Unable to replicate observed detail in photograph

[Matt Hayden]

Hello!

What with all this locking down business and home schooling my ten year old son, I have dusted off my TAL-1 and created a slightly less than ideal setup in his room. The westward facing window has been providing great views of the moon and venus over the past week. Obviously doing this indoors is not great (the floor is pretty solid, as is the TAL stand!) but it does mean we get to use the scope every evening, rather than going through the process of carrying the whole rig outside every day.

I have a T-mount converter for my old-ish Pentax k-M DSLR, but have quite disappointing results with the camera, when compared to the observed image using the eye. The eyeball view is nothing less than banging - crystal clear detail with a 25mm eyepiece, strong contrast - it's spectacular. I add the camera with an eyepiece inside a tube, and can't replicate the same result, or anything like it. It's OK, but not good enough.

I've cleaned the eyepiece today and collimated the scope. The primary mirror looks fine other than a couple of tiny dust particles, no scratches or weirdness on the coating. The camera is working pretty well as far as I can tell. Apart from a little clumsy-ness with the adjustments, the clarity in the eyepiece suggests it's all working fairly well. Photo attached of best result from last night.

My question is: is this a focusing issue or some sort of aberration? Should I expect focusing to be difficult in the camera eyepiece? What's going on?! Does anyone have any other tips I can try to get this working better?

[Laurin Dave]

Maybe focus or camera shake from shutter release if you don't use a remote or from the mirror rising... does it have mirror lock and  do you use a remote to release the shutter?   Also you want the shortest exposure you can get to freeze the seeing...   Have you thought about taking a video (DSLR or smartphone) and trying the "lucky imaging" technique? 

[Stu]

Focusing is always tricky and critical to good results. It may also be a little vibration, how are you triggering the shutter, can you use a remote release, or even just the timer to let it settle before the shutter opens?

I normally just use my smartphone but on that I often zoom in digitally on the image to focus as sharply as possible, you could do this if your DSLR has live view?

It could also just be the seeing conditions, if you take plenty of shots, you will normally find one or two which are sharper having caught a moment of better seeing.

Keep at it, I sure you will get some better results with practise. 👍👍

[CraigT82]

If you've got a decent smartphone I'd have a go with that. Even just holding it up to the eyepieve can produce some really nice results, maybe even better than your DSLR

 

 

[Stu]

5 minutes ago, CraigT82 said:

If you've got a decent smartphone I'd have a go with that. Even just holding it up to the eyepieve can produce some really nice results, maybe even better than your DSLR

 

 

I do agree with this, particularly if you have a new smartphone vs an old DSLR. Sensor technology is progressing so fast that each iteration of phones has better cameras on them, lower noise and better low light performance.

[Matt Hayden]

Thanks for the replies - I do have the shutter on a 12 second timer, and it's clear from looking through the eyepiece that all perceptible vibration settles down after 3-4 seconds, then we hold our breaths!

It did occur to me that the torque of the mirror moving might be twisting the camera slightly so I've gone to great lengths to stiffen up the interfaces of the gear, it's all very solid now and the TAL stand is rock solid and heavy already. I don't think this is a major factor though, as the focus through the eyepiece looks similar to the final exposure. Shutter is 1/30s at 800ISO. Camera is oldish and the sensor a little noisy, particularly at higher ISO, but again I don't think this is a major factor.

Don't have live view through the DSLR, that's an interesting option - indeed I'm sure my smartphone sensor is waaaay better than my camera. I'm having a real problem getting the smartphone lined up properly and still - how do you do this?! Looked into getting a holder but not sure how well they would perform as they're quite cheap, and cheap looking. Anybody have experience of these or do you just hold it there and hope for the best?

'Lucky Imaging' is new to me - will give this a go. I do have an old Phillips SPC900 webcam and converter that I have miraculously persuaded Win10 to talk to, only to find that it's really hopeless! Amazing how things have moved on since I last dabbled with this about ten years ago!

Do keep the ideas coming; just to re-emphasise, my view with the eye through the 'scope is about 100 times better than the photo 👁️👌

[Stu]

3 minutes ago, Matt Hayden said:

Anybody have experience of these or do you just hold it there and hope for the best?

I’ve used a few, most of them work ok, although it depends to some degree on the shape and size of the eyepiece. Straight sided ones work best.

I like the Orion SteadyPix EZ Pro, works well, but also the Celestron NeXYZ has plenty of adjustment although can be less rigid. Even the very cheap ones can be fine. I wrote up some reviews of them here which may be useful:

http://www.waltonastrogroup.co.uk/equipment-reviews.html

 

[Ships and Stars]

I just took these tonight by quickly holding my average Motorola G6 smartphone up to the eyepiece - SW 300p flextube (non-GOTO) with APM 9mm 100deg at c.175x magnification.

It utterly blows away what I could ever manage with a full-frame 36mp Nikon D810 and 600mm tele lens with 1.4x teleconverter on a tripod with remote release.

I find the moon tricky to photograph with a DSLR for some reason, very rare for me to really get a tack sharp photo over the years, and it wasn't for lack of trying, even tried my DSLR on a Baader 36mm using eyepiece projection and the mobile phone snaps are better. 

Edited April 1, 2020 by Ships and Stars

[JeremyS]

14 hours ago, Ships and Stars said:

I just took these tonight by quickly holding my average Motorola G6 smartphone up to the eyepiece - SW 300p flextube (non-GOTO) with APM 9mm 100deg at c.175x magnification.

Impressive with just a phone!

[Ships and Stars]

11 minutes ago, JeremyS said:

Impressive with just a phone!

Thanks, after this I may invest in a phone holder now for the eyepiece. I was using a 100degree APM which helped a lot. I tried a plossl and it didn't work very well, phone placement is much easier (perhaps not surprisingly) with uwa EPs. Fainter stuff of course will require a DSLR or dedicated astro camera, a route I might go down someday.

[Stu]

Just now, Ships and Stars said:

Thanks, after this I may invest in a phone holder now for the eyepiece. I was using a 100degree APM which helped a lot. I tried a plossl and it didn't work very well, phone placement is much easier (perhaps not surprisingly) with uwa EPs. Fainter stuff of course will require a DSLR or dedicated astro camera, a route I might go down someday.

You may struggle getting a phone holder to fit a large 2” eyepiece.

[Matt Hayden]

First chance to try new tricks tonight and I definitely have an improvement so thanks to you all for the encouragement and advice - I will be trying to continue this upward tragectory!

Taken on my Samsung S6 through a 25mm eyepiece. Also had a look at venus this evening and this looks way better after a really careful colimation. Next I guess I'm going to have to bite the bullet and drag the rig outside, as of course the seeing is messy from inside. Now if I could only persuade the fam to let me have that shed we don't really use that much.....

Next things to fix: eyepiece image viewed with the eye is still way crispier than I'm getting on film, so there's more detail available. Disc looks distorted to me, a holder might sort this and also make the whole process a bit less frantic. Image attached has been worked quite a bit with Lightroom and I'd like to reduce this input. Must clean the optics as well. Love moonwatching though - so satisfying, especially over a series of nights.

 

Edited April 6, 2020 by Matt Hayden