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12-11-2012, 05:13 AM   #646
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QuoteOriginally posted by ChopperCharles Quote
I understand how stacking works for celestial objects... but the moon is big and bright. Why stack for that?

Charles.
Further to Mutley365's fully adequate answer, here's a small animation showing what poor seeing may do to lunar images within 1 second of exposure time:



For more details, please see the following on my home page:

Camera Settings for Astrophotography

12-11-2012, 01:47 PM   #647
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QuoteOriginally posted by Stone G. Quote
Further to Mutley365's fully adequate answer, here's a small animation showing what poor seeing may do to lunar images within 1 second of exposure time:



For more details, please see the following on my home page:

Camera Settings for Astrophotography
I must congratulate you on a very good web page. I will be doing some experimenting with my mirror lens when I have all the bits I need. You gave me the idea with 2 adaptall tc's (must admit, as I haven't had good experiences with TC's, I thought that might be pushing it, but for a bit of small change, it's worth a go, at the very least it will be a back up for the other tc), so I'll buy another and give it a go, it should give me good reach on a 500mm mirror lens (sturdy tripod at the ready). I have an o-gps1 unit for my K-5, although it has an astrotracer function I think it will be limited with applying it to (before taking into account the crop factor of the sensor) an effective focal length of about 2000mm (if my maths is right). Although the astrotracer gives a maximum tracking time of 5 minutes, that's only at shorter focal lengths, the longer the focal length, the shorter the tracking time; I think if I attempt 2000mm with it, the o-gps1 unit may have a meltdown in protest!
12-12-2012, 03:20 AM   #648
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QuoteOriginally posted by Mutley365 Quote
------

I think if I attempt 2000mm with it, the o-gps1 unit may have a meltdown in protest!
The O-GPS1 will surely have a problem. But fear not, it won't melt down as you can only enter focal lenghts up to 800mm in the camera

Anyway, my experience with the O-GPS1 and my 350 mm lens (w/o TC) is that on a good night, you can have decent tracking up to some 45 seconds. On a normal night that would be some 15-20 seconds, and on the worst of nights, everything conspires against you..........

On another note: The 500mm mirror lens has a more narrow field of view and may differ from my 350mm, but I consitently find that my lens actually becomes a tad sharper and gives a tad more contrast with a TC (both 1.4X and 2X) than without. My guess is that this is because the image formed by a mirror lens is so dependent upon the outer beams of the light cone and at f/5.6 the central obstruction is fairly big.

PS.: And thank you for your kind comments to my webpage.

Last edited by Stone G.; 12-12-2012 at 03:27 AM.
12-12-2012, 09:17 AM   #649
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I've found exactly the opposite with my teleconverter. It makes my 500mm mirror look even more like ass.

Charles.

12-19-2012, 10:08 AM   #650
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QuoteOriginally posted by ivoire Quote
And we're off! These are from my Tokina 500mm f8 lens. Unfortunately, fungus has attacked it so a replacement Tamron 500mm f8 is arriving this week. Mirrors are quirky and controversial... 2 good reasons to own one. The moon of course, is a crop.
I've come across the pictures shown here using Mirror Lens. They are quite good. I, also, want to shoot a Vivitar 500mm Mirror Lens, but have had some limited results with it. I have a Pentax K100D, and just can't get the settings right. I've tried using different ISO speeds and found the it does work using a 400 ISO and a 800 ISO on Manual. The Pentax K100D has no "green button" that I can use. I've used a tripod, as always, and a remote shutter trip. I know that this Lens will work just fine, if only I could get Images like these. What settings did you use?
12-19-2012, 12:49 PM - 1 Like   #651
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QuoteOriginally posted by IMCorker2 Quote
I've come across the pictures shown here using Mirror Lens. They are quite good. I, also, want to shoot a Vivitar 500mm Mirror Lens, but have had some limited results with it. I have a Pentax K100D, and just can't get the settings right. I've tried using different ISO speeds and found the it does work using a 400 ISO and a 800 ISO on Manual. The Pentax K100D has no "green button" that I can use. I've used a tripod, as always, and a remote shutter trip. I know that this Lens will work just fine, if only I could get Images like these. What settings did you use?
Mirror lenses are more easily shot in Av mode, so the camera sets the appropriate shutter speed (and you can add EV comp. to taste); no Green Button needed, though the K100D does have one, except it's not green and is labelled 'AE-L'

Keep ISO as low as possible while ensuring shutter speed is faster than 1/500s. If you have a K100D Super (which has image stabilisation) you can get away with slower speeds. This assuming you're shooting handheld; if using a sturdy tripod you can shoot at slower speeds too.

If you want, you can shoot in M mode, but make sure you understand the relationship between aperture, shutter speed and ISO first.

Hope this helps!
12-26-2012, 04:54 PM   #652
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QuoteOriginally posted by Miserere Quote
Mirror lenses are more easily shot in Av mode, so the camera sets the appropriate shutter speed (and you can add EV comp. to taste); no Green Button needed, though the K100D does have one, except it's not green and is labelled 'AE-L'

Keep ISO as low as possible while ensuring shutter speed is faster than 1/500s. If you have a K100D Super (which has image stabilisation) you can get away with slower speeds. This assuming you're shooting handheld; if using a sturdy tripod you can shoot at slower speeds too.

If you want, you can shoot in M mode, but make sure you understand the relationship between aperture, shutter speed and ISO first.

Hope this helps!

Greetings, Miserere

I am sorry that it took me so long to respond to your comment about my 500mm Lens. The Holidays have a habit of taking up alot of my time, but anyway . . . .

I have read your response to my problem using my Vititar 500mm Lens. I decided to try these suggestions that you have made. Just yesterday, I took the Pentax out with my 500mm Lens attached to my tripod and set the dial to AV Priority Mode. The light was fading quite fast, since it was towards the evening of Christmas Day. I did have a Pixal Remote Shutter Release, then snapped this Image. I know that it's not really all that great, but I found that your suggestions seem to work much better. I'm thinking that I may have found the answer to my problem.

Using the AV Mode, I found that I could increase the Shutter compensation by +/- 2.0 using the thumb wheel on the right side. When I shot it at +2.0 it seem'd to work much better. The weather was not too good, but I thought that this would be an opportunity to find out just how well it would work. My ISO setting was 200. I have not had a chance to do this in Manual Mode quite yet, but will do so in the near future.

Granted that the weather was not great, I'm thinking that on a sunny day or a bit overcast, this Lens will work just fine. I also have purchased a 72mm Flower Lens Hood and 3 different Filters that came with it. Here, someone had suggested that I have one, so I thought why not. Lets see what happens. Can't hurt anything that I know of.

The AE-L button I am not sure just how to use it quite yet. There is a whole lot I have to learn with this Lens, so I'll be playing with it as time goes by.

Thanks for your help. It was appreciated, as always!
Les Barr (IMCorker2)

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01-08-2013, 04:10 AM - 1 Like   #653
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Time to rejuvenate this fine collection of images:

Surf's up
01-08-2013, 07:14 AM   #654
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I'm pleasantly surprised at how sharp the Tamron 500mm f/8 is:

01-08-2013, 01:51 PM   #655
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QuoteOriginally posted by Ash Quote
I'm pleasantly surprised at how sharp the Tamron 500mm f/8 is:
The two subjects were sharp. How far away were they?

What was the temperature when you took it? There has been extreme heat this way in recent days and I found that played havoc with the Rubinar 1000 (rated as good for -10 to +45C), meaning the lens itself, but actually quite useless at 400m at 35C because of thermal movement of the air. It is hard to tell with your background being so far behind whether the softness is DoF related or thermal induced - probably DoF.
01-08-2013, 02:01 PM   #656
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Tim, they were probably about 200m away. Too far to recognise me shooting them straight on with a K-5 + grip + Tamron 500mm lens...

It was mild on the coast, around 27-28 degrees Celsius that day. The bizarre-like bokeh is characteristically the expected DoF and bokeh from this mirror lens. Another example of how nice this lens can render subjects, this time, the subject was closer (perhaps around 100m) and the background a little more pleasantly rendered (still harsh, but I don't mind it too much with such sharp results):


captured with assistance of the catch-in-focus feature.
01-08-2013, 03:49 PM   #657
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QuoteOriginally posted by Ash Quote
Another example of how nice this lens can render subjects, this time, the subject was closer (perhaps around 100m) and the background a little more pleasantly rendered (still harsh, but I don't mind it too much with such sharp results):
Background.......what background?

Very nice results Ash - I am surprised with the sharpness and the great contrast of these images - the subjects just pop off the background.
01-08-2013, 04:13 PM   #658
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That's what I like about this mirror lens I have: in good ambient lighting, it is as crisp as a non-mirror lens:



only it has a unique OOF effect like here:

01-08-2013, 04:20 PM   #659
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QuoteOriginally posted by Ash Quote
That's what I like about this mirror lens I have: in good ambient lighting, it is as crisp as a non-mirror lens:
Well that certainly makes a difference. When I had my 55BB, I always struggled with it always shooting here in the woods under a canopy most of the time. I can see how the good bright light really helps the lens work.
01-08-2013, 04:56 PM   #660
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It's good to pick a lens's strengths to capture what you want. A dull overcast day won't produce very flattering results with these lenses, and indeed some of my images from this series were taken on cloudy days, and the histogram was so narrow, I had trouble optimising the image contrast on those shots. But in good sun is where the 55BB does shine:

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