2800mm f/10 !!!! - DPChallenge Forums

Canon EF 100mm f/2.8 USM Macro

05/07/2008 04:10:12 PM · #26

Originally posted by kirbic:

Given that this is a go-to 'scope, he'll have no problem tracking for visual observation, but for photography...
- He'll need to accurately polar align the mount in order to avoid field rotation
- He'll probably want to invest in a field flattener/focal reducer which will decrease focal length somewhat but give him much better star images to the edge of the field. This is important for photography with cameras with relatively large sensors, like DSLRs.

I will be investing in the field flattener/focal reducer.
With the wedge I can polar align in EQ mode. (As I understand it from the manual)
And Fritz I will take all the advice you can give me!

I am still reading about the guide scope and I fear I may be going broke in the future...

Spork99

OM System OM-1

05/07/2008 04:16:34 PM · #27

Originally posted by thegrandwazoo:

Yeah we have a few places we can go. We are in Phoenix so we could head up to Sedona or Flagstaff. We have even talked about taking or gear down to Kitt Peak National Observatory . After messing with it last night for a while I can see there is going to be a big learning curve but after all that is half the fun!

When I lived in Los Angeles, we used to go out to the middle of the Mojave desert and camp in the middle of a dry lakebed to look at the stars. Talk about dark skies...

Of course here in Lower Michigan it just sucks, I sold my big scope and got a smaller refractor just because all the work to get the big scope set up wasn't worth the reward anymore.

SteveJ

Canon EOS-7D

Canon EF-S 18-135mm f/3.5-5.6 IS STM

05/07/2008 04:21:16 PM · #28

Erick,

Here is the link to Brian's site which is still under construction. It has his e-mail addy, if you need info, tell him Steve directed you. He uses DSLR and CCD for photos, all kinds of computer gizmos for tracking, fine focus etc.

//www.brianjohnson.co.uk/observatory/index.html

Enjoy!!

Canon EF 24-70mm f/2.8L USM

05/07/2008 04:26:41 PM · #29

Originally posted by SteveJ:

That is AWESOME!!!!! What a wonderful project and incredible craftsmanship!

hanneke

Canon EOS-5D Mark II

05/07/2008 04:31:35 PM · #30

What's that coming over the hill, is it a MONSTER? Is it a monsterrrrr? (The Automatic)

Nope. It's Wazzie's new lens ;)

Sweeeet!

Message edited by author 2008-05-07 16:36:41.

SteveJ

Canon EOS-7D

Canon EF-S 18-135mm f/3.5-5.6 IS STM

05/07/2008 04:38:17 PM · #31

Originally posted by thegrandwazoo:

Originally posted by SteveJ:
Erick,

Here is the link to Brian's site which is still under construction. It has his e-mail addy, if you need info, tell him Steve directed you. He uses DSLR and CCD for photos, all kinds of computer gizmos for tracking, fine focus etc.

//www.brianjohnson.co.uk/observatory/index.html

Enjoy!!

That is AWESOME!!!!! What a wonderful project and incredible craftsmanship!

We had real fun building it and solving problems on the fly. Brian is a great guy (he is also a World Champion Drag Biker), he will give you so much help and guidance as he has been there and done it:))

Canon EF 17-40mm f/4.0L USM

05/07/2008 09:47:29 PM · #32

OK I am outta my mind amazed at this optic. I just aligned the finder scope to the SCT and I was using a block decoration on a neighbors house about 150 yards away. Using the widest eye piece, I can count the rust pits in the Phillips head screw that is holding up the cable TV cable.

a m a z i n g

Judi

Canon EOS-5D Mark III

05/07/2008 09:52:13 PM · #33

Originally posted by thegrandwazoo:

Don't lie......we know what you were really looking at!!! Was she cute!!!!?

Canon EF 17-40mm f/4.0L USM

05/07/2008 09:54:57 PM · #34

Originally posted by Judi:

Was she cute!!!!?

I don't know I was looking at her screw! Um... HAHAHAHAHHAHAHAHAHAHAHAHAHa

;-P

Judi

Canon EOS-5D Mark III

05/07/2008 09:56:59 PM · #35

Originally posted by thegrandwazoo:

Originally posted by Judi:
Was she cute!!!!?

I don't know I was looking at her screw! Um... HAHAHAHAHHAHAHAHAHAHAHAHAHa

;-P

Gotcha!!

BHuseman

Sigma 150-600mm f/5-6.3 DG OS HSM | C

05/07/2008 09:58:24 PM · #36

Originally posted by thegrandwazoo:

Originally posted by Judi:
Was she cute!!!!?

I don't know I was looking at her screw!

Isn't that called voyeurism?

Tamron SP AF 17-50mm f/2.8 Di II LD Aspherical (IF) for Nikon

05/07/2008 10:02:36 PM · #37

Originally posted by BHuseman:

Isn't that called voyeurism?

No it was a Screw.

:-))

levyj413

Apple iPhone 15 Pro Max

05/07/2008 11:11:52 PM · #38

Originally posted by thegrandwazoo:

2800mm f/1.8 are you kidding me!

I finally found a DOF calculator that'd let me enter my own numbers. Assuming the above with a subject distance of 150m as you said, you'd get a DOF of 22 cm. That's just about enough to get that whole woman you were peeping in focus, if she was facing you. ;)

(yes, I know those online calculators are probably way off under these conditions)

05/08/2008 09:00:03 PM · #39

So update here it is with the T-adapter and focal reducer/corrector in place and my D80 ready for action.

With the focal reducer in place it make this 1764mm f/6.3. It works but I need to try it under the starts!

Message edited by author 2008-05-08 22:12:56.

Canon EF 70-200mm f/2.8L IS USM

05/10/2008 01:18:56 AM · #40

Here is my first attempt from my light polluted back yard.

I can tell I am going to need more gear to get planets and deep space objects in focus.

jtf6agent

Canon EOS-1D Mark III

05/10/2008 03:28:13 AM · #41

Can I borrow that thing for a wedding I have coming up?

kirbic

Canon EOS R5

Canon RF 24-70mm f/2.8 L IS

05/10/2008 11:25:03 AM · #42

Ya, the DSLr is not going to be the best tool for planetary photography. Try an inexpensive webcam (tiny sensor with small pixel pitch), capture video and sort out the best frames. Seeing conditions are going to be a big factor in the quality of results you get for planetary photography, and there are often "moments of clarity" even during periods of moderately bad seeing. the trick is capturing them and sorting them out.

Canon RF 24-105mm f/4.0L IS USM

05/10/2008 03:14:27 PM · #43

Thanks Fritz. Celestron has this. I think for the extra few bucks I will give it a try.

Venom

Canon EOS R

05/12/2008 04:10:36 PM · #44

Originally posted by thegrandwazoo:

So update here it is with the T-adapter and focal reducer/corrector in place and my D80 ready for action.

With the focal reducer in place it make this 1764mm f/6.3. It works but I need to try it under the starts!

#1: Did you find that having the camera body inline with the scope is better or have you tried using the angled eye piece? I was just wondering about either setup? It's just my opinion but I would imagine that I could get a sharper image with less corners/glass in the way?

#2: Is the "focal reducer/corrector" something additional to the T-Ring and the camera addapter?

Thanks Brandon.

scalvert

Canon EOS-5D Mark III

Canon EF 24-105mm f/4.0L IS

05/12/2008 04:35:00 PM · #45

Don't forget the crop factor. I believe that telescope would be 4200mm f/10 on your Nikon D200.

kirbic

Canon EOS R5

Canon RF 24-70mm f/2.8 L IS

05/12/2008 04:38:46 PM · #46

Originally posted by Venom:

The t-adapter screws directly into the back of the 'scope, so diagonal mirror use is not possible. In any case, you do want as few opportunities as possible for mechanical misalignment, and as few optical surfaces as possible. In addition, focus might be impossible to achieve with the distance of the diagonal considered.

Originally posted by Venom:

#2: Is the "focal reducer/corrector" something additional to the T-Ring and the camera adapter?

Yes, it is. It's essentially a corrector lens. With SCTs (Schmidt Cassegrain Telescopes) it is normally necessary to use a field flattener for photographic use, especially with large-sensor cameras like DSLRs. They are not necessary for visual use, or for use with cameras with small sensors. Focal reducers usually incorporate the function of flattening the field.

Edit for grammar

Message edited by author 2008-05-12 16:39:24.

Canon RF 24-70mm f/2.8 L IS

05/12/2008 05:35:58 PM · #47

Originally posted by scalvert:

Don't forget the crop factor. I believe that telescope would be 4200mm f/10 on your Nikon D200.

Oh yeah! I did forget that! :-D

And

Venom what

kirbic said!

The next purchase will be this. So I can really dial in the focus without having to touch the telescope.

kirbic

Canon EOS R5

05/12/2008 05:38:35 PM · #48

Originally posted by thegrandwazoo:

The next purchase will be this. So I can really dial in the focus without having to touch the telescope.

Oooooh, now that is SEXY!

05/12/2008 05:44:07 PM · #49

Sure is! JMI makes some really good looking stuff and by all accounts it works exceptionally well.

Message edited by author 2008-05-12 18:03:17.