Help Identifying Mystery Object In Photos

[Darren (Darren Miller)]

Hi Guys,
I was out testing/comparing lenses late thursday night/early friday morning as the skies were clear and Jupiter was conveniently placed.
I was using a Sigma 400mm F5.6 Mirror Telephoto FD Mount, a Sun Optic 85-210 F4.5 Zoom M42 Mount, Canon 50mm F1.8 FD Mount and 18-55mm Canon EFS Standard Lens with my Canon EOS 1000D.
The FD lenses use a corrective lens in the mount adapter to achieve infinity focus, the M42 focusses to infinity without corrective optics in the adapter.
Every image contains a mystery (to me) object thats moves as time passes. The attached images are cropped from the full size originals and were taked at 2.05am, 2.08am and 2.11am Friday 26th June 2009 from Moe Victoria.
At first I thought it may be a comet, but there are 3 distinct trails.
Any help would be greatly appreciated.
Regards,
Darren LRSM

[Blue Skies (Jacquie)]

Jupiter is pretty bright and widefield imaging with it in the field of view usually gives some internal reflection in the lens. I'd day that's all it is, an internal lens reflection.

[Lumen Miner (Mitchell)]

Alert, Noob Warning!!

Given the above, those pics looks suspiciously like a drift error. My scope drifts on error by itself a fair bit, causing irregularities such as those.

How long exposure are these shots on? Too highh mag + time = those shots, see the star lines?


Although I hope it is a said comet..

[iceman (Mike)]

Hi Darren

Jacqui is right - the greeny lines are internal reflections. Usually they're caused by a front filter (like a UV filter) on the front of the lens.

Hi Mitchell,

Darren wasn't asking about the star trails, but the greeny colour objects.
But you are right - when the exposure is too long (when not properly polar aligned) you'll get star trails like that.

Cheers

[Darren (Darren Miller)]

Hi Jacquie and Iceman - You guys are spot on, I had a chance to do a quick shot of the crescent moon last night and the image had a green reflection of the crescent.

Also, the lens in question also had a UV filter on the front - as you said Iceman - which I had left there to protect the lens, but is now removed so hopefully the problem will have gone.

The adapter I am using to mount the M42 lens to the EOS body is for lenses with a A/M switch for the aperature, so it DOESNT push the lens aperature pin in, so the aperature is wide open at F4.5 until I get an adapter to suit - but I'm not sure how much of an issue this is as yet.

Hi Mitchell - The shots where non-tracked, just 30 second exposures on a normal camera tripod mainly to test the infinity focus ability of the lenses I have - old/er cheap lenses bought off Ebay - and I use the star trails for an indication of focus as I figured that the trails would be thinnest at best focus.

On lens adapters - I found I had to modify the FD to EFS adapter so it would achieve infinity focus - even though it was claimed it would when I purchased it - the corrective lens in the adapter had a flange at one end that is supposed to stop it in the correction position inside the adapter but I had to cut and file the flange away so I could screw the corrective lens in around 0.5mm to 1mm more than I could with the flange present and then the FD lenses will focus to infinity - even past it depending how far you can screw the corrective lens in before it touches the rear of the FD lens.

As soon as the skies permit I'll be back out to see if the reflections have gone and will post an update.

Thanks Heaps for the help guys,
Regards,
Darren

[MrB (Simon)]

Hi Darren,
I also have an EOS-M42 adapter, the type that has the AF-confirm board included so I can use it for terrestrial photography too.
With mine there is a flange machined directly behind the internal M42 thread that the lenses apperature pin touches, and then gets pushed in as the lens is screwed down, I'm surprised yours does not have this.
Does yours have just a straight thru thread?
I had been looking at getting a couple of the non-AFC adaptors, now I'm not so sure.

One thing I have noticed, the manufacturer of the adapter I have has played cautious by making the adaptor considerably thinner than it needs to be(1.45mm instead of 1.5mm), causing lenses to focus well past infinity.
Kinda annoying considering most lens designers make them focus a very small amount past infinity anyway.
I wish they had been less cautious and made it 1.49mm instead of 1.45mm.

[Darren (Darren Miller)]

Hi Simon,
The M42 adapter I have has the thread going all the way through and no flange unfortunately.
I didnt realise the difference at the time time of purchase.
Both types are available on ebay - with or without the flange - for less than $20
I would ask the seller though first - in case it is just a sample/stock photo was used - that there is a flange and its not threaded all the way through.
Kind Regards,
Darren