Planetary Imaging Methods

[pook]

I'm researching stuff... In fact that's all I've done since I bought my scope, as I've had a grand total of 30 minutes clear sky in the last 5 days

Anyway. I'd like to know what methods you all use for attaching cameras for planetary imaging?

My SW 150P is great for prime focus as the OTA just takes the SLR straight onto it, but obviously, at f5, planets will appear very, very small.

I was wondering are you all using EP projection methods or is there something else I'm not aware of?

If you are, what EPs and projection adaptors you using?

[Space Cowboy]

Webcam for Planets with Barlow lens at prime focus. I use 3x or 5x Barlow with my f5 makes a nice big image.

[Pete Presland]

its not going to be easy holding an image in view at x5 without a motorised mount.

x2 would be a good start and use to do it with x3 as well with a bit of practice.

[Space Cowboy]

Sorry did not realise its a manual mount. You really need a motorised mount.

[pook]

Oh indeed. I realise this. I'm just sort of planning ahead.

I used the field of view calculator at http://www.12dstring.me.uk/fov.htm

shows Jupiter as really really small when I set it to use a dSLR.

Could I not use EP projection with a dSLR?

As a professional photographer, the thought of a low res webcam sort of makes me shudder. Is there a reason for webcam use? I assume it's the extra magnification you get by such a small sensor, but most web cams struggle to reach even HD TV resolution. Prints from that must look awful.

Is the only way to get a good image with a dSLR using EP projection then?

[jgs001]

The webcam will produce much better results than a DSLR will... the crop factor is the key here... If your SLR is full frame, which being a pro photog is likely, then a webcam (like the SPC900) has a crop factor of 8.5x. The high frame rate you can achieve with a webcam (10 to 15 for the SPC900) helps you overcome atmospheric conditions, and you want to capture between 1000 and 2000 frames... I wouldn't want to do that with my SLR, unless you have one with HD video I guess..

I can dig out an example of Jupiter, with my SLR and webcam sensor sized cameras...

[neil phillips]

I had a discussion like this years ago, someone said the dslr had to be better and the way foward, since that time, little has changed except the video cameras have got better and better. There are some semi reasonable dslr planetary shots around, But not many. and even those from what ive seen do not approach a good webcam or video camera. Reason being is you need hundreds if not thousands of images to reduce noise, something i gather isnt particulaly easy with a dslr, but with a webcam or dedicated astro camera stackks of 5 or 6 thousand become possible. My advice if on a budget get a philips spc 880, and a 4x barlow at f20 saturn for example or jupiter will be big enough for quite some detail.hope this helps

[pook]

I can dig out an example of Jupiter, with my SLR and webcam sensor sized cameras...

That would be good actually.. seeing the difference between the two. I think my worry is that I'd like the option to print at some point, and despite the advantages if a small sensor, the resolution would mean printing is not really a possibility.. well, it is, but the aliasing would be terrible.

Am I wanting the impossible? BTW.. I'm not necessarily talking about using my current scope. I'm thinking about in the near future. Both my wife and I are pretty much in agreement that the SW150P is an interim solution.

Anyone got any shots taken with a ep projection adaptor and SLR?

[jgs001]

I've got a lunar or two with ep projection... that's actually far harder than using a webcam...

All taken with my C80ED (80mm refractor, 600mm focal length)

This is cropped to death, the pixels are full size.. at 1200mm (with a 2xTC) from a static camera tripod, I have to admit I was truly amazed at the fact I got any detail at all

This is with my QHY5v (752x480) using LRGB (ish) filters at the same focal length

And this is with my QHY5v (for details) and SPC900 (for colour) with a 5x magnifier... the exposure length with the SLR at f/37.5 would have been impossible, and the image would still be tiny...

This is Clavius, I think it was with EP projection. I have an adapter that allows me to affix a T ring to the top of my Hyperion ep's... The exposure time is way too long for the seeing conditions, nothing I can do about the messiness of it, that's down to the wobbles.

[brianb]

You need to remember that the pixel sensor elements on a DSLR are about the same size as those in a webcam. It's just that the DSLR has more of them on its larger sensor.

When imaging Jupiter with my CPC1100 and a 2x barlow, Jupiter is about 250 pixels in diameter. If I go bigger, the image gets fainter & the exposure time increases, making blurring due to bad seeing much more of an issue than aliasing from small scale. In any case the image is pretty fully resolved at f/20 and fully resolved at f/25 (2x oversampled) with the 5.6 micron pixel pitch in my DMK21 camera.

The vibration from the mirror & shutter action in the SLR makes it difficult.

When we had to use film, eyepiece projection was often used to get a larger image scale - which was necessary because film tended to have a lower resolution than the high density sensors used these days.

Here are examples of eyepiece projection to film SLR - using a 6" scope in exceptionally steady conditions - and modern stacked imaging technique - with a 4" scope in poorish conditions. I guess you can tell the difference easily enough.

[Jupiterholic]

I'll weigh in here aswell. I used a compact camera for eyepiece projection for a short time and then moved onto webcam. There's absolutely no contest in my eyes as I think the images below show.

Admittedly you would get slightly better afocal results with a DSLR especially for the moon but a DSLR (unless you're using its video facility) relies on one shot, a webcam will take thousands of shots in an avi form so you'll capture the planet/craters at those precious moments when the atmosphere is steady, something a one shot method can never match.

Printing of planets taken with a webcam won't be any worse than if you were to print a planet taken with a DSLR, in fact it will be better purely because a webcam will capture more detail than a DSLR, the final images will be about the same size because planets are just... small. Also if you're shooting the moon you want to do a mosaic of webcam shots for a nice big crisp image, this is also the best way to ensure your entire lunar disc is in focus (you can manually adjust the focus as you pan across the surface and shoot the segments). My mosaics are about 40cm wide at 300dpi, perfect for printing.

The rules of earth bound photography really do go out of the window when you have to peer through a planets atmosphere to shoot something

Good luck

[neil phillips]

I think your new to all this by the looks. To put it bluntly, If you want exceptional quality either for printing or just capturing and processing drop the DSLR idea for planets, a DMK will blow the DSLR away big time. Printing as mentioned wont be inferior at all. Your looking at it the wrong way. the final processed stacked webcam shot. will be far superiour for printing what would you rather print from Brians shots, i know which one i would rather print ? the likes of Damien peach Chris Go Pete lawarence ( John H recently ) do you really think these guys would not be using A dslr if the results were better. Think again. these are some of the best images in the world. And as mentioned capturing those fast moments of good seeing with a dslr is almost impossible. i mostly shoot at 30 frames a second, to try and capture the very fast moments of good seeing. try shooting off 30 dslr shots a second to beat seeing. My advice learn from the guys mentioned. And good luck hope you get seriouse about Planetary imaging. For those that are, it often becomes a life long pursuit. One last thing you can do EP projection with a webcam or video camera. and get good results, ( certainly better than a SLR EP projection )

But i prefer a straight Barlow to webcam or planetary camera. as do most of the seriouse Guys into this.

[pook]

Ok.. I get it now. I was working on the assumption that if you fill the 35mm sized chip with a projected image, then you have better quality, but in reality you're all saying that yes.. that's true, but I will just have a high res BLURRY image due to relying on one shot that also records seeing defects.

Understood.

Thanks guys.