Tripod mounting long lenses and vibration problems.
 

Having swapped my 80-200 zoom for an old AIS manual focus 400mm lens. sorting possible tripod mounted vibration problems was todays mission. I had read Bjørn Rørslett's review, and although he gives it a good score for image quality, he does note that as it is a light lens, 1200 grams, it is prone to vibration when tripod mounted. As for image quality I was very impressed with performance when used on a monopod yesterday but had concerns over the tripod mounting bit.

With dismal light again today I decided to measure ( clock it ), when mounted on the Manfrotto sliding plate for the 501 fluid head. This was done by clamping it in a machine vice on the milling table so a very solid clamp. Although the lens has a good clamshell collar the pliable rubber on the sliding mounting plate allowed for a deflection of 50 thousands of an inch. I made a intermediate plate of significantly greater surface area that could be mounted on the lens then screwed using 2 screws to the sliding plate so compressing the rubber better and over a greater area. Back in the machine vice and the set up was reclocked. The maximum deflection under a load has been reduced from 50 to 2 thousands of an inch. The plate has effectively added 500grams of mass to the lens. Hopefully this will counter vibration problems noted by Bjørn. The clocks do not register mirror up or shutter movement, but mirror down gives about a thou of movement. Still the shutter has closed then so it should not be a problem.

When we get some decent light I will give it a proper test.

I knew Rob would have a good laugh, so I took a pic of the final clocking and have attached it.

Don

LOL - Yes Don I love it. I'll be interested in your findings.

Hi Don

It's interesting to read your very methodical and engineering approach to the problem of vibration in long lenses.

Mine is more Heath Robinson, my longest lens is the AFS 300 f4, which I use in conjunction with the TC 1.7. The lens collar on that lens is useless, so much so that I almost gave up on it, just could not get a sharp image due to vibration.

I bought a Manfrotto 501head and the images improved somewhat but were still a bit fluffy.

I read one thread on the net, where the responder had lodged a canister from an asthma inhaler between the collar foot and the lens barrel and had found a marked improvement in the quality of his images.

I improvised using a plastic cork from a wine bottle, around which I super glued a covering of 3mm thick rubber sheet, cut to size, and with that lodged in the gap between the barrel and foot plus the 501 have been very happy with the results.

Best of luck with your lens.

Brian

I have read somewhere that putting a bean bag on top of the lens when mounted on a tripod helps a lot with vibrations although I have not tried this myself.

Brian,

I found as much of the problem in the spongy nature of the rubber on the sliding foot hence the longer base I made.

I will take some close ups of the mount and test pics using Robs bar code tests. Trouble is this lens has turned into a cloud magnate. :( :(

I have managed to sneak a moon shot in the dark but have never managed more than 2 shots before the cloud mysteriously appears.:rolleyes:

A bean bag would certainly help as Roy has suggested but that does require the lens to be at less than 45 deg. I did a test with a bag of sunflower kernals and another with a sheet of lead ( same thing but not so handling friendly ) and it did absorb vibrations.

Don

Not a good day for the bar code test even though it is fairly bright. I have just put it on hold as windspeed is 24mph gusting 39mph. :(

Don

All amateur astronomers have this problem, especially if their telescope is new:D

Dave

Brian,

A bit off track but out of personal interest, and for the possible benefit of others, have you had an opportunity to try the 300 f4 AFS on a monopod for comparison. I am wondering if because in that situation you are holding the lens and camera, any vibrations would be to a degree damped.

Neat idea to overcome your problem. Your foot is obviouly of greater area than mine to overcome the spongy rubber on the sliding foot. When I see a suitable bit of thin cork I will use that to replace the rubber on mine.

Don

Extremely sturdy-looking tripod mount, Don, but looks a bit heavy to lug around and the dials are confusing.

The dials are to test deflection in various planes. The lens itself is very light, 1200gms so even with a bit of weight added it does not compare with what I would really like but could not afford, the f3.5 version at 2.8kg. I might baulk a bit at the f2.8 as thats 5.15kg.

In this case weight = image sharpness when on a tripod. For monopod use the additional foot I have made is not necessary as any vibration is damped by the weight of the hand on top of the lens barrel as tested by my gallery Starling pic.

Note I also added a bit of foam to the barrel for hand comfort in the cold. :D

Don

Don

Only use the monopod with the 70-200 f2.8 and 1.7 as my ability to keep the 300 rig steady is suspect due to old age ( the 70-200 +1.7 is fast at f4 but the same set up with the 300 is f6.7 and need at least 1/500 to get a clean sharp shot).

Since I bought the Magfibre tripod, I find even with the 501 head I have no difficulty carrying it around and as you know the 501 has a very convenient handle that rests over the shoulder for easy lugging

Brian.

Brian,

Quite understand that. I would be a good test of a VR system also. :D

501 is super job for this lens range as you have discovered.

When you get an opportunity it would be interesting if you could post a 3/4 view of the lens mount so I can get some idea of the foot width and position of the fixing point. I have yet to find a decent sized pic of this on the net and I am 50+ miles from anyone that stocks it.

Don

Don

Here are a couple of shots - as I said - very Heath Robinson - but it works:)

Thanks Brian,

From the pics I can see simple but effective. I am really quite surprised by the smallness of the collar locking screw head in comparison with my AIS 400mm. I would guess quite hard to really screw it down if you have large fingers.

I will post a similar angle or comparison.

Going to be a busy day as I am doing some other stuff to help Lello.

I am interested in your setup as I had a play with various Sigma at Focus and also this lens at the Nikon stand. Unfortunately it did not have the foot, and as I suggested that this may be the next lens for him to save for as I was impressed with the glass, I want to be happy with that recommendation.

Thanks again

Don

Here are my comparison shots with the 400mm that show the clamping ring/mounting foot.

Don

Conditions not the best for this Rob, but from the forecast they are getting worse for the week ahead, so I have now done the vibration on a tripod test for the 400mm lens.

We back onto open fields, and with Marham 5 1/4 miles away in a straight line soI have attatched a screen grab of Met Office recorded conditions at Marham.
I had to weigh the table used for the test subject down with my 10kg rotary table due to the wind induced movement. The grey card backdrop, even in a machine vice kept being blown sideways.

As the test was to check if I had solved the issue of lens vibrations as noted in Bjørn Rørslett's review a 5kg weight was suspended from the tripod to minimise the effect of the wind.

Camera : D2X, with cable release used but NOT mirror lock. ISO 100, aperture f7.1, shutter speed 1/125 sec.
Lens : Nikon 400mm f5.6 IFED AIS
Tripod : Slik proffesional.
Subject distance : 20 feet.

Pics attatched.

Screen grab of Marhams wind state during the test.
A full frame, and two levels of crop. These do contain the exif so there is some form of independant confirmation from the time stamp that the crops are from the posted full frame.

So from my point of view making of the intermediate lens foot is a success.

Don

Looking good Don.

Have you tried the same setup without your improvements to make a direct image comparison ?

What me post a fuzzy image. :D :D :D

For the record I will do that Rob. As the new foot has taken deflection down from 50mm to 2mm, mainly counteracting the relatively small lens mount footprint on the softish rubber on the sliding plate, I would expect a lot worse performance.

Don

Rob I did suspect something like this after my clocking exercise, but when you see it in the flesh so as to speak its quite a shock. :eek:

The light was getting a bit poor and it was spitting with rain so this is not in the same conditions and I will wait for a decent day before I do a side by side. So this is a taster of the result I expect.

Ignore the red colour showing through the bar code label, its the red electrical tape sticking it in position showing through. :D

As before there is a full frame, crop 1, a more severe crop in crop 2, a 100% crop where the bounce really shows, and a side by side with the earlier test.

Whether lens vibration is a contributory factor to the general softness seen here is anybodys guess but the Slik tripod with 501 head is quite a heavy beast. The size of the lens footprint on the rubber of the sliding foot is I feel the major factor. When clocking it, I found that you cannot significantly reduce deflection no matter how tight you turn the locking screw. Hence I decided on increasing that footprint with the sub base.

Don

Don, I did much the same around the hood of my Tamron 300mm f/2.8...I wrapped around some neoprene, cut it to the right length, took it back off again and superglued the edge to make a tube....it very slightly stretches over the hood outer, enough to stay in place without using any tape or bands around the lens itself....
Yes, it makes a big difference, particularly the other night in the cold....

All my lenses have that uncanny ability! LOL