Astro Photography Help

[jasondh]

I've have my Skywatcher 250 Flex Tube for a while now.

I've been getting use to looking nothing else.

Run before walk etc.

I have today bought myself a T2 Extending Camera Adapter and the suitable T Mount for my Nikon Camera. I'm heavily into my photography so I have a Full Frame DSLR without any astronomy type modifications.

So looking at my camera adapter I have a few questions that you helpful folk can obviously clear up.

Judging by the build of the unit I can insert an eyepiece into the unit. Size wise my 10mm or 25mm would fit inside it. But with the narrow aperture of the 10mm do you need to heavily crop the image it you can focus it at all that is.

I also have a 2x Celestron Barlow Lens. I this any use with the adapter.

Sorry for all the questions.

[Tinker1947]

You should consider Prime Focus, any thing you place between the scope and camera will reduce the image quality by magnifying the image and also the tracking errors at the same time, this just ends in tears..

[jasondh]

You should consider Prime Focus, any thing you place between the scope and camera will reduce the image quality by magnifying the image and also the tracking errors at the same time, this just ends in tears..

O.k. thanks. So nothing to begin with then, just the camera and the adapter?

[Tinker1947]

Thats it, Camera, Adapter, Scope, and a some decent tracking or keep the image time very short. depending on your Nikon Model one of these are worth there weight in Gold....search E-bay for your model type...

TIMER REMOTE CONTROL FOR NIKON D3S D2HS D300S D700 | eBay

[jasondh]

Thats it, Camera, Adapter, Scope, and a some decent tracking or keep the image time very short. depending on your Nikon Model one of these are worth there weight in Gold....search E-bay for your model type...

TIMER REMOTE CONTROL FOR NIKON D3S D2HS D300S D700 | eBay

Bought one of those timers a few years ago in the US but have never used it. Great that I will now have a use it.

What's the theory then? An image every few seconds/minutes etc?

[hemihaggis]

hi there , your mount will struggle with long exposure deep sky photography , due to the way the mount tracks .. your pics with this setup will suffer from "roatation" , on the other hand you should be able to get some great shots of the planets and thier moons .....but your dslr will not be ideal for this ..most people use a webcam/philips spc 880 type thing !! sorry !!

[carastro]

Yes, unfortunately for deep sky imaging you need an equatorial tracking mount capable of guiding.

Carole

[jasondh]

Why does a DSLR struggle where a webcam does not.

Surely the resolution and sensitivity of the DLSR is much greater than that of a webcam?

I notice a lot of photos taken by DSLR's. Are these therefore likely taken with the mounts you describe and not like mine?

[hemihaggis]

hi jason a dslr is great for long exposure pics , on a guided eq mount .

a webcam works better on planets better because planets are very bright and do not need long exposures , they film the object , then you stack the individual frames .

a good bookto read on astrophotography is steve richards, every photon counts , he is a member on here !!

ps most of the dso` images you see on here will be taken using a big eq type mount .. they track the stars in a circular motion to avoid the rotation of field . usually a motorised eq5 type is the minimum requirment , many long exposures are taken using huge amounts of equipment ££££ get a copy of the above book !!!

[pilkinn]

A friend uses a Canon DSLR for planetary imaging. His camera has the advantage in that he can select a region of interest and then create a video using just that area at a high frame rate. So he uses his multi-mega pixel camera to video a 640 x 480 area - just like a webcam would. Luckily he has a NEQ6 mount so the weight of the camera isn't a concern.

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[jasondh]

So is the point of the webcam that it takes several frames per second rather than the DSLR single shot?

Typically how long would you take a movie for and how many images would you stack for the final image?

[Tinker1947]

I don't have or do the webcam stuff (yet) but its frames per second, were as imagine DSO's are many seconds per frame, i normally with no Moon set 45 seconds on the remote and take 20 - 40 images, this is unguided, with a autoguide set-up 5 minutes per image with 20 - 40 images is not uncommon, just leads to a lot of i wish i had another scope to do some visuals while i'm waiting..

[jasondh]

So it is fair to say then that for a Equatorial mount to be used for photograph it has to be motorised so that it tracks your object? I assume also that this tracking is more than simple movement and is in fact computer controlled tracking.

[hemihaggis]

if you are serious on AP then get a copy of the book , it might save you a bundle

[Tinker1947]

Depending on your Scope will determine the type of mount, but as a rule of thumb, a HEQ5 takes a 200mm and a NEQ6 a 250mm Reflector, srri i'm not up on refractor weights ect...

[hemihaggis]

jason ,have a good look through the astrophotography sections on here , there are sections on dslr, webcam , and video astronomy , all of the questions you are looking for answer to are in there

[Digz]

Get Steve's book it will explain a great deal.

Astrophotography can be done with you setup but just don't expect glorious images of DSO's. Your images will suffer from field rotation, this is where an EQ mount is better.

Webcams are favoured for planetary works because they have a high frame rate i.e. record video, but also because of the crop factor associated with them. An image of a planet with a DSLR will be very small in the frame (more so on an FX camera) where the smaller sensor of a webcam has the 'effect' of enlarging the apparent size of the planet on the finished shot.

You can get motorised EQ mounts which, when powered, will run automatically to counteract the Earths rotation in RA. This is a simplified explanation and you will soon find that even the most precision engineered mount will have limitations meaning some intervention in the tracking is required (google periodic error, wormgear error, guiding)

It can be quite a minefield so I would say, again, get the book and read it and by all means ask away here.

HTH

[rowan46]

If you are handy with the diy look up equatorial platform I believe it was moonshane who built one

[jasondh]

Right first thing I noticed is that I cannot focus on the moon with prime focus alone. It is possible to get focus on the moon if I include the 25mm eyepiece but the depth of field is so shallow I only get half of the visible surface in focus.

I didn't get to try the 2x Barlow because it clouded over while I was still messing with the setup above.

I'm wondering if the lack of focus without any eye pieces is due to my full frame camera, Any thoughts?

[Digz]

Inward Focus - google or search the forums here about that. A common problem with large reflectors not a symptom of a full frame DSLR.

On my scope I can unscrew the EP holder which allows direct connection of my camera (via a T mount) moving it closer to the secondary thus given more 'room for movement' in the focussing, figuratively speaking. A barlow will also achieve the same effect but will also magnify the image.

Including an eyepiece will move you into the realm of afocal astrophotography which you could try but would need a lens on your DSLR - not sure how sensible this is, or how practical it is either.....

[jasondh]

Inward Focus - google or search the forums here about that. A common problem with large reflectors not a symptom of a full frame DSLR.

On my scope I can unscrew the EP holder which allows direct connection of my camera (via a T mount) moving it closer to the secondary thus given more 'room for movement' in the focussing, figuratively speaking. A barlow will also achieve the same effect but will also magnify the image.

Including an eyepiece will move you into the realm of afocal astrophotography which you could try but would need a lens on your DSLR - not sure how sensible this is, or how practical it is either.....

Thanks for that.

I'm going to get the EP assembly in from my scope and have a play around in the daylight to see how short I can get it.

Using a Barlow was to be my second test last night but it clouded over so I gave up. I might try that tomorrow if I can. Busy tonight with football.

[pilkinn]

Jason. For planetary and moon then barlow projection or eyepiece projection are the ways to go - Barlow being the preferred. Do not go afocal (where you have an eyepiece and a camera lens). Getting your target in the frame and then focussing are hard. Perserverence and patience are the name of the game. You'll find having the mount tracking the target whilst focussing makes it a lot easier. Don't expect the live image to look too good unless the seeing is perfect which it never is. The magic comes in the post processing. Take 1000 to 2000 frames at between 5 and 20 frames per second. You'll need to experiment with your own setup to get the optimum. If you were using the scp900 webcam there's lots of advice on this forum but you'd still need to experiment.

Post processing use Registax or Avistack - both free. An image processing program will also be useful e.g. Photoshop, Gimp.

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[sabana]

Hi

A bit late but you mentioned the 'heaviy into photography' bit and I have to comment being likeminded.

I have a D3 and you are right. The resolution and hi ISO will blow any cheap webcam away. But only for certain types of Astrophotography. Widefield (ie 10mm) photos of the milky way etc are stunning if done correctly. There is a device caled the 'Astrotrac' (which Steve Richards recommends for photographers). Look it up, it is a way you can use your expensive camera gear in astrophotography and may be all you'l need.

[jasondh]

Hi

A bit late but you mentioned the 'heaviy into photography' bit and I have to comment being likeminded.

I have a D3 and you are right. The resolution and hi ISO will blow any cheap webcam away. But only for certain types of Astrophotography. Widefield (ie 10mm) photos of the milky way etc are stunning if done correctly. There is a device caled the 'Astrotrac' (which Steve Richards recommends for photographers). Look it up, it is a way you can use your expensive camera gear in astrophotography and may be all you'l need.

I went to ancient monument in SW Wales not so long ago (Pentre If an). Pitch black and the milky way was really clear. Only bit of equipment that I had that I didn't need was my wife and two kids. So I didn't get to spend as long as I needed. Photos were rubbish.

I will be back there this summer so I am planning a night to spend a few hours with camera and tripod to see what I can get.

Really worth a visit.

Sorry to veer off topic slightly.

[Vega]

I adhere, you'll get inward focus issued with DSLR and your reflecter. A low profile adaptor is what you need (which you'll find your Eyepiece holder doubles up as one anyway). Some people have also tried bringing the primary mirror closer to the secondary using the collimation screws (or spacers) to allow you to reach focus.

Cheers