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06-08-2008, 03:14 PM - 1 Like   #1
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Tips using big mirror lenses like C5

The greater the magnification the more exacting the use. Here are some tips that work well for me. Many supplied by dad who has actually ground telescope mirrors for a hobby.

1. Can't have too big or sturdy a tripod. C5 is approx 25X with camera. Tripod should settle down in 3 seconds are less when tapped lightly. Don't shoot off deck and don't move around while camera is shooting. Camera strap can't be flopping in the wind. Use quick release strap and remove it.

2. Vibration must be kept to a minimum. With K10/20D use 3 sec mirror lockup with wireless remote. Gotta love that rear mounted remote sensor.

3. Consider hanging weight from tripod to increase mass. This could be a milk jug full of water or a home made bean bag on top of lens. Also hanging the camera bag can help.

4. Make sure lens is clean optically. Remember clean in straight "spokes" from center to edge. Do not leave back of lens open to the elements! It is hollow. Dirt that enters rear can't be cleaned out without disassembling lens! Some people will put a high quality UV filter between back of lens and T adapter tube to "seal" the system to dust.

5. Lens shade is a must with large element lenses. You will increase contrast a lot. Also slows dew from forming for night time astronomy.

6. Be careful with lens. No shakes or bumps. It is possible to knock a mirror out of alignment. This can be adjusted by using the screws hidden under the front obstruction. This should not be done unless you know how. It is tedious and must be done while observing points of light (stars are great).

7. Old timers will focus the moving mirror all the way back for moving and storage. This parks it in a stronger position. Pia to me. Lots of turns to get back to normal focusing range.

8. Find that the Pentax magnifying eye cup helps with focus. Also use the Oly varimagni finder for higher mag.

9. C5 tube is solid - doesn't turn to focus. Uses a back knob that is like a caliper. So smooth. Since tube is solid, I often put a white sheet of typing paper around it to reduce day time heat. Also will make a camo one for skittish birds. C5 is strong enough (1250mm) that most animals don't mind you. C90 tube turns to focus so this tweak may not work as well if at all.

10. Long lenses are very much affected by temperature differences. It takes time for the lens to settle down and offer its sharpest performance. Carbon tubes help but the actual glass and mirrors also change and must have time to do so.

11. Atmosphere affects quality. You can see it "boiling" thru lens on a hot day. Shooting out of warm house into cool air or vice versa is bad. Shooting over asphalt or concrete is bad. Shooting over grass or water is good.

12. Check tripod mount where it attaches to lens. Have seen these get loose with time (especially C90 & C5). Can't have play in it. Don't go crazy and over tighten.

13. Put tripod as low to ground as semi-comfortable. It will shake less if you dont use extra leg extension or center column.

14. Shoot moon when it is higher overhead- less atmoshere. It will be sharper.

15. For moon shots set lens outside for an hour before shooting. Gives lens better chance to adjust to temperature. Will be sharper.

16. If tripod has spikes sink them hard into the ground. Ground helps absorb vibration.

17. If shooting jpeg set contrast higher in camera. Might also want to do sharpening - though I prefer to do that in computer.

18. If tripod doesn't have leg braces consider making some out of light chain. Just go from leg to leg. Can attackh with hose clamps. Not pretty.

19. Try to shoot decent shutter speed since we are moving. Wouldn't want less than 1/60 sec if possible. Would rather rise iso. Not over 800.

20. Recheck lens focus. It can change with time. Also use the zoom function on camera lcd to check focus of shots.

21. Adding a plate or brace between lens and camera body can help stop vibration or slop between them. Haven't found this a problem with C5 or larger mirrors. Seems to help C90 users.

22. For tripods that are still twitchy you can also mount a monopod to the camera body for extra stability. A little ingenuity could make it clamp to the tripod leg. Manfrotto makes a good clamp for this. This will slow down pointing the lens.

23. A finder scope is helpful for aiming the lens. When you get into the 1000mm range it is hard to figure out what you are pointed at. A finder scope that is properly aligned will speed up subject acquisition considerably.

24. A small battery powered blow dryer can be used to "clear" the inevitable dew that occurs at night when doing astronomical shots. Lens shade also helps.

Hope these tips help. Shooting high magnification takes time and practice.
Have fun with these long lenses.
thanks
barondla


Last edited by barondla; 06-17-2008 at 05:51 AM.
06-08-2008, 07:31 PM   #2
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Thanks for the info, will be useful when the celestron arrives
06-09-2008, 05:29 PM   #3
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What;s your definition of "big". I've noticed a 1000mm mirror lens up for sale here, is that "big"? Thought it may be worth a play if I can get it cheap enough.
06-09-2008, 06:01 PM   #4
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with mirror lenses, 500mm and up will qualify in my book, althought there are those that can shoot mirrors handheld. they are subject to vibration from the action of 'mirror up', tripod shake, etc. the tips listed in first post should get me some better quality moon shots (if it ever stops raining in chicago). i'm awaiting a 1250mm mirror to arrive and it will definitely be vibration prone. if you can get a 1000 mirror lens for just a few $'s, i'd recommend it. mirrors are quirky, but i'm having a great time with the 500mm tokina i picked up.

mirror lens post on the tokina: https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/27457-tokina-f8-mirror-lens.html


Last edited by ivoire; 06-09-2008 at 06:08 PM.
06-09-2008, 08:10 PM   #5
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Would consider 1000mm and up as big. Have Quantaray 300 5.6, Celestron C5 1250mm f10, Questar 3.5" 1400mm f14 or f16 don't remember, Meade 2010 10" scope. Between dad and I, have also had Tamron 500 ( the first one unfortunately. It was only okay IQ wise. Thanks to Ben I know why now), Olympus 500 f8 (probably the best small mirror I ever shot), Sigma 600 f8, a Dynamax 8", and probably a few others I have forgotten.
Really gets fun at about 800mm and above. A whole nother ball game! C5 moon image fills the frame on apsc camera. Just a little room to spare which you will need because of earth rotation and movement thru the frame (unless you are tracking with motorized mount).
Buy the 1000mm and play with it. If you don't like it resell it. Just give the lens a chance. Any big lens requires work! Don't put it on a $29 tripod and expect anything. Big lenses are fun. As much fun as the 10-17 fisheye zoom.
thanks
barondla

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06-10-2008, 05:16 PM   #6
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No good for sports shooting then!
06-10-2008, 06:21 PM   #7
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QuoteOriginally posted by barondla Quote
Buy the 1000mm and play with it. If you don't like it resell it. Just give the lens a chance. Any big lens requires work! Don't put it on a $29 tripod and expect anything. Big lenses are fun. As much fun as the 10-17 fisheye zoom.
thanks
barondla

Check out POINT & SHOOT CONTEST #7 in P&S forum. Winners have been selected.
I wholly agree.

my summer project is to dust off my celestron C90 1000mm F11

I have only done test shots since I went digital
06-12-2008, 10:32 AM   #8
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This beast arrived and will be howling at the moon tonite. The previous tips will come in very handy as this thing shakes like a rattlers tail! Its an older celestron c5 1250mm mirror telescope/lens using a T mount to K mount adapter. It has a few minor exterior scars but the glass and mirrors look great. You'll have to excuse me while i go out and fill some sandbags for tonites festivities. Hope to have pics to post later tonite.


Last edited by ivoire; 04-12-2009 at 10:29 AM.
06-12-2008, 11:04 AM   #9
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Thanks for all the info here, I've been looking at one of these to play around with but thought they would likely be a waste of money and time.

I look forward to seeing more pics from these monsters!
06-12-2008, 11:09 AM   #10
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QuoteOriginally posted by LSR Quote
Thanks for all the info here, I've been looking at one of these to play around with but thought they would likely be a waste of money and time.

I look forward to seeing more pics from these monsters!

HOLY MOSES THAT'S A HUGE LENS!

Phew. Sorry about that, I just couldn't contain myself
06-12-2008, 09:14 PM   #11
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QuoteOriginally posted by LSR Quote
Thanks for all the info here, I've been looking at one of these to play around with but thought they would likely be a waste of money and time.

I look forward to seeing more pics from these monsters!
Heres the first from the celestron. will need a lot of practice. wind was gusting to 15 tonite, clouds blew in frequently, tripod shake, a real challenge. good practice for the upcoming fullmoon:

Last edited by ivoire; 04-12-2009 at 10:29 AM.
06-12-2008, 09:26 PM   #12
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Not bad at all !!!
06-12-2008, 09:33 PM   #13
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Ivoire:

Have fun shooting the full moon but bear in mind that it is the least photogenic phase. The sunlight is straight on and there is minimal shadow. Angled sunlight yield shadows that give much greater contrast and contour to the moon's surface.
06-13-2008, 06:02 AM   #14
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Nice looking lens ivorie. Good first moon shot. She can do better but it will take practice! Did I mention vibration? She can be twitchy. Don't let her be twitchy. Will add more tips to original list. Enjoy that lens! A beauty.
thanks
barondla

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06-13-2008, 06:54 AM   #15
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QuoteOriginally posted by barondla Quote
Nice looking lens ivorie. Good first moon shot. She can do better but it will take practice! Did I mention vibration? She can be twitchy. Don't let her be twitchy. Will add more tips to original list. Enjoy that lens! A beauty.
thanks
barondla

Check out POINT & SHOOT CONTEST 7 winners and enter #8 in P&S forums. Any camera type except slr. Any brand. Any subject.
Thanks everyone for your comments.

Barondla, twitchy is an understatement. Found it quite difficult to focus while it is having an epileptic fit. This will be a challenge. Am thinking a focus screen and larger eye cup may be in my future. Do you think a split focusing screen would be of any use? and does the Oly varimagni finder fit the K10-20D?

Last edited by ivoire; 06-13-2008 at 07:03 AM.
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