66 replies to this topic

[PeterWar]

In my view, the capabilities of fast astrophotography lenses are often underestimated in these forums, with a preference for generally slower telescopes.

This image of the Pleiades was taken using a 20-year-old Nikon Nikkor 300mm AFS-II lens.

 

At f/2.8 under Bortle 4 skies, I only needed 13-second exposures, which allowed me to capture round stars in every frame without the need for guiding on my lightweight and affordable Star Adventurer mount.
 

With a low-noise camera, the signal-to-noise ratio (SNR) loss in one-shot color (OSC) imaging is minimal. This setup also reduces the impact of wind and satellite trails. The main trade-off, in my view, is the increased CPU time required for stacking.
 

While this setup isn’t perfect, I’d be hard-pressed to find telescope images on Astrobin—often taken with equipment costing four times as much—that deliver significantly better results.


I'm strongly leaning towards upgrading this lens to a modern Sony 300mm F2.8 GM OSS lens when I travel to Japan next month.

Edited by PeterWar, 30 October 2024 - 09:37 AM.

[Tapio]

What a lovely image.

I know many who use and respect these older Nikkor lenses.

[vidrazor]

In my view, the capabilities of fast astrophotography lenses are often underestimated in these forums, with a preference for generally slower telescopes.
This image of the Pleiades was taken using a 20-year-old Nikon Nikkor 300mm AFS-II lens.

At f/2.8 under Bortle 4 skies, I only needed 13-second exposures, which allowed me to capture round stars in every frame without the need for guiding on my lightweight and affordable Star Adventurer mount.
With a low-noise camera, the signal-to-noise ratio (SNR) loss in one-shot color (OSC) imaging is minimal. This setup also reduces the impact of wind and satellite trails. The main trade-off, in my view, is the increased CPU time required for stacking.
While this setup isn’t perfect, I’d be hard-pressed to find telescope images on Astrobin—often taken with equipment costing four times as much—that deliver significantly better results.
I'm strongly leaning towards upgrading this lens to a modern Sony 300mm F2.8 GM OSS lens when I travel to Japan next month.

Very nice shot.

 

Your argument, however, is rather odd. You're ready to spend "four times as much" on a lens.

 

Now, unless you also plan to use it terrestrially, fine.

 

But if your goal is astrophotography, the money you plan to spend on that lens is much better spent on a better mount than you're using now, like an AM5N, and one of those slower, but well corrected, telescopes, like an Askar 71F, for example.

 

This gives you a higher precision tracking mount, a scope with a longer focal length, and you still have your 300mm Nikkor, which is obviously giving you rather good quality images. A mount like the AM5 will be able to be used with a variety of scopes up to 2000mm, and can track accurately to give sharp stars at longer sub times with longer scopes.

 

Just a thought.

Edited by vidrazor, 30 October 2024 - 11:39 AM.

[Avgvstvs]

I agree that many underestimate quality lenses from yesteryear. If it works for you then that's brilliant. I use many older Pentax lenses from the 1970's and they can produce amazing pictures. Especially when slowed down by 2 stops depending on lens, model, quality etc. Some people just get sulky because they spend $1,000's on gear that you can have for a few $100's. They believe that anything old is 'no good'. Ignore their biases and enjoy the 300mm F4. Clear skies.

[PeterWar]

My point being:

1-Use a fast lens (f2.8) even if old.

2-Use a low noise CMOS camera
3-Use low exposure times (10-15 seconds)

4-Forget about guiding and heavy setups.
5-Let the CPU do the heavy work for you.
6-Results will be comparable or better than with F4 telescopes and heavier mounts guiding.

[vidrazor]

My point being:
1-Use a fast lens (f2.8) even if old.

2-Use a low noise CMOS camera
3-Use low exposure times (10-15 seconds)

4-Forget about guiding and heavy setups.
5-Let the CPU do the heavy work for you.
6-Results will be comparable or better than with F4 telescopes and heavier mounts guiding.

All fine and well with wide field shooting, but good luck trying to shoot distant targets that require focal length to reach.

[PeterWar]

All fine and well with wide field shooting, but good luck trying to shoot distant targets that require focal length to reach.

Small pixel sizes cameras and good optics might get you there. Look at RASA telescopes

[vidrazor]

Small pixel sizes cameras and good optics might get you there. Look at RASA telescopes

You're new to this aren't you?
 

[Alen K]

Actually, _I’m_ not new to this, having been in the AP game for a few decades, imaging “seriously” (if using a standard camera is indeed “serious” astrophotography) off and on for over 20 years and dabbling in it since the 1970’s. Yet what I have seen over those decades is that the trajectory of imaging technology has been to reduce the scale of the equipment required to achieve a given level of detail on astronomical targets. Results I now achieve with an old vintage 300mm lens and a 24Mp APS-C DSLR using the camera to track (that Astrotracer thang) are better than the best I could achieve on 35mm color film using a telescope with over 750mm of focal length on a suitable EQ mount.

 

Sure, I am comparing an ancient technology (film) to a newer technology (2015 CMOS sensor). Of course we expect a huge difference in capability. The color film I used had no better than 10MP equivalent resolution and had terrible sensitivity compared to the DSLR. But the improvement is my point. More recently, the pixel pitches of cameras with CMOS sensors have been dropping and sensor sensitivities have been increasing (if only modestly). Combine that with newest lenses designed for those newer sensors, with better MTF’s, and we get another reduction in equipment scale, although a more modest one since we are (apparently) approaching the limits of CMOS imaging technology. 
 

Edited by Alen K, 31 October 2024 - 06:46 PM.

[PeterWar]

You're new to this aren't you?
 

Vidrazor, I appreciate the discussion, but I stand by my argument. I've backed up my perspective with an example that illustrates the advantages of a 300mm f/2.8 lens with the Pleiades. This isn’t just a preference; it’s based on clear results that meet my goals for imaging.

While it might not be the typical choice, these lenses can produce excellent results when used appropriately.A year ago I chose the Nikkor AFS-II because it was the first Nikkor lens optimized to be used on DSLR sensors and I could affort the experiment as the lens is relatively inexpensive alveit a bit hard to find. Now I'm strongly leaning towards buying the new Sony 300mm f2.8 as opposed to a Takahashi FSQ-106 because I definitely think it's a much better choice for OSC travel astrophotography.

 

If there are specific issues you see with my approach, I’d be interested in constructive feedback, ideally grounded in comparable examples. However, I think the images speak for themselves in demonstrating the effectiveness of this setup. In my view, the equipment in your signature would also be able to get you comparable results with the Pleiades, but it would take you much longer. I could be wrong though.

 

I also dare to argue that a 11" RASA with an ASI6200MC unguided will get better results than typical 10-12" 2000mm-3000mm focal lenght RC/SC telescopes with guiding mounts under normal seeing conditions, but I could be wrong on that. I'll be traveling to Namibia in May and will test this.

 

I've had my job as astronomer long enough to realize the skies of today are not the same than the skies of the last decade, it's getting crowded with satellites out there and a fast imaging instrument is a great way of mitigating the impact of satellites, it also adds the extra advantage of requiring no guiding in OSC. I'm sure the AM5N is a great mount for guiding setups in narrowband, I might buy an harmonic mount with encoders soon but this is not what this topic is discussing.

Edited by PeterWar, 31 October 2024 - 08:50 PM.

[vidrazor]

Well, my point is some targets are simply going to need a larger scope and an appropriate mount. It's fine to use for instance the setup you used here, but a RASA is not going on a Star Adventurer.   Sooner or later you're going to have to deal with the larger and heavier gear you're trying to avoid, at least, for certain targets. A RASA has it's own complications in setup as well. By the time you're there, you have a whole large rig. Might as well autoguide, etc. The simplicity of what you're trying to achieve is long gone.

Edited by vidrazor, 31 October 2024 - 10:53 PM.

[17.5Dob]

You're comparing oranges to eggplants. I do 90% of my shooting at 650mm fl and longer. The SA is woefully inadequate to handle those focal lengths and I can count the number of targets that I would have to shoot at 300mm, to be able to fit them in the FOV of a single frame, on one hand with fingers to spare.

If you think an 11" RASA can compete with an 11" Edge, I'm dying to see your images of Saturn or the Coma or Hercules galaxy clusters taken with the RASA.

There's a whole lot more to AP than just UWA panoramas. Your goals are your goals, but low fl/ wide angle shots are not one of mine.

Edited by 17.5Dob, 01 November 2024 - 02:18 AM.

[sharkmelley]

What camera are you using?  Was it the Moravian G4-9000 in your signature?

[PeterWar]

What camera are you using?  Was it the Moravian G4-9000 in your signature?

Thanks a lot for asking.

Last year I did this in 3500mm focal lenght with my 16" Meade ACF and Moravian G4-9000 mono with narrowband filters and with an Moravian G1 OAG:

 

 

The 16" Meade ACF+Moravian+10Micon GM HPS is a setup weighting more than 100Kg and would require 1-2 days to setup. I now suspect I can get better results with the same amount of time with an 11" RASA+ASI 6200MC+HAE69C-EC+ASKAR DUO+ filters and no guiding. The RASA would require 30 minutes of setup time including polar aligment. I can't move the 16 Meade to chase good seeing and even better darkness. I can do that with a 11" RASA. With high megapixels cameras you will want to crop the image if the target looks too small, that's it, as long as the limiting resolution of the telescope remains well below the seeing and enough pixels remain to properly sample target DSO.

I can't travel with my 16" Meade to Namibia, I can easily grab a 300mm f2.8 lens and my Sony A7III camera+ Staradventurer and go there.

 

Just for fun, last month I used my Skywatcher 100i+925 Edge HD and Sony A7III camera to take a total of 10 minutes of exposure time with sub 10second images of the Dumbbell Nebula while dodging clouds. This is a setup that many would qualify as crazzy, I wouldn't recommend an harmonic mount without encoders to be used unguided with this telescope. But because I was dodging clouds I decided not to guide. The results are not perfect but look more encouraging than what I though I would get at this long focal lenght.

Regarding planets, I'm still processing this picture of Saturn taken with my 20" f3.5 DocTelescope, unguided:

 

Dave I agree with you, a 11" Rasa is not a good planetary instrument, but I've never claimed that was the case. I would argue the 11" Edge HD is a more versatile instrument than the RASA because it can do planets and thanks to Hyperstar, it can also become a very fast telescope. But this isn't what we're discussing. What I'm talking about is that wether we like it or not, the sky is filling up with satellites and extraordinary dark sky places are long gone in Europe and the US, thankfully, fast telescopes/lenses and low noise CMOS tecnology are there to help.

 

Thanks to low noice CMOS, I'm also beginning to see very good narrowband results with 2" exposures too. I did not think this was possible, now I'm changing my mind.

To re-iterate, my current view is as follows:

When targeting DSOs of almost any size in OSC, get the fastest lens/telescope possible, don't guide, use short exposures with a good, low noise CMOS camera. This will eliminate layers of complexity and will enable imaging with even low end/low weight mounts. In the end you will get better SNR because you'll be trowing out less subs due to satellites, clouds and failed tracking and you will get a much more portable setup. This will encourage you to travel to better places to image and get better results. The only real tradeoff is slower computing times but let the CPU be misserable while you sleep, instead of loosing sleep while being miserable guiding away from home.

 

Of course, I don’t claim to possess the absolute truth here; these are simply my observations and preferences based on my experiences and current goals. I’m always open to constructive discussion and different perspectives, especially if they bring valuable insights. I welcome any feedback or suggestions that might add to the conversation.

Edited by PeterWar, 01 November 2024 - 10:35 AM.

[primeshooter]

Thanks a lot for asking.

Last year I did this in 3500mm focal lenght with my 16" Meade ACF and Moravian G4-9000 mono with narrowband filters and with an Moravian G1 OAG:

 

 

The 16" Meade ACF+Moravian+10Micon GM HPS is a setup weighting more than 100Kg and would require 1-2 days to setup. I now suspect I can get better results with the same amount of time with an 11" RASA+ASI 6200MC+HAE69C-EC+ASKAR DUO+ filters and no guiding. The RASA would require 30 minutes of setup time including polar aligment. I can't move the 16 Meade to chase good seeing and even better darkness. I can do that with a 11" RASA. With high megapixels cameras you will want to crop the image if the target looks too small, that's it, as long as the limiting resolution of the telescope remains well below the seeing and enough pixels remain to properly sample target DSO.

I can't travel with my 16" Meade to Namibia, I can easily grab a 300mm f2.8 lens and my Sony A7III camera+ Staradventurer and go there.

 

Just for fun, last month I used my Skywatcher 100i+925 Edge HD and Sony A7III camera to take a total of 10 minutes of exposure time with sub 10second images of the Dumbbell Nebula while dodging clouds. This is a setup that many would qualify as crazzy, I wouldn't recommend an harmonic mount without encoders to be used unguided with this telescope. But because I was dodging clouds I decided not to guide. The results are not perfect but look more encouraging than what I though I would get at this long focal lenght.

Regarding planets, I'm still processing this picture of Saturn taken with my 20" f3.5 DocTelescope, unguided:

 

Dave I agree with you, a 11" Rasa is not a good planetary instrument, but I've never claimed that was the case. I would argue the 11" Edge HD is a more versatile instrument than the RASA because it can do planets and thanks to Hyperstar, it can also become a very fast telescope. But this isn't what we're discussing. What I'm talking about is that wether we like it or not, the sky is filling up with satellites and extraordinary dark sky places are long gone in Europe and the US, thankfully, fast telescopes/lenses and low noise CMOS tecnology are there to help.

 

Thanks to low noice CMOS, I'm also beginning to see very good narrowband results with 2" exposures too. I did not think this was possible, now I'm changing my mind.

To re-iterate, my current view is as follows:

When targeting DSOs of almost any size in OSC, get the fastest lens/telescope possible, don't guide, use short exposures with a good, low noise CMOS camera. This will eliminate layers of complexity and will enable imaging with even low end/low weight mounts. In the end you will get better SNR because you'll be trowing out less subs due to satellites, clouds and failed tracking and you will get a much more portable setup. This will encourage you to travel to better places to image and get better results. The only real tradeoff is slower computing times but let the CPU be misserable while you sleep, instead of loosing sleep while being miserable guiding away from home.

 

Of course, I don’t claim to possess the absolute truth here; these are simply my observations and preferences based on my experiences and current goals. I’m always open to constructive discussion and different perspectives, especially if they bring valuable insights. I welcome any feedback or suggestions that might add to the conversation.

I for one, understand at least part of what you are trying to say. I image very wide DSO with 50mm lenses on mirrorless / DSLR cameras, and also use a 200/2.8 a great deal. That said, I am under no illusions that I can suddenly start shooting tiny targets like the firework galaxy at 200mm because I just cannot get enough pixels on target. Even at 300mm it is pushing it. So whilst you aren't wrong for larger objects, you are for the tiny ones because it's simply not going to work. Yes I can crop deeply, and I can drizzle some information back but there comes a point were you are just fighting physics. You've shown this with your deep field shots of planets, and the horsehead with a large scope, yes? You didn't shoot them with your 300mm lens, but you allude that any deep sky object, no matter the size will work with this advice. You also have to factor in your sensor size of the camera you are using for the advice to begin to be 'functional'. You're advice isn't wrong; as long as you are keeping to the larger DSO in the night sky. PS I myself like the simple approach, I use it myself and enjoy being mobile.
 

Edited by primeshooter, 06 November 2024 - 05:01 PM.

[PeterWar]

I for one, understand at least part of what you are trying to say. I image very wide DSO with 50mm lenses on mirrorless / DSLR cameras, and also use a 200/2.8 a great deal. That said, I am under no illusions that I can suddenly start shooting tiny targets like the firework galaxy at 200mm because I just cannot get enough pixels on target. Even at 300mm it is pushing it. So whilst you aren't wrong for larger objects, you are for the tiny ones because it's simply not going to work. Yes I can crop deeply, and I can drizzle some information back but there comes a point were you are just fighting physics. You've shown this with your deep field shots of planets, and the horsehead with a large scope, yes? You didn't shoot them with your 300mm lens, but you allude that any deep sky object, no matter the size will work with this advice. You also have to factor in your sensor size of the camera you are using for the advice to begin to be 'functional'. You're advice isn't wrong; as long as you are keeping to the larger DSO in the night sky. PS I myself like the simple approach, I use it myself and enjoy being mobile.
 

primeshooter I'm afraid it is you that don't completely get it, I invite you to re-read this topic.

Nowhere in my posts did I say that a 300mm 2.8 lens would work on everything. My argument stands in favour of FAST lenses/telescopes and there are many with focal lenghts longer than 300mm and those lenses would obviously have bigger apperture as well so laws of physics don't become a bottleneck. In fact some RASA telescopes I aluded to in post #7 could probably work just fine in the FireWorks galaxy under typical 2' seeing if the camera has enough resolution.

 

Considering the ASI 6200MC camera with its 3.76-micron pixel size, pairing it with the 11" RASA's 620mm focal length gives an image scale of approximately 1.25 arcseconds per pixel. This is quite close to the optimal sampling rate for 2-arcsecond seeing. Atmittedly, if the seeing is superb you'll slightly undersample your target, specially at wavelenghts that deviate from 550nm as per RASA whitepaper.
 

While the 11" RASA is designed for wide-field imaging, it could probably still effectively capture the Fireworks galaxy with a good balance of detail and field of view. The galaxy's size (about 11.5 x 9.8 arcminutes) fits well within the frame, and the fast f/2.2 aperture allows for shorter exposure times. This setup can help mitigate issues like long integration times, wind, satellites etc. while still providing sufficient resolution to capture the galaxy's features.

 

Therefore, my points still stand in my view:

1-Use a fast lens/telescope (f2.8) even if old.

2-Use a low noise CMOS camera
3-Use low exposure times (10-15 seconds)

4-Forget about guiding and heavy setups.
5-Let the CPU do the heavy work for you.
6-Results will be comparable or better than with F4 telescopes and heavier mounts guiding.
 

Edited by PeterWar, 06 November 2024 - 08:45 PM.

[Kevin_A]

primeshooter I'm afraid it is you that don't completely get it, I invite you to re-read this topic.

Nowhere in my posts did I say that a 300mm 2.8 lens would work on everything. My argument stands in favour of FAST lenses/telescopes and there are many with focal lenghts longer than 300mm and those lenses would obviously have bigger apperture as well so laws of physics don't become a bottleneck. In fact some RASA telescopes I aluded to in post #7 could probably work just fine in the FireWorks galaxy under typical 2' seeing if the camera has enough resolution.

 

Considering the ASI 6200MC camera with its 3.76-micron pixel size, pairing it with the 11" RASA's 620mm focal length gives an image scale of approximately 1.25 arcseconds per pixel. This is quite close to the optimal sampling rate for 2-arcsecond seeing. Atmittedly, if the seeing is superb you'll slightly undersample your target, specially at wavelenghts that deviate from 550nm as per RASA whitepaper.
 

While the 11" RASA is designed for wide-field imaging, it could probably still effectively capture the Fireworks galaxy with a good balance of detail and field of view. The galaxy's size (about 11.5 x 9.8 arcminutes) fits well within the frame, and the fast f/2.2 aperture allows for shorter exposure times. This setup can help mitigate issues like long integration times, wind, satellites etc. while still providing sufficient resolution to capture the galaxy's features.

 

Therefore, my points still stand in my view:

1-Use a fast lens/telescope (f2.8) even if old.

2-Use a low noise CMOS camera
3-Use low exposure times (10-15 seconds)

4-Forget about guiding and heavy setups.
5-Let the CPU do the heavy work for you.
6-Results will be comparable or better than with F4 telescopes and heavier mounts guiding.
 

I agree that for some bigger targets, and ones that fit the frame at 300mm a fast lens is an awesome option and solution that can reduce guiding requirements to a point under certain requirements. Will they work on small targets… not very well. Does it work on a SA mount that is perfectly polar aligned and set up… sure it can work. Is it as good as a precision mount… depends on if you pixel peep or do not care! Now, I would also have to state that some expensive and fast lenses are horrible for astrophotography, but exquisite for terrestrial photography. My Sigma Sport 70-200 f2.8 is one of those. So my point is that spending lots of money on a fast lens may not always work, but if an older lens is great and it works… heck yeah. I have slow scopes and fast lenses and each one serves a purpose and has a guiding requirement from who cares to sub arcsec guiding needed to keep stars in check. Diversity is good solution to the need and use.

Edited by Kevin_A, 07 November 2024 - 03:42 PM.

[PeterWar]

I agree that for some bigger targets, and ones that fit the frame at 300mm a fast lens is an awesome option and solution that can reduce guiding requirements to a point under certain requirements. Will they work on small targets… not very well. Does it work on a SA mount that is perfectly polar aligned and set up… sure it can work. Is it as good as a precision mount… depends on if you pixel perp or do not care! Now, I would also have to state that some expensive and fast lenses are horrible for astrophotography, but exquisite for terrestrial photography. My Sigma Sport 70-200 f2.8 is one of those. So my point is that spending lots of money on a fast lens may not always work, but if an older lens is great and it works… heck yeah. I have slow scopes and fast lenses and each one serves a purpose and has a guiding requirement from who cares to sub arcsec guiding needed to keep stars in check. Diversity is good solution to the need and use.

You raise an important point Kevin, not all lenses, new or older work for astrophotography. I like to use this video as the basis to asess what lens to buy. For longer focal lenght fast lenses, the digital picture website has a starshots of lenses. Dxomark or Kenrockwell could also work but they never mention astrophotography. Does anyone know of any other website?

[Kevin_A]

You raise an important point Kevin, not all lenses, new or older work for astrophotography. I like to use this video as the basis to asess what lens to buy. For longer focal lenght fast lenses, the digital picture website has a starshots of lenses. Dxomark or Kenrockwell could also work but they never mention astrophotography. Does anyone know of any other website?

I used a website called Lenstip but they said my Sigma was great! However, just like telescopes, some lenses have very tight lens cells that show pinching at cooler temperatures and mine is one of those. My stars all look like limp starfish! I sent it to Japan under warranty and I got another lens and it was the same. The Japan techs only comments were… the lens was abnormally sharp. Haha so I use it for day use only. My best lens is still my Rokinon 135.

 

[primeshooter]

primeshooter I'm afraid it is you that don't completely get it, I invite you to re-read this topic.

Nowhere in my posts did I say that a 300mm 2.8 lens would work on everything. My argument stands in favour of FAST lenses/telescopes and there are many with focal lenghts longer than 300mm and those lenses would obviously have bigger apperture as well so laws of physics don't become a bottleneck. In fact some RASA telescopes I aluded to in post #7 could probably work just fine in the FireWorks galaxy under typical 2' seeing if the camera has enough resolution.

 

Considering the ASI 6200MC camera with its 3.76-micron pixel size, pairing it with the 11" RASA's 620mm focal length gives an image scale of approximately 1.25 arcseconds per pixel. This is quite close to the optimal sampling rate for 2-arcsecond seeing. Atmittedly, if the seeing is superb you'll slightly undersample your target, specially at wavelenghts that deviate from 550nm as per RASA whitepaper.
 

While the 11" RASA is designed for wide-field imaging, it could probably still effectively capture the Fireworks galaxy with a good balance of detail and field of view. The galaxy's size (about 11.5 x 9.8 arcminutes) fits well within the frame, and the fast f/2.2 aperture allows for shorter exposure times. This setup can help mitigate issues like long integration times, wind, satellites etc. while still providing sufficient resolution to capture the galaxy's features.

 

Therefore, my points still stand in my view:

1-Use a fast lens/telescope (f2.8) even if old.

2-Use a low noise CMOS camera
3-Use low exposure times (10-15 seconds)

4-Forget about guiding and heavy setups.
5-Let the CPU do the heavy work for you.
6-Results will be comparable or better than with F4 telescopes and heavier mounts guiding.
 

I invite you to read what vidrazor and 17.5Dob say here...

Edited by primeshooter, 08 November 2024 - 09:45 AM.

[xonefs]

My point being:

1-Use a fast lens (f2.8) even if old.

2-Use a low noise CMOS camera
3-Use low exposure times (10-15 seconds)

4-Forget about guiding and heavy setups.
5-Let the CPU do the heavy work for you.
6-Results will be comparable or better than with F4 telescopes and heavier mounts guiding.

 

There's nothing that special about fast lenses for this argument though. There is nothing stopping you from shooting shorter exposures on slower scopes without guiding and getting similar results if that's what you're after. I've done 10-15 second subs on f5 scopes just fine. 

 

You can overcome speed with more integration, but it is harder to overcome optical defects of many lesser lenses. 

 

That lens does look pretty good but I would be curious to see a raw unprocessed sub without any optical correction tools applied. 

Edited by xonefs, 07 November 2024 - 10:20 PM.

[PeterWar]

There's nothing that special about fast lenses for this argument though. There is nothing stopping you from shooting shorter exposures on slower scopes without guiding and getting similar results if that's what you're after. I've done 10-15 second subs on f5 scopes just fine. 

 

You can overcome speed with more integration, but it is harder to overcome optical defects of many lesser lenses. 

 

That lens does look pretty good but I would be curious to see a raw unprocessed sub without any optical correction tools applied. 

I believe you are right, above you'll see my Dumbbell Nebula done with 8-10 second subs at f10, unguided, I was surprised with the results.

EDIT: There are limitations to this approach though, please refer to Dr Robin Glover conference (around minute 41).
 

I'm uploading a sub and the WBPP integration outcome in pixinsight, very interested in your opinions.
 

https://www.dropbox....TThdR2jq4r8vSfk

 

I invite you to read what vidrazor and 17.5Dob say here...

I think I get what they are trying to say. In my view though, there are MUCH better (possibly cheaper) alternatives than imaging with 60mm f6 telescopes+guiding and I would be very interested to see their results with the Pleyades with their setup. Happy to be proved wrong.

Edited by PeterWar, 08 November 2024 - 10:28 AM.

[xonefs]

 

I'm uploading a sub and the WBPP integration outcome in pixinsight, very interested in your opinions.
 

https://www.dropbox....TThdR2jq4r8vSfk

 

 

All things considered that looks pretty good. CA seems well controlled. Looks like some minor astigmatism. 

 

Despite the age it's still not an inexpensive lens and I see decent condition ones selling for $2200+ 

[Shubham]

Chiming in late here, but I absolutely agree with PeterWar and also feel like most people here completely missed his point and were too ignorant or biased with their thinking to grasp what he was trying to say. I would go so far as to say that one should get a faster and lighter lens/scope that is at least decently well corrected under the stars even if it comes at a higher expense. People just do not understand the significance of a faster system and the possibilities it can uncover for them.

 

While this will hold true at any focal length, this allows a vastly superior experience upto 300mm. I’d rather have a Sony 300mm f2.8 GM that weighs just 3.3lbs on a Polarie U and shoot with a modern Sony camera unguided (meaning no unnecessary cables and no computer required at all!) than lug around a slow RedCat 61 that weighs 7.5lb and need at least an AM3 (which is again, much heavier!) and have to deal with autoguiding (which again involves additional equipment, setup time and weight!).

 

What you can capture in a single session at f2.8 on a not-so-frequent dark sky trip can be multiple nights worth of much more complicated “light gathering” in a slower f4.9 likely under worse skies. Get this, a modest 3hrs of integration @f2.8 would equal the same SNR as 9hrs worth of integration @4.9. And 9hrs of integration @f2.8 would be equivalent to a mighty 27hrs @f4.9. Being able to gather signal 3x faster is no joke, not to mention using just a lens and a star tracker.

 

Anyone coming up with the “yeah, try imaging the black eye galaxy with that 300mm lens” may go and re-read the whole thing again. The point being made was for speed, not the focal length. At any given focal length a higher speed would almost always be superior and allow possibilities that a slower speed just wont.

 

Cheers & clear skies!

 

Shubham

[PeterWar]

Chiming in late here, but I absolutely agree with PeterWar and also feel like most people here completely missed his point and were too ignorant or biased with their thinking to grasp what he was trying to say. I would go so far as to say that one should get a faster and lighter lens/scope that is at least decently well corrected under the stars even if it comes at a higher expense. People just do not understand the significance of a faster system and the possibilities it can uncover for them.

 

While this will hold true at any focal length, this allows a vastly superior experience upto 300mm. I’d rather have a Sony 300mm f2.8 GM that weighs just 3.3lbs on a Polarie U and shoot with a modern Sony camera unguided (meaning no unnecessary cables and no computer required at all!) than lug around a slow RedCat 61 that weighs 7.5lb and need at least an AM3 (which is again, much heavier!) and have to deal with autoguiding (which again involves additional equipment, setup time and weight!).

 

What you can capture in a single session at f2.8 on a not-so-frequent dark sky trip can be multiple nights worth of much more complicated “light gathering” in a slower f4.9 likely under worse skies. Get this, a modest 3hrs of integration @f2.8 would equal the same SNR as 9hrs worth of integration @4.9. And 9hrs of integration @f2.8 would be equivalent to a mighty 27hrs @f4.9. Being able to gather signal 3x faster is no joke, not to mention using just a lens and a star tracker.

 

Anyone coming up with the “yeah, try imaging the black eye galaxy with that 300mm lens” may go and re-read the whole thing again. The point being made was for speed, not the focal length. At any given focal length a higher speed would almost always be superior and allow possibilities that a slower speed just wont.

 

Cheers & clear skies!

 

Shubham

Shubham,

Thank you very much for your kind words, I appreciate them. I ended up buying the Sony 300mm f2.8 GM in Japan and the Vixen VSD90SS+0,71xReducer as well. I plan to compare them side-by side as soon as the necessary adapters ship. The goal will be to see how the sony lens with the staradventurer mount compares to the Vixen and Skywatcher 100i Mount at similar focal lenghts, I'll be glad to share the results.