A Couple of Galaxies

[ScubaDude]

Here are a couple of galaxies I've shot. I need a more stable mount so I can get longer exposures, but I'm happy with the way these turned out.

M104, aka the Sombrero Galaxy.
16 shots, 14 seconds each, 3200 ISO. Stacked with Deep Sky Stacker.

M51, aka the Whirlpool Galaxy, with a new supernova (the bright "star" on the left edge of the lower galaxy) that was discovered May 31st.
34 shots, 15 seconds each, 3200 ISO.

 

[analog.universe]

Nice! What focal length were these done at?

 

[Trever1t]

those are pretty cool, nice definition!

 

[ScubaDude]

Nice! What focal length were these done at?

They were taken with an Orion 8" f/4.9 telescope. The effective focal length was 1600mm.

 

[pen]

That is really cool, love the second one.

Sent from my iPhone using PhotoForum

 

[Patrice]

Those are really nice images.

Nice! What focal length were these done at?

They were taken with an Orion 8" f/4.9 telescope. The effective focal length was 1600mm.

The Orion 8 inch Starblast newtonian has a focal length of 1000 mm, how do you figure 1600 mm effective focal length?

You mention you would prefer a more stable mount, I'd be interested to know hoe your newt is mounted now. I take it you did not need to guide your scope.


I have an 8 inch newt that I mount on an auto-uided EQ6 pro. I also use that mount with a 4 inch apochromatic refractor. My guide scope is a 3 inch achromat refractor with a Synta auto-guider. Astrophotography is even harder to get right than weddings.

 

[ScubaDude]

Those are really nice images.

Nice! What focal length were these done at?

They were taken with an Orion 8" f/4.9 telescope. The effective focal length was 1600mm.

The Orion 8 inch Starblast newtonian has a focal length of 1000 mm, how do you figure 1600 mm effective focal length?

You mention you would prefer a more stable mount, I'd be interested to know hoe your newt is mounted now. I take it you did not need to guide your scope.


I have an 8 inch newt that I mount on an auto-uided EQ6 pro. I also use that mount with a 4 inch apochromatic refractor. My guide scope is a 3 inch achromat refractor with a Synta auto-guider. Astrophotography is even harder to get right than weddings.

Due to the 1.6 crop factor of the sensor in the T1i, the effective focal length is 1600mm. If I was using a full-size 35mm sensor, it would be 1000mm.

I have the SkyView Pro mount, unguided. The plan is to get an Atlas mount and guide scope, eventually. Another big problem is the cheap stock focuser (the old rack and pinion style) won't hold the camera perfectly perpendicular to the scope, so focus changes across the image. I'm getting a Moonlite next month.

 

[Nightstr]

:thumbsup: very nice!

 

[Patrice]

Due to the 1.6 crop factor of the sensor in the T1i, the effective focal length is 1600mm. If I was using a full-size 35mm sensor, it would be 1000 mm.

Does not really work like that. You are just imaging on a smaller sensor thus recording a smaller part of the projected image. The optical properties of your telescope have not changed nor has it's resolving power. Your mirror still has a focal length of 1000 mm. What if you had used a smaller but much better actively cooled high resolution SBIG camera as the imaging unit? Would then say you had a 2000 mm focal length? Your images are really nice given the equipment you have at your disposal, you have done just about as well as possible with it. Really well done and nicely processed. Be accurate with the description of your techniques and imaging tools so that others may benefit from your excellent results.

 

[ScubaDude]

Which is why I said "effective focal length." It's like putting the same lens on an APS-C or a full-frame camera... the optics don't change in that case, either, but the effective focal length does. It's not about the optical properties of the lens, it's about the magnification level of the photo and the commonly accepted terminology (for example, DPReview's review of the Canon EF-S 18-55mm lens lists "29-88mm equivalent focal length range" in the specifications section). After all, the telescope is just another lens when attached to a camera.

 

[Josh66]

After all, the telescope is just another lens when attached to a camera.

Exactly. Which is why it has a fixed focal length, which doesn't magically change based on which sensor you're using.

"Effective focal lengths" are BS, to me. It's another way of trying to dumb things down so people not in the loop understand it. Personally, I'm against the dumbing down of things.


I did enjoy your photos, BTW. Nice work.

 

[cgipson1]

Very nice shots! Good work!

I prefer the term "Crop Factor" myself.. much less confusing!

 

[ScubaDude]

Everybody on the planet uses phrases such as "effective focal length," "equivalent focal length," etc. The purpose is so that a photo taken at (an effective) X mm covers the same angle of view no matter what the sensor size is. Why pick on me about it?

 

[Forkie]

Nicely done. Curse the day I sold my telescope

 

[Dp-PARIS]

Love the shots. Very well done. Makes me want to go out and buy a telescope, though instead I will content myself with looking at the work of others.