Video

Hey up, here's a full video covering the settings in detail: czcams.com/video/Pd3lJ0OaGOc/video.html

I hope to do another side by side test soon.

You are welcome :)

Thank you! :)

Same here. Not sure of the interval between the images being taken as scene conditions can change within a matter of minutes but the larger tube likely needed to cool down more IMHO. I love imaging with my 5 inch refractor despite the loss of magnification.

Hey there Astro Ape :) I'll try not to be jealous of your mountains. I live in a place called Suffolk, UK. A place renowned for being as flat as a pancake :D I totally agree that the 5" doublet usually performs well when the seeing allows but the focus is vague compared to to Tak which seems to be tack sharp and snappy no matter what. The Tak was a big purchase, but I'm yet to regret it! Clear skies : )

Thanks so much Mohamed! Crazy coincidence, I've just dropped a video about RGB align to tame atmospheric dispersion.

@@Astrolavistanice ! ill make sure to see it !!

Haha! yeah, I still can't get my head around why they need so many lights! Thankfully I think they are away at the moment, pitch black once the street lights went out at 12 :)

Thanks Mike! The Takahashi FC-100dc is a flourite doublet, arguably one of the best though! On previous comparisons between the two, the 5" ED doublet and the 4" Flourite doublet have performed remarkably close, but something didn't seem right with the 5" image this night, I couldn't nail down the focus like I could with the Tak. Collimation was fine so maybe the seeing and atmospheric dispersion with Saturn at 22 degrees in the south. I performed RGB alignment on the 5" ED doublet data to do my best without an ADC. I've actually just dropped a video about that wondering how RGB align in Sharpcap compares to an ADC. Cheers!

@@Astrolavista Okay, I have to agree your Takahashi is spot on. I did purchase a ADC a while back for the very reason your 5" suffered as demonstrated in your test, also when you have dispersions like that focusing will be difficult anyway. I wish you could have reversed your telescope setups with the 5" inch first, just to see how well your Takahashi handles dispersions,...yes at 22 degrees you will definitely be afflicted by dispersion and is bit low. I was not impressed using my ADC, it was very picky as to the exactness and took a lot of fiddling, I lost patience, then decided to keep planetary captures above 25 degrees and preferably 30. If you've ever done 45 deg. or more that is where the best atmosphere for planetary I've ever seen, unless it's unsteady skies anyway. I was amazed how well you pics converted to video for public showing...nice going!

How amazing and heart warming! Thanks so much for dropping back by with your story; really great to hear this! Clear skies :)

Thanks Tony! the Tak always seems to give razor sharp images no matter what, and easily snaps into focus, whilst the larger frac appears to be a bit more seeing and cool down dependant, then focus can then feel a little more vague.

Here's a copy of the pinned comment in case it's not visible on your device "I observed a noticeable increase in atmospheric dispersion with the 5" refractor that night, which made achieving precise focus more challenging compared to the 4", which snapped into focus with ease as usual. To mitigate this, I captured four sets of AVI files, stacked them, and selected the sharpest of the four for further processing. Additionally, I applied RGB adjustments in SharpCap to correct the prominent blue and red shifts caused by atmospheric dispersion. This was applied specifically to the 5" and was the only difference in the processing. While this did help to some extent, the image still appeared a touch soft at this large image scale. Investing in an Atmospheric Dispersion Corrector (ADC) seems necessary, especially with planets being so low on the horizon most of the time. I've included links to better results captured with the 5". Just click on one of the videos at the end of this one. There is an article on atmosperic dispersion and how it scales with aperture here: britastro.org/2017/atmospheric-dispersion-and-its-effect-on-high-resolution- imaging I might tweak the title to mention this issue. It may be seeing related despite capturing all the data in the space of an hour or two. I spent a lot of time making sure everything else was ok - E.g. Four attempts of focus with 4 AVI files for each scope, both were checked for collimation during focusing, and the same process was applied with post processing bar some RGB adjustment to improve the image of the 5". Both scopes were stored in my garage so should be close to ambient in terms of temperature, but I guess the 5" would take longer to cool, so that could be partly to blame. Whilst capturing the AVI's I felt that I knew the Tak was well focused but never felt sure with the 5" despite spending significantly longer trying to nail focus. I don't think stacking 50% helped (I usually stack 20-30%), The images looked noisy when stacking only 30% of 2000 total frames for each AVI. I was limited to 2000 frames because of low frame rates (I kept finding slow USB2 cables, but not my faster USB3)."

I've also changed the video title because I agree this isn't typical.

Hi, please see my pinned comment :)

Here's a copy of the pinned comment in case it's not visible on your device "I observed a noticeable increase in atmospheric dispersion with the 5" refractor that night, which made achieving precise focus more challenging compared to the 4", which snapped into focus with ease as usual. To mitigate this, I captured four sets of AVI files, stacked them, and selected the sharpest of the four for further processing. Additionally, I applied RGB adjustments in SharpCap to correct the prominent blue and red shifts caused by atmospheric dispersion. This was applied specifically to the 5" and was the only difference in the processing. While this did help to some extent, the image still appeared a touch soft at this large image scale. Investing in an Atmospheric Dispersion Corrector (ADC) seems necessary, especially with planets being so low on the horizon most of the time. I've included links to better results captured with the 5". Just click on one of the videos at the end of this one. There is an article on atmosperic dispersion and how it scales with aperture here: britastro.org/2017/atmospheric-dispersion-and-its-effect-on-high-resolution- imaging I might tweak the title to mention this issue. It may be seeing related despite capturing all the data in the space of an hour or two. I spent a lot of time making sure everything else was ok - E.g. Four attempts of focus with 4 AVI files for each scope, both were checked for collimation during focusing, and the same process was applied with post processing bar some RGB adjustment to improve the image of the 5". Both scopes were stored in my garage so should be close to ambient in terms of temperature, but I guess the 5" would take longer to cool, so that could be partly to blame. Whilst capturing the AVI's I felt that I knew the Tak was well focused but never felt sure with the 5" despite spending significantly longer trying to nail focus. I don't think stacking 50% helped (I usually stack 20-30%), The images looked noisy when stacking only 30% of 2000 total frames for each AVI. I was limited to 2000 frames because of low frame rates (I kept finding slow USB2 cables, but not my faster USB3)."

@@Astrolavista Thanks!

Hi! The 4" was much easier to work with-it snapped into focus effortlessly. Although collimation was spot on, the 5" showed significantly more atmospheric dispersion and may have needed more time to cool down. I've pinned a post that details the steps I took and the challenges I encountered. I might also update the title to highlight the differences. Plus, I've linked to additional comparison videos with both telescopes at the end of the video. Thanks for watching!

Hi! The 4" was much easier to work with-it snapped into focus effortlessly. Although collimation was spot on, the 5" showed significantly more atmospheric dispersion and may have needed more time to cool down. I've pinned a post that details the steps I took and the challenges I encountered. I might also update the title to highlight the differences. Plus, I've linked to additional comparison videos with both telescopes at the end of the video. Thanks for watching!

@@Astrolavista Thank you! What was the altitude of Saturn in your location?

@@infinitychannel450 I just checked Stellarium and Saturn was at 22 degrees at the time. If you checkout the following video, I've had better results at low latitudes before now, so it's all very strange. I found the data from the 5" frustrating and time consuming to work with this time around, whereas the 4" Tak data started looking good the moment I touched the wavelet sliders in Registax6: czcams.com/video/grH0O3RekgU/video.html

​@Astrolavista 22° is getting pretty low.

Hey thanks James. It seems to be cloudy more often than not, though it was clear right up until 5 minutes before I shot the footage, I was watching the clouds roll in just as Saturn was approaching! Still nice to see the scale difference like you say, cheers!

Cheers Ron :)

No, I used a Logitech webcam which I modified to fit my telescope.

​@@Astrolavistais this telescope have auto guide?

Hi Tony! thanks for watching. I've not tried stacking with ASI stack but heard good things from Ben at the narrowband channel about it producing pretty nicely processed JPEGS straight the way. I'd forgot about ASI Studio so I appreciate the reminder :) I did mean to give it a go! I know it only accepts FITS files, so I will look at converting my files and try it out, cheers!

Hi Stuart! Thank you. It means a lot to hear you enjoy the videos and find the content relatable. It’s easy to get caught up in the gear chase, especially with all the options out there, but it’s great that you’re finding satisfaction in sticking with the basics. Astrophotography with a star tracker is a straightforward, enjoyable and raw experience, and there is a lot to be said for that. Wishing you the best with your astrophotography, and thanks again for your support!

Thanks Tony Mate, I think we can do even better once I've sorted out a remote trigger release so we can go above 30 seconds :D

Hey Tich, mate! OnStep sounds awesome! Getting back out there after a break is usually all it takes to get your mojo back. The real challenge is pulling yourself out of that Netflix vortex! 😄

Thanks Mike!

Hey thanks! I was shooting with the 55-210mm kit zoom all the way out at 210mm, and the image was cropped in post. That's amazing you can achieve 2 minutes plus with an EQ5 at 1000mm. I had an EQ5 and 80mm 420mm focal length refractor as my first imaging rig in 2012 and could only manage 30 seconds at that time, but from what you're saying I think I should investigate how far I can push this mount :) Cheers!

Thanks, Philip! That's great to hear. I've heard good things about OnStep, and your experience reinforces that. My plan, though, is to get a second mount so I can keep the motor-driven EQ5 in the garage at the front of my house where the planets are visible, and have another mount in my shed/observatory dedicated to deep-sky imaging. Just for fun, I might first see how far I can push the basic servo motors on the EQ5 for deep-sky imaging. Thanks for taking the time to comment! Clear skies :)

Dawes limit which basically says the larger the aperture the more you can resolve. The more you can resolve the sharper the image will appear. For example, a 4k TV appears sharper than HD.

Hi, It's the Enhanced Motor drive kit with ST4, but the plan is to keep this mount as it is, stored in the garage at the front of my house where the planets pass by, and get a second goto mount for my shed obsy in my back yard for deep sky. cheers!

Saturn will look fairly uniform in colour (white/yellow), however, you should be able to reduce the exposure and gain to reveal the brown/red weather belts on Jupiter. Are you using a Barlow lens between the camera and Skymax to increase image scale and reduce image brightness? You'll also need an IR cut filter on the front of your cameras nosepiece to remove the pink colour cast of IR wavelengths and sharpen things up. If you are still having an issue there are two work arounds I can think off, 1) try different capture software such as Firecapture, 2) place a polarising ND filter on the front of the camera.

I mainly use 1.25" eyepieces. The only disadvantage is that you cannot have ultra wide apparent field of views with long focal length / low power 1.25" eyepieces, for example, you are limited to 52 degrees with a 32mm 1.25" eye pieces. This isn't a problem in most cases, and you can still use ultra wide fields of view at shorter focal lengths E.g 82 degrees at 14mm.

I've never found this to be a problem

Thanks Tony. The clouds were annoying but I we still got it.

Exactly the same thing happened here. I had to pump the gain right up to punch through the cloud and Saturn completely disappeared by the time it touched the limb lol Typical, but like you say, it was nice to see them clearly approach each other before the clouds :)

Thankfully the street lights go off at midnight. Just the usual clouds to contend with instead :D It was perfectly clear up until about 5 or 10 minutes before the occultation as well!