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Walking on the Moon

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Wasted Wizard
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8 minutes ago, wesdon1 said:

I actually started out with using the 8 inch reflector for planetary, but I have decided to use the refractors instead, because  I'm assuming it'll be easier framing them in post processing ? In the 8 incher, I'm finding it very hard to "zoom in" enough ? even with my SVBONY EP Projector fitted with a 9mm planetary EP ? The planets are STILL small in the final image ? I read yesterday that I should be using F20, up to F30 if the conditions allow, and my refractors are naturally longer FL's than my big f5 reflector. Obviously I'm a novice in imaging so please bare with me if I sound stupid!? LOL

Wes

I would not use EP projection for planetary. You would be much better off using a Barlow lens. When I do planetary with my C8 I use a 2.5 televue barlow, a flip mirror and the ASI224 camera. It can be challenging finding the planet sometimes to get it centred but the flip mirror is invaluable in this respect. I don't know what camera you are using but you can get Canons to zoom in using Backyard EOS.

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4 minutes ago, PeterCPC said:

I would not use EP projection for planetary. You would be much better off using a Barlow lens. When I do planetary with my C8 I use a 2.5 televue barlow, a flip mirror and the ASI224 camera. It can be challenging finding the planet sometimes to get it centred but the flip mirror is invaluable in this respect. I don't know what camera you are using but you can get Canons to zoom in using Backyard EOS.

I am using a canon eos rebel T1i unmodified, and cheap light pollution filter. I did use a 2x barlow, but the planet still tiny ? I am surprised about the EP projector advice, I thought I was doing the right thing using it to get zoomed in ? I must say though, focusing with EP Projector is v hard! I even tried a 5mm EP in the projector with a 2x barlow but I just could not find the planet! I will buy a flip mirror system for that purpose, sounds a great solution thanks Peter! I have heard of backyard EOS, how do i get it please Peter ? 

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1 minute ago, PeterCPC said:

https://www.otelescope.com/files/ An alternative is APT https://www.astrophotography.app/  which is free but I can't tell you if it would be as useful for zooming in because I have never used my Canon with APT.

Best of luck with it all.

Thanks so much for your help and advice Peter! I'll update you in coming weeks and post my astro pics! 

Wes

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5 hours ago, wesdon1 said:

I actually started out with using the 8 inch reflector for planetary, but I have decided to use the refractors instead, because  I'm assuming it'll be easier framing them in post processing ? In the 8 incher, I'm finding it very hard to "zoom in" enough ? even with my SVBONY EP Projector fitted with a 9mm planetary EP ? The planets are STILL small in the final image ? I read yesterday that I should be using F20, up to F30 if the conditions allow, and my refractors are naturally longer FL's than my big f5 reflector. Obviously I'm a novice in imaging so please bare with me if I sound stupid!? LOL

Wes

It's not the focal ratio that determines image size, but the effective focal length, so your f5 8 in Reflector with a focal length of 1000 mm, will actually give you a slightly larger sized planetary image than your 80/90 mm f11/f10 refractors.

To get a decent sized planetary image even using a dedicated planetary camera with a small sized senor, such as the ZWO ASI 224 & 462, ideally you need an effective focal length not less than around 3-4,000 mm (which you would achieve with a 2.5 - 3x Barlow), one planetary imager in particular likes to use a 2x Barlow even with his C14 giving an effective focal length of nearly 8,000 mm at f22. 

Although some observers will disagree with me, in my opinion if you are using a digital SLR, then you will probably need to use eyepiece projection (which can provide greater amplification than a Barlow/Powermate) to get a decent image size. To those that disagree with me I would love to see some large scale detailed planetary images taken using a digital SLR, using no more than a 2-3x Barlow for amplification. If the initial image size is too small it can be difficult to achieve correct focus, and to obtain sufficient alignment points in processing software such as AutoStakkert and Registax.

I don't understand why so many observers rubbish eyepiece projection these days, it was the method commonly used 20 years ago before the advent of digital cameras. An observer recently posted on 'Cloudy Nights' some quite nice images taken with a small Takahashi Refractor, using a Baader Zoom eyepiece, coupled directly to his planetary camera. 

John 

Edited by johnturley
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6 hours ago, johnturley said:

It's not the focal ratio that determines image size, but the effective focal length, so your f5 8 in Reflector with a focal length of 1000 mm, will actually give you a slightly larger sized planetary image than your 80/90 mm f11/f10 refractors.

To get a decent sized planetary image even using a dedicated planetary camera with a small sized senor, such as the ZWO ASI 224 & 462, ideally you need an effective focal length not less than around 3-4,000 mm (which you would achieve with a 2.5 - 3x Barlow), one planetary imager in particular likes to use a 2x Barlow even with his C14 giving an effective focal length of nearly 8,000 mm at f22. 

Although some observers will disagree with me, in my opinion if you are using a digital SLR, then you will probably need to use eyepiece projection (which can provide greater amplification than a Barlow/Powermate) to get a decent image size. To those that disagree with me I would love to see some large scale detailed planetary images taken using a digital SLR, using no more than a 2-3x Barlow for amplification. If the initial image size is too small it can be difficult to achieve correct focus, and to obtain sufficient alignment points in processing software such as AutoStakkert and Registax.

I don't understand why so many observers rubbish eyepiece projection these days, it was the method commonly used 20 years ago before the advent of digital cameras. An observer recently posted on 'Cloudy Nights' some quite nice images taken with a small Takahashi Refractor, using a Baader Zoom eyepiece, coupled directly to his planetary camera. 

John 

Thanks for advice John. I actually do have a SVBONY EP projector, but was still getting small planet ? I must be doing something wrong ? I have just ordered a ZWO ASI 120MM, to do mono planetary, and increase frame rates with software on my laptop. I am also going to experiment with different sized Ep's and see what works best. I am only 4 planetary imaging sessions in from total beginner status, so I am sure with practice and experimentation, I'll finally get my planets looker big and detailed! Thanks again John, i'd be lost without dcecent people like yourself on here!

Wes. 

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16 hours ago, wesdon1 said:

Thanks for advice John. I actually do have a SVBONY EP projector, but was still getting small planet ? I must be doing something wrong ? I have just ordered a ZWO ASI 120MM, to do mono planetary, and increase frame rates with software on my laptop. I am also going to experiment with different sized Ep's and see what works best. I am only 4 planetary imaging sessions in from total beginner status, so I am sure with practice and experimentation, I'll finally get my planets looker big and detailed! Thanks again John, i'd be lost without dcecent people like yourself on here!

Wes. 

You will get much better results with a dedicated planetary camera than with a digital SLR, not only does the much smaller sized sensor give you larger planetary images, but you can reduce the capture area of the sensor (or ROI) further to enlarge the image even more, which you cannot do with some digital SLR's. In addition, most planetary cameras enable frame rates of up to around 200 frames per second, whereas most digital SLR's are limited to around 30 fps.

I attach for example processed images of roughly the same area of Mars, the first was taken on 15 September 2020 (when the South Polar Cap was visible and Mars exhibited a 20 arc second disc) through my 14in Newtonian, using my Canon 6D digital SLR (which has a maximum frame rate of 30 fps) and eyepiece projection with a 9.7mm Plossl eyepiece. The second was taken through the same telescope on 13 November 2022 (when Mars exhibited just a 16 arc second disc) using a ZWO ASI 462 Planetary Camera (which I did not have in 2020) with a 2.5x Powermate giving an effective focal length of 4,500 mm at f12.5, the capture area being reduced from the full 1936 x 1096 to 544 x 548, and a 2-minute exposure of 13,000 frames at 111 fps. Images were processed in PIPP (for the one with the Canon 6D), AutoStakkert and/or Registax, plus Adobe Lightroom. 

The differences between the 2 images are quite obvious, both in terms of size and detail, despite Mars being further away in November 2020, and if I recall correctly more detail was visible through the eyepiece in September 2020. 

I should stress that I am a relative beginner to planetary imaging, my images are nowhere near as good as those of other observers such as Neil Philips, and I made all sorts of mistakes to begin with, such as using the full capture area of the camera and then wondering why my images still appeared very small. I've also tried enlarging the images in programs such as GIMP, but generally this did not seem to give very good results. 

John 

Mars 15 09 20 Best Processed.jpg

Mars 1 Reprocessed.jpg

Edited by johnturley
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10 minutes ago, johnturley said:

You will get much better results with a dedicated planetary camera than with a digital SLR, not only does the much smaller sized sensor give you larger planetary images, but you can reduce the capture area of the sensor (or ROI) further to enlarge the image even more, which you cannot do with some digital SLR's. In addition, most planetary cameras enable frame rates of up to around 200 frames per second, whereas most digital SLR's are limited to around 30 fps.

I. 

John 

I beg to differ. The smaller sensor does not capture a larger image for a given focal length. The size of image projected onto the sensor is dependent only on the effective focal length of the optical system.

Reducing the capture area of the sensor does not, in any way, change the image scale or number of pixels that the object of interest covers, hence no enlargement takes place. This equivalent to so-called "digital zoom" and is correctly known as cropping.

I don't know of any modern DSLR which does not offer in camera cropping, but it is a pointless exersize anyway as none will crop to the sort of size needed in astro photography. In any case it will not enlarge the image.

What matters is the pixel size and this where some astro cameras will beat a DSLR by having smaller pixels, hence an image of a given size covers more of them leading to greater resolution for a given focal length.

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48 minutes ago, Mandy D said:

I beg to differ. The smaller sensor does not capture a larger image for a given focal length. The size of image projected onto the sensor is dependent only on the effective focal length of the optical system.

Reducing the capture area of the sensor does not, in any way, change the image scale or number of pixels that the object of interest covers, hence no enlargement takes place. This equivalent to so-called "digital zoom" and is correctly known as cropping.

 

The images do however appear larger after cropping when you post them on this website, although they do appear the same size in Windows Photo Viewer, which confused me at first. When I posted my first Jupiter image (with Io shadow transit) on this site, I could not understand why it appeared so small compared to other observers' images, but it was because I had used the full capture area of my ASI 462 camera (no cropping), plus not used a Barlow.

John 

Jupiter 3 29.08,21 Reprocessed.jpg

Edited by johnturley
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8 minutes ago, johnturley said:

The images do however appear larger after cropping when you post them on this website, although they do appear the same size in Windows Photo Viewer, which confused me at first. When I posted my first Jupiter image (with Io shadow transit) on this site, I could not understand why it appeared so small compared to other observers' images, but it was because I had used the full capture area of my ASI 462 camera, plus not used a Barlow.

John 

Jupiter 3 29.08,21 Reprocessed.jpg

It all comes down to scaling once an image is cropped. I've noticed that this site tends to display small images at a larger scale. I think it is a CSS setting that is forcing small images to be scaled to fit the box on the web page. I, personally, find it annoying. Windows photo viewer displays small images with a 1:1 pixel matching for the screen, but scales large images that exceed screen size to fit, thus lower resolution.

Cropping planetary images is vitally important to get them to display how you desire. To get them to display at the size you want on websites like this, you can always add a white (or grey, or any other colour) border around them to pad the space in the cell, once you have figured out approximately how big it is. Then, your black(ish) background appears at the size and scale you desire, if that makes sense.

In my down to Earth photography, landscapes and the like, I always shoot at the maximum resolution and quality my DSLR is capable of, even if that means I will need to crop later. It keeps every possibility open right up to the moment editing decisions are made. I know of some professional photographers who claim to shoot at lower resolution / quality, because the best is not necessary, but I never really understand that.

Digital zoom is a term I hate, as it gives completely the wrong impression to beginners. No zoom is involved, as you can see, it is merely cropping in camera and should simply be called digital cropping.

Nice Jupiter image, by the way.

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6 hours ago, johnturley said:

You will get much better results with a dedicated planetary camera than with a digital SLR, not only does the much smaller sized sensor give you larger planetary images, but you can reduce the capture area of the sensor (or ROI) further to enlarge the image even more, which you cannot do with some digital SLR's. In addition, most planetary cameras enable frame rates of up to around 200 frames per second, whereas most digital SLR's are limited to around 30 fps.

I attach for example processed images of roughly the same area of Mars, the first was taken on 15 September 2020 (when the South Polar Cap was visible and Mars exhibited a 20 arc second disc) through my 14in Newtonian, using my Canon 6D digital SLR (which has a maximum frame rate of 30 fps) and eyepiece projection with a 9.7mm Plossl eyepiece. The second was taken through the same telescope on 13 November 2022 (when Mars exhibited just a 16 arc second disc) using a ZWO ASI 462 Planetary Camera (which I did not have in 2020) with a 2.5x Powermate giving an effective focal length of 4,500 mm at f12.5, the capture area being reduced from the full 1936 x 1096 to 544 x 548, and a 2-minute exposure of 13,000 frames at 111 fps. Images were processed in PIPP (for the one with the Canon 6D), AutoStakkert and/or Registax, plus Adobe Lightroom. 

The differences between the 2 images are quite obvious, both in terms of size and detail, despite Mars being further away in November 2020, and if I recall correctly more detail was visible through the eyepiece in September 2020. 

I should stress that I am a relative beginner to planetary imaging, my images are nowhere near as good as those of other observers such as Neil Philips, and I made all sorts of mistakes to begin with, such as using the full capture area of the camera and then wondering why my images still appeared very small. I've also tried enlarging the images in programs such as GIMP, but generally this did not seem to give very good results. 

John 

Mars 15 09 20 Best Processed.jpg

Mars 1 Reprocessed.jpg

Thanks so much for the very deatiled advice and amazing examples John! I will try out all your advice and let you know how I get on/post pics etc thanks mate! Thanks so much John!

Wes

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