osteomark
sage
Reged: 05/09/07
Posts: 478
Loc: Oswego, NY
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What is the magnification of a 210mm lens on my Nikon FE 35mm SLR film camera? What would a 400mm be?
Thanks,
Mark
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Meade LX50 8"SCT
Magellan II autofinder
WO 1.25" binoviewer with 3-in-1 Sieberts OCA
Marcus Luden Intes Micro 703 Maksutov 7"
Meade LXD55 GEM mount
Syracuse, NY
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ClownFish
Post Laureate
Reged: 04/26/05
Posts: 5599
Loc: Islamabad, Pakistan
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While we do not talk about magnification anymore, but instead talk about field of view, I will give you what you are looking for.
A standard 50mm SLR lens is considered 1X
Thus a 200mm lens is 4X (200/50) and a 400mm lens is 8X.
CF
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Learn all about POLAR ALIGNMENT with my Drift Method Tutorial and simulator!! Or visit my Foreign Service Blog!
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osteomark
sage
Reged: 05/09/07
Posts: 478
Loc: Oswego, NY
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CF,
So, if I do camera astrophotography, is it hopeless to get DSO's or plants or even the moon with much magnification or detail? I was hoping to go this route for cheaper cost. I just am having an awful time getting the LX50 SCT 8" on a wedge, to focus or track right at prime focus.
Thanks,
Mark
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Meade LX50 8"SCT
Magellan II autofinder
WO 1.25" binoviewer with 3-in-1 Sieberts OCA
Marcus Luden Intes Micro 703 Maksutov 7"
Meade LXD55 GEM mount
Syracuse, NY
Edited by osteomark (03/27/08 09:49 AM)
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ZachK
professor emeritus
Reged: 08/21/05
Posts: 667
Loc: Israel
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Check out this web site: http://www.mat.uc.pt/~rps/photos/angles.html it will give you the field of view for any FL lens on any size of film. Your 210mm lens should give your a FOV that is about 9.5 ° by 6.5° This would very nicely frame parts of the Milky Way, M31, M43, M44, M45 and a lot of other larger DSO's.
For the moon or planets you will want a lot longer a lens. For example see my recent moon shot, using a 1900mm Lens (telescope) I am still able to catch the entire disk of the moon on my 35mm frame.
Edited by ZachK (03/27/08 10:46 AM)
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osteomark
sage
Reged: 05/09/07
Posts: 478
Loc: Oswego, NY
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I'm trying to get my homemade Hartman mask to focus but no luck yet. I think I need larger triangles. I had 3 of them at 3/4" side but way too small. I made them 1.5" sides and now some bigger. I might try 3 circles and see if any better.
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Meade LX50 8"SCT
Magellan II autofinder
WO 1.25" binoviewer with 3-in-1 Sieberts OCA
Marcus Luden Intes Micro 703 Maksutov 7"
Meade LXD55 GEM mount
Syracuse, NY
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ClownFish
Post Laureate
Reged: 04/26/05
Posts: 5599
Loc: Islamabad, Pakistan
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This was shot with a very wide 28MM lens:
It shows the North American nebula and a whole lot more!
And the following closeup was with a 150mm lens.
You can grab a lot with ordinary lenses!
CF
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Learn all about POLAR ALIGNMENT with my Drift Method Tutorial and simulator!! Or visit my Foreign Service Blog!
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ZachK
professor emeritus
Reged: 08/21/05
Posts: 667
Loc: Israel
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I was thinking about getting a 210mm lens for my big camera (a 4x5 LF)
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Zach Kessin
Yesha Israel
Meade ETX 127 Mak-Cass
15x70 Celestron Skymaster Binoculars
Sinar F 4x5 view camera
Rolliflex Camera 80mm F2.8
Pentax K-1000 Camera 35,50 and 60--300mm zoom
3 kids, Large cat, small dog
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osteomark
sage
Reged: 05/09/07
Posts: 478
Loc: Oswego, NY
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CF,
Ok.Gorgeous pics!! So it sounds like I have enough lens. Now what do you use for tracking? What were the exposure times and type of film did you use? I don't know if my LX50 can track well. I poloar align it and it still trails even with a 5-8 sec exposure which seems impossible. Do you do the "hat method" with the "B mode"?
Mark
Edited by osteomark (03/27/08 04:58 PM)
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ClownFish
Post Laureate
Reged: 04/26/05
Posts: 5599
Loc: Islamabad, Pakistan
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The above shots were taken with Kodak E200 slide film, the best film for AP.
I used 30 minute exposures on a Meade LXD75 mount.
Your mount may trail after 8 seconds if you are talking about through a long focal length lens. What an 8" SCT shows in 8 seconds would take 10 minutes with a 50mm lens. But it sounds like you have a problem.
How do you know your scope is Polar Aligned? Of you see ANY declination drift then you are not 100% polar aligned. I suggest you use the Drift Method and see how your tracking is. You must not see ANY declination drifting within 5 minutes, 10 is better.
The "Hat Trick" is for short exposures under 10 seconds or so. There is no need to use it for long deep exposures.
CF
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Learn all about POLAR ALIGNMENT with my Drift Method Tutorial and simulator!! Or visit my Foreign Service Blog!
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jrw11
professor emeritus
Reged: 06/09/07
Posts: 501
Loc: U.S.A.
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Ostemark, have you tried this hartman mask template generator? It makes perfect masks everytime. That can be printed out on the printer. It will design 2or more circles and/or triangles. It has sure helped me. It will design the mask for any size scope.
http://billyard.servehttp.com/Hartmann.html
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Celestron C6n -HD Reflector
dual axis drive motors added
Orion 80mm Short tube refractor
Skyscout
Early 70's Pentax 7x50
Garrett Optical 12x60
Garrett Optical 15x70
Oberwerk 20x80 Standards
Canon Rebel Ti (film)
4 Minolta Srt cameras
Mamiya RB67 Pro-s with 180 lens
127mm KL lens for RB, Bellows hood for RB67
120 and 220 film backs
Cambo SCII 4x5 view camera
over 50 other film cameras
several eyepieces
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jrw11
professor emeritus
Reged: 06/09/07
Posts: 501
Loc: U.S.A.
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On the mask template generator. I put in the diameter of the scope tube,the diameter of the mirror and the number of circles, (triangles) desired. It will print full size the mask and the desired size and placement of the circles and triangles. So, the person has a choice on the shape of the holes. Clownfish taught me about the Hartman mask and someone else gave me a link to this website.
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Celestron C6n -HD Reflector
dual axis drive motors added
Orion 80mm Short tube refractor
Skyscout
Early 70's Pentax 7x50
Garrett Optical 12x60
Garrett Optical 15x70
Oberwerk 20x80 Standards
Canon Rebel Ti (film)
4 Minolta Srt cameras
Mamiya RB67 Pro-s with 180 lens
127mm KL lens for RB, Bellows hood for RB67
120 and 220 film backs
Cambo SCII 4x5 view camera
over 50 other film cameras
several eyepieces
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tommyhawk13
sage
Reged: 09/28/07
Posts: 490
Loc: Jacksonville, Fl
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I take it you are piggy backing the camera to a telescope on an eq mount, or a wedge?
I've tried to use a hartmaan mask with a regular lens, and I think they are just too small. Add to the fact that you are looking through a viewfinder, and it is just too difficult.
I haven't tried this, but books recommend setting up a fixed tripod and take a series of 5 minute exposures with different focus settings. Do it on one frame, cover the lens with a hat between shots, and it should look like a series of dotted lines. When you get the slide processed, you will be able to see which setting has the best focus.
I'm going to try this as soon as I get the chance, and I'm going to mark the lens with a couple of pieces of white tape with multiple lines on one piece, and one on the other, like timing marks on an engine.
As far as polar aligning goes, it's very frustrating and time consuming in the beginning. My last attempt took over 2.5 hours, but that was with a mount intended for visual use only. Wide angle lenses are MUCH more forgiving for alignment error. Cygnus should be up early in the morning this time of year, and is an excellent wide field target in a dark site.
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Meade Starfinder 8,Meade SN-8 OTA, Orion Atlas, and a handfull of film cameras
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Mike D
scholastic sledgehammer
Reged: 08/15/07
Posts: 855
Loc: South GA
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Quote:
Now what do you use for tracking? What were the exposure times and type of film did you use?
I started out using an old Meade 2080 with my camera piggybacked using Meade's piggyback adapter for 8" SCTs. So I'm sure your LX50 is up to the task (as long as the clock drive still works). The two biggest things you are going to have to worry about are light polution and polar alignment.
My advice to you is to get on Clownfish's website and try to get a feel for drift alignment. Then, get out under the stars to practice it until you get the hang of it. One night under the stars dedicated to learning how to drift align is usually enough to get the hang of it.
Also, Kodak E200 slides are considered the gold standard for AP. The majority of the film targets will require 30 minutes of exposure, so finding dark skies is going to be critical. However, 5 or 10 minutes on the summer milky way will give a NICE image.
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Vixen SXD
Vixen ED80Sf
Hutech 350D
STI Stiletto
Meade 2080
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mysky
member
Reged: 09/06/07
Posts: 84
Loc: CN
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very nice shot 
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