DSLR close-up question

[ballaratdragons]

I like the FOV of the Toucam when used with and without a Focal Reducer in my ED80, but it would be nice to occasionally get a slight fraction wider too.

Then there are you DSLR'ers who take great DSLR shots that all seem to be wide-field. Wider than I would normally like for many objects.

How do you get a DSLR in an ED80 to be a similiar FOV as the Toucam? What equipment would be involved?

I can't plan which way I have to go next (coz my Toucam is dying) without knowing what gear I would have to save for, to get similiar scale as I use now, and hopefully a tiny fraction wider as well.

Or is there another capture device (cheap) which gives good quality like a DSLR (even the cheapest ones) that would give the FOV I am after?

[h0ughy]

well if its important get a Gstar or one of those wizzbang mono thingys that Mike and Paul use:P , if not then you can get a second hand 300D for around 450, or a brand new pentax K100D for around the 650 mark, or go the whole hog and get either a pentax K10D, canon 400D or that Nikon 40D for around the same price range of 1200 plus.

you could use a barlow?:whistle:

[ving]

you can get a nikon d40 like mine for around the $700 mark brand new :)
add a barlow of whatever magnificatio to the image train to get what ykou desire.

[ballaratdragons]

Ahhh, so it's as simple as using a Barlow! :doh:




Personally, I don't want to go Monochrome. It's hard enough work imaging in colour without having to change filters and re-combine images etc.

And for the same price as the G-Star kit, I could probably get a DSLR. Only problem is I have no idea which is which, they are all just numbers to me (20D, 300D, 350D, etc). Some say in here that 300D is better than 350D and Vise-Versa. I've been reading all the posts over the last 2 years about the different makes and models and yet it's still all mumbo jumbo to me :lol:

I did notice an Ebay Store selling Brand new 350D bodies on Ebay for $699 (that's a lot of $$$ to me, but cheaper than a G-Star kit). I can't afford one, but anyone wanting one might like to know.

I know that CCD webcams like a SBIG is in the thousands, so they are ruled out straight away.

When it comes to imaging with anything other than the Toucam, consider me as a Noob!

[JohnG]

Hi Ken

I am not sure what a Toucam is equivilant to in an eyepiece (I think I read somewhere 6mm) so I will give you some figures based on that and a 3x Barlow.

Using a Canon 350D, and the equivilant to a 6mm eyepiece as above, you would have a focal length on the ED80 of around 4900mm, this would give you Arc Secs/Pixel of about 0.31 x 0.31.

Using a 3x Barlow, focal length would be about 1800mm, your Arc Secs/Pixel would then be around 0.76 x 0.76

At Prime Focus, it is 600mm, Arc Secs/Pixel is 2.19 x 2.19.

Which is close to ideal for normal seeing as I understand it.

Cheers

[ballaratdragons]

Thanks John.

Yep, a Toucam is equal to a 6mm EP.

It will take me a week of study to understand what you just said, but I gotta learn if I want to do. :thumbsup:

P.S. I have a 2" 2x GS Barlow :)

[[1ponders]]

:lol: basically Ken if you think of the ToUcam as a 6 mm eyepiece and the 300 D as a 30-35mm eyepiece. Sorta Kinda. The big downer about using multiple barlows to achieve a similar FOV to the ToUcam is you will increase your f ratio to such an extent that you will have to image much much much much long to achieve similar results.

If you like the FOV of the ToUcam then you might be better off grabbing the DFK. It has the same size chip as the ToUcam.See here for image example with the DMK (http://www.iceinspace.com.au/forum/showthread.php?t=18351&highlight=DMK). The DFK is the colour version. That isn't the one that Dennis is using. He is using the DBK bayer camera. While the Bayer is a colour camera it is differnt to the purely colour camera.

The DMK is seriously brilliant for a relatively inexpensive uncooled camera, but I would imaging you would like to steer away from having to do RGB combining. That is why I suggest the DFK 21F04 (http://www.theimagingsource.com/en/products/cameras/firewire_color/dfk21f04/overview/). It is much more like the ToUcam than the other two. I don't know if the DFK 21F04 is being sold in Aus but it is $100 cheaper than the DFK 21AF04.AS. The first one only does 30 fps and the second 60 fps. For DSOs that won't matter. I know Bintel have the DBK for $500, but you could get the DFK 21F04 from OS for $260 US

Something to think about. ;) I think you would really like it ;);):poke: :poke:

[[1ponders]]

Here ya go Ken.

Image comparison:
ED80 and ToUcam size Chip
ED80 and 300D

Statistics:
ED80 and ToUcam type Chip
ED80 and 300D

Note the comparison to the 35mm frame at the bottom right.

[JohnG]

Hi Ken

Maybe this will explain what I mean a bit better. A lot has to do with your actual seeing conditions, if you have an image scale of 0.31 arcsecs/pixel, the ED80 at 4900mm f/l and your actual seeing conditions limit you to 2 arcsecs/pixel, the majority of the pixels are being wasted as your setup far exceeds the resolution you can get.

That said, it is generally considered that the optimum resolution is around 2 arcsecs/pixel although I generally drop down to around 1.03 x 1.03 arcsecs/pixel when conditions are really calm.

Cheers

[[1ponders]]

Hang on I've just checked, the DMK 21AF04.AS up to 1 hour exposure, :thumbsup: the DBK 21F04 up to 30sec, unfortunately the DFK 21F04 have exposures only up to 1/30 sec :(

To get the full 60 min exposure you have to go for the .AS models http://www.astronomycameras.com/en/products/

A couple more DMK DSOs
http://www.iceinspace.com.au/forum/showthread.php?t=18342&highlight=DMK
http://www.iceinspace.com.au/forum/showthread.php?t=18298&highlight=DMK

[ballaratdragons]

Paul,

Sorry to sound picky, but I am yet to see an image by a DMK camera, a G-Star, or any other webcam style based camera that has stars like a DSLR does. They are all still blobby. Whereas every image I see from a DSLR (even the beginners at it) get nice sharp pin-prick stars.

The webcam style cameras are probably excellent for Planetary, but I'm not into Planets. I like Deep Space and I've grown tired of imaging blobby stars.

And it seems that I can get a DSLR for the same prices as the others.

I could be wrong about all this. I haven't experienced much in the way of Astrphotography outside my Toucam world.

[ballaratdragons]

John, it is still waaayyy over my head.

"0.31 arcsecs/pixel, the ED80 at 4900mm f/l and your actual seeing conditions limit you to 2 arcsecs/pixel,"

"optimum resolution is around 2 arcsecs/pixel although I generally drop down to around 1.03 x 1.03 arcsecs/pixel"

What the . .! :shrug:

I think Paul showed in his attachments what you are trying to say, I think :shrug:

[[1ponders]]

You can get better stars, from memory I don't think I used an IR filter with those shots. If I get a chance I'll try to take some shots out at Duckadang and post them when I get back and compare them with the 300D.

Don't think the 300D is immune from blobby stars. Here is a center un-resized crop of M7 using the 300D and the ED80. Often the blobbiness of stars (or lack thereof) can be brought about by the scale that the image is being viewed at. Among other things.

Certainly from a width field of view perspective the 300D wins hands down. Just don't hope to get the same sort of field of view with a 300 that you did with the ToUcam in the 80. If you want a narrow field of view like the ToUcam then you will have to either go for a small chip, or use multi-barlows and that would be extremely frustrating and time consuming as far as guiding and exposure times are considered.

[[1ponders]]

Here is a comparison of the 300D with the same FOV as the ToUcam. This is using a 6x barlow. If the ED80 has an f ratio of f/7.5 then the ratio will jump to f/45. This means if it will take 2 to the power of 37.5 (a huge number) times longer to achieve the same level of exposure as the straight ED80.

[ballaratdragons]

Thanks Paul.

Gee this gets complicated :lol:

Be nice if there was a chip the size of the Toucam, or up to 0.3" with the pixel size, well depth and quality of a DSO. But then there wouldn't be many pixels on the chip :doh:

Maybe a IR/UV filter could help the colour DMK's stars?

[[1ponders]]

Don't jump into anything yet Ken. I know you like the ease of the ToUcam. Give me a chance to do some trials out at Duckadang. In the mean time see if you can borrow a 300D or similar off someone to try it out. It is very different to using the ToUcam.

[ballaratdragons]

I can't anyway, I'm broke and been forced onto a pension. :sadeyes:



I don't know anyone around here with one. And even if I did borrow one to try out, it would frustrate me more coz I couldn't buy one :lol:
Mick Pinner was going to lend me a Minitron to try out to see if I like them, but that never eventuated.

But your trial images will help, thanks.

[[1ponders]]

I could send you down a colour DSI to play with that I use occassionally for autoguiding, but I reacon that would frustrate you even more than the 300D :lol:

[ballaratdragons]

:lol: I definately not into frustration thanks Paul. But thanks for the offer.

[ballaratdragons]

I was just reading up on the technical data for the DMK 21AF04.AS (with no IR filter), and it doesn't mention anything about 'Long Exposure' mode up to 60 minutes.

The way it is written is that it can image at 60 fps for up to 60 minutes. :shrug:

[[1ponders]]

Check this link for the DFK
http://www.astronomycameras.com/en/products/firewire-cameras/colorir/dfk21af04as/
and this one for the DMK
http://www.astronomycameras.com/en/products/firewire-cameras/mono/dmk21af04as/

Max exposure time 60 min

In testing the DMK 21AF04.AS I went up to 1800sec for a single exp.

[Astroman]

The Canon 300D can be picked up on ebay for around $100 body only. You would need a 2" adapter to attach it to the 2" focuser of the ED80. If you looking for the same FOV as the TOucam, sorry Ken this will not happen (cheaply), although you can crop the full size image with good results. The other things you would need with a DSLR are either a serial adapter or Bulb cable to allow you to do longer than 30s exposures.

It's a completely different game than what you were playing with the Toucam. It can be frustrating at times as not everything works perfectly. Good luck with your decisions.

[ballaratdragons]

Thanks Paul.
I definately won't be going Monochrome. Colour is nice and simple :)

[ballaratdragons]

Thanks Andrew, I have only ever seen them in there for around $500.



I think my ED already has the adaptor. :shrug:



and probably a host of other 'things'.



It seems that whatever I move up to is going to be an exercise in frustration.

I've been spoilt with the simplicity of the Toucam.

[[1ponders]]

Ahhh but Ken there is a whole new world waiting for you out there.

Yes your Orion will have the threaded T on the end of the 1.25" adapter that slots into the focuser, and you can use that, but you will need one of these T-ring adapters (http://www.myastroshop.com.au/products/details.asp?id=MAS-001) and I would suggest one of these (http://www.myastroshop.com.au/products/details.asp?id=MAS-129)over the threaded 1.25" adapter that is already in the scope. It will give less vignetting (shadowing) around the edges being a full 2" wide. You can pick up the same thing but at bintel for only $59 and an EOS T ring for $35 (must be Canon EOS T ring)

[ballaratdragons]

:lol: I can't even afford a picture of a camera let alone the real thing and Andrews got me buying cables and bulbs (whatever they are), and you've got me buying adaptors :rofl:

[xelasnave]

Ken you can afford it..you are just feeling guilty about spending that sort of money... dont... when you accept that you can happily save for it... eat less or something..sell some art work you can do it when you dont feel guilty.

You will pick up a cheap SLR its getting that time.

I would not be worried by the field of view just work with what you get.. it will all seem right after a while...if you want a smaller fov make sure you capture well and crop smart.

I feel confident that whatever your selection you will have fun.. 300d and a 80mm is as about as much fun as you can have... and wide fields just with the standard lens from where you are will be fabulous.

You really only need the camera (card power pac etc standard come in the deal stuff) a T ring and a remote and you are doing it...sure there is other stuff and there always will be..go for what you personally can get your hands on..that is what you have to work with and the option I suggest , with a bit of hunting wont be the end of the world price wise... say a good or even fair300d at $350 as a max and hope for that...I know you will be able to push the 300d or anything you get to its limit..and thats all it is about really..doing the best with the gear and the night before you.

I settled down to what I could manage realistically and have yet to push that gear to its limit and your efforts I must say encouraged me to stick at it..so here it is back for you.

good luck..I know how you feel but it wont be long I just know it.
You know that you can take a dslr and do great things with it ..your location will give you a big edge in captures ... be patient it will all unfold as it should.
alex