Posts Made By: Peter Kennett

So let's come up with the perfect calculation to cover all this.
I want to be able to calculate for any camera F/L system and I will post the end result on my astro website along with drawings etc..

I also want to calculate for 28mm, 50mm, 135mm and 200mm camera lenses

I agree that it's all about magnification of the guidestar vs the camera image.
So I have been guiding with an 11 times the camera

Oh by the way.. where did the 50x come from again? Is that based on the average distance to the film plane for most SLR's?

WOW! That's a gorgeous nebula! Where is it?

jim renard said:

THIS IS A 150 MIN EXPOSURE ON E200 6&7 FORMAT 61CM F7.5 RC COMMENTS WELCOME JIM

Great shot Jim!!!
Blows digital away!

Just currious... am I the only one going to this?

Yes, this is an excellent image!
I love the the galaxies!!!
(ok, and the Perseid too!)

Peter

hey, I don't have my charts with me here at work.. so what is the red nebula in the mid-upper left side of the pic?

Pete

Here's my GREMLIN.

Pete

While it will take a while to complete, I am writing a website just for people like you!
Check it out at www.PetesAstrophotography.com

Pete

length of exposure? where should I get it developed?

Larry, I would go 10 minutes or even longer. While 6 min will indeed show the nebula, you will not get much of it at f/7. You will however, show more detail in the bright inner core than if you go for the longer exposures.

I shoot at f/4, and even then I find 30 to 40 minutes ideal to capture the fainter outer parts.

If, like you said you will stack, then yes, 6 to 10 minutes should be fine, as long as you shoot 5 to 10 images. I have never done that, as it was too expensive. I just went for the one, long shot. If you are having someone else scan and transfer to CD.. that can get very expensive real quick. I would definitely ask if you can SEE your slides before they transfer, so you can use a loop (magnifier) and only select the ones worth transferring. You do not need to pay for a CD scan and transfer for a slide with trails or out of focus.

As for where to get them done? I would try and find a small company who develops film / slides LOCALY, so you can go in and talk to them personally. Tell them NOT to cut the negatives and slides until after you have looked at them. They always CUT through your images, as they can not tell where one slide ends and the next begins. And this way, you can also toss out the bad ones, rather then pay for scanning and CD transfer.

When you start to get really involved in this, consider a Minolta Dimage slide scanner. They are great and you can get them on eBay.

Focus is the second most common problem with 35mm film photography. You should always use a tool to achieve focus, as your eyes will bring into focus an image that in reality is not. I use an STI Stiletto. Some use a Hartman mask.

The biggest problem, done over and over, is people who think you can correct Declination drift during a guided shot. This is just not true. Declination error is Polar Alignment error, and it will accumulate with each "correction" you make. in reality, every time you touch the DEC control, you are introducing rotation to the camera, not putting the camera back on track, as with RA corrections. The solution - Get your polar alignment down to the point where you see NO drift in at least 10 minutes with the drift method.

Good luck!

Peter

One more thing... M42 is better with Fujichrome 400F Provia vs Kodak E200.
The reason is Provia is MUCH better at capturing the faint BLUES in M42, and still does a great job at the reds. E200 is poor blue response. Here's my shot of M42 with Provia. It's a single 40 minute shot with a Meade LXD75 8" f/4 SN.

Peter