Moving into widefield astrophotography

[Phil Hart]

hey Martin

I think your idea of widefield must be different to mine!

This meteor shower pic was taken with a 24mm f1.4 lens on 5DmkII:
Geminid Meteor Shower

You *really* need fast lenses for meteors and I couldn't conceive of using anything longer than 50mm. There are very fast 24, 35 and 50mm prime lenses which is mainly where I would be looking. For a cropped sensor camera you 'could' consider the 10-22mm zoom but it's nowhere near as fast.

For widefield milky way scenes/landscapes I also use the 24mm (and my new-ish 14mm ultra wide).

For classic 'widefield' shots I have heavily used my 50mm lens. These two milky way mosaics are both three parts on a 40D with 50mm 1.4 lens:

Southern Cross

Centre of the Milky Way

For comparison, this is four part mosaic with 200mm f2.8 lens on 40D:

Antares, Rho Ophiuchi and the Blue Horsehead

And this is a single image with 200mm f2.8 lens on 5DmkII:

Large Magellenic Cloud

Hopefully that gives you some food for thought.

cheers
Phil

Originally Posted by Martin Pugh

Thanks guys.

actually - what I am looking for is a lens that can do (in priority order)

1. Milky Way, large asterism shots.
2. star trails
3. Meteorite showers.

So, I think about 100mm is good for Milky Way, but think that about 200mm is optimum for star trails.

100mm is probably too long for meteorite showers.

So, can 1 thru 3 be done with a single lens? Probably a zoom lens like 70-200mm would cut it?

any other thoughts?
cheers
Martin

[iceman (Mike)]

I'd agree with Phil - for widefield, you really want between 15 and 50mm - not 100mm or 200mm.

Star trails look best when there's some foreground interest/scene. At 200mm, you won't get anything in the foreground.

Mine aren't nearly as good as Phil's, but this Southern Cross and Eta Carinae was at 35mm, and this Scorpius one was at 24mm.

[Martin Pugh]

Thanks again all.

I see that I was unwittingly setting myself up to do multi-panel mosaic shots!

All of your sound advice has been taken in...but clearly there are differing opinions about covering the lens with a filter - I guess the reality is that they are not terribly expensive to add.

I will go off and price up some of these lenses you mention and I hadnt looked to see what I can rent in the low fl range.

I appreciate all the advice thus far.

Next question:
I kind of noticed that the quality of the images, when captured in RAW format (using the EOS utility) and then importing into Photoshop via the Canon DPP utility was somewhat better than acquiring via Maxim.

Maxim only gives you the option to capture in RAW Mono or RAW Colour, and I understand RAW Mono is better for dark subtraction. However, the image size is massively less than the .CR2 format coming off the camera. Indeed, Maxim saves them as FITS files.

have you found this? What procedure do you use to capture your lights?

At least you can set up a sequence in Maxim, I have not found that yet in the EOS utility.

cheers
Martin

[Martin Pugh]

Phil

one of your links is double up to the same image.

Hadnt realised you had an APOD with your meteorite shot! Congrats

cheers
Martin

[Octane (Humayun)]

Martin,

You can use the EOS Utility to set up a sequence using the Remote Timer shooting. Click on the icon with the stopwatch on it. Set the number of shots you want to take, the bulb exposure and the interval. Note, if your bulb exposure is 5 minutes, set your interval to 5:10 which will allow 10 seconds for the image to download to the PC (or save to the card).

There's a couple of very clever guys on this forum who have written their own software for controlling EOS cameras. One of the programs is called APT (Astro Photography Tool) and another one is BackyardEOS. Check out the software and computers sub-forum for links. Both of those will allow you to program multiple sets of exposures of differing lengths, etc.

Myself, I prefer to keep things as simple as possible and just shoot RAW with the EOS Utility, using Digital Photo Professional for chimping.

I process my images in IRIS and it does its own conversion from CR2 to its proprietory PIC format.

H

[Phil Hart]

sorry.. have fixed the LMC image link above.

i'm pretty old school on this.. i use liveview focus on the camera and capture to the camera memory card and then calibrate, stack and digital develop the RAW files in ImagesPlus with final processing in Photoshop.

that means my laptop is free to guide and control the CCD camera running on a separate mount at the same time. the widefield happily looks after itself unguided and i spend all my efforts and frustration on the CCD

phil

Originally Posted by Martin Pugh

Phil

one of your links is double up to the same image.

Hadnt realised you had an APOD with your meteorite shot! Congrats

cheers
Martin

[dannat (Daniel)]

some great reading in here - i am thinking of a lens myself -the tamron 90mm macro -anyone used one?

[Martin Pugh]

Hello again all

I am returning to this post, because I am about to buy a fixed focal length lens to go on to the ST8300 and/or the 550D.

I can see that 24mm or 50mm is the way to go for what I want to do, but there is this one intermedite lens - the 35mm f1.4L.

It kind of sits in the middle and would appear to be a good choice.

any comments or owners have a view?

cheers
Martin

[troypiggo (Troy)]

I have that lens, but haven't used it for astrophotography. It is an awesome lens, certainly one of the top-of-the-line Canon primes.

[hotspur (Chris)]

Originally Posted by Martin Pugh

Hello again all

I am returning to this post, because I am about to buy a fixed focal length lens to go on to the ST8300 and/or the 550D.

I can see that 24mm or 50mm is the way to go for what I want to do, but there is this one intermedite lens - the 35mm f1.4L.

It kind of sits in the middle and would appear to be a good choice.

any comments or owners have a view?

cheers
Martin

Had a look at the reviews-this will be my next Canon prime lens.You cannot beat a prime L lens.

[Phil Hart]

Originally Posted by Martin Pugh

Hello again all

I am returning to this post, because I am about to buy a fixed focal length lens to go on to the ST8300 and/or the 550D.

I can see that 24mm or 50mm is the way to go for what I want to do, but there is this one intermedite lens - the 35mm f1.4L.

It kind of sits in the middle and would appear to be a good choice.

any comments or owners have a view?

cheers
Martin

It might be good to rent or borrow some of these to try first. They will all be capable of very sharp images at f2.8-4.

One problem I find at the very wide end is that star halos and chromatic aberration have a greater effect on the total image and as you lose the resolving ability bright star fields start losing the crisp appearance you can still get with a 50mm lens. The 35mm would certainly be better than the 24mm in these respects, but I'd still be more tempted by the 50mm depending on your goals.

Creating mosaics out of frames with the 24/35 also very difficult due to sky gradients but certainly possible with the 50.

Phil

[gregbradley]

I think Phil is right on the money here. I have used quite a few lenses over the years with CCD cameras.

Nikkor 50mm F1.8, Nikkor 180mm F2.8 ED Canon FD 85 and 105mm, on an STL11, a Pentax 67 55mmF4, 165mm F2.8, 300mm F4 and Canon 18-55mm on a Proline 16803.

The Nikkor 50mm was definitely one of the better ones. The bigger the sensor though as you'd expect the tougher it is on the lens.

The Pentax 67 55mm F4 showed quite a bit of coma but cleaned up mostly with 2x2 binning. The 165 though was quite aberration free fully open at F2.8 as is the 300mm on the Proline 16803 which is quite a feat.

I found in an old camera bag a Pentax 50mm F1.2 which I would like to use on my ML8300. The 8300 should not be so demanding on the lens being aberration free but unless you want to do manual focusing you need something with some decent backfocus.

My imaging train with the Pentax 67 lenses is Proline, filter wheel, PDF focuser, Precise Parts adapter, Pentax 67 lens. I notice focus is like a telescope and quite particular and I think it would be hard to adjust manually.

In the case of FLI the 8300 chip is about 22mm inside the body and the Proline 30. I imagine the ST8300 is similar to the FLI in chip placement.

Another way of focusing I have seen is a rubber belt around the focus ring of the lens attached to a wheel run by a Robofocus.

The Canon FD lenses were a bit disappointing but I did a couple of shots that were OK.

You really need ED lenses in there otherwise there will be some chromatic aberration. In the case of the Pentax 67 it is minor and you can process it out mainly being bright stars look magenta.

The 55mm F4 gives a very widefield view with the Proline 16803 so that 2 images would cover 1/2 the Milky Way approximately.

I am beginning to feel a Canon 5D would be the best camera for this type of shot with a nice fast short focal length lens like Phil uses or Alex uses with his Nikon D3

The Nikon 14-24 would be very tempting if you have the budget for it.
I am waiting for the 5D Mark 111 to be released before I get a 5D camera but it may not be that different for wide field images than the current model.


I found this guide to Pentax 67 lenses very helpful:

http://www.antiquecameras.net/pentax6x7lenses.html

There was another table I read which listed the backfocus of many different lenses. There are only a few that match this 87mm or so backfocus. The Pentax 67 lenses are fairly plentiful on ebay as are adapters to make them fit Canon cameras.

I am not sure how they compare to Canon L lenses but they are very good for CCD cameras.

So in summary the Nikkor 50mm and the Pentax 67 165mm F2.8 so far have been the standouts. The Nikkor 180mm F2.8 ED as I recall was also good but too long for what you have in mind.

Of course any lens you get for an APS sized sensor you need to multiply the focal length by 1.6 to match a full frame 5D or Nikon D3 etc. Full frame will be wider field for any lens. So when Phil mentions a particular lens his camera is a 5D and the same on your 550D will be a factor of 1.6 less in FOV.

Best,

Greg.

[Martin Pugh]

Thanks for the input and comprehensive replies.

Greg - my 550D will be relegated to daytime photography, as I am pretty disappointed with it. It is no use on my Solarmax DS90 and too noisy to be used in astro way. Obviously I will try out the lens on the camera, but the primary use will be with the ST8300/CFW8. I have no idea at this point whether I will need extra adapters to come to focus....I obviously have the one adapter that interfaces the CFW to the lens.

Phil - thanks a lot. I think I will follow your advice and opt for the 50mm.

cheers
Martin

[gregbradley]

With my setup I can easily substitute the ML8300 for the Proline 16803.

I'll try that out at some point but unfortunately the Milky Way is fast disappearing soon until next year.

But I should try it on some other target. Perhaps Vela.

Greg.

[Martin Pugh]

Hello all
thought I would pick up on this thread from last year.
I am back in Australia and have set up the Canon 50mm f1.2 L lens and the ST8300. Given the expense of this lens, I expected super results, but instead, they are very disappointing.

I have tried the lens at the native f1.2, 1.4 and 1.6, and the off-axis aberrations are terrible.

I am not getting this? These results should be really good. Is it something to do with the size of the ST8300 chip? However, when I review Phil Hart's post, and I am now curious as to whether f2.8-f4 is where this lens should operate?

This is a brand new lens, so what is a simple test to see that the lens itself is ok?

cheers
Martin

[Paul Haese]

Probably you are too wide open. Maybe trying 2.8 or even at 3.5. I generally use 3.5 now for most of my DSLR imaging with primes. Do you have an image to take a look at Martin?

[Martin Pugh]

Thanks for the post Paul

image attached.

cheers
Martin

[gregbradley]

I have used quite a few lens with CCD cameras over the years. Nikkor 50mm F1.8 ( a good one), Canon FD 85mm, 135mm these were quite good. Pentax 67 55mm F4, 165mm F2.8 (the best).Nikon 180mm F2.8 ED (good) and a few others.

As Paul said most need to be stopped down and it makes you wonder how some of these lenses go being marketed as being really good and you see how poorly they perform.

Of these only the Pentax 67 105mm F2.8 (I think that is what it is) works fine at F2.8 with a Proline 16803 camera. The 55mm does all right as well but best stopped down 2 stops. Also using 2x2 binning helps a lot as well with some. It doesn't affect the resolution much anyway as they are so widefield. So the 55mm I used at F5.6 and 2x2 binning and similar aberrations as your sample image went away.

Greg.

[h0ughy (David)]

Originally Posted by Martin Pugh

Thanks for the post Paul

image attached.

cheers
Martin

to me it looks quite simple - the lens is not orthagonal to the imaging plane. how you fix that - no idea but when i was using the 127 i bought a hotech field flattener which worked wonders as it was self centering. For this you might need to get an adaptive collar that is correctable - the qhy10 came with one (not that i have used that the camera is still BNIB) http://www.gamaelectronics.com.au/QHY10.html if you look here you can see it here. maybe you can get something like that to correct for the imaging plane

[Octane (Humayun)]

You have to note that these lenses are primarily designed for terrestrial use. The bokeh at f/1.2 on the 50mm is amazing. I have taken some gorgeous portraits with it. I ended up selling it back to Leon, though.

You might want to try the 200mm f/2.8L II USM or the 135mm f/2L USM for astrophotography. Much, much better suited and once stopped down a stop, aberration free.

H