Topic: Canon 400mm lens with a 20d (Read 4417 times)

dandill · « **on:** August 27, 2005, 05:03:14 pm »

I would think, in general, yes, the more so with longer lenses. You could try two shots, one with MLU, one without, to see.

DLMST · « **Reply #1 on:** August 27, 2005, 08:24:29 pm »

Hi, so I probably should run some tests first before I go out on a critter shoot. I'd hate to mess up what potentially could be dandy shots.

Say, are there any problems I should be aware of when using mirror lock? (I haven't needed to use this feature before. I just got the 400mm lens.)

Thanks for all your help,
DLMST

Ray · « **Reply #2 on:** August 28, 2005, 04:49:17 am »

Quote

Hi, so I probably should run some tests first before I go out on a critter shoot. I'd hate to mess up what potentially could be dandy shots.

By all means do some tests but there's sometimes an unavodable variability out in the field. With MLU, tripod stability is crucial. If you haven't got a rock solid tripod then turning on the IS would probably serve more purpose than MLU.

You should wait at least 2 secs after flipping the mirror, before taking the shot. Waiting for the slightest breeze to abate before pressing the shutter button a second time can cause you to miss the moment.

I tend to think the benefits of MLU in practice are sometimes over-rated. I'm all in favour of better dampening and lower noise at high ISOs

.

DLMST · « **Reply #3 on:** August 28, 2005, 09:24:01 am »

Quote

I tend to think the benefits of MLU in practice are sometimes over-rated. I'm all in favour of better dampening and lower noise at high ISOs .

Hi, thanks everyone for all your helpful advice.

Assuming I'm focusing at distance (rather than near), about how fast would you suggest the shutterspeed needs to be to offset blur induced by the action of the mirror when mirror lock up is not enabled? How fast is fast enough with everything else being steady (sturdy tripod, no wind, etc.)? Effective focal length on the 20d is about 640mm with the 400mm f4 lens. I'm thinkin' 1/500'ish. Does that sound about right?

Lin Evans · « **Reply #4 on:** August 28, 2005, 10:46:34 pm »

Just a quick question. Why are you considering using a tripod with a stabilized 400mm lens? In general, unless hand holding is problematic because of physical strength issues, there is no need for a tripod to get really sharp images with such a combination. Even if you are somewhat disabled and need to support the weight, a monopod can be used with the IS enabled.

I shoot the 100-400L IS and the Sigma 80-400 OS with 1.4x teleconverters hand held and have yet to miss a shot due to camera shake. I really think using a tripod defeats the purpose of the stabilized lens. Also, even though the manual may tell you not to use a tripod with IS on, I've found that it works fine with IS enabled when mounted on a tripod. In fact, most of the newer model IS lenses have no tripod restrictions with IS enabled.

Lin

Jonathan Wienke · « **Reply #5 on:** August 29, 2005, 10:47:58 am »

For most images, the IS will be of more benefit than MLU. When there's any wind at all, the vibration from that source will be at least as significant as vibration from mirror slap. IS doesn't black out the viewfinder, and dampens all vibrations, not just those from mirror slap. There is no disadvantage to using IS, MLU, and a remote release together; doing so will yield the best results as long as the viewfinder blackout associated with MLU is not a problem.

DLMST · « **Reply #6 on:** August 27, 2005, 04:00:03 pm »

Hi there, I'm curious. Does the mirror movement of a 20d cause blur when using a 400mm lens (IS turned off on tripod) at slow shutter speeds?

Ray · « **Reply #7 on:** August 27, 2005, 08:17:48 pm »

Mirror slap always produces some blur at slow shutter speeds, typically between 2 secs and 1/60th, with the worst blur occurring at shutter speeds somewhere in between those two figures.

I think the question you're asking is, do the critical shutter speeds for MLU with telephoto lenses follow the 1/FL35mm rule?

I haven't found this to be the case, but there might be some slight tendency in that direction. For example, with a 50mm lens, no MLU and shutter speed of 1/60th there would probably be undetectable blur. Not worth bothering with.

However, the 400mm lens at 1/60th might produce a very small amount of blur due to mirror slap, but probably undetectable at 1/125th. At least this is what I have found with the 100-400 zoom.

It's difficult to be definitive about such matters because of other contributing factors to blur. Even though the camera is on a tripod, the slightest breeze might disguise or swamp any benefit from MLU. Also. the sharper the lens, the more noticeable will be the effect of mirror slap.

AJSJones · « **Reply #8 on:** August 27, 2005, 10:39:54 pm »

Not so much problems but there are two major ways of shooting with MLU

One is to use the self-timer, which locks the mirror up at the press of the shutter-release button, waits the (typically) 2 sec and then fires the shutter. 2 sec should usually be enough for the vibration from mirror slap to die down.

The other way is with a remote cable release. The first press locks the mirror up as before, but now you can wait as long as you like until you fire the shutter. Make sure the cable release is not able to move the camera. Wait at least 2 sec to let the vibrations die down. Then you can wait until the critter is in just the right place before you press again. With this, you don't have to predict by 2 sec but you have to pre-focus/meter and set the shot up ahead of time (AF and metering need the mirror) ....

DLMST · « **Reply #9 on:** August 28, 2005, 09:22:42 am »

Quote

I tend to think the benefits of MLU in practice are sometimes over-rated. I'm all in favour of better dampening and lower noise at high ISOs .

Hi, thanks everyone for all your helpful advice.

Assuming I'm focusing at distance (rather than near), about how fast would you suggest the shutterspeed needs to be to offset blur induced by the action of the mirror when mirror lock up is not enabled? How fast is fast enough with everything else being steady (sturdy tripod, no wind, etc.)? Effective focal length on the 20d is about 640mm with the 400mm f4 lens. I'm thinkin' 1/500'ish. Does that sound about right?

dandill · « **Reply #10 on:** August 28, 2005, 09:32:06 am »

How about setting your gear up, foucsed as you typilcally would like to use, and then do a series of the same shot varying iso (to keep f/stop fixed, if you wished) and shutter speed, without MLU, through the shutter speed range thought to be a potential problem, and then do the same series with MLU. You would then have a nice set of images to use as a guide to when MLU is needed for your setup.

Dan

DLMST · « **Reply #11 on:** August 28, 2005, 10:14:18 am »

Hey, that's a super idea! Then afterwards, I can view the enlarged images simultaneously and make my comparisons. I'm off to set up .................

DLMST · « **Reply #12 on:** August 29, 2005, 10:19:47 am »

Hi Lin, good question! I know what you mean. I just got the 400mm (and haven't gotten a monopod yet). I had already practiced with it handheld but was curious about all the "talk" I was reading about mirror flip causing blur. I already have a tripod and so was wanting to test it out with that setup and familiarize myself with it before I left for my trip. I'll be shooting for hours at a time so handholding it that long is sure to be a bit tiresome. I'm also thinking that as the lighting dims, slightly slower shutterspeeds may be needed (subject stationary) that are slower than IS and I can manage effectively handheld. I know I could use faster ISOs to offset this and probably will but I wanted to check alternatives out. Hence, the tripod idea. Anyway I needed to know whether or not MLU even was necessary. As it turns out, I ran tests and from what I could tell MLU isn't needed. Images without it enabled were crisp at slow shutterspeeds.

Thanks for letting me know about your experiences with IS lenses. I'm delighted to hear that they've been so great! This is my first IS lens and I'm really excited to use it.

DLMST · « **Reply #13 on:** August 29, 2005, 11:22:49 am »

Hi Jonathan, IS certainly is amazing! Thank you for your tip.

Author Topic: Canon 400mm lens with a 20d (Read 4417 times)