary images are best with very long lenses (2,000mm) to fill more of the sensor.

This one was at 2100mm, but the sensor is a DSLR which is bigger than the planetary webcams so the size of the planet relative to the frame is small.

Also, the lens and Barlow quality is not that great, so the rings are not clear. I will probably move to a used bigger scope and better optics, I'm just fiddling around with the present one till I save up some bucks. At least I was able to partially resolve the rings, let's see how much juice I can extract from this scope while I'm at it.

Edit: BTW, do you think looking at the image that my barlow is actually 3x?
Image size: 1920x1080 (3.7 micron pixel)
Cropped to: 1000x1000
Objective FL: 700mm
Barlow: 3x (?)

I have seen some images of Saturn at 2000mm like this and it is much larger. Even though that image is 1280x720, the proportion by which the planet is bigger than mine seems to indicate that my Barlow could be a 2x.

 

[sophiecentaur]

The rule is “Spend spend spend” I’m afraid.

 

[PhysicoRaj]

The rule is “Spend spend spend” I’m afraid.

It is rather scary. But now I am starting to believe that Celestron might have kind of duped me with this scope. Check the edit on my last post.

Even without a barow, my aperture seems to have a dawes limit resolution that is larger than what the focal length can extract. On top of it they gave a Barlow which seems ridiculous unless my math is wrong.

 

[Devin-M]

Image size: 1920x1080 (3.7 micron pixel)
Objective FL: 700mm
Barlow: 3x (?)

In my earlier test shot of Saturn which appeared to have similar detail, I was shooting at 1/3.5 the focal length (600mm f/9), but the imaging sensor on the D800 was 7360x4912… 3.8x the sensor resolution… The following shot (which I posted before) has been cropped & also upscaled with interpolation.

https://www.speakev.com/attachments/saturn_stacked_mono_green2-gif.150147/
If you crop the image before uploading it, the planet will have a larger final display size on the web page without sacrificing resolution. This website is downsizing your final image to below 1920x1080 when you upload it to conserve bandwidth.

For best final display you’ll want to determine what size this website downsizes your final image to, and then do a 100% crop at those same dimensions before you upload it.

You could also host the image elsewhere and include a link to it to avoid the final downsizing that occurs after you upload it.

 

[PhysicoRaj]

In my earlier test shot of Saturn which appeared to have similar detail, I was shooting at 1/3.5 the focal length (600mm f/9), but the imaging sensor on the D800 was 7360x4912… 3.8x the sensor resolution… The following shot (which I posted before) has not only been cropped but also upscaled with interpolation...

I have cropped a bit - just checked that the image I have uploaded is 1000x1000. Note that I am not worried about planet resolution, but the size of the planet in relation to the frame size. But me cropping it should only give an even bigger planet. And your frame size being 3.8x the size of mine before cropping, and 3.5 times lower focal length, I should have definitely gotten a bigger relative size of the planet. Something definitely seems off.

 

[Devin-M]

I think it’s as simple as cropping out the empty space around the planet before uploading and what remains will be displayed at a larger apparent size.

 

[Devin-M]

Image size: 1920x1080 (3.7 micron pixel)

Doesn’t your camera shoot in RAW mode higher than 1920x1080?

 

[Devin-M]

And your frame size being 3.8x the size of mine before cropping, and 3.5 times lower focal length, I should have definitely gotten a bigger relative size of the planet.

I’m not sure this is all accurate… we haven’t factored the different sensor size… I was using a 35mm sensor.

 

[PhysicoRaj]

I’m not sure this is all accurate… we haven’t factored the different sensor size… I was using a 35mm sensor.

I use a crop sensor, 1.6x. Now the more cropped it is the bigger my planet has to be, so I'm even more suspicious now.

Doesn’t your camera shoot in RAW mode higher than 1920x1080?

It does, but the FPS is low. I use a lower size to get more FPS.