Mirror Slap

[Swampy]

Ok, so I get this new "lens" today. Let's just call it a manual Zoom, f10, anywhere from 2032mm to 6000mm and up.

At the lower end of 2032mm, I am dead focused in. Sharp as all get out (it's not me, I've tried manually focusing slightly off in either direction and it looks real bad then). I can only guess that it's mirror slap that's causing me to get the blurry shots. I notice that right after I get my viewfinder back, you can see it moving real slightly. I'm using 1/60 to 1/125 shutter speed and it doesn't seem to matter. I can't use a higher speed without going to 800 or 1600 ISO, which I do not want to do.

This is on an extremely sturdy tripod, maybe not sturdy enough for the 43 pounds of lens and counter weights.

Anyone have any idea's on how to reduce the mirror slap or to steady the whole thing down?

Here's a crop of the full frame. I'll post the full frame in the next picture. Both had had some USM applied and that's it.

[Swampy]

Here's the full frame...

[sandman]

Swampy
Christ mate with lense that size on full zoom ,you'd have to strap it down to a mountain to stop shake
Have you tried the self timer, or a cable release.
I can see how you could stablize it on the ground, with a beanbag or something, but pointing up in the air?
Saying that, the 2nd pic 's not bad, try a radio telescope if your back yard's big enough, might get a second hand one for a few million dollars. LOL

Good luck
Sandman

[mmaathuis]

Hi Swampy!

This is strange, I just did a couple of moonshots last night, and this morning I read about your "moon experiment".

Can't help you the shaking, I shot this shot last night with a 80-300mm ED on "Self Timer" so I would not shake the camera when I pressed the shutter. Shot taken at ISO 200, F5,6 and S 1/10. The shot whas at 12M pixels to get as much detail as possible. Cropped out the moon and applied USM in photoshop. It is not as sharp as your photo, but that may be my lens.

I tried different settings but this was my best. Love to come over and help you hold that canon pointed at the moon! :D

[Andre]

I see I wasn't alone in pointing my lens skyward last night. Nice shots guys.

Swampy, this might be really dumb, but have you tried hanging something heavy from the end of the lens?

Andre

[Tom Nolle]

Swampy, the movement of the earth (rotation) has a major effect on pictures taken of the moon, stars, etc. If your exposure is more than about a half-second, you'll get motion blur enough to diddle the quality levels. What was your shutter speed? I have a telescope and did some photography (film back, N70) through it using the T-mount adapter, and I found that it wasn't possible to take exposures of even a second and still have sharp details.

Tom

[Swampy]

As I said in the original post, I'm using a shutter speed of 1/60 to 1/125. Should be fine for the movement problem right now (waiting for my tracking motors to come in - on back order :( ).

I know what I'm doing pretty much when it comes to the moon, movement and shake. The scope has counterweights to help with the shake. My only issue is with the camera mirror. That's the only thing I can think of that is causing the shake. I use a cable release and the self timer set at 10 seconds. I look through the view finder with cable pressing the shutter halfway, wait for the shake to stop, then I click the shutter smoothly with hardly any shake. After 10 seconds, the shutter goes (still not seeing any shake) and after the shutter closes, the image is shaking slightly. I'm an avid shooter (guns), and I know how to "pull the trigger" slowly and smoothly which helps quite a bit.

Let me take a picture of the set up and post it here, and you'll see that it's pretty stable. In the mean time, I've posted this before, here's a moon shot I took a couple months ago, 50-500mm Sigma lens, tripod, no cable release, no selftimer. Just so you know this is a different problem than user shake. :)

[Swampy]

Ok, here's the setup...

[Swampy]

And another shot...

[Andre]

Gotta be the biggest lens I've ever seen :)

[lightwrangler]

First let me say that I don't have any experience with telescope photography so if this comes off as being unhelpful just ignore me :-)

Have you considered opening the shutter on "B" with a dark card in front of, but not touching the lens. Once the camera has settled you move the card away quickly and back again. Then close the shutter - in effect you make a shutter outside of the camera and avoid the shake issue. This is something I used to do way back in the old studio days with view cameras that could not be made steady and shutters that weren't too trust worthy. You should be able to make a shutter speed of a 1/15th or better. Another trick we used was to make a slit in a long black card and pass that infront of the lens to make a faster "shutter speed".

Looking at your pictures, I think another tripod could be used with a yoke to completely steady the telescope, and/or use a Manfrotto magic arm to the tripod mount on the camera and then to the tripod to again steady the whole arrangement.

Best of luck.

[Swampy]

I will definitly be using the black card when taking deeper space objects, but with a shutter speed of 1/60 to 1/125, it's going to be extremely hard to do the black card thing. I may want to try the slit thing though.

Just kind irks me that this tripod is so shaky considering its cost and beef, let alone that the mirror would be able to make this thing shake. I mean, what, I've got probably 30 pounds of equipment on top of a 20 pound tripod. Just doesn't seem right that a mirror that weighs, what, 1/4 of an ounce at the most, can make this thing move at all.

It also seems to me that it shakes more with the counter weights attached, so I may try it again without the weights tonight.

And I would never ignore your comments Lightwrangler!

You're one of the "old timers" (not referring to your age mind you) that has been around with much wisdom in the field.

[Wichita Wayne]

What a rig. Trouble is, I usually only take pictures at weddings. You know, I could probably save some money if I did have one of these. I could shoot weddings in Dallas without ever leaving Wichita. That would save on gas, hotel, and time. What an idea. I could use a cell phone to line up and pose them. But I would be limited to shooting outdoor weddings. Think of the possibilities.

[sandman]

JESUS !!!
Had no idea you were talking about a rig that size, makes my suggestions lightweight. maybe N.A.S.A. might be able to help?.
The only thing i can think of ,if it is vibration (god knows how) is, does the counterweight slide on that bar ,so you might be able to experiment with different settings. Or is that an extension tube connecting the S2 to the scope, can you take it off, and mount the camera nearer the lense.
Tried to find an article on mirror lock up, the only advice i can find on shake, is to use the self timer (which you've done), and dampen the camera with your hands to stop any vibration, but honestly with the size of that mother ,i don't think that would help , but maybe worth a try .
Like you i don't think it's the lense shaking, the weak spot seems to be the length between the camera and the scope allowing the mirror to shake the camera, maybe you could clamp the extension tube, or clamp the camera, thoughts are racing through my mind , so i'm just putting things down as they come to me.

Some of these ramblings might strike a cord with someone else. you never know,

[Swampy]

at MINIMUM magnification, it seems to do pretty well at a shutter speed of 1/180th. Here's a flower in a flower box on someone's balconey down the street from me. (Joke's on them - I know they're SILK flowers now, not real - looks good from the street though!).

As soon as I jump up to the next magnification though, 1/180th doesn't cut it. Still, this all leans towards getting this thing steady. And with the tracking motors hooked up, I won't be able to really clamp it all down to steady it. Hmm. All the suggestions are appreciated, and keep them coming if you think of anything.

Here's the flower... ISO 200, 1/180th, f10.

[dhphy]

Swampy
I use video cameras and that lens and weight is pretty heavy.
The tripods we use are steel and look heavier than your tripod.
Our cameras aren't anywhere near as heavey as your lens, counter weight and camera
I don't think that tripod is substantial enough particularly if it is aluminium.
You have a tray that you could put some weight on which might help, but a couple of RSJ's cemented in the ground would hold it.
The fact that you see slight image movement after you have taken the picture is, I think, just the mirror falling back into place
Some nice pictures here though.
Dave

[Swampy]

And here's the flower again, at the next magnification step...

1/350, ISO 800, f10

Blurry now, with shake. Gets better and better as I raise the shutter speed of course.

[Swampy]

Originally posted by dhphy
Swampy
The tripods we use are steel and look heavier than your tripod.


The tri-pod it's on is extremly solid. Where all the shake is coming from is the top half of the head. I know what I'm asking for is probably quite a bit, but it's all going to come down to the S2 doesn't have mirror lock up and mirror slap is going to kill this for me for faster shutter speeds (1/15-1/350). The real slow shutter speeds, I can go with bulb and use a card like Lightwrangler mentioned, but that limits what I'm going to be able to shoot to real deep space stuff that I'm probably not going to get into for quite a while.

Keep them ideas rolling though!

[Tom Nolle]

I'm sorry, Swampy, I missed the first part of the thread with the shutter speed noted!

If you had your tracking motors, you could do the opposite tack, which is to set a relatively long exposure. Even if you get mirror slap, the jitter period would be short in relation to the exposure overall, and you probably would not be able to see it in the results.

Tom

[Swampy]

Unfortunalty, I don't have much choice on the shutter speed for closer items like the moon. This is a fixed aperture.

After playing around a little now, I do have two problems. Mirror Slap, and as Dave mentioned, the tripod. The Tripod isn't as steady as I believed it to be. It's solid for up and down, but it does twist easily which is giving me grief. I put the legs all the way down and it alleviates some of this issue, but it does still exist enough to hose my shots. Amazing that the mirror slap is great enough to twist a tripod of this size.

[sandman]

Could'nt you put it on grass so that the spikes bite, ,and/or shorten the legs to stablize it a bit more

[Swampy]

yeah, I could, but I know the legs are biting, it's above that and below the head that's twisting. :(


Shortening the legs helped, but not enough.

[sandman]

i've been a truck driver now for nearly 40 yrs ,and in that time i've cobbled together many weird and wonderful things to get me out of holes. If you reckon it's twisting below the head, then you'll need to get additional support about 6'' down, have you got a small engineering works nearby who could knock you out one?, a small three legged screw on devise should do it. but to make sure it is that ,why not loan a sturdier tripod just to test?

[Swampy]

yeah, I'm in Southern California. We got everything here Sandman. I mean, heck, we got Holleywood, so there's all kinds of modification places out here. hahaha.

Hmm. After getting home from a long dinner party, I was looking up and saw a really bright star, thought it was mars, but when I got all pointed, it ended up being jupiter! That was pretty cool. Never had anything that would allow me to see the big eye on jupiter. I would have taken a picture, but that was at max magnification and it wouldn't have even come out.

I did, however, repoint back to the moon, and with the legs shortened all the way down (Yeah, I'm on my knees in the middle of my street with this thing now), I did manage to get a semi decent shot of the moon. It was brighter tonight and I shot in RAW so I could brighten it up afterwards with a faster shutterspeed (1/180 was the best I was able to manage).

Anyway, here's the shot from last night. Think I'll go find a welder and weld the legs solid. hahaha.

Wonder if my Bogen will hold this thing? LOL

[Claude Ollieuz]

Swampy,
Just three ideas:
1: If you can rotate the S2 mount relative to the Celestron, try various positions on a same point-object. Its images, magnified sufficiently in PS, would show a directional motion blur the amplitude of which could be dependant on the position of the S2.This relies on the assumption the whole structure has a main vibration plane. If the mirror travel path can be brought perpendicular to that plane, the blur would be reduced.

2.If you have a monopod, screw it to the S2 and rest it on the ground or on the tripod platform.

3.If at all possible, insert a ND filter(gelatine cut to size?) in the imtermediary mount and set exposure to be about 3X the shake your observed.

With kind regards and fingers crossed.

[Swampy]

I told everyone I wouldn't use anything I learned in high school! Ha!

Claude. THANK YOU. Vibration plane will probably help quite a bit! I'll also try the monopod idea as well, or even a second tripod all together. My Bogen is pretty versatile. This will work for the moon, but Mars, I'm sure it won't as I'll have motors turning the whole top half to track it during exposure. Although, with a long (a few seconds to 10 minutes) exposure, I won't worry about mirror slap as I'll use a black card during an open shutter.

Appreciate the ideas! I'll let you guys know probably tomorrow after I take some tonight.

[sandman]

i got the impression you think i'm joking ,or possibly mad, i'm not , i was thinking about a portable brace that you could dismantle and take on any job ,where you might need extra stablizeation

You sandwich it betwwen the leg struts of the tripod legs, tighten the inner nut to lock it, then tension it on the outside nut , make it out of aluminium ,put in a bag and you take it with you.

I could make this in a morning ,in my workshop , if i had the ally.
maybe i am nuts ,but we're known for eccentric inventions, look at the umbrella top hat, who would have thought that would catch on ?, (thats a brit joke),
See my diagram.

[dhphy]

Swampy, I am serious here. Thinking about this problem it is quite likely that mirror slap is the problem, although I do think that tripod isn't sbustantial enough.
It looks like there is some kind of extension tube that connects the lens to the camera. If so and it is not too expensive it might be worth investigating the possibilty of fitting a mechanical leaf shutter in the middle of the tube.
Dave

[Tom V]

I would suggest a secondary brace, possibly even a 2nd secondary brace. I like the idea of a monopod with adjustable head for the camera, and an adjustable Bogen arm for the front of the lens.

While your tripod may be sturdy enough, I would guess that all that vibration caused by the mirror and shutter are still going to make tiny but noticeable vibrations in the mass of lens and camera. The tripod head looks like one weak spot, and the extension tube (whatever it is between the camera and the scope) looks like the other weak link. I would work on bracing them.

Naturally, all that stuff will require you to aim and brace the camera before the moon enters the frame.

****

When I shot jewelry for catalogs, we shot an entire page at a time, life size on 11x14 film. I used a gigantic view camera with a 24" lens, and 48" of bellows. The camera was mounted on a SUPER HEAVY DUTY bi-post camera stand which we used a ladder to climb onto, and could fully support my weight. When the product was positioned correctly, the film was loaded, the darkslide pulled, the lights were turned off, and the shutter opened. I then waited 30 seconds for the mass to stop vibrating. Then I would pop the flash units to build up a sufficient exposure.

The point is, even with such a sturdy camera stand, all that mass still had a vibration to it that took a while to subside.The more mass there is, the more the vibration lingered. If I shot too early, I would end up with double or ghosted images.

Shooting a bracket of film took quite a while. It was tedious work that caused a lot of photographers to call in sick.

[Ben]

Swampy,

A shot in the dark, I don`t think your problem is mirror slap.
I think it has to do with the optical quality of the telescope lens.
(Not that I`m an optical expert, but I do work with other optics allot)

I`ve had a similar experience with a lens once, with the naked eye, no problem, but as soon as one starts to close in on a subject a eary glow started to appear arount the subject edges.

Another example is non coated lenses and optical coated lenses.
If one looks at objects at night, the one gives a white glow and the coated one is clear.

A couple of suggestions:
- Ask a friend with an S2 to come and take a PIC and compare.
- Try and hook up a high quality DV cam and look at the results.
- Try and find another telescope and try the same thing....

I now these things are expensive, but it could have a flaw ?

Then again the S2 has some sort of mask attached to the mirror, that is absent in the F80, that is why the S2 mirror sound is much louder that the film based F80....

[Swampy]

It's not the optics. I know it's mirror slap because I can see the scope shake after the shutter releases. I set the selftimer to 30 seconds. I keep looking through the viewfinder, it's steady as a rock, when the shutter releases, bam. The scope is shaking.

It's gotten better with some additional weights and the tracking motors though.

Thanks

[Wichita Wayne]

I really do think your tripod is not up to the task, but you might try using two other tripods loaded with bags of sand or shot. Mount slide projector platforms on the two other tripods so you have a good flat surface. Then raise one of the tripods with the bag up to support the front of the lens and the other tripod up to support the camera. I suspect that the real problem is the oscillation that is started by the mirror slap and the heavy bags on the tripods should help dampen the oscillation. You might also drape some bags over the main tripod.

[Swampy]

I'm getting a new tripod for it, hopefully by Friday, but most likely next week. I can say I've done it now (lining up the polar axis) and what not, it's not fun. I want this to be fun, so I'm dumping the current tripod and tracking motors and getting the GPS Tripod. Orginal way to set it up - 30-40 minutes. GPS way - 10 minutes. We'll see what the new tripod does.