duct tape!

[goldblade1983]

Hi all

Looking for some advice relating to Sony alpha 300.

Going to be upgrading some of my equipment soon to try and 'develop' (pardon the pun) my astrophotography. I think I'm going to get a Williams gt81.

Here's the thing. The Sony alpha 300 doesn't have a mirror lock function and there's no firmware upgrade available for it. I've used it for photos before and haven't noticed any vibration but shots to date have been relatively short exposures (30 seconds) and not a huge amount of data (20 mins or so)

So I'm thinking for a solution which doesn't involve getting a new camera for now. The only two i can think of are 1) remove the mirror which isn't helpful for using the camera for terrestrial or use duct tape to hold the mirror up. Unfortunately the latter won't allow me to use the viewfinder or liveview and so focusing would need to be completed first. The last alternative is to do nothing and see how i get on and hope vibrations are minimal? (I'm not prepared to stand in front of scope with a cover for hours on end!)

Brian

[David Smith]

I would go with the last suggestion - if it's a problem then address it. I would have concerns about taping the mirror in the up position, can'y imagine it will do the internal mechanisms much good but may be wrong.

[Davey-T]

If you're doing long exposures you can hold your hat in front of the lens/scope briefly to let it settle. Why would you have to stand there for hours ?

Dave

[PeterCPC]

You could try anti-vibration pads under the tripod legs. 

Peter

[jgs001]

Brian, with the long exposures, you won't notice anything, especially if you're not noticing anything at 30s. I used to always use mirror lockup, then started using APT to control my camera. Since then, as it uses liveview on the 450d to simulate mirror lock up and that causes heat problems, I've not bothered, and I do not see any problems... 

[Alien 13]

I agree that under some circumstances mirror slap can be seen on an image usually if there is a bright star in the FOV and you are running with a high ISO, if your camera can shoot in liveview mode you can try that but from memory i think you need to put a delay into the timer sequence to allow the camera to get back into live view mode after each sub.

The downside is that the sensor is nearly allways on so heats up if you do ever get a camera with a dedicated mirror lockup function it does again require the timing sequence to include a delay i  do it by allwowing the camera to do the self shoot mode single shot with mirror lock up enabled then a timer to set the number and lengths of subs etc.

Alan

[Scott]

If there's no vibration at 30sec, increasing exposure time won't change anything.

Edit:- Or you could just read Johns post 

[Steve Ward]

Try using the self-timer , usually the mirror flips up first then the timer counts down before the shutter activates , this should give you a 2 second settling down slot to eliminate vibrations , or if that's not enough then set to 10 seconds.

[goldblade1983]

Thanks all

Will keep going with it at moment. I'm fairly new to astrophotography and to date i have been imaging through 8 inch lx90. Going to be getting wo gt81 and so just thinking about what things may or may not go wrong.

The camera doesn't have mlu facility even if on timer - Sony removed the feature and no firmware upgrades available despite lots of people moaning about it. Also live view doesn't work either as Sony live view sensor (for camera screen) is actually above mirror and doesn't use main camera sensor. And there is no live view streaming to computer.

Quite frustrating but there it is!

[Alien 13]

I think you should be ok i have seen it with fast ISO but mainly with camera lenses it has not been an issue with my scope (i think the extra mass quickly dampens any vibs).

Alan

[wxsatuser]

Don't use it here.

Tried the mlu but on a solid mount I cannot see any difference without it.

[sgazer]

as mentioned above, any blur is caused when the mirror moves at the start of the exposure, so it makes no difference whether it's 30s or 30mins. You'll only notice blur if there's a bright enough object to be sufficiently exposed during the period of shake eg. a bright star. It will of course get worse with longer focal length, but not longer exposure. In fact, chances are you will be imaging even darker objects using the longer exposure, so will be less of an issue than at short exposure.