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IP/CCTV lens for RT224 camera

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#51 mclewis1

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Posted 29 April 2018 - 01:48 PM

If you had more aberrations, especially at the edges it might make sense to stop down the lens a bit but it looks quite nice  wide open at f1.4 so I'd leave it like that (speed like that is very valuable). Darker skies should allow you to use more gain, thus going even deeper. I might also work with the histogram a bit and try for a darker background with brighter objects. 

 

What software are you using?

 

Point the camera at the galaxy cluster area in Coma Berenices (off the back end of Leo) and see what you get. I'll bet you won't be able to count all the galaxies. Later in the night the star fields and large nebulae in Cygnus would be good targets.

 

It looks like lots of fun for under $300.


Edited by mclewis1, 29 April 2018 - 01:50 PM.

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#52 Adun

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Posted 29 April 2018 - 04:41 PM

What software are you using?

 

I still use SharpCap, since that's what seemed to work best for me when I got started doing EAA about a year ago.

 

However, I had to downgrade to version 2.9 around October when it stopped working with my RT224 camera (something to do with it not being Altair).

 

Lately I've read nice things about the upgrades to ToupSky/RisingSky, so I might give that a chance again.

 

The stretching was done with startools (the "wipe" feature goes beyond what I can get with SharpCap's 2.9 Histogram).

 

 

It looks like lots of fun for under $300.

 

This one lens was just $18, but it's not flexible enough to recommend as a low cost, entry point for EAA. I think Cmooney's 8-50 zoom looks much more promising in that regard, although that one is a little more expensive.

 

After seeing how well it performs even at just 1s or 2s exposures, it made me wonder what'd happen if you paired one of these to an IMX225 security cam.


Edited by Adun, 29 April 2018 - 04:42 PM.


#53 Adun

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Posted 30 April 2018 - 04:10 PM

25mm lens is ~12°fov, 7x35 Binos are 9.3°fov)

Yes that was the 25mm F1.4. I love how well it matches the FOV of 7x35 binoculars.
The light pollution map says it was 20.08mag/sqrarc-sec bortle 5 skies


I'm wondering how you get 12º and I get 6.3º both using a 25mm F1.4 lens on an IMX224 camera.

My theorycrafting calculations for a 25mm F1.4 and 6mm sensor tell me to expect around 6.9º.

Platesolving said 6.3º (but I had to crop the field rotated edges).

¿How did you get 12º?

 

Edit: Well, I checked again the platesolving, and the view with the IMX224 and the 25mm F1.4 lens was 9.74º x 7.22º, which makes for a 12º diagonal.

 

I think maybe I was considering 25mm to be the aperture, but probably it's actually the focal length (which would make the aperture 17mm). That'd explain it.


Edited by Adun, 30 April 2018 - 04:44 PM.

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#54 fromEarth

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Posted 06 May 2018 - 09:35 PM

Any new updates on the performance of CCTV zoom or fixed focal lenses? I am quite interested in the 8-50mm zoom lens cmooney91 has tested, but still not sure if this specific lens is the best (or reasonable) choice or not.   



#55 cmooney91

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Posted 07 May 2018 - 07:13 AM

I received my 50mm f1.4 prime lens.

 

The next clear night I want to do a side by side comparison of the 25mm F1.4 prime, 50mm F1.4 prime, and the 8-50mm zoom. 

 

I plan on posting single exposures of fixed gain and time, to compare the brightness and sharpness of the  prime vs zoom lenses.   


Edited by cmooney91, 07 May 2018 - 07:14 AM.

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#56 fromEarth

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Posted 16 May 2018 - 01:36 PM

I received my 50mm f1.4 prime lens.

 

The next clear night I want to do a side by side comparison of the 25mm F1.4 prime, 50mm F1.4 prime, and the 8-50mm zoom. 

 

I plan on posting single exposures of fixed gain and time, to compare the brightness and sharpness of the  prime vs zoom lenses.   

 

Hi Corey, I hope to see your new report soon. BTW, what's the magnification scale of the 8-50mm CCTV zoom lens?  

 

fromEatrh


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#57 cmooney91

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Posted 18 May 2018 - 08:00 AM

The results are in!

 I did this may 7th, but It took this long to get back to it and export and post.

 

I tried to do the comparison with M44, but it got too close to my street light, so the comparison was done on Coma Berenices.  Not very spectacular, but it is a good target for edge to edge field sharpness, and minimum detectable magnitude.

 

I settled on 4000Gain, 4s for the exposure (RT224 in SharpCap).

 

My process was,

  • mount lens
  • Max gain, short exposure,+ stretch, for focus
  • type lens as object name (for capture folder)
  • 4000 gain, 4s, reset histogram.
  • save snapshot (png)
  • Defocus to check for spherical aberation
  • save snapshot (png)
  • change lens & repeat

 

 

It took some time to find the right exposure that would work across all the lenses, and also to make sure I put an unstretched image in the properly named folder, it took an embarrassing number of attempts to get it all straight. 

 

 

25mm F1.4 

Mel111 25mm F1.4

(this looks stretched to me. it's possible I did not reset the histogram, but after many screw-ups I was vigilant).Note the bright image but bloated stars & distorted edges.

 

 

8-50mm F1.4 IR Zoom @25mm

Mel111 8-50mm F1.4 IR Zoom @25mm
 Note the dim image but crisp stars
 

50mm F1.4

Mel111 50mm f1.4

Note the bright image but bloated stars & distorted edges.

Also note that 2x the magnification = ~1/2 the sky brightness in the comparably designed lenses

 

8-50mm F1.4 IR Zoom @50mm

Mel111 8-50mm F1.4 IR Zoom @50mm

Note the dim image but crisp stars

 

 

Now I really don't know what to recommend. The primes are super bright but blurry, the IR zoom is sharp but dim.

 

For me, I think I will go back to using the 25mm prime for binocular outreach so I can use shorter frames with less noisy gain for more crowd immediacy, at the cost of sharpness.


Edited by cmooney91, 18 May 2018 - 04:20 PM.

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#58 will w

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Posted 18 May 2018 - 09:02 AM

Has anyone here that have these lens and are using them thought of using a 2x converter with these lens? will w 



#59 fromEarth

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Posted 18 May 2018 - 12:59 PM

Corey, I guess all these images are from 4s single exposure. If you use stacking (as you did before), don't you think the 8-50mm zoom lens generally outperforms your single focus lenses?


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#60 Adun

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Posted 18 May 2018 - 01:15 PM

Corey, I guess all these images are from 4s single exposure. If you use stacking (as you did before), don't you think the 8-50mm zoom lens generally outperforms your single focus lenses?

 

Would be worth a try, both with stacking and with longer exposures (tracking)


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#61 cmooney91

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Posted 18 May 2018 - 04:05 PM

I agree, with tracking and/or stacking the 8-50mm IR zoom definitely outperforms the prime lenses  in sharpness and distortion.

 

But the primes look more than 2x brighter at the same F1.4, which is a big benefit for use without tracking (manual photo tripod), even when stacking(more data faster, resulting in less field shift).

 

I will definitely keep experimenting. I'd like to compare how the different lenses stack on large defuse nebula.

 

What do you think would be the most valuable experiment?

 

For Example

Target: north america, lagoon, veil nebula or the like

Total Exposure time: Fixed at 296s

Individual exposure time: Fixed at 4s or 8s

Gain: Varied to get a similar histogram for each lens (+ fresh dark frames). 

 

Output: 

Screen caps showing settings and Histogram, or raw FITS?


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#62 Adun

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Posted 18 May 2018 - 09:47 PM

I'd like to compare how the different lenses stack on large defuse nebula.
 
What do you think would be the most valuable experiment?

 
This is where I'd be aiming the 25mm F1.4 if it wasn't completely overcast right now (as has been for more than 2 weeks):
 
EAA targets for 25mm F1.4 lens + IMX224

 
M8, M24, M20, M17 and Saturn in the same FoV.

Bright large emission nebula, faint reflection nebula, big star field, several small open clusters and a planet, all in the same view. M22/M23 may not fit, but the rest should

Edited by Adun, 18 May 2018 - 09:50 PM.

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#63 fromEarth

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Posted 19 May 2018 - 03:10 PM

Any large nebulae and galaxy clusters could be good targets for your next experiments (Thanks a lot!!). You once mentioned that 4 seconds are the limit without tracking, but could you try stacking (+ tracking) this time? I did not place my order yet, but if I purchase the 8-50mm zoom, I am definately going to use my single-axis EQ platform. I am wondering if this lens nicely captures nebulae and galaxy clusters.

I am really interested in these nebulae/galaxy cluster targets to make my 10yr old son impressed - it seems that he does not care about stars =)

Edited by fromEarth, 19 May 2018 - 06:08 PM.

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#64 cmooney91

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Posted 21 May 2018 - 06:33 AM

I am hoping to shoot that region, weather/moon permitting.

 

Unfortunately I don't have a tracking mount so I can't test that yet, but I can get get 8s exposures at 50mm FL without trailing in certain parts of the sky.

 

 

In posts 41 and 42 there are shots of M81+82 from both the 25mm and the 8-50@50.

I know they are are not comparable integration times or gains, and it doesn't mean much without showing the un-stretched histograms, but it shows that both lenses can image galaxies, even from a stationary photo tripod. 

 

25mm  was             3500Gain, 10x4s=40s

8-50@50mm was   5000Gain, 55x4s=220s



#65 astropinci

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Posted 21 May 2018 - 07:01 AM

The results are in!

 I did this may 7th, but It took this long to get back to it and export and post.

 

I tried to do the comparison with M44, but it got too close to my street light, so the comparison was done on Coma Berenices.  Not very spectacular, but it is a good target for edge to edge field sharpness, and minimum detectable magnitude.

 

I settled on 4000Gain, 4s for the exposure (RT224 in SharpCap).

 

My process was,

  • mount lens
  • Max gain, short exposure,+ stretch, for focus
  • type lens as object name (for capture folder)
  • 4000 gain, 4s, reset histogram.
  • save snapshot (png)
  • Defocus to check for spherical aberation
  • save snapshot (png)
  • change lens & repeat

 

 

It took some time to find the right exposure that would work across all the lenses, and also to make sure I put an unstretched image in the properly named folder, it took an embarrassing number of attempts to get it all straight. 

 

 

25mm F1.4 

 

(this looks stretched to me. it's possible I did not reset the histogram, but after many screw-ups I was vigilant).Note the bright image but bloated stars & distorted edges.

 

 

8-50mm F1.4 IR Zoom @25mm

 
 Note the dim image but crisp stars
 

50mm F1.4

 

Note the bright image but bloated stars & distorted edges.

Also note that 2x the magnification = ~1/2 the sky brightness in the comparably designed lenses

 

8-50mm F1.4 IR Zoom @50mm

 

Note the dim image but crisp stars

 

 

Now I really don't know what to recommend. The primes are super bright but blurry, the IR zoom is sharp but dim.

 

For me, I think I will go back to using the 25mm prime for binocular outreach so I can use shorter frames with less noisy gain for more crowd immediacy, at the cost of sharpness.

Hi

I do not understand why there is so much different in brightness between the two lenses? They are both 1.4 and even if the zoom is not as  bright as a prime lens the different here  is huge.



#66 cmooney91

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Posted 21 May 2018 - 08:13 AM

Check out the cut away on post #32. The zoom lenses have a lot more lens elements in them. In the case of this cheap Chinese lens, maybe some elements are lacking AR coatings, or have low transmission.

 

This is known issue in the cinema industry that has lead to using T-stops instead of F-stops.

 

That said, I was not expecting this much of a difference either. 



#67 Censustaker

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Posted 22 May 2018 - 10:24 AM

I made a 3D printable 1.25" camera nose mount that works with a vixen clamp, or 1/4-20 tripod thread.

 

wYLmUSt.jpg

 

Files are here

 

 

I will make a Synta finder dovetail version so it can easily be piggybacked on an existing scope/mount.

This is awesome, thanks for this!


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#68 cmooney91

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Posted 18 June 2018 - 07:42 PM

Over the weekend I had a chance to compare the lenses on the Sagittarius area with a guest appearance by Saturn.

 

 

With live stacking the 8-50mm zoom lens definitely pulls ahead of the lower cost prime lenses. 

I tried to keep the total exposure time to 120s.

 

First, the 25mm f1.4 prime

2s x 61 = 122s @ 2500 Gain

gallery_280529_9355_104421.jpg

A little distorted around the edges, but the lens allowed short exposures at comparatively low gain.

 

Here's 8-50mm f1.4 Zoom at ~25mm.

I Messed up and did not save the stack, I only have a single frame to compare. Sorry.

4s @4000 Gain SINGLE!

gallery_280529_9355_309009.jpg

Even though its only a single frame, you can see that the stars are much sharper. The stack looked very nice for what it's worth. Oops......

 

 

Next the 50mm f1.4 prime

4s x 30 = 120s @ 2000 Gain

gallery_280529_9355_67044.jpg

This lens is particularly bad, quite a bit of spherical aberration leading to soft focus and bad contrast. At least the edges aren't too bad compared to the center, and it allowed lower gain. I would be curious to try a 5-8 MP rated prime lens.

 

Here's the 8-50mm f1.4 zoom at 50mm

4s x 30 =120s @ 4000Gain

gallery_280529_9355_25111.jpg

Night and day difference.

 

 

Keep in mind these are all taken on a stationary manual alt-az mount, no tracking needed.

 

 

While I had the 8-50mm zoom lens pointed at Sagittarius I took two more bonus stacks at ~15mm and 8mm. I don't have prime lenses to compare against, but it will give a better idea of the 1/3" sensor FOV range for the zoom lens.

 

Here's the 8-50mm f1.4 zoom at ~15mm

4s x 31 =124s @ 4000Gain

gallery_280529_9355_169263.jpg

starting to get a light pollution gradient.

 

Here's the 8-50mm f1.4 zoom at 8mm

4s x 30 =120s @ 4000Gain

gallery_280529_9355_83901.jpg

Y0u can see the handle to my alt-az in the upper left, and the misaligned lens shroud in the lower left, too wide FOV for its own good. You can also see whole teapot sitting in my light pollution near the horizon.

 

looks like like we are looking out a space ship porthole cruising over some aurora. 

 

 

Extra bonus stack.

After the lens comparison I tried for the north america nebula

8-50mm f1.4 Zoom at 50mm

8s x 15 = 120s @4000 Gain

gallery_280529_9355_255578.jpg

Definitely visible,  but at 8s I can start to see star trails

 

 

Can't wait to get out there again. 

 


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#69 Adun

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Posted 19 June 2018 - 10:25 AM

Here's the 8-50mm f1.4 zoom at 50mm

4s x 30 =120s @ 4000Gain

gallery_280529_9355_25111.jpg

Night and day difference.

 

 

I can clearly see M20 above M8.  Really nice!



#70 fromEarth

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Posted 19 June 2018 - 01:59 PM

Corey, 

 

Great comparisons!  I ordered my 8-50mm zoom lens ($40 at AliExpress) two weeks ago and recently got it.

 

....and this is my wide-angle EAA equipment setup.  

 

I ordered a synta/vixen shoe (ScopeStuff) and drilled a 1/4”-20 screw hole in its center to attach it to the camera mount. Now I can attach a red dot finder, a laser, or a 8x50 finder scope quite easily. I originally planned to use my single-axis EQ platform, but you proved that I may not need it for this wide-angle EAA observation.

 

20180615_235831.jpg

IMG_4971.JPG20180619_201219.jpg

 

To point targets, I am using SkEye_Pro android app. 

 

http://lavadip.com/skeye/

 

If your android device has a magnetometer AND an accelerometer, you can use this app's "indirect mode" as a virtual digital setting circle after multi-star alignment.  

 

Now I think I need better (wider) light shield for this lens. How did you make yours? 3D printing?

 

 

fromEarth 


Edited by fromEarth, 20 June 2018 - 01:00 PM.

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#71 Adun

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Posted 19 June 2018 - 02:14 PM

What is that black clamp you're using to hold your red camera?

 

Looks much better than all the tape I'm using



#72 fromEarth

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Posted 19 June 2018 - 02:36 PM

What is that black clamp you're using to hold your red camera?

 

Looks much better than all the tape I'm using

 

That clamp and (horizontal) aluminum bar were from my old universal camera adapter. Orion SteadyPix? But mine was a much cheaper generic adapter bought from ebay. 

 

https://www.telescop...ount/p/5228.uts

 

The adapter has not been used for many years, so I decided to recycle its parts!


Edited by fromEarth, 19 June 2018 - 02:42 PM.

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#73 cmooney91

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Posted 20 June 2018 - 07:11 AM

Slick setup!

 

I did 3d print my shroud.

 

Here is the file.

 

If you don't have access to a 3d printer you could try "3D Hubs" it's like uber for printing.

 

Yours will probably be fine above half zoom.

 

If you want to fabricate a new one, the cone should to be 42° or wider to not clip the lowest zoom with our 1/3" sensors. 

 

Although, to be honest I haven't used the lower powers much. 

 

-Corey



#74 fromEarth

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Posted 20 June 2018 - 01:57 PM

Slick setup!

 

I did 3d print my shroud.

 

Here is the file.

 

If you don't have access to a 3d printer you could try "3D Hubs" it's like uber for printing.

 

Yours will probably be fine above half zoom.

 

If you want to fabricate a new one, the cone should to be 42° or wider to not clip the lowest zoom with our 1/3" sensors. 

 

Although, to be honest I haven't used the lower powers much. 

 

-Corey

 

Thanks, but I have a zero-experience with 3D printing and 3D-hubs. Is the service expensive? How heavy is this light shroud?  

 

I will first try some garbage stuffs in my garage, such as a big and cheap plastic funnel and a mid-size plastic lamp shade. 


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#75 Adun

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Posted 20 June 2018 - 02:47 PM

Thanks, but I have a zero-experience with 3D printing and 3D-hubs. Is the service expensive? How heavy is this light shroud?  

 

I used them once... its sort of like Uber:

 

Some guy near you bought himself a fancy car 3D printer and registered in the 3D-hubs network to help pay the bill. You send them the address blueprint of what you want printed, choose the type of material to use, and they print it and mail it to you.

 

The cost will depend on how much material (plastic) is used. The bigger the part the more expensive, but I'd say it's rather affordable, at least for small parts. They'll be very lightweight.

 

For a shroud, the lack of mechanical complexity makes me think using 3D hubs would be overkill, but for the adapter to attach an UHC filter, that's more interesting.


Edited by Adun, 20 June 2018 - 02:47 PM.

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